Cogni tive abilities include perception, memory, judgment , perceptual speed, spatial manipulatio... more Cogni tive abilities include perception, memory, judgment , perceptual speed, spatial manipulation and reasoning. Both cross sectional and longitudinal studies have shown that different cognitive abilities have different developmental trajectories across the lifespan, and may be grouped into two broad types. 1 The first type is described as 'crystallised' and involves accumulated knowledge and expertise and relies on long term memory. Crystallised abilities are assessed with tests of vocabulary, word knowledge, general knowledge, understanding proverbs, and measures of occupational expertise. The second type are known as 'fluid' and involve novel problem solving, spatial manipulation, mental speed, and identifying complex relations among stimulus patterns. These are usually measured with tests that involve identifying the next in a series of abstract patterns, matrices or a series of numbers. Fluid abilities rely on short term memory storage while processing information.
Background: Little is known about the role of resilience in the likelihood of suicidal ideation (... more Background: Little is known about the role of resilience in the likelihood of suicidal ideation (SI) over time. Aims: We examined the association between resilience and SI in a young-adult cohort over 4 years. Our objectives were to determine whether resilience was associated with SI at follow-up or, conversely, whether SI was associated with lowered resilience at follow-up. Method: Participants were selected from the Personality and Total Health (PATH) Through Life Project from Canberra and Queanbeyan, Australia, aged 28–32 years at the first time point and 32–36 at the second. Multinomial, linear, and binary regression analyses explored the association between resilience and SI over two time points. Models were adjusted for suicidality risk factors. Results: While unadjusted analyses identified associations between resilience and SI, these effects were fully explained by the inclusion of other suicidality risk factors. Conclusion: Despite strong cross-sectional associations, resilience and SI appear to be unrelated in a longitudinal context, once risk/resilience factors are controlled for. As independent indicators of psychological well-being, suicidality and resilience are essential if current status is to be captured. However, the addition of other factors (e.g., support, mastery) makes this association tenuous. Consequently, resilience per se may not be protective of SI.
White matter lesions (WMLs), seen as hyperintensities on T2-weighted magnetic resonance imaging b... more White matter lesions (WMLs), seen as hyperintensities on T2-weighted magnetic resonance imaging brain scans, are common in the brains of healthy older individuals. They are thought to be related to cerebral small vessel disease and to have a genetic component to their aetiology, and hypertension is thought to be an important risk factor. Genetic polymorphisms in hypertension-related genes may therefore be associated with the formation of WMLs. In this study, a sample of 445 Australians aged 60-65 years was drawn from a larger longitudinal epidemiological study, the Personality and Total Health Through Life Project. The associations of single nucleotide polymorphisms (SNPs) in the genes encoding angiotensinogen (AGT, rs699), angiotensin-converting enzyme (ACE, rs4362), and angiotensin II receptor type 1 (AGTR1, rs5182) with WMLs were examined. No individual SNPs showed a significant association with WMLs for the whole sample. When the cohort was stratified by sex, ACE rs4362 and AGT ...
Understanding of the origins of adolescent antisocial behaviour is important for two reasons. Fir... more Understanding of the origins of adolescent antisocial behaviour is important for two reasons. First, crime is a source of concern and cost to many communities throughout the world as well as Australia. Second, clear identification of the pathways to crime lead to the possibility of early prevention programs. This essay, based on a large longitudinal study of Queensland children, reports
Australian and New Zealand Journal of Psychiatry, 2004
Objective: To outline the strengths and limitations of longitudinal research designs in psychiatr... more Objective: To outline the strengths and limitations of longitudinal research designs in psychiatry, and to describe different types of longitudinal designs and methods for analyzing longitudinal data. Method: Key references on longitudinal methods were reviewed and examples drawn from literature in psychiatry and psychology. Results: Longitudinal studies provide important information regarding the incidence and developmental trajectories of mental disorders. They allow for identification of risk factors and developmental concomitants. Recent developments in statistical methods for analyzing longitudinal data provide efficient estimates of change and predictors of change over time, identification and characteristics of distinct subgroups defined by change pattern, and improved methods for obtaining unbiased population estimates when data are incomplete. Conclusion: Longitudinal designs, methods and analysis can contribute to psychiatric studies on risk factors for common mental disorders, studies of early intervention and prevention and treatment outcomes.
