ORCID Profile
0000-0003-3265-2700
Current Organisation
University of Leeds
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Publisher: Oxford University Press (OUP)
Date: 02-2019
Abstract: No longitudinal epidemiological research has reported associations between physical frailty and performance in specific cognitive domains. Our aim was to investigate whether such associations existed in the absence of accompanying neurodegenerative disorders such as mild cognitive impairment (MCI) and dementia. We addressed this issue in a population-based s le of 896 adults aged 70 years and older over 4 waves of data covering a 12-year period. Physical frailty was assessed and a cognitive battery included measures of processing speed, verbal fluency, face and word recognition, episodic memory and simple and choice reaction time (RT). Latent growth models showed frailty was associated with poorer baseline performance in processing speed, verbal fluency, simple and choice RT, and choice intrain idual RT variability. However, no significant effects of frailty on slopes of cognition were observed, suggesting that frailty was not associated with cognitive decline. Importantly, when the models took possible dementia into account, significant effects were retained suggesting that differences were not associated with dementia-related neurodegenerative disorders. The findings suggest that frailty-related cognitive deficits may exist independently of mechanisms underpinning neurodegenerative disorders such as MCI and dementia. If confirmed, this finding suggests a new avenue for preventative and therapeutic interventions in clinical and public health contexts for older adults.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2013
Publisher: Cambridge University Press (CUP)
Date: 29-10-2019
DOI: 10.1017/S0033291718002994
Abstract: It has been proposed that vascular disease is the mechanism linking depression and cognition, but prospective studies have not supported this hypothesis. This study aims to investigate the inter-relationships between depressive symptoms, cognition and cerebrovascular disease using a well-characterised prospective cohort. Data came from waves 1 (2005–2007) and 2 (2007–2009) of the Sydney Memory and Ageing Study ( n = 462 mean age = 78.3 years). At wave 1, there was an association between depressive symptoms and white matter hyperintensity (WMH) volume [ b = 0.016, t (414) = 2.34, p = 0.020]. Both depressive symptoms [ b = −0.058, t (413) = −2.64, p = 0.009] and WMH volume [ b = −0.011, t (413) = −3.77, p 0.001], but not stroke/transient ischaemic attack (TIA) [ b = −0.328, t (413) = −1.90, p = 0.058], were independently associated with lower cognition. Prospectively, cerebrovascular disease was not found to predict increasing depressive symptoms [stroke/TIA: b = −0.349, t (374.7) = −0.76, p = 0.448 WMH volume: b = 0.007, t (376.3) = 0.875, p = 0.382]. Depressive symptoms predicted increasing WMH severity [ b = 0.012, t (265.9) = −3.291, p = 0.001], but not incident stroke/TIA (odds ratio = 0.995 CI 0.949–1.043 p = 0.820). When examined in separate models, depressive symptoms [ b = −0.027, t (373.5) = −2.16, p = 0.032] and a history of stroke/TIA [ b = −0.460, t (361.2) = −4.45, p 0.001], but not WMH volume [ b = 0.001, t (362.3) = −0.520, p = 0.603], predicted declines in cognition. When investigated in a combined model, a history of stroke/TIA remained a predictor of cognitive decline [ b = −0.443, t (360.6) = −4.28, p 0.001], whilst depressive symptoms did not [ b = −0.012, t (359.7) = −0.96, p = 0.336]. This study is contrasted with previous prospective studies which indicate that depressive symptoms predict cognitive decline independently of vascular disease. Future research should focus on further exploring the vascular mechanisms underpinning the relationship between depressive symptoms and cognition.
Publisher: Oxford University Press (OUP)
Date: 08-08-2014
Abstract: very few studies have examined the association between intra-in idual reaction time variability and subsequent mortality. Furthermore, the ability of simple measures of variability to predict mortality has not been compared with more complex measures. a prospective cohort study of 896 community-based Australian adults aged 70+ were interviewed up to four times from 1990 to 2002, with vital status assessed until June 2007. From this cohort, 770-790 participants were included in Cox proportional hazards regression models of survival. Vital status and time in study were used to conduct survival analyses. The mean reaction time and three measures of intra-in idual reaction time variability were calculated separately across 20 trials of simple and choice reaction time tasks. Models were adjusted for a range of demographic, physical health and mental health measures. greater intra-in idual simple reaction time variability, as assessed by the raw standard deviation (raw SD), coefficient of variation (CV) or the intra-in idual standard deviation (ISD), was strongly associated with an increased hazard of all-cause mortality in adjusted Cox regression models. The mean reaction time had no significant association with mortality. intra-in idual variability in simple reaction time appears to have a robust association with mortality over 17 years. Health professionals such as neuropsychologists may benefit in their detection of neuropathology by supplementing neuropsychiatric testing with the straightforward process of testing simple reaction time and calculating raw SD or CV.
