ORCID Profile
0000-0002-9746-8771
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Publisher: Elsevier BV
Date: 2006
DOI: 10.1016/J.BIOPSYCHO.2005.02.003
Abstract: Increasing the emotionality of target material often facilitates memory performance which may be linked to the liberation of glucose. Conversely, increasing mental effort leads to reduced performance and measurable falls in blood glucose. A 2 x 2, parallel groups experiment examined these two phenomena directly by assessing blood glucose levels and memory for neutral and emotional word lists, both with and without a secondary task. Co-performing the secondary task significantly reduced blood glucose in the neutral word condition only and resulted in a global reduction of memory performance in both neutral and emotional word conditions. Processing emotional material resulted in significantly raised blood glucose levels, however, there was no advantage for memory of emotional words. A follow-up study confirmed that the emotionality manipulation was effective. We conclude that there exists a clear relationship between reduced blood glucose and impaired memory performance during periods of mental effort. However, the relationship between physiological and cognitive processes associated with processing emotional material are more complex.
Publisher: Informa UK Limited
Date: 23-02-2005
DOI: 10.1080/13803390490515450
Abstract: Forty elderly patients with asthma or chronic obstructive pulmonary disorder (COPD) were compared to a comparison group of forty age-matched healthy volunteers on a range of measures of cognitive performance, and levels of arterial haemoglobin oxygen saturation recorded. Members of the patient group were found to have significantly lower oxygen saturation compared to the comparison group, and performed significantly poorer on tests of delayed word recall and serial subtractions, but not on other tasks. Correlational analysis between participants' oxygen saturation levels and test scores across the whole s le indicated significant positive relationships existed for the digit symbol substitution and serial subtractions tasks. The results are discussed in terms of cerebral oxygen delivery, glucose metabolism, age related cognitive decline, and relative task demands.
Publisher: MDPI AG
Date: 09-06-2021
Abstract: Background: Unexplained fatigue is a common complaint. When underlying disease causes have been eliminated, lifestyle measures and supplementation can be indicated. Elaborating on clinical findings that G115®, a dry extract from the root of Panax ginseng, combined with vitamins and minerals could alleviate fatigue, this open label study aimed at assessing its effect on perceived fatigue and energy. Methods: Healthy adults self-reporting fatigue (n = 103) completed the Multidimensional Fatigue Inventory questionnaire. They rated their perceptions of mental and physical fatigue, energy, performance, and stress at baseline and 15, 30, 60 and 90 days after a daily intake of 40 mg G115® formulated with vitamins and minerals. Results: Compared with baseline values, mean self-perception of general fatigue was reduced by −7.55 units [95% CI: −8.44 −6.66] (−41.8%, p 0.0001) at 90 days. All assessed perception ratings (mental and physical fatigue, reduced activity and motivation, performance, and stress) were significantly and steadily improved from two weeks after supplementation up to study’s end. Overall satisfaction with the ability of the product to reduce fatigue reached 85% at Day 90. Conclusion: Daily intake with G115® extract formulated with vitamins and minerals suggests an improvement of self-perception of fatigue and energy in a fatigued adult population.
Publisher: SAGE Publications
Date: 20-09-2005
Abstract: In recent years working memory de.cits have been reported in users of MDMA (3,4-methylenedioxymeth hetamine, ecstasy). The current study aimed to assess the impact of MDMA use on three separate central executive processes (set shifting, inhibition and memory updating) and also on ëprefrontalí mediated social and emotional judgement processes. Fifteen polydrug ecstasy users and 15 polydrug non-ecstasy user controls completed a general drug use questionnaire, the Brixton Spatial Anticipation task (set shifting), Backward Digit Span procedure (memory updating), Inhibition of Return (inhibition), an emotional intelligence scale, the Tromso Social Intelligence Scale and the Dysexecutive Questionnaire (DEX). Compared with MDMA-free polydrug controls, MDMA polydrug users showed impairments in set shifting and memory updating, and also in social and emotional judgement processes. The latter two de.cits remained signi.cant after controlling for other drug use. These data lend further support to the proposal that cognitive processes mediated by the prefrontal cortex may be impaired by recreational ecstasy use.
Publisher: Elsevier BV
Date: 12-2009
DOI: 10.1016/J.APPET.2009.07.024
Abstract: This double-blind, placebo-controlled study examined the influence of appetitive state on glucose enhancement of memory. Participants rated their mood, hunger and thirst, then consumed a 25 g glucose drink or a matched placebo 20 min prior to a verbal memory task. There was a double dissociation when the effects of thirst ratings and drink on subsequent memory performance were considered. Those who were initially less thirsty recalled significantly more words following glucose than placebo those who were more thirsty recalled significantly fewer words after glucose than placebo. Glucose enhancement of memory may therefore critically depend on participants' initial thirst.
Publisher: Springer Science and Business Media LLC
Date: 15-05-2003
Publisher: Elsevier BV
Date: 06-2004
Publisher: Wiley
Date: 19-08-2010
DOI: 10.1002/HUP.1138
Abstract: There is a lack of research into the cognitive and mood effects of repeated ginseng ingestion. The present study assessed the effects of Panax ginseng (G115) on subjective mood and aspects of 'working' memory processes, following a single dose and following sub-chronic (7 days) ingestion, in healthy volunteers. A placebo-controlled, double-blind, randomised, crossover was utilised. Thirty volunteers (mean age 22.87 years SD 4.01) received each treatment (200 mg 400 mg placebo) for 8 days, in a counter balanced order, with a 6-day wash-out period. Testing was on days 1 and 8 of each treatment period, at pre-dose, 1, 2.5 and 4 h post-dose. Results revealed dose-related treatment effects (p < 0.05). Two hundred milligrams slowed a fall in mood at 2.5 and 4 h on day 1 and at 1 and 4 h on day 8, but slowed responding on a mental arithmetic task across day 1 and at 1 and 2.5 h on day 8. The 400 mg dose also improved calmness (restricted 2.5 and 4 h on day 1) and improved mental arithmetic across days 1 and 8. We found no evidence of additional benefits, nor attenuation of acute effects following repeated ingestion of Panax ginseng (G115).
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8FO01997E
Abstract: Consuming polyphenols is associated with benefits to cardiometabolic health and brain function, which are driven by their complex interrelationship with the gut microbiome, their bioactive metabolites, and other phytochemicals.