Purpose: The purpose of this article was to investigate the role of control beliefs in mediating ... more Purpose: The purpose of this article was to investigate the role of control beliefs in mediating the relationship between driving cessation and change in depressive symptoms in a population-based sample of older adults. Design and Methods: We report results from a prospective, community-based cohort study that included two waves of data collected in 1992 and 1994. Participants consisted of 700 men and women aged 70 and older, including 647 drivers and 53 participants who ceased driving between baseline (1992) and follow-up (1994). Participants took part in interviews that included assessments of driving status, sociodemographic characteristics, self-rated health, sensory function, depressive symptoms (through the Center for Epidemiologic Studies-Depression scale), and expectancy of control. Using multilevel general linear models, we examined the extent to which driving status, expectancy of control, and relevant covariates explained change in depressivesymptom scores between baseline and follow-up.
Intraindividual variability in cognitive test performance has the potential to be a good marker o... more Intraindividual variability in cognitive test performance has the potential to be a good marker of preclinical Alzheimer's disease status (S. C. Li & U. Lindenberger, 1999). Using cross-sectional community data from 2,317 individuals aged 60-64 years, the authors of this study found that variability was greater in individuals who met criteria for mild cognitive impairment or aging-associated cognitive decline but not for age-associated memory impairment. Higher variability was associated with lower education and a non-English-speaking background. In contrast to previous findings, variability in this study did not contribute uniquely to meeting criteria for mild cognitive impairment. The reasons for the differences may reside in the authors' method of estimating mean independent variability, the use of an occasion-specific measure, or the relatively younger age of the participants. Follow-up of the cohort in 4 years will yield data on the prospective validity of variability as a risk factor for impairment.
Purpose: Research concerned with the relationship between volunteer activity and psychological we... more Purpose: Research concerned with the relationship between volunteer activity and psychological wellbeing has typically reported higher levels of wellbeing among older adult volunteers relative to nonvolunteers. However, few studies have examined nonlinear associations between frequency of volunteer activity and well-being. We examined nonlinear associations between hours spent volunteering and psychological well-being, controlling for employment status, partner status, physical health, and education. We also investigated associations between different domains of volunteer activity and well-being, along with the possible moderating effects of gender on these relationships. Design and Methods: We used data from the PATH Through Life Project, a populationbased study of Australian adults. Participants consisted of 2,136 older adults aged 64 to 68. Results: Nonlinear associations between hours spent volunteering and psychological well-being were evident, with these associations characterized by inverted U shapes, with nonvolunteers and those volunteering at high levels producing lower well-being scores relative to those volunteering at moderate levels. Few associations between specific domains of volunteer activity and well-being were evident, and no notable gender interactions emerged. Implications: The results point toward optimal frequency of engagement in volunteer activity for psychological well-being as being bounded by upper and lower levels, outside of which benefits to well-being diminish.
Recent cross-sectional research in cognitive aging has demonstrated a robust association between ... more Recent cross-sectional research in cognitive aging has demonstrated a robust association between visual acuity, auditory thresholds and cognitive performance in old age. However, the nature of the association is still unclear, particularly with respect to whether sensory and cognitive function are causally related. This study aimed to determine whether marked declines in performance on screening measures of either visual acuity or auditory thresholds have an effect on cognitive decline over 2 years. The sample from the Australian Longitudinal Study of Ageing (n = 2,087) were assessed in 1992 and 1994 on measures of sensory and cognitive function as part of a larger clinical assessment. A quasi-experimental design involving comparison of extreme groups using repeated measures MANCOVA with age as a covariate was used. Group performance on measures of hearing, memory, verbal ability and processing speed declined significantly. Decline in visual acuity had a significant effect on memory decline, but not on decline in verbal ability or processing speed. Decline in hearing was not associated with decline in any cognitive domain. The common association between visual acuity, auditory thresholds and cognitive function observed in cross-sectional studies appears to be disassociated in longitudinal studies.