Publisher: Cambridge University Press (CUP)
Date: 26-03-2014
DOI: 10.1017/S1355617714000174
Abstract: There is continuing debate about long-term effects of brain injury. We examined a range of traumatic brain injury (TBI) variables (TBI history, severity, frequency, and age of injury) as predictors of cognitive outcome over 8 years in an adult population, and interactions with apolipoprotein E ( APOE ) genotype, sex, and age cohorts. Three randomly s led age cohorts (20–24, 40–44, 60–64 years at baseline N = 6333) were each evaluated three times over 8 years. TBI variables, based on self-report, were separately modeled as predictors of cognitive performance using linear mixed effects models. TBI predicted longitudinal cognitive decline in all three age groups. APOE ε4 + genotypes in the young and middle-aged groups predicted lower baseline cognitive performance in the context of TBI. Baseline cognitive performance was better for young females than males but this pattern reversed in middle age and old age. The findings suggest TBI history is associated with long-term cognitive impairment and decline across the adult lifespan. A role for APOE genotype was apparent in the younger cohorts but there was no evidence that it is associated with impairment in early old age. The effect of sex and TBI on cognition varied with age cohort, consistent with a proposed neuroprotective role for estrogen. ( JINS , 2014, 20 , 444–454)
Publisher: Oxford University Press (OUP)
Date: 31-07-2014
Abstract: We examined whether the apolipoprotein E (APOE) ε4 allele was associated with cognitive benefits in young adulthood and whether it reversed to confer cognitive deficits in later life ("antagonistic pleiotropy") in the absence of dementia-related neuropathology. We also tested whether the ε2 allele was associated with disadvantages in early adulthood but offered protection against cognitive decline in early old age. Eight-year cognitive change was assessed in 2,013 cognitively normal community-dwelling adults aged 20-24, 40-44, or 60-64 years at baseline. Although cognitive decline was associated with age, multilevel models contrasting the ε2 and ε4 alleles provided no evidence that the APOE genotype was related to cognitive change in any of the age groups. The findings suggest that in the absence of clinically salient dementia pathology, APOE ε2 and ε4 alleles do not exhibit antagonistic pleiotropy in relation to cognition between the ages of 20 and 72 years.
Publisher: Elsevier BV
Date: 12-2012
DOI: 10.1016/J.JPSYCHIRES.2012.08.023
Abstract: Although there is evidence of associations between anxiety, depression and cognitive function in old age, there is little work investigating relations between those variables over an extended period of time. Therefore, we used data from the Canberra Longitudinal Study to investigate 12-year cognitive change over four measurement points in relation to anxiety and depression symptoms. Latent growth models on over 836 community-dwelling persons aged 70 years and over, recruited from the electoral roll suggested that higher depression symptom scores were associated with poorer initial performance in processing speed, verbal fluency and episodic memory while higher anxiety symptom scores were associated with verbal fluency. We found no evidence that mental health variables affected change in cognition over time. Importantly, when possible mild cognitive impairment or dementia cases were removed from the models, associations between the cognitive variables and depression symptoms disappeared while those for anxiety symptoms strengthened. The findings are consistent with the possibility that depression-related cognitive deficits represent a prodrome or risk factor for dementia while associations between anxiety and cognition may be more characteristic of normal aging.
Publisher: Oxford University Press (OUP)
Date: 03-09-2016
Abstract: Reaction time measures have considerable potential to aid neuropsychological assessment in a variety of health care settings. One such measure, the intrain idual reaction time variability (IIV), is of particular interest as it is thought to reflect neurobiological disturbance. IIV is associated with a variety of age-related neurological disorders, as well as gait impairment and future falls in older adults. However, although persons diagnosed with Mild Cognitive Impairment (MCI) are at high risk of falling, the association between IIV and prospective falls is unknown. We conducted a longitudinal cohort study in cognitively intact (n = 271) and MCI (n = 154) community-dwelling adults aged 70-90 years. IIV was assessed through a variety of measures including simple and choice hand reaction time and choice stepping reaction time tasks (CSRT), the latter administered as a single task and also with a secondary working memory task. Logistic regression did not show an association between IIV on the hand-held tasks and falls. Greater IIV in both CSRT tasks, however, did significantly increase the risk of future falls. This effect was specific to the MCI group, with a stronger effect in persons exhibiting gait, posture, or physiological impairment. The findings suggest that increased stepping IIV may indicate compromised neural circuitry involved in executive function, gait, and posture in persons with MCI increasing their risk of falling. IIV measures have potential to assess neurobiological disturbance underlying physical and cognitive dysfunction in old age, and aid fall risk assessment and routine care in community and health care settings.