Publisher: Wiley
Date: 25-04-2007
DOI: 10.1002/HUP.837
Abstract: Recent data suggest that the complexation of standardised Ginkgo biloba extract (GBE) with soy-derived phospholipids enhances the bioavailability of GBE's active components. The current study therefore aimed to assess the comparative cognitive and mood effects of a low dose of GBE and products complexing the same extract with either phosphatidylserine or phosphatidylcholine. The study utilised a placebo-controlled, multi-dose, double-blind, balanced-crossover design. Twenty-eight healthy young participants received 120 mg GBE, 120 mg GBE complexed with phosphatidylserine (Virtiva), 120 mg GBE complexed with phosphatidylcholine and a matching placebo, on separate days 7 days apart. Cognitive performance was assessed using the Cognitive Drug Research (CDR) computerised test battery and Serial Subtraction tasks immediately prior to dosing and at 1, 2.5, 4 and 6 h thereafter. The primary outcome measures were the four aspects of cognitive performance, which have previously been derived by factor analysis of CDR subtests. Levels of terpenoids (bilobalide, ginkgolide A and ginkgolide B) were concomitantly assessed in plasma s les taken pre-dose and at 3 and 6.5 h post-dose.In keeping with previous research utilising the same methodology, 120 mg of GBE was not associated with markedly improved performance on the primary outcomes. However, administration of GBE complexed with phosphatidylserine resulted both in improved secondary memory performance and significantly increased speed of memory task performance across all of the post-dose testing sessions. Enhancement following GBE complexed with phosphatidylcholine was restricted to a modest improvement in secondary memory performance which was restricted to one post-dose time point. All three treatments were associated with improved calmness. There were no significant differences in post-dose levels of terpenoids between the Ginkgo containing treatments, although this latter finding may be attributable to methodological factors. Complexation with phosphatidylserine appears to potentiate the cognitive effects associated with a low dose of GBE. Further research is required to identify whether this effect is due to the complexation of the extracts, their mere combination, or the separate psychopharmacological actions of the two extracts.
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.APPET.2007.10.007
Abstract: Guaraná (Paullinia cupana) extracts are most commonly used in Western markets as putatively psychoactive food and drink additives. This double-blind, randomised, placebo-controlled, parallel groups study assessed the acute effects of either a vitamin/mineral/guaraná supplement or placebo drink in 129 healthy young adults (18-24 years). Participants completed a 10min version of the Cognitive Demand Battery (comprising: Serial 3s and Serial 7s subtraction tasks, a Rapid Visual Information Processing (RVIP) task, 'mental fatigue' scale). Thirty minutes following their drink participants made six consecutive completions of the battery (i.e. 60 min). The vitamin/mineral/guaraná combination resulted in improved task performance, in comparison to placebo, in terms of both increased speed and accuracy of performing the RVIP task throughout the post-dose assessment. The increase in mental fatigue associated with extended task performance was also attenuated by the supplement. This research supports previous findings demonstrating guaraná's cognition enhancing properties and provides evidence that its addition to a multi-vitamin-mineral supplement can improve cognitive performance and reduce the mental fatigue associated with sustained mental effort.
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.NEUROPHARM.2012.06.030
Abstract: The administration of a glucose drink has been shown to enhance cognitive performance with effect sizes comparable with those from pharmaceutical interventions in human trials. In the memory domain, it is currently debated whether glucose facilitation of performance is due to differential targeting of hippoc al memory or whether task effort is a more important determinant. Using a placebo-controlled, double-blind, crossover 2(Drink: glucose lacebo) × 2(Effort: ± secondary task) design, 20 healthy young adults' recognition memory performance was measured using the 'remember-know' procedure. Two high effort conditions (one for each drink) included secondary hand movements during word presentation. A 25 g glucose or 30 mg saccharine (placebo) drink was consumed 10 min prior to the task. The presence of a secondary task resulted in a global impairment of memory function. There were significant Drink × Effort interactions for overall memory accuracy but no differential effects for 'remember' or 'know' responses. These data suggest that, in some circumstances, task effort may be a more important determinant of the glucose facilitation of memory effect than hippoc al mediation. This article is part of a Special Issue entitled 'Cognitive Enhancers'.
Publisher: Springer Science and Business Media LLC
Date: 05-10-2005
Abstract: Salvia officinalis (sage) has previously been shown both to possess in vitro cholinesterase inhibiting properties, and to enhance mnemonic performance and improve mood in healthy young participants. In this double-blind, placebo-controlled, crossover study, 30 healthy participants attended the laboratory on three separate days, 7 days apart, receiving a different treatment in counterbalanced order on each occasion (placebo, 300, 600 mg dried sage leaf). On each day mood was assessed predose and at 1 and 4 h postdose. Each mood assessment comprised completion of Bond-Lader mood scales and the State Trait Anxiety Inventory (STAI) before and after 20 min performance of the Defined Intensity Stress Simulator (DISS) computerized multitasking battery. In a concomitant investigation, an extract of the sage leaf exhibited dose-dependent, in vitro inhibition of acetylcholinesterase and, to a greater extent, butyrylcholinesterase. Both doses of sage led to improved ratings of mood in the absence of the stressor (that is, in pre-DISS mood scores) postdose, with the lower dose reducing anxiety and the higher dose increasing 'alertness', 'calmness' and 'contentedness' on the Bond-Lader mood scales. The reduced anxiety effect following the lower dose was, however, abolished by performing the DISS, with the same dose also being associated with a reduction of alertness during performance. Task performance on the DISS battery was improved for the higher dose at both postdose sessions, but reduced for the lower dose at the later testing session. The results confirm previous observations of the cholinesterase inhibiting properties of S. officinalis, and improved mood and cognitive performance following the administration of single doses to healthy young participants.
Publisher: Cambridge University Press (CUP)
Date: 11-2008
DOI: 10.1017/S0007114508959213
Abstract: Adequate levels of vitamins and minerals are essential for optimal neural functioning. A high proportion of in iduals, including children, suffer from deficiencies in one or more vitamins or minerals. This study investigated whether daily supplementation with vitamins/minerals could modulate cognitive performance and mood in healthy children. In this randomised, double-blind, placebo-controlled, parallel groups investigation, eighty-one healthy children aged from 8 to 14 years underwent laboratory assessments of their cognitive performance and mood pre-dose and at 1 and 3 h post-dose on the first and last days of 12 weeks' supplementation with a commercially available vitamins/mineral product (Pharmaton Kiddi™). Interim assessments were also completed at home after 4 and 8 weeks at 3 h post-dose. Each assessment comprised completion of a cognitive battery, delivered over the Internet, which included tasks assessing mood and the speed and accuracy of attention and aspects of memory (secondary, semantic and spatial working memory). The vitamin/mineral group performed more accurately on two attention tasks: ‘Arrows’ choice reaction time task at 4 and 8 weeks ‘Arrow Flankers’ choice reaction time task at 4, 8 and 12 weeks. A single task outcome (Picture Recognition errors) evinced significant decrements at 12 weeks. Mood was not modulated in any interpretable manner. Whilst it is possible that the significant improvements following treatment were due to non-significant numerical differences in performance at baseline, these results would seem to suggest that vitamin/mineral supplementation has the potential to improve brain function in healthy children. This proposition requires further investigation.