Objective: We aimed to evaluate whether gender and different patterns of change in depressive sta... more Objective: We aimed to evaluate whether gender and different patterns of change in depressive status over 2 years were associated with different risks of mortality in the subsequent 6 years. Methods: Depression (CES-D) was assessed in 1947 participants in 1992 and a smaller proportion of the sample in 1994. The mortality risk at July 30, 2000, associated with depression and change in depression was estimated using proportional hazards models. Results: After controlling for demographic variables, smoking, alcohol, and medical conditions, depression was associated with mortality for men but not women. In men, incident depression was associated with mortality after controlling for all other variables. Chronic depression and remitted depression were also associated with mortality, but this effect was explained by medical conditions. In women, change in depressive status was not associated with mortality. Conclusions: Depression confers a greater risk of mortality for men than women with incident depression in old age representing the greatest risk for men. The course of depressive illness must be considered when evaluating mortality risk.
The relationships between alcohol consumption and dementia and cognitive decline were investigate... more The relationships between alcohol consumption and dementia and cognitive decline were investigated in a systematic review including meta-analyses of 15 prospective studies. Follow-ups ranged from 2 to 8 years. Meta-analyses were conducted on samples including 14,646 participants evaluated for Alzheimer disease (AD), 10,225 participants evaluated for vascular dementia (VaD), and 11,875 followed for any type of dementia (Any dementia). The pooled relative risks (RRs) of AD, VaD, and Any dementia for light to moderate drinkers compared with nondrinkers were 0.72 (95% CI = 0.61-0.86), 0.75 (95% CI = 0.57-0.98), and 0.74 (95% CI = 0.61-0.91), respectively. When the more generally classified "drinkers," were compared with "nondrinkers," they had a reduced risk of AD (RR = 0.66, 95% CI = 0.47-0.94) and Any dementia (RR = 0.53, 95% CI = 0.53-0.82) but not cognitive decline. There were not enough data to examine VaD risk among "drinkers." Those classified as heavy drinkers did not have an increased risk of Any dementia compared with nondrinkers, but this may reflect sampling bias. Our results suggest that alcohol drinkers in late life have reduced risk of dementia. It is unclear whether this reflects selection effects in cohort studies commencing in late life, a protective effect of alcohol consumption throughout adulthood, or a specific benefit of alcohol in late life.
Both brain atrophy and T2-weighted white matter hyperintensities (WMH) are common findings in the... more Both brain atrophy and T2-weighted white matter hyperintensities (WMH) are common findings in the brains of asymptomatic elderly individuals as well as in disease-specific brains. The study of the relationship between these two salient features is therefore important. To investigate such a relationship, we performed a brain magnetic resonance imaging (MRI) study on 397 asymptomatic individuals aged between 60 and 64 years, who were recruited randomly from a large community sample. WMH were delineated on T2-weighted fluid attenuation inversion recovery (FLAIR) whole brain scans using an automated procedure. The results showed that gray matter reduction, subarachnoid CSF (SA-CSF) increase and lateral ventricular dilation were significantly correlated with WMH load. Deep white matter hyperintensity (DWMH) had significant correlation with all three global atrophy indices, but periventricular white matter hyperintensity (PVWMH) was correlated only with gray matter volume. Voxel-based morphometric (VBM) analysis showed that regional gray matter reduction correlated more closely with WMH load of the proximate region than with WMH elsewhere. The results suggest that WMH have a relationship with brain atrophy in middle age, although the study cannot determine which process, i.e. the development of WMH or atrophy, is primary. The study also demonstrates that DWMH has a more significant relationship with structural brain changes, and may therefore be more functionally relevant than PVWMH. Further delineation of this relationship needs a longitudinal study of the changes in both WMH and indices of brain atrophy. D
We aimed to identify demographic, health, and biomarker correlates of reaction time performance a... more We aimed to identify demographic, health, and biomarker correlates of reaction time performance and to determine whether biomarkers explained age differences in reaction time performance. TIhe sample comprised three representative cohorts aged 20-24, 40-44, and 60-64 years, including a total of 7,485 participants. Reaction time measures of intraindividual variability and latency were used. The measure of intraindividual variability used was independent of mean reaction time. Older adults were more variable than younger adults in choice reaction time performance but not simple reaction time performance. The most important correlates of reaction time performance after gender and education were biological markers such as forced expiratory volume at one second, grip strength, and vision. Few measures of physical or mental health or lifestyle were associated with poorer performance on reaction time measures. Biomarkers explained the majority of age-related variance in simple reaction time and a large proportion of variance in choice reaction time. We conclude that for the ages studied, biomarkers are more important than health factors for explaining age differences in reaction time performance.