Publisher: Cambridge University Press (CUP)
Date: 08-08-2013
DOI: 10.1017/S1355617713000830
Abstract: Intrain idual variability (IIV) refers to reaction time (RT) variation across the trials of a given cognitive task. Little research has contrasted different measures of IIV or assessed how many RT trials are required to provide a robust measure of the construct. We, therefore, investigated three measures of IIV (raw SD , coefficient of variation, and intrain idual SD statistically removing time-on-task effects) in relation to frontal white matter hyperintensities (obtained through structural MRI) in 415 cognitively normal community-dwelling adults aged 44 to 48 years. Results indicated the three IIV measures did not differ greatly in predictions of white matter hyperintensities, although it is possible that time-on-task effects were influential. As few as 20 trials taking approximately 52 s to administer provided a reliable prediction of frontal white matter hyperintensities. We conclude that future work should evaluate the comparative utility of different IIV measures in relation to persons exhibiting clear neuropathology. ( JINS , 2013, 19 , 1–6)
Publisher: Elsevier BV
Date: 09-2012
Publisher: Public Library of Science (PLoS)
Date: 09-08-2017
Publisher: American Psychological Association (APA)
Date: 2014
DOI: 10.1037/A0032650
Abstract: Moment-to-moment intrain idual variability (IIV) in cognitive speed is a sensitive behavioral indicator of the integrity of the aging brain and brain damage, but little information is known about how IIV changes from being relatively low in young adulthood to substantially higher in older adulthood. We evaluated possible age group, sex, and task differences in IIV across adulthood using a large, neurologically normal, population-based s le evaluated thrice over 8 years. Multilevel modeling controlling for education, diabetes, hypertension, and anxiety and depressive symptoms showed expected age group differences in baseline IIV across the adult lifespan. Increase in IIV was not found until older adulthood on simple tasks but was apparent even in the 40s on a more complex task. Females were more variable than males but only at baseline. IIV in cognitive speed is a fundamental behavioral characteristic associated with growing older, even among healthy adults.
Publisher: Public Library of Science (PLoS)
Date: 21-10-2010
Publisher: Elsevier BV
Date: 06-2011
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2011.02.042
Abstract: There is considerable evidence that the apolipoprotein E (APOE) ɛ4 allele is associated with cognitive deficits in older persons, and is a risk factor for dementia. However, it has recently been suggested that possession of the ɛ4 allele may benefit cognition in early adulthood. We tested this possibility in 5445 community-dwelling persons aged 20-24, 40-44, and 60-64 years using a comprehensive battery of cognitive measures. As the APOE ɛ2 allele may offer protection against cognitive deficits, in order to robustly test the hypothesis, we removed persons carrying this allele from the analyses. Older persons with possible dementia were also removed. We found no evidence of higher cognitive performance in young ɛ4 carriers, or cognitive deficits in older ɛ4 carriers. This did not change when a range of health variables were taken into account. We conclude that it is premature to suppose ɛ4-related benefits to cognition in healthy young adulthood and findings consistent with this hypothesis may have been related to methodological issues, or the pathology of the s le investigated.
Publisher: Elsevier BV
Date: 2007
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2007.02.006
Abstract: Estimates of white matter hyperintensities (WMH) derived from T2-weighted MRI were investigated in relation to cognitive performance in 469 healthy community-dwelling adults aged 60-64 years. Frontal lobe WMH but not WMH from other brain regions (temporal, parietal, and occipital lobes, anterior and posterior horn, periventricular body) were associated with elevated within-person reaction time (RT) variability (trial to trial fluctuations in RT performance) but not performance on several other cognitive tasks including psychomotor speed, memory, and global cognition. The findings are consistent with the view that elevated within-person variability is related to neurobiological disturbance, and that attentional mechanisms supported by the frontal cortex play a key role in this type of variability.