Publisher: SAGE Publications
Date: 09-01-2006
Abstract: Single doses of the traditional herbal treatment Panax ginseng have recently been shown to lower blood glucose levels and elicit cognitive improvements in healthy, overnight-fasted volunteers. The specific mechanisms responsible for these effects are not known. However, cognitive improvements may be related to the glycaemic properties of Panax ginseng. Using a double-blind, placebo-controlled, balanced-crossover design, 27 healthy young adults completed a 10 minute “cognitive demand” test battery at baseline. They then consumed capsules containing either ginseng (extract G115) or a placebo and 30 minutes later a drink containing glucose or placebo. A further 30 minutes later (i.e. 60 minutes post-baseline/capsules) they completed the “cognitive demand” battery six times in immediate succession. Depending on the condition to which the participant was allocated on that particular day, the combination of capsules/drink treatments corresponded to a dose of: 0mg G115/0mg glucose (placebo) 200mg G115/0mg glucose (ginseng) 0mg G115/25g glucose (glucose) or 200mg G115/25g glucose (ginseng/glucose combination). The 10 minute “cognitive demand” battery comprised a Serial Threes subtraction task (2 min) a Serial Sevens subtraction task (2 min) a Rapid Visual Information Processing task (5 min) and a “mental fatigue” visual analogue scale. Blood glucose levels were measured prior to the day's treatment, and before and after the post-dose completions of the battery. The results showed that both Panax ginseng and glucose enhanced performance of a mental arithmetic task and ameliorated the increase in subjective feelings of mental fatigue experienced by participants during the later stages of the sustained, cognitively demanding task performance. Accuracy of performing the Rapid Visual Information Processing task (RVIP) was also improved following the glucose load. There was no evidence of a synergistic relationship between Panax ginseng and exogenous glucose ingestion on any cognitive outcome measure. Panax ginseng caused a reduction in blood glucose levels 1 hour following consumption when ingested without glucose. These results confirm that Panax ginseng may possess glucoregulatory properties and can enhance cognitive performance.
Publisher: Bentham Science Publishers Ltd.
Date: 12-2006
DOI: 10.2174/138161206779010387
Abstract: Extensive research suggests that a number of plant-derived chemicals and traditional Oriental herbal remedies possess cognition-enhancing properties. Widely used current treatments for dementia include extracts of Ginkgo biloba and several alkaloidal, and therefore toxic, plant-derived cholinergic agents. Several non-toxic, European herbal species have pan-cultural traditions as treatments for cognitive deficits, including those associated with ageing. To date they have not received research interest commensurate with their potential utility. Particularly promising candidate species include sage (Salvia lavandulaefolia/officinalis), Lemon balm (Melissa officinalis) and rosemary (Rosmarinus officinalis). In the case of sage, extracts possess anti-oxidant, estrogenic, and anti-inflammatory properties, and specifically inhibit butyryl- and acetyl-cholinesterase. Acute administration has also been found to reliably improve mnemonic performance in healthy young and elderly cohorts, whilst a chronic regime has been shown to attenuate cognitive declines in sufferers from Alzheimer's disease. In the case of Melissa officinalis, extracts have, most notably, been shown to bind directly to both nicotinic and muscarinic receptors in human brain tissue. This property has been shown to vary with extraction method and strain. Robust anxiolytic effects have also been demonstrated following acute administration to healthy humans, with mnemonic enhancement restricted to an extract with high cholinergic binding properties. Chronic regimes of aromatherapy and essential oil respectively have also been shown to reduce agitation and attenuate cognitive declines in sufferers from dementia. Given the side effect profile of prescribed cholinesterase inhibitors, and a current lack of a well tolerated nicotinic receptor agonist, these herbal treatments may well provide effective and well-tolerated treatments for dementia, either alone, in combination, or as an adjunct to conventional treatments.
Publisher: SAGE Publications
Date: 13-03-2006
Abstract: The present study aimed to systematically assess acute, dose-related behavioural effects of an extract of guaraná plant for the first time in humans. This double-blind, counterbalanced, placebo-controlled study ( n = 26) assessed the acute mood and cognitive effects throughout the day of four different doses (37.5mg, 75mg, 150mg and 300mg) of a standardised guaraná extract (PC-102). Assessment included the Cognitive Drug Research computerized test battery and Bond-Lader mood scales. Guaraná improved secondary memory performance and increased alert and content mood ratings. The two lower doses produced more positive cognitive effects than the higher doses. This research supports previous findings of cognitive improvements following 75mg guaraná and provides the first exploration of different dose effects of guaraná in humans. The findings suggest that the effects cannot be attributed to caffeine alone.
Publisher: Cambridge University Press (CUP)
Date: 03-10-2011
DOI: 10.1017/S0007114511004041
Abstract: The impact of dietary n -3 PUFA on behavioural outcomes has been widely researched however, very little attention has been given to their impact on brain functioning in physiological terms. A total of twenty-two healthy adults took part in this double-blind, placebo-controlled study, wherein the cerebral haemodynamic effects of 12 weeks of daily dietary supplementation with either 1 g DHA-rich or 1 g EPA-rich fish oil (FO) or placebo (1 g olive oil) were assessed. Relative changes in the concentration of oxygenated Hb (oxy-Hb) and deoxygenated Hb were assessed in the prefrontal cortex using near IR spectroscopy (NIRS) during the performance of four computerised cognitive tasks. Supplementation with DHA-rich FO, in comparison with placebo, resulted in a significant increase in the concentrations of oxy-Hb and total levels of Hb, indicative of increased cerebral blood flow (CBF), during the cognitive tasks. In comparison, no effect on CBF was observed following supplementation with EPA-rich FO, where concentration changes in the chromophores followed the same pattern as placebo. These encouraging pilot data warrant further application of NIRS in this area.
Publisher: Wiley
Date: 2006
DOI: 10.1002/PTR.1787
Abstract: Melissa officinalis (lemon balm) and Valeriana officinalis (valerian) have been used both traditionally and contemporaneously as mild sedatives, anxiolytics and hypnotics. Recent research has suggested that both may attenuate laboratory induced stress. As the two herbs are most often sold in combination with each other the current study assessed the anxiolytic properties of such a combination during laboratory-induced stress. In this double-blind, placebo-controlled, randomized, balanced cross-over experiment, 24 healthy volunteers received three separate single doses (600 mg, 1200 mg, 1800 mg) of a standardized product containing M. officinalis and V. officinalis extracts, plus a placebo, on separate days separated by a 7 day wash out period. Modulation of mood and anxiety were assessed during pre-dose and 1 h, 3 h and 6 h post-dose completions of a 20 min version of the Defined Intensity Stressor Simulation (DISS) battery. Cognitive performance on the four concurrent tasks of the battery was also assessed. The results showed that the 600 mg dose of the combination ameliorated the negative effects of the DISS on ratings of anxiety. However, the highest dose (1800 mg) showed an increase in anxiety that was less marked but which reached significance during one testing session. In addition, all three doses led to decrements in performance on the Stroop task module within the battery, and the two lower doses led to decrements on the overall score generated on the DISS battery. These results suggest that a combination of Melissa officinalis and Valeriana officinalis possesses anxiolytic properties that deserve further investigation.
Publisher: Elsevier BV
Date: 02-2008
DOI: 10.1016/J.BIOPSYCHO.2007.09.008
Abstract: L-Theanine is an amino acid found naturally in tea. Despite the common consumption of L-theanine, predominantly in combination with caffeine in the form of tea, only one study to date has examined the cognitive effects of this substance alone, and none have examined its effects when combined with caffeine. The present randomised, placebo-controlled, double-blind, balanced crossover study investigated the acute cognitive and mood effects of L-theanine (250 mg), and caffeine (150 mg), in isolation and in combination. Salivary caffeine levels were co-monitored. L-Theanine increased 'headache' ratings and decreased correct serial seven subtractions. Caffeine led to faster digit vigilance reaction time, improved Rapid Visual Information Processing (RVIP) accuracy and attenuated increases in self-reported 'mental fatigue'. In addition to improving RVIP accuracy and 'mental fatigue' ratings, the combination also led to faster simple reaction time, faster numeric working memory reaction time and improved sentence verification accuracy. 'Headache' and 'tired' ratings were reduced and 'alert' ratings increased. There was also a significant positive caffeine x L-theanine interaction on delayed word recognition reaction time. These results suggest that beverages containing L-theanine and caffeine may have a different pharmacological profile to those containing caffeine alone.