To determine whether cognitive performance, as distinct from cognitive impairment, predicts falli... more To determine whether cognitive performance, as distinct from cognitive impairment, predicts falling during an 8-year follow-up in a community-based sample of very old adults and to evaluate how cognitive change is associated with falling. Prospective cohort study including three waves of data collected in 1992, 1994, and 2000. Population based, with the baseline sample drawn from the electoral roll. Inclusion criteria were completion of at least three cognitive tests at baseline and completion of the falls questionnaire at Wave 6 (N=539). Assessments of health and medical conditions, visual acuity, cognitive function, functional reach, semitandem stand, and grip strength were conducted in 1992 (baseline), 1994, and 2000. Self-report information on falls in the previous 12 months was obtained on each of these occasions. Marginal models using generalized estimating equations were used to assess the association between baseline cognitive performance and falling over 8 years, adjusting for sociodemographic, health, and sensorimotor variables. Random effects models were used to assess the relationship between change in cognitive performance and change in fall rate and fall risk over 8 years. Mini-Mental State Examination and verbal reasoning at baseline predicted rate of falling over an 8-year period. Within individuals, declines in verbal ability, processing speed, and immediate memory were associated with increases in rates of falling and fall risk. Cognitive performance is associated with falling over 8 years in very old adults and should be assessed in clinical practice when evaluating short- and long-term fall risk.
Cross-sectional studies have identified a number of health and lifestyle factors that correlate w... more Cross-sectional studies have identified a number of health and lifestyle factors that correlate with cognitive function in old age. It is important to know whether these factors also predict change in cognitive function over time. To evaluate published findings on genetic, health and lifestyle predictors of cognitive change in late adulthood. Studies reporting data on education, health, blood pressure, activity and apolipoprotein E (APOE) as predictors of cognitive change were reviewed. A total of 34 studies were identified that reported data on these predictors. The average follow-up period of studies reviewed was 7.68 years. Results showed that education, hypertension, objective indices of health and cardiovascular disease, and APOE were associated with cognitive change. Results regarding the effect of physical activity on cognitive change were inconclusive. Despite the lack of data on some predictors, the longitudinal trends are generally consistent with cross-sectional findings on predictors of cognitive performance in old age. More research is required to compare the influence of predictors on different types of cognitive abilities.
The distinction between primary aging, representing innate maturational processes, and secondary ... more The distinction between primary aging, representing innate maturational processes, and secondary aging, representing the effects of environment and disease (Busse, 1969), was used to develop a model for the assessment of factors that are associated with age-related individual differences in intelligence. Intelligence was measured by performance on a number of tests that measure cognitive abilities known to decline with age. In a hierarchical multiple regression analysis, primary aging and education but not health explained a significant portion of the variance in fluid intelligence. Chronological age had a residual effect over and above that of primary and secondary aging, indicating that there was remaining age-associated variance unaccounted for in the proposed model. The results suggest that the model of primary and secondary aging is a valid means of operationalizing chronological age.
The authors investigated the association between sensorimotor variables indicative of biological ... more The authors investigated the association between sensorimotor variables indicative of biological aging and cognition. A community sample of 202 women ages 60-86 was assessed on 5 measures of lower limb strength, visual contrast sensitivity (VisCS), and reaction time (RT). Hierarchical multiple regression revealed that the sensorimotor variables explained age-related variance in measures of reasoning and total variance in measures of reasoning after education, health, mood, and physical activity were controlled for. It is concluded that in addition to better known predictors of cognitive aging, such as RT and VisCS, lower limb strength is an important predictor of performance on cognitive tests.
Cogni tive abilities include perception, memory, judgment , perceptual speed, spatial manipulatio... more Cogni tive abilities include perception, memory, judgment , perceptual speed, spatial manipulation and reasoning. Both cross sectional and longitudinal studies have shown that different cognitive abilities have different developmental trajectories across the lifespan, and may be grouped into two broad types. 1 The first type is described as 'crystallised' and involves accumulated knowledge and expertise and relies on long term memory. Crystallised abilities are assessed with tests of vocabulary, word knowledge, general knowledge, understanding proverbs, and measures of occupational expertise. The second type are known as 'fluid' and involve novel problem solving, spatial manipulation, mental speed, and identifying complex relations among stimulus patterns. These are usually measured with tests that involve identifying the next in a series of abstract patterns, matrices or a series of numbers. Fluid abilities rely on short term memory storage while processing information.