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2017.01.021
Abstract: In old age, a relationship has been reported between intrain idual variability (IIV) in reaction time and white matter integrity as evidenced by white matter hyperintensities (WMH). However, it is unclear how far such associations are due to incipient neurodegenerative pathology in the s les investigated. The present study examined the relationship between IIV and WMH in older in iduals (N=526) drawn from the Sydney Memory and Ageing Study. Using a complex reaction time (RT) task, greater IIV and mean-RT were related to a higher WMH burden in the frontal lobe. Critically, significant associations remained having taken future dementia into account suggesting that they were not explained by incipient dementia. Additionally, independent measures of executive function accounted for the association between RT metrics and WHM. The results are consistent with the view that frontally-supported cognitive processes are involved in IIV-WMH relations, and that RT measures are sensitive to compromise in white matter structures in non-demented older in iduals.
Publisher: Public Library of Science (PLoS)
Date: 17-10-2012
Publisher: Oxford University Press (OUP)
Date: 06-03-2014
Abstract: A critical question in the activity engagement literature is whether physical exercise alters the trajectory of age-related cognitive decline (differential preservation) or is associated with enhanced baseline cognitive ability (preserved differentiation). Further, investigations considering that these relations may differ across young, middle, and older adulthood are rare. We evaluated data from the PATH Through Life Project, where participants aged 20-24, 40-44, and 60-64 years at baseline (n = 6,869) completed physical activity (PA mild, moderate, and vigorous) and cognitive measurements thrice over 8 years. Multilevel models accounting for employment status, sex, education, health, and mental and social activity showed that between-person differences in PA participation positively predicted baseline performance on fluid cognitive ability (perceptual speed, short-term memory, working memory, and episodic memory). These effects were similar across age groups, but strongest for the youngest cohort, for whom there was also evidence of covariation between within-person change in PA and cognitive score. PA was not associated with change in cognition over time. Results support preserved differentiation, where physically active adults have higher initial cognitive ability, and the advantage is maintained over time. PA appears to be unique in showing differences across young, middle, and older adulthood in predicting cognition.
Publisher: Elsevier BV
Date: 03-2016
Publisher: Elsevier BV
Date: 12-2014
DOI: 10.1016/J.JAGP.2014.01.004
Abstract: To evaluate the temporal association between depression symptoms and cognitive function in older adults over a 4-year period. Using a longitudinal, cross-lagged, population-based design, we studied depression symptoms and cognitive domains (including processing speed, verbal fluency, face and word recognition, episodic memory, and simple and choice reaction time) in 896 community-dwelling adults aged 70-97 years. Cross-lagged structural equation models suggested that initial depression symptoms affected subsequent processing speed and simple and choice reaction time but that cognition did not predict depression symptoms over time. The associations between depression and cognitive variables were attenuated when the models were adjusted for sensory impairment, physical health, and locus of control. The findings suggest that, causally, depression precedes cognitive impairment in this age group and that the association is related to physical health and perceptions of a lack of control.
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.JAGP.2013.01.035
Abstract: Presence of the apolipoprotein E (APOE) ε4 allele is a risk factor for dementia, whereas the ε2 allele offers protection against dementia. There is also evidence for a relationship between APOE genotype and changes in cognitive function. It is not clear, however, whether this relationship stems from undetected disease in persons genetically more vulnerable to dementia. This study examined whether APOE genotype was associated with either initial performance or change in performance on a range of cognitive and noncognitive tasks, after accounting for possible preclinical dementia. A population-based cohort was assessed up to four times over 12 years. The s le was an Australian cohort of 590 participants age 70 years and older who were genotyped for APOE. The outcomes were processing speed, verbal fluency, episodic memory, word recognition, face recognition, grip strength, and reaction time. Adjusted latent growth models indicated that ε4 carriers had significantly poorer initial memory performance and greater declines in processing speed and word recognition than ε2 and ε3 carriers. In addition, ε2 carriers exhibited significantly less decline in right grip strength than ε3 carriers. However, after excluding 125 participants with low global cognition scores, all genotype effects became nonsignificant. Over a 12-year period, findings indicate that APOE ε4-related cognitive decline in older community-dwelling populations is due to a higher likelihood of preclinical dementia among ε4 carriers. When possible dementia cases are removed from the analyses, ε4 associations with cognitive decline become statistically unreliable.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for David Bunce.