Publisher: Wiley
Date: 2007
DOI: 10.1002/HUP.885
Abstract: Previous research from our laboratory demonstrated that administration of single doses (120, 240, 360 mg) of standardised Ginkgo biloba extract (GBE) had linear, dose-dependent, positive effects on the speed of performing attention tasks in comparison to placebo. However, whilst the lowest dose, which is typical of a recommended daily dose, had no effect on the speed of attention task performance it did engender mild improvements in secondary memory performance. The current study presents a reanalysis of data from three methodologically identical studies that each included a treatment of 120 mg GBE and matched placebo. All three studies were of a multiple dose, placebo-controlled, double-blind, balanced-crossover design, employing four or five treatment arms in total. Across the studies 78 healthy young participants received 120 mg GBE and placebo in randomly counterbalanced order, separated by a wash-out period of at least 7 days. On each study day participants' performance on the Cognitive Drug Research (CDR) computerised cognitive assessment battery was measured immediately prior to dosing and at 1, 2.5, 4 and 6 hr following treatment, with scores collapsed into the six measures (speed of attention, accuracy of attention, secondary memory, working memory, speed of memory, quality of memory) which have previously been derived by factor analysis of the data from CDR subtests. The results showed that 120 mg of Ginkgo engendered a significant improvement on the 'quality of memory' factor that was most evident at 1 and 4 hr post-dose, but had a negative effect on performance on the 'speed of attention' factor that was most evident at 1 and 6 hr post-dose. The current study confirmed the previous observation of modestly improved memory performance following 120 mg of GBE, but suggests that acute administration of this typical daily dose may have a detrimental effect on the speed of attention task performance which is opposite to that seen previously following higher doses.
Publisher: Springer Science and Business Media LLC
Date: 31-07-2004
DOI: 10.1007/S00213-004-1935-2
Abstract: Both glucose and caffeine can improve aspects of cognitive performance and, in the case of caffeine, mood. There are few studies investigating the effects of the two substances in combination. We assessed the mood, cognitive and physiological effects of a soft drink containing caffeine and glucose as well as flavouring levels of herbal extracts. The effects of different drink fractions were also evaluated. Using a randomised, double-blind, balanced, five-way crossover design, 20 participants who were overnight fasted and caffeine-deprived received 250 ml drinks containing 37.5 g glucose 75 mg caffeine ginseng and ginkgo biloba at flavouring levels a whole drink (containing all these substances) or a placebo (vehicle). Participants were assessed in each drink condition, separated by a 7-day wash-out period. Cognitive, psychomotor and mood assessment took place immediately prior to the drink then 30 min thereafter. The primary outcome measures included five aspects of cognitive performance from the Cognitive Drug Research assessment battery. Mood, heart rate and blood glucose levels were also monitored. Compared with placebo, the whole drink resulted in significantly improved performance on "secondary memory" and "speed of attention" factors. There were no other cognitive or mood effects. This pattern of results would not be predicted from the effects of glucose and caffeine in isolation, either as seen here or from the literature addressing the effects of the substances in isolation. These data suggest that there is some degree of synergy between the cognition-modulating effects of glucose and caffeine which merits further investigation.
Publisher: Springer Science and Business Media LLC
Date: 11-2008
DOI: 10.1007/S00213-008-1387-1
Abstract: The cognition-enhancing effects of glucose administration to humans have been well-documented however, it remains unclear whether this effect preferentially targets episodic memory or other cognitive domains. The effect of glucose on the allocation of attentional resources during memory encoding was assessed using a sensitive dual-attention paradigm. One hundred and twenty volunteers (mean age 21.60, SD 4.89, 77 females) took part in this randomised, double-blind, placebo-controlled, parallel groups study where each consumed a 25-g glucose drink or a placebo. Half of the participants in each drink condition attempted to track a moving on-screen target during auditory word presentation. The distance between the cursor and the tracking target was used as an index of attentional cost during encoding. Effects of drink and tracking on recognition memory and drink on tracking performance were assessed. Self-rated appetite and mood were co-monitored. Co-performing the tracking task significantly impaired memory performance irrespective of drink condition. In the placebo-tracking condition, there was a cost to tracking manifest as greater deviation from target during and immediately following word presentation. Compared with placebo, the glucose drink significantly improved tracking performance during encoding. There were significant time-related changes in thirst and alertness ratings but these were not differentially affected by drink or tracking conditions. Tracking but not memory was enhanced by glucose. This finding suggests that, under certain task conditions, glucose administrations does not preferentially enhance memory performance. One mechanism through which glucose acts as a cognition enhancer is through allowing greater allocation of attentional resources.
Publisher: SAGE Publications
Date: 11-10-2010
Abstract: Extracts of sage ( Salvia officinalis/lavandulaefolia) with terpenoid constituents have previously been shown to inhibit cholinesterase and improve cognitive function. The current study combined an in vitro investigation of the cholinesterase inhibitory properties and phytochemical constituents of a S. lavandulaefolia essential oil, with a double-blind, placebo-controlled, balanced crossover study assessing the effects of a single dose on cognitive performance and mood. In this latter investigation 36 healthy participants received capsules containing either 50 µL of the essential oil or placebo on separate occasions, 7 days apart. Cognitive function was assessed using a selection of computerized memory and attention tasks and the Cognitive Demand Battery before the treatment and 1-h and 4-h post-dose. The essential oil was a potent inhibitor of human acetylcholinesterase (AChE) and consisted almost exclusively of monoterpenoids. Oral consumption lead to improved performance of secondary memory and attention tasks, most notably at the 1-h post-dose testing session, and reduced mental fatigue and increased alertness which were more pronounced 4-h post-dose. These results extend previous observations of improved cognitive performance and mood following AChE inhibitory sage extracts and suggest that the ability of well-tolerated terpenoid-containing extracts to beneficially modulate cholinergic function and cognitive performance deserves further attention.
Publisher: Springer Science and Business Media LLC
Date: 28-01-2005
DOI: 10.1007/S00213-004-2104-3
Abstract: The cognitive and mood effects of caffeine are well documented. However, the majority of studies in this area involve caffeine-deprived, habitual caffeine users. It is therefore unclear whether any beneficial findings are due to the positive effects of caffeine or to the alleviation of caffeine withdrawal. The present placebo-controlled, double-blind, balanced crossover study investigated the acute cognitive and mood effects of caffeine in habitual users and habitual non-users of caffeine. Following overnight caffeine withdrawal, 24 habitual caffeine consumers (mean=217 mg/day) and 24 habitual non-consumers (20 mg/day) received a 150 ml drink containing either 75 or 150 mg of caffeine or a matching placebo, at intervals of > or =48 h. Cognitive and mood assessments were undertaken at baseline and 30 min post-drink. These included the Cognitive Drug Research computerised test battery, two serial subtraction tasks, a sentence verification task and subjective visual analogue mood scales. There were no baseline differences between the groups' mood or performance. Following caffeine, there were significant improvements in simple reaction time, digit vigilance reaction time, numeric working memory reaction time and sentence verification accuracy, irrespective of group. Self-rated mental fatigue was reduced and ratings of alertness were significantly improved by caffeine independent of group. There were also group effects for rapid visual information processing false alarms and spatial memory accuracy with habitual consumers outperforming non-consumers. There was a single significant interaction of group and treatment effects on jittery ratings. Separate analyses of each groups' responses to caffeine revealed overlapping but differential responses to caffeine. Caffeine tended to benefit consumers' mood more while improving performance more in the non-consumers. These results do not support a withdrawal alleviation model. Differences in the patterns of responses to caffeine by habitual consumers and habitual non-consumers may go some way to explaining why some in iduals become caffeine consumers.