Background: Little is known about the role of resilience in the likelihood of suicidal ideation (... more Background: Little is known about the role of resilience in the likelihood of suicidal ideation (SI) over time. Aims: We examined the association between resilience and SI in a young-adult cohort over 4 years. Our objectives were to determine whether resilience was associated with SI at follow-up or, conversely, whether SI was associated with lowered resilience at follow-up. Method: Participants were selected from the Personality and Total Health (PATH) Through Life Project from Canberra and Queanbeyan, Australia, aged 28–32 years at the first time point and 32–36 at the second. Multinomial, linear, and binary regression analyses explored the association between resilience and SI over two time points. Models were adjusted for suicidality risk factors. Results: While unadjusted analyses identified associations between resilience and SI, these effects were fully explained by the inclusion of other suicidality risk factors. Conclusion: Despite strong cross-sectional associations, resilience and SI appear to be unrelated in a longitudinal context, once risk/resilience factors are controlled for. As independent indicators of psychological well-being, suicidality and resilience are essential if current status is to be captured. However, the addition of other factors (e.g., support, mastery) makes this association tenuous. Consequently, resilience per se may not be protective of SI.
White matter lesions (WMLs), seen as hyperintensities on T2-weighted magnetic resonance imaging b... more White matter lesions (WMLs), seen as hyperintensities on T2-weighted magnetic resonance imaging brain scans, are common in the brains of healthy older individuals. They are thought to be related to cerebral small vessel disease and to have a genetic component to their aetiology, and hypertension is thought to be an important risk factor. Genetic polymorphisms in hypertension-related genes may therefore be associated with the formation of WMLs. In this study, a sample of 445 Australians aged 60-65 years was drawn from a larger longitudinal epidemiological study, the Personality and Total Health Through Life Project. The associations of single nucleotide polymorphisms (SNPs) in the genes encoding angiotensinogen (AGT, rs699), angiotensin-converting enzyme (ACE, rs4362), and angiotensin II receptor type 1 (AGTR1, rs5182) with WMLs were examined. No individual SNPs showed a significant association with WMLs for the whole sample. When the cohort was stratified by sex, ACE rs4362 and AGT ...
Understanding of the origins of adolescent antisocial behaviour is important for two reasons. Fir... more Understanding of the origins of adolescent antisocial behaviour is important for two reasons. First, crime is a source of concern and cost to many communities throughout the world as well as Australia. Second, clear identification of the pathways to crime lead to the possibility of early prevention programs. This essay, based on a large longitudinal study of Queensland children, reports
Australian and New Zealand Journal of Psychiatry, 2004
Objective: To outline the strengths and limitations of longitudinal research designs in psychiatr... more Objective: To outline the strengths and limitations of longitudinal research designs in psychiatry, and to describe different types of longitudinal designs and methods for analyzing longitudinal data. Method: Key references on longitudinal methods were reviewed and examples drawn from literature in psychiatry and psychology. Results: Longitudinal studies provide important information regarding the incidence and developmental trajectories of mental disorders. They allow for identification of risk factors and developmental concomitants. Recent developments in statistical methods for analyzing longitudinal data provide efficient estimates of change and predictors of change over time, identification and characteristics of distinct subgroups defined by change pattern, and improved methods for obtaining unbiased population estimates when data are incomplete. Conclusion: Longitudinal designs, methods and analysis can contribute to psychiatric studies on risk factors for common mental disorders, studies of early intervention and prevention and treatment outcomes.
Purpose: The purpose of this article was to investigate the role of control beliefs in mediating ... more Purpose: The purpose of this article was to investigate the role of control beliefs in mediating the relationship between driving cessation and change in depressive symptoms in a population-based sample of older adults. Design and Methods: We report results from a prospective, community-based cohort study that included two waves of data collected in 1992 and 1994. Participants consisted of 700 men and women aged 70 and older, including 647 drivers and 53 participants who ceased driving between baseline (1992) and follow-up (1994). Participants took part in interviews that included assessments of driving status, sociodemographic characteristics, self-rated health, sensory function, depressive symptoms (through the Center for Epidemiologic Studies-Depression scale), and expectancy of control. Using multilevel general linear models, we examined the extent to which driving status, expectancy of control, and relevant covariates explained change in depressivesymptom scores between baseline and follow-up.
Intraindividual variability in cognitive test performance has the potential to be a good marker o... more Intraindividual variability in cognitive test performance has the potential to be a good marker of preclinical Alzheimer's disease status (S. C. Li & U. Lindenberger, 1999). Using cross-sectional community data from 2,317 individuals aged 60-64 years, the authors of this study found that variability was greater in individuals who met criteria for mild cognitive impairment or aging-associated cognitive decline but not for age-associated memory impairment. Higher variability was associated with lower education and a non-English-speaking background. In contrast to previous findings, variability in this study did not contribute uniquely to meeting criteria for mild cognitive impairment. The reasons for the differences may reside in the authors' method of estimating mean independent variability, the use of an occasion-specific measure, or the relatively younger age of the participants. Follow-up of the cohort in 4 years will yield data on the prospective validity of variability as a risk factor for impairment.
Purpose: Research concerned with the relationship between volunteer activity and psychological we... more Purpose: Research concerned with the relationship between volunteer activity and psychological wellbeing has typically reported higher levels of wellbeing among older adult volunteers relative to nonvolunteers. However, few studies have examined nonlinear associations between frequency of volunteer activity and well-being. We examined nonlinear associations between hours spent volunteering and psychological well-being, controlling for employment status, partner status, physical health, and education. We also investigated associations between different domains of volunteer activity and well-being, along with the possible moderating effects of gender on these relationships. Design and Methods: We used data from the PATH Through Life Project, a populationbased study of Australian adults. Participants consisted of 2,136 older adults aged 64 to 68. Results: Nonlinear associations between hours spent volunteering and psychological well-being were evident, with these associations characterized by inverted U shapes, with nonvolunteers and those volunteering at high levels producing lower well-being scores relative to those volunteering at moderate levels. Few associations between specific domains of volunteer activity and well-being were evident, and no notable gender interactions emerged. Implications: The results point toward optimal frequency of engagement in volunteer activity for psychological well-being as being bounded by upper and lower levels, outside of which benefits to well-being diminish.
Recent cross-sectional research in cognitive aging has demonstrated a robust association between ... more Recent cross-sectional research in cognitive aging has demonstrated a robust association between visual acuity, auditory thresholds and cognitive performance in old age. However, the nature of the association is still unclear, particularly with respect to whether sensory and cognitive function are causally related. This study aimed to determine whether marked declines in performance on screening measures of either visual acuity or auditory thresholds have an effect on cognitive decline over 2 years. The sample from the Australian Longitudinal Study of Ageing (n = 2,087) were assessed in 1992 and 1994 on measures of sensory and cognitive function as part of a larger clinical assessment. A quasi-experimental design involving comparison of extreme groups using repeated measures MANCOVA with age as a covariate was used. Group performance on measures of hearing, memory, verbal ability and processing speed declined significantly. Decline in visual acuity had a significant effect on memory decline, but not on decline in verbal ability or processing speed. Decline in hearing was not associated with decline in any cognitive domain. The common association between visual acuity, auditory thresholds and cognitive function observed in cross-sectional studies appears to be disassociated in longitudinal studies.
Objective: We aimed to evaluate whether gender and different patterns of change in depressive sta... more Objective: We aimed to evaluate whether gender and different patterns of change in depressive status over 2 years were associated with different risks of mortality in the subsequent 6 years. Methods: Depression (CES-D) was assessed in 1947 participants in 1992 and a smaller proportion of the sample in 1994. The mortality risk at July 30, 2000, associated with depression and change in depression was estimated using proportional hazards models. Results: After controlling for demographic variables, smoking, alcohol, and medical conditions, depression was associated with mortality for men but not women. In men, incident depression was associated with mortality after controlling for all other variables. Chronic depression and remitted depression were also associated with mortality, but this effect was explained by medical conditions. In women, change in depressive status was not associated with mortality. Conclusions: Depression confers a greater risk of mortality for men than women with incident depression in old age representing the greatest risk for men. The course of depressive illness must be considered when evaluating mortality risk.