Publisher: SAGE Publications
Date: 26-11-2009
Abstract: Cocoa flavanols (CF) positively influence physiological processes in ways that suggest their consumption may improve aspects of cognitive function. This study investigated the acute cognitive and subjective effects of CF consumption during sustained mental demand. In this randomized, controlled, double-blinded, balanced, three period crossover trial 30 healthy adults consumed drinks containing 520 mg, 994 mg CF and a matched control, with a three-day washout between drinks. Assessments included the state anxiety inventory and repeated 10-min cycles of a Cognitive Demand Battery comprising of two serial subtraction tasks (Serial Threes and Serial Sevens), a Rapid Visual Information Processing (RVIP) task and a ‘mental fatigue’ scale, over the course of 1 h. Consumption of both 520 mg and 994 mg CF significantly improved Serial Threes performance. The 994 mg CF beverage significantly speeded RVIP responses but also resulted in more errors during Serial Sevens. Increases in self-reported ‘mental fatigue’ were significantly attenuated by the consumption of the 520 mg CF beverage only. This is the first report of acute cognitive improvements following CF consumption in healthy adults. While the mechanisms underlying the effects are unknown they may be related to known effects of CF on endothelial function and blood flow.
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.BIOPSYCHO.2011.10.006
Abstract: A number of recent studies have assessed the impact of dietary omega-3 polyunsaturated fatty acids (n-3 PUFAs) on behavioral outcomes however, very little attention has been given to their impact upon brain function in physiological terms. Sixty-five healthy adults aged 18-29yrs took part in this double-blind, placebo-controlled study assessing the effects of 12 weeks daily dietary supplementation with docosahexaenoic acid-rich fish oil (1g, 2g) or placebo (olive oil). Relative changes in the concentration of oxyhemoglobin and deoxyhemoglobin were assessed in the prefrontal cortex using near-infrared spectroscopy during performance of nine computerized cognitive tasks. Supplementation with both doses of fish oil, in comparison with placebo, resulted in significantly increased concentrations of oxyhemoglobin and total levels of hemoglobin, indicative of increased cerebral blood flow, during the cognitive tasks. Changes in hemodynamic response to tasks were not accompanied by consistent changes in cognitive performance.
Publisher: Elsevier BV
Date: 07-2002
DOI: 10.1016/S0091-3057(02)00777-3
Abstract: Melissa officinalis (lemon balm) is a traditional herbal medicine, which enjoys contemporary usage as a mild sedative, spasmolytic and antibacterial agent. It has been suggested, in light of in vitro cholinergic binding properties, that Melissa extracts may effectively ameliorate the cognitive deficits associated with Alzheimer's disease. To date, no study has investigated the effects on cognition and mood of administration of Melissa to healthy humans. The present randomised, placebo-controlled, double-blind, balanced-crossover study investigated the acute effects on cognition and mood of a standardised extract of M. officinalis. Twenty healthy, young participants received single doses of 300, 600 and 900 mg of M. officinalis (Pharmaton) or a matching placebo at 7-day intervals. Cognitive performance was assessed using the Cognitive Drug Research (CDR) computerised test battery and two serial subtraction tasks immediately prior to dosing and at 1, 2.5, 4 and 6 h thereafter. In vitro IC(50) concentrations for the displacement of [3H]-(N)-nicotine and [3H]-(N)-scopolamine from nicotinic and muscarinic receptors in human occipital cortex tissue were also calculated. Results, utilising the cognitive factors previously derived from the CDR battery, included a sustained improvement in Accuracy of Attention following 600 mg of Melissa and time- and dose-specific reductions in both Secondary Memory and Working Memory factors. Self-rated "calmness," as assessed by Bond-Lader mood scales, was elevated at the earliest time points by the lowest dose, whilst "alertness" was significantly reduced at all time points following the highest dose. Both nicotinic and muscarinic binding were found to be low in comparison to the levels found in previous studies.
Publisher: Springer Science and Business Media LLC
Date: 06-09-2000
Abstract: Chronic administration of extracts from the leaves of the tree Ginkgo biloba is known to improve aspects of cognitive performance. However, little is known about the effects of acute doses of Ginkgo on coherent cognitive domains. Recent factor analysis of test measures from subtasks of the Cognitive Drug Research (CDR) computerised assessment battery has revealed that four primary cognitive 'factors' corresponding to speed of attention, accuracy of attention, speed of memory and quality of memory can be useful to describe cognitive function changes. The present study aimed at assessing whether acute administration of Ginkgo biloba had any consistent effect on the four CDR factors. The study utilised a placebo-controlled, multi-dose, double-blind, balanced, crossover design. Twenty participants received 120 mg, 240 mg and 360 mg of a standardised extract of Ginkgo (GK501, Pharmaton, SA) or a matching placebo. Cognitive performance was assessed using the CDR computerised test battery immediately prior to dosing and at 1, 2.5, 4 and 6 h thereafter. The primary outcome measures were the four aspects of cognitive performance, which have previously been derived by factor analysis of CDR subtests. Compared with the placebo, administration of Ginkgo produced a number of significant changes on the performance measures. The most striking of these was a dose-dependent improvement of the 'speed of attention' factor following both 240 mg and 360 mg of the extract, which was evident at 2.5 h and was still present at 6 h. Additionally, there were a number of time- and dose-specific changes (both positive and negative) in performance of the other factors. We conclude that acute administration of Ginkgo biloba is capable of producing a sustained improvement in attention in healthy young volunteers.
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.RESP.2013.12.015
Abstract: Dietary inorganic nitrate supplementation causes physiological effects which may enhance exercise tolerance. However it is not known whether nitrate might alter cognitive function during exercise. In a double-blind, cross-over study, sixteen subjects ingested either nitrate-rich beetroot juice or a placebo and completed a continuous cycle exercise test involving 20min stages at 50% and 70% V˙O2peak and a final stage at 90% V˙O2peak until volitional exhaustion. Cognitive tasks were completed before, during and after exercise. In the dietary nitrate condition: plasma [nitrite] increased (p<0.01), systolic blood pressure decreased (p<0.05) and there was a trend for a reduced oxygen uptake at 50% V˙O2peak. Tissue oxygenation improved across exercise intensities and exercise tolerance was greater at 90% V˙O2peak (p<0.05). Rating of perceived exertion, energy levels and cognitive performance were similar between conditions with mental fatigue being evident from 70% V˙O2peak onwards (p<0.05). Dietary nitrate supplementation enhanced short-term endurance exercise performance with concomitant mental fatigue but did not improve cognitive performance post-fatigue.
Publisher: Informa UK Limited
Date: 04-2009
Publisher: Cambridge University Press
Date: 2001
Publisher: Elsevier BV
Date: 04-2002
DOI: 10.1016/S0031-9384(02)00665-0
Abstract: It has previously been demonstrated in separate studies that single doses of Ginkgo biloba, Panax ginseng, and a combination of the two extracts can improve different aspects of cognitive performance in healthy young volunteers. The present study directly compared the effects of single doses of G. biloba, ginseng, and a product combining the two on aspects of mood and cognitive performance in the same cohort of healthy, young adult volunteers. The study followed a randomised placebo-controlled, double-blind, balanced, cross-over design. Twenty participants received 360 mg of ginkgo, 400 mg of ginseng, 960 mg of a product combining the two extracts, and a matching placebo. Treatment order was dictated by random allocation to a Latin square, with a 7-day wash-out period between treatments. Cognitive testing comprised completion of the Cognitive Drug Research (CDR) computerised assessment battery and two serial subtraction mental arithmetic tasks. Mood was assessed with Bond-Lader visual analogue scales. Following a baseline cognitive assessment, further test sessions took place 1, 2.5, 4, and 6 h after the day's treatment was taken. The results largely supported previous findings. All three treatments were associated with improved secondary memory performance on the CDR battery, with the ginseng condition evincing some improvement in the speed of performing memory tasks and in the accuracy of attentional tasks. Following ginkgo and the ginkgo/ginseng combination performance of both the Serial Threes and Serial Sevens, subtraction tasks was also improved at the later testing sessions. No modulation of the speed of performing attention tasks was evident. Improvements in self-rated mood was also found following ginkgo and to a lesser extent the combination product.
Publisher: Cambridge University Press (CUP)
Date: 25-08-2011
DOI: 10.1017/S000711451100403X
Abstract: The n -3 PUFA are a unique class of fatty acids that cannot be manufactured by the body, and must be acquired via dietary sources. In the UK, as well as in other Western nations, these ‘essential’ fatty acids are consumed in quantities that fall below government guidelines. The present study explored the effects of 12 weeks' dietary supplementation with 1 g/d of two types of fish oil (FO DHA-rich and EPA-rich) in 159 healthy young adults aged 18–35 years. An assessment of performance on a battery of computerised cognitive tasks and mood measures took place before and following the 12-week treatment regimen. Venous blood s les were also supplied by participants at both time points which were later analysed for serum fatty acid concentrations. Despite good adherence to the study protocol – as reflected in increased concentrations of n -3 serum fatty acids – compared with placebo, the observed effects of both active treatments were minimal. The only finding of note revealed that supplementation with EPA-rich FO may reduce subjective mental fatigue at times of high cognitive demand, although further investigation is required. These findings, taken together with other recent reports of null effects, suggest that dietary supplementation with n -3 PUFA in healthy, normally developing and impairment-free populations is unlikely to result in cognitive enhancement.
Publisher: Elsevier BV
Date: 06-2003
DOI: 10.1016/S0091-3057(03)00126-6
Abstract: Ginseng has been used medicinally in the Far East for several millennia and is currently one of the most widely taken herbal products throughout the world. It has been attributed with a plethora of physiological effects that could potentially benefit cognitive performance or mood. Studies involving animals show that ginseng and its constituent ginsenosides can modulate indices of stress, fatigue, and learning. However, there is a lack of adequately controlled research showing behavioural effects following chronic administration to humans. Recent research has demonstrated that single doses of ginseng most notably engender cognitive benefits in terms of improved memory, but can also be associated with 'costs' in terms of attention task deficits following less mnemonically beneficial doses. A single dose of ginseng has also been shown to modulate cerebroelectrical (EEG) activity. It is suggested that ginseng would benefit from rigorous research further delineating its acute effects and exploring the relationship between acute effects and those seen during and following chronic administration regimens.
Publisher: Elsevier BV
Date: 06-2003
DOI: 10.1016/S0091-3057(03)00122-9
Abstract: Sage (Salvia) has a longstanding reputation in British herbal encyclopaedias as an agent that enhances memory, although there is little evidence regarding the efficacy of sage from systematized trials. Based on known pharmacokinetic and binding properties, it was hypothesised that acute administration of sage would enhance memory in young adult volunteers. Two experiments utilised a placebo-controlled, double-blind, balanced, crossover methodology. In Trial 1, 20 participants received 50, 100 and 150 microl of a standardised essential oil extract of Salvia lavandulaefolia and placebo. In Trial 2, 24 participants received 25 and 50 microl of a standardised essential oil extract of S. lavandulaefolia and placebo. Doses were separated by a 7-day washout period with treatment order determined by Latin squares. Assessment was undertaken using the Cognitive Drug Research computerised test battery prior to treatment and 1, 2.5, 4 and 6 h thereafter. The primary outcome measures were immediate and delayed word recall. The 50 microl dose of Salvia essential oil significantly improved immediate word recall in both studies. These results represent the first systematic evidence that Salvia is capable of acute modulation of cognition in healthy young adults.
Publisher: Elsevier BV
Date: 07-2001
DOI: 10.1016/S0031-9384(01)00476-0
Abstract: Previous research has identified that glucose administration can enhance cognitive performance, especially during more intense cognitive processing. There appears to be a reciprocal relationship between falling glucose levels and cognitive performance, particularly under conditions of cognitive demand. The present placebo-controlled, double-blind, balanced, crossover study examined the possibility that a high cognitive load may produce changes in blood glucose levels. A secondary aim was to examine the effects of glucose on tasks of varying cognitive demand load. The effects of a glucose drink on participants' performance of a serial subtraction task (computerised Serial Sevens), a somatically matched control task (key-pressing), a short interval Word Memory task and a Word Retrieval (Verbal Fluency) task were assessed. The change in blood glucose during the demanding computerised Serial Sevens was compared to the change occurring during the key-pressing control. Glucose consumption significantly improved performance on Serial Sevens, with a trend for improved performance on Word Retrieval and no effect on the Word Memory task. Compared with the control task, Serial Sevens resulted in a significant reduction in blood glucose in both drink conditions. This accelerated decay was significantly greater following glucose than placebo. It is suggested that the amount of cognitive load associated with task performance is an index of its sensitivity to enhancement by glucose. Furthermore, a period of intense cognitive processing leads to a measurable decrease in levels of peripherally measured blood glucose, which may be linked to increased neural energy expenditure. However, the relative contribution of central and peripheral (e.g. cardiac) activity to this effect has yet to be determined.