The relationships between alcohol consumption and dementia and cognitive decline were investigate... more The relationships between alcohol consumption and dementia and cognitive decline were investigated in a systematic review including meta-analyses of 15 prospective studies. Follow-ups ranged from 2 to 8 years. Meta-analyses were conducted on samples including 14,646 participants evaluated for Alzheimer disease (AD), 10,225 participants evaluated for vascular dementia (VaD), and 11,875 followed for any type of dementia (Any dementia). The pooled relative risks (RRs) of AD, VaD, and Any dementia for light to moderate drinkers compared with nondrinkers were 0.72 (95% CI = 0.61-0.86), 0.75 (95% CI = 0.57-0.98), and 0.74 (95% CI = 0.61-0.91), respectively. When the more generally classified "drinkers," were compared with "nondrinkers," they had a reduced risk of AD (RR = 0.66, 95% CI = 0.47-0.94) and Any dementia (RR = 0.53, 95% CI = 0.53-0.82) but not cognitive decline. There were not enough data to examine VaD risk among "drinkers." Those classified as heavy drinkers did not have an increased risk of Any dementia compared with nondrinkers, but this may reflect sampling bias. Our results suggest that alcohol drinkers in late life have reduced risk of dementia. It is unclear whether this reflects selection effects in cohort studies commencing in late life, a protective effect of alcohol consumption throughout adulthood, or a specific benefit of alcohol in late life.
Both brain atrophy and T2-weighted white matter hyperintensities (WMH) are common findings in the... more Both brain atrophy and T2-weighted white matter hyperintensities (WMH) are common findings in the brains of asymptomatic elderly individuals as well as in disease-specific brains. The study of the relationship between these two salient features is therefore important. To investigate such a relationship, we performed a brain magnetic resonance imaging (MRI) study on 397 asymptomatic individuals aged between 60 and 64 years, who were recruited randomly from a large community sample. WMH were delineated on T2-weighted fluid attenuation inversion recovery (FLAIR) whole brain scans using an automated procedure. The results showed that gray matter reduction, subarachnoid CSF (SA-CSF) increase and lateral ventricular dilation were significantly correlated with WMH load. Deep white matter hyperintensity (DWMH) had significant correlation with all three global atrophy indices, but periventricular white matter hyperintensity (PVWMH) was correlated only with gray matter volume. Voxel-based morphometric (VBM) analysis showed that regional gray matter reduction correlated more closely with WMH load of the proximate region than with WMH elsewhere. The results suggest that WMH have a relationship with brain atrophy in middle age, although the study cannot determine which process, i.e. the development of WMH or atrophy, is primary. The study also demonstrates that DWMH has a more significant relationship with structural brain changes, and may therefore be more functionally relevant than PVWMH. Further delineation of this relationship needs a longitudinal study of the changes in both WMH and indices of brain atrophy. D
We aimed to identify demographic, health, and biomarker correlates of reaction time performance a... more We aimed to identify demographic, health, and biomarker correlates of reaction time performance and to determine whether biomarkers explained age differences in reaction time performance. TIhe sample comprised three representative cohorts aged 20-24, 40-44, and 60-64 years, including a total of 7,485 participants. Reaction time measures of intraindividual variability and latency were used. The measure of intraindividual variability used was independent of mean reaction time. Older adults were more variable than younger adults in choice reaction time performance but not simple reaction time performance. The most important correlates of reaction time performance after gender and education were biological markers such as forced expiratory volume at one second, grip strength, and vision. Few measures of physical or mental health or lifestyle were associated with poorer performance on reaction time measures. Biomarkers explained the majority of age-related variance in simple reaction time and a large proportion of variance in choice reaction time. We conclude that for the ages studied, biomarkers are more important than health factors for explaining age differences in reaction time performance.