Publisher: Springer Science and Business Media LLC
Date: 19-03-2008
DOI: 10.1007/S00213-008-1101-3
Abstract: Species of Salvia (sage) have a long-standing reputation in European medical herbalism, including for memory enhancement. In recent controlled trials, administration of sage extracts with established cholinergic properties improved cognitive function in young adults. This randomised, placebo-controlled, double-blind, balanced, five-period crossover study investigated the acute effects on cognitive performance of a standardised extract of Salvia officinalis in older adults. Twenty volunteers (>65 years of age, mean = 72.95) received four active doses of extract (167, 333, 666 and 1332 mg) and a placebo with a 7-day wash-out period between visits. Assessment involved completion of the Cognitive Drug Research computerised assessment battery. On study days, treatments were administered immediately following a baseline assessment with further assessment at 1, 2.5, 4 and 6 h post treatment. Compared with the placebo condition (which exhibited the characteristic performance decline over the day), the 333-mg dose was associated with significant enhancement of secondary memory performance at all testing times. The same measure benefited to a lesser extent from other doses. There also were significant improvements to accuracy of attention following the 333-mg dose. In vitro analysis confirmed cholinesterase inhibiting properties for the extract. The overall pattern of results is consistent with a dose-related benefit to processes involved in efficient stimulus processing and/or memory consolidation rather than retrieval or working memory efficiency. These findings extend those of the memory-enhancing effects of Salvia extracts in younger populations and warrant further investigation in larger series, in other populations and with different dosing regimes.
Publisher: Elsevier BV
Date: 07-2007
DOI: 10.1016/J.APPET.2006.06.009
Abstract: This study investigated whether the glycaemic index (GI) of breakfast cereal differentially affects children's attention and memory. Using a balanced cross-over design, on two consecutive mornings 64 children aged 6-11 years were given a high GI cereal and a low GI cereal in a counterbalanced order. They performed a series of computerised tests of attention and memory, once prior to breakfast and three times following breakfast at hourly intervals. The results indicate that children's performance declines throughout the morning and that this decline can be significantly reduced following the intake of a low GI cereal as compared with a high GI cereal on measures of accuracy of attention (M=-6.742 and -13.510, respectively, p<0.05) and secondary memory (M=-30.675 and -47.183, respectively, p<0.05).
Publisher: Cambridge University Press (CUP)
Date: 19-11-2008
DOI: 10.1017/S0007114508123418
Abstract: In the absence of effective pharmacotherapy for diabetes there has been an increase in the use of, and research into, alternative treatment strategies. These include exercise, dietary interventions and the use of supplements including extracts of ginseng. Two separate, placebo-controlled, double-blind, cross-over studies investigating the effects of chronic ingestion of Panax ginseng (study 1 used G115, study 2 used Cheong Kwan Jang) on glycated Hb (HbA1c study 1, n 18 study 2, n 11), fasting plasma insulin (study 1, n 17 study 2, n 12), fasting plasma glucose and postprandial response (following breakfast) (study 1, n 23 study 2, n 14) in healthy volunteers are reported. In both studies it was found that Panax ginseng had no effect on any gluco-regulatory parameter investigated. These results are not consistent with those reported for a diabetic s le (albeit using slightly different outcomes). These results would suggest that chronic use of Panax ginseng by non-diabetic in iduals will have little long-term effect on glucose regulation. The benefits to glucose regulation associated with long-term ginseng use may only be present in populations with compromised glucose control however, further research is needed to confirm such a speculation.
Publisher: Elsevier BV
Date: 06-2009
DOI: 10.1016/J.PHYSBEH.2009.02.028
Abstract: The notion that chewing gum may relieve stress was investigated in a controlled setting. A multi-tasking framework which reliably evokes stress and also includes performance measures was used to induce acute stress in the laboratory. Using a randomised crossover design forty participants (mean age 21.98 years) performed on the multi-tasking framework at two intensities (on separate days) both while chewing and not chewing. Order of workload intensity and chewing conditions were counterbalanced. Before and after undergoing the platform participants completed the state portion of the State-Trait Anxiety Inventory, Bond-Lader visual analogue mood scales, a single Stress Visual Analogue Scale and provided saliva s les for cortisol measurement. Baseline measures showed that both levels of the multi-tasking framework were effective in significantly reducing self-rated alertness, calmness and contentment while increasing self-rated stress and state anxiety. Cortisol levels fell during both levels of the stressor during the morning, reflecting the predominance of a.m. diurnal changes, but this effect was reversed in the afternoon which may reflect a measurable stress response. Pre-post stressor changes (Delta) for each measure at baseline were subtracted from Delta scores under chewing and no chewing conditions. During both levels of stress the chewing gum condition was associated with significantly better alertness and reduced state anxiety, stress and salivary cortisol. Overall performance on the framework was also significantly better in the chewing condition. The mechanisms underlying these effects are unknown but may involve improved cerebral blood flow and/or effects secondary to performance improvement during gum chewing.
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.PHYSBEH.2015.05.035
Abstract: Nitrate derived from vegetables is consumed as part of a normal diet and is reduced endogenously via nitrite to nitric oxide. It has been shown to improve endothelial function, reduce blood pressure and the oxygen cost of sub-maximal exercise, and increase regional perfusion in the brain. The current study assessed the effects of dietary nitrate on cognitive performance and prefrontal cortex cerebral blood-flow (CBF) parameters in healthy adults. In this randomised, double-blind, placebo-controlled, parallel-groups study, 40 healthy adults received either placebo or 450 ml beetroot juice (~5.5 mmol nitrate). Following a 90 minute drink/absorption period, participants performed a selection of cognitive tasks that activate the frontal cortex for 54 min. Near-Infrared Spectroscopy (NIRS) was used to monitor CBF and hemodynamics, as indexed by concentration changes in oxygenated and deoxygenated-haemoglobin, in the frontal cortex throughout. The bioconversion of nitrate to nitrite was confirmed in plasma by ozone-based chemi-luminescence. Dietary nitrate modulated the hemodynamic response to task performance, with an initial increase in CBF at the start of the task period, followed by consistent reductions during the least demanding of the three tasks utilised. Cognitive performance was improved on the serial 3s subtraction task. These results show that single doses of dietary nitrate can modulate the CBF response to task performance and potentially improve cognitive performance, and suggest one possible mechanism by which vegetable consumption may have beneficial effects on brain function.
Publisher: Springer Science and Business Media LLC
Date: 07-10-2014
DOI: 10.1007/S00213-014-3750-8
Abstract: Current research suggests that glucose facilitates performance on cognitive tasks which possess an episodic memory component and a relatively high level of cognitive demand. However, the extent to which this glucose facilitation effect is uniform across the lifespan is uncertain. This study was a repeated measures, randomised, placebo-controlled, cross-over trial designed to assess the cognitive effects of glucose in younger and older adults under single and dual task conditions. Participants were 24 healthy younger (average age 20.6 years) and 24 healthy older adults (average age 72.5 years). They completed a recognition memory task after consuming drinks containing 25 g glucose and a placebo drink, both in the presence and absence of a secondary tracking task. Glucose enhanced recognition memory response time and tracking precision during the secondary task, in older adults only. These findings do not support preferential targeting of hippoc al function by glucose, rather they suggest that glucose administration differentially increases the availability of attentional resources in older in iduals.
Publisher: SAGE Publications
Date: 07-2005
Abstract: Single doses of the traditional herbal treatment Panax ginseng have recently been shown to elicit cognitive improvements in healthy young volunteers. The mechanisms by which ginseng improves cognitive performance are not known. However, they may be related to the glycaemic properties of some Panax species. Using a double-blind, placebo-controlled, balanced crossover design, 30 healthy young adults completed a 10min test battery at baseline, and then six times in immediate succession commencing 60min after the day’s treatment (placebo, 200mg G115 or 400mg G115). The 10 min battery comprised a Serial Threes subtraction task (2min) a Serial Sevens task (2min) a Rapid Visual Information Processing task (5min) then a ‘mental fatigue’ visual analogue scale. Blood glucose was measured prior to each day’s treatment, and before, during and after the post-dose completions of the battery. Both the 200mg and 400mg treatments led to significant reductions in blood glucose levels at all three post-treatment measurements ( p 0.005 in all cases). The most notable behavioural effects were associated with 200mg of ginseng and included significantly improved Serial Sevens subtraction task performance and significantly reduced subjective mental fatigue throughout all (with the exception of one time point in each case) of the post-dose completions of the 10min battery ( p 0.05). Overall these data suggest that Panax ginseng can improve performance and subjective feelings of mental fatigue during sustained mental activity. This effect may be related to the acute gluco-regulatory properties of the extract.
Publisher: Cambridge University Press (CUP)
Date: 07-05-2014
DOI: 10.1017/S0007114514000737
Abstract: Previous research has shown that resveratrol can increase cerebral blood flow (CBF) in the absence of improved cognitive performance in healthy, young human subjects during the performance of cognitively demanding tasks. This lack of cognitive effects may be due to low bioavailability and, in turn, reduced bioefficacy of resveratrol in vivo . Piperine can alter polyphenol pharmacokinetics, but previous studies have not investigated whether this affects the efficacy of the target compound. Therefore, the objective of the present study was to ascertain whether co-supplementation of piperine with resveratrol affects the bioavailability and efficacy of resveratrol with regard to cognition and CBF. The present study utilised a randomised, double-blind, placebo-controlled, within-subjects design, where twenty-three adults were given placebo, trans- resveratrol (250 mg) and trans- resveratrol with 20 mg piperine on separate days at least a week apart. After a 40 min rest/absorption period, the participants performed a selection of cognitive tasks and CBF was assessed throughout the period, in the frontal cortex, using near-IR spectroscopy. The presence of resveratrol and its conjugates in the plasma was confirmed by liquid chromatography–MS analysis carried out following the administration of the same doses in a separate cohort ( n 6). The results indicated that when co-supplemented, piperine and resveratrol significantly augmented CBF during task performance in comparison with placebo and resveratrol alone. Cognitive function, mood and blood pressure were not affected. The plasma concentrations of resveratrol and its metabolites were not significantly different between the treatments, which indicates that co-supplementation of piperine with resveratrol enhances the bioefficacy of resveratrol with regard to CBF effects, but not cognitive performance, and does this without altering bioavailability.
Publisher: Elsevier BV
Date: 06-2003
DOI: 10.1016/S0091-3057(03)00120-5
Abstract: Both Ginkgo biloba and Panax ginseng exert a number of physiological effects and have been shown to modulate aspects of cognitive performance. Whilst a number of studies have examined ginkgo's effects on electroencephalograph (EEG) recordings, to date, none have investigated the EEG effects of ginseng. In this double-blind, placebo-controlled, balanced crossover experiment, the effects of single doses of G. biloba (360 mg GK501), P. ginseng (200 mg G115), and an identical placebo, on auditory-evoked potentials, contingent negative variation (CNV), and resting power within the delta, theta, alpha, and beta wavebands, were assessed in 15 healthy volunteers. Each participant was assessed on three separate occasions 4 h after consuming that day's treatment. The order of presentation of the treatments was dictated by a Latin square with 7 days between testing sessions. The results showed that ginseng led to a significant shortening of the latency of the P300 component of the evoked potential. Both ginseng and ginkgo also led to significant reductions in frontal 'eyes closed' theta and beta activity, with additional reduction for ginseng in the alpha waveband. These findings demonstrate for the first time that P. ginseng can directly modulate cerebroelectrical activity, and that these effects are more pronounced than those following G. biloba.
Publisher: Elsevier BV
Date: 11-2004
DOI: 10.1016/J.PBB.2004.07.014
Abstract: Extracts from the plant guarana (Paullinia cupana) feature as putatively stimulating ingredients in a number of foods, drinks and dietary/herbal supplements. To date, little research in humans has examined the potential psychoactive effects of these extracts. Extracts of Panax ginseng, which are often sold in combination with guarana, contain similar potentially active components, and have been shown to modulate cognitive performance. In this double-blind, counterbalanced, placebo-controlled study, the cognitive and mood effects of separate single doses of: 75 mg of a dried ethanolic extract of guarana (approx 12% caffeine), 200 mg of Panax ginseng (G115), and their combination (75 mg/200 mg), were assessed in 28 healthy young (18-24) participants. On each day of the study (separated by a 7-day washout), cognitive performance and subjective mood were assessed pre-dose and at 1, 2.5, 4 and 6 h post-dose using the Cognitive Drug Research computerised assessment battery, Serial subtraction tasks and Bond-Lader mood scales. In comparison to placebo, all three treatments resulted in improved task performance throughout the day. In the case of guarana, improvements were seen across 'attention' tasks (but with some evidence of reduced accuracy), and on a sentence verification task. While also increasing the speed of attention task performance, both ginseng and the ginseng/guarana combination also enhanced the speed of memory task performance, with little evidence of modulated accuracy. Guarana and the combination, and to a lesser extent ginseng, also led to significant improvements in serial subtraction task performance. These results provide the first demonstration in humans of the psychoactive effects of guarana, and confirmation of the psychoactive properties of ginseng. Given the low caffeine content (9 mg) of this dose of guarana extract, the effects are unlikely to be attributable to its caffeine content.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2004
Publisher: Springer Science and Business Media LLC
Date: 19-01-2005
Publisher: Elsevier BV
Date: 17-01-2005
DOI: 10.1016/J.PHYSBEH.2004.09.010
Abstract: Members of the Sage family, such as Salvia officinalis and Salvia lavandulaefolia, have a long history of use as memory-enhancing agents coupled with cholinergic properties that may potentially be relevant to the amelioration of the cognitive deficits associated with Alzheimer's disease. The current study utilised a placebo-controlled, double-blind, balanced, crossover design in order to comprehensively assess any mood and cognition modulation by S. lavandulaefolia. Twenty-four participants received single doses of placebo, 25 microl and 50 microl of a standardised essential oil of S. lavandulaefolia in an order dictated by a Latin square. Doses were separated by a 7-day washout period. Cognitive performance was assessed prior to the day's treatment and at 1, 2.5, 4 and 6 h thereafter using the Cognitive Drug Research (CDR) computerised test battery. Subjective mood ratings were measured using Bond-Lader visual analogue scales. The primary outcome measures were scores on the five cognitive factors that can be derived by factor analysis of the task outcomes from the CDR battery. The results showed that administration of S. lavandulaefolia resulted in a consistent improvement for both the 25- and 50-microl dose on the 'Speed of Memory' factor. There was also an improvement on the 'Secondary Memory' factor for the 25-microl dose. Mood was consistently enhanced, with increases in self-rated 'alertness', 'calmness' and 'contentedness' following the 50-microl dose and elevated 'calmness' following 25 microl. These results represent further evidence that Salvia is capable of acute modulation of mood and cognition in healthy young adults. The data also suggest that previous reports of memory enhancement by Salvia may be due to more efficient retrieval of target material.
Publisher: Elsevier BV
Date: 12-2001
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for David Kennedy.