To determine whether cognitive performance, as distinct from cognitive impairment, predicts falli... more To determine whether cognitive performance, as distinct from cognitive impairment, predicts falling during an 8-year follow-up in a community-based sample of very old adults and to evaluate how cognitive change is associated with falling. Prospective cohort study including three waves of data collected in 1992, 1994, and 2000. Population based, with the baseline sample drawn from the electoral roll. Inclusion criteria were completion of at least three cognitive tests at baseline and completion of the falls questionnaire at Wave 6 (N=539). Assessments of health and medical conditions, visual acuity, cognitive function, functional reach, semitandem stand, and grip strength were conducted in 1992 (baseline), 1994, and 2000. Self-report information on falls in the previous 12 months was obtained on each of these occasions. Marginal models using generalized estimating equations were used to assess the association between baseline cognitive performance and falling over 8 years, adjusting for sociodemographic, health, and sensorimotor variables. Random effects models were used to assess the relationship between change in cognitive performance and change in fall rate and fall risk over 8 years. Mini-Mental State Examination and verbal reasoning at baseline predicted rate of falling over an 8-year period. Within individuals, declines in verbal ability, processing speed, and immediate memory were associated with increases in rates of falling and fall risk. Cognitive performance is associated with falling over 8 years in very old adults and should be assessed in clinical practice when evaluating short- and long-term fall risk.
Cross-sectional studies have identified a number of health and lifestyle factors that correlate w... more Cross-sectional studies have identified a number of health and lifestyle factors that correlate with cognitive function in old age. It is important to know whether these factors also predict change in cognitive function over time. To evaluate published findings on genetic, health and lifestyle predictors of cognitive change in late adulthood. Studies reporting data on education, health, blood pressure, activity and apolipoprotein E (APOE) as predictors of cognitive change were reviewed. A total of 34 studies were identified that reported data on these predictors. The average follow-up period of studies reviewed was 7.68 years. Results showed that education, hypertension, objective indices of health and cardiovascular disease, and APOE were associated with cognitive change. Results regarding the effect of physical activity on cognitive change were inconclusive. Despite the lack of data on some predictors, the longitudinal trends are generally consistent with cross-sectional findings on predictors of cognitive performance in old age. More research is required to compare the influence of predictors on different types of cognitive abilities.
The distinction between primary aging, representing innate maturational processes, and secondary ... more The distinction between primary aging, representing innate maturational processes, and secondary aging, representing the effects of environment and disease (Busse, 1969), was used to develop a model for the assessment of factors that are associated with age-related individual differences in intelligence. Intelligence was measured by performance on a number of tests that measure cognitive abilities known to decline with age. In a hierarchical multiple regression analysis, primary aging and education but not health explained a significant portion of the variance in fluid intelligence. Chronological age had a residual effect over and above that of primary and secondary aging, indicating that there was remaining age-associated variance unaccounted for in the proposed model. The results suggest that the model of primary and secondary aging is a valid means of operationalizing chronological age.
The authors investigated the association between sensorimotor variables indicative of biological ... more The authors investigated the association between sensorimotor variables indicative of biological aging and cognition. A community sample of 202 women ages 60-86 was assessed on 5 measures of lower limb strength, visual contrast sensitivity (VisCS), and reaction time (RT). Hierarchical multiple regression revealed that the sensorimotor variables explained age-related variance in measures of reasoning and total variance in measures of reasoning after education, health, mood, and physical activity were controlled for. It is concluded that in addition to better known predictors of cognitive aging, such as RT and VisCS, lower limb strength is an important predictor of performance on cognitive tests.
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Papers by Kaarin Anstey
effects were fully explained by the inclusion of other suicidality risk factors. Conclusion: Despite strong cross-sectional associations, resilience and SI appear to be unrelated in a longitudinal context, once risk/resilience factors are controlled for. As independent indicators of psychological
well-being, suicidality and resilience are essential if current status is to be captured. However, the addition of other factors (e.g., support, mastery) makes this association tenuous. Consequently, resilience per se may not be protective of SI.
effects were fully explained by the inclusion of other suicidality risk factors. Conclusion: Despite strong cross-sectional associations, resilience and SI appear to be unrelated in a longitudinal context, once risk/resilience factors are controlled for. As independent indicators of psychological
well-being, suicidality and resilience are essential if current status is to be captured. However, the addition of other factors (e.g., support, mastery) makes this association tenuous. Consequently, resilience per se may not be protective of SI.