Association between mortality and cognitive change over 7 years in a large representative sample of UK residents

Interaction between the animal-based dietary pattern and green space on cognitive function among Chinese older adults: A prospective cohort study

Green space is associated with better cognition, while the animal-based dietary pattern can be a risk factor. We aimed to verify the associations and explore their interaction among the elderly. The China Longitudinal Healthy Longevity Survey (CLHLS) cohort including 17,827 participants was used. The average green space coverage rate was used to measure green space exposure. The animal-based diet index (ADI) was scored based on the non-quantitative frequency questionnaire of ten types of food intake (three types of animal foods and seven types of plant foods). We used the Mini-Mental State Examination (MMSE) to assess cognitive function. The Cox proportional hazard regression was applied to explore the correlations and interactions. In the models, we gradually adjusted for the potential risk factors. Compared with participants living in the area with the lowest green space, those living with the highest were associated with a 20% decrease in the risk of cognitive impairment (hazard ratio (HR): 0.80, 95% CI: 0.73, 0.89). As for ADI, the highest group was related to a 64% increase in the risk of cognitive impairment (HR: 1.64, 95% CI: 1.38, 1.95). The protective effect of the highest green space group on cognitive impairment was more evident among participants with low ADI (HR = 0.72, 95% CI: 0.62, 0.83), compared to those with high ADI. Green space was positively associated with cognition, while the animal-based dietary pattern was a cognitive disadvantage. The animal-based dietary pattern may mitigate the beneficial effects of green space on cognition.

Is simple reaction time or choice reaction time an indicator of all-cause mortality or CVD mortality?

OBJECTIVES

Simple reaction time (SRT) and choice reaction time (CRT) have been shown to be good indicators for quantitatively assessing the level of human cognitive impairment, but these parameters have also been linked to the risk of human death. This study aimed to quantitatively assess the independent predictive value of SRT or CRT for all-cause mortality or cardiovascular disease (CVD) mortality by conducting a meta-analysis of prospective studies.

STUDY DESIGN

The study design of this study is a prospective cohort study.

METHODS

We conducted a meta-analysis by combining hazard ratios (HRs) and 95% confidence intervals (95% CIs) of SRT or CRT with all-cause mortality or CVD mortality in healthy community residents aged 18 and over. Heterogeneity was evaluated by using Q statistics and Cochrane's I² statistics.

RESULTS

A total of seven prospective studies that examined all-cause mortality and CVD mortality were included. The pooled HR of all-cause mortality in SRT was 1.099 (1.065-1.134, I² = 11.9%), and an increased risk of CVD mortality was associated with lower SRT (HR = 1.186, 95% CI = 1.137-1.236; I² = 52.4%). Similarly, the pooled HR of all-cause mortality in CRT was 1.140 (95% CI = 1.085-1.197, I² = 33.7%). However, lower CRT was not statistically associated with an increased risk of CVD mortality.

CONCLUSION

SRT may be a predictor of all-cause-mortality and CVD mortality, and CRT is significantly associated with an increased risk of all-cause mortality.

Association of change in cognitive function from early adulthood to middle age with risk of cause-specific mortality: the Vietnam Experience Study

BACKGROUND

Studies with single baseline measurements of cognitive function consistently reveal inverse relationships with mortality risk. The relation of change in functioning, particularly from early in the life course, which may offer additional insights into causality, has not, to the best of our knowledge, been tested.

AIMS

To examine the association of change in cognition between late adolescence and middle age with cause-specific mortality using data from a prospective cohort study.

METHODS

The analytical sample consisted of 4289 former US male military personnel who were administered the Army General Technical Test in early adulthood (mean age 20.4 years) and again in middle age (mean age 38.3 years).

RESULTS

A 15-year period of mortality surveillance subsequent to the second phase of cognitive testing gave rise to 237 deaths. Following adjustment for age, a 10-unit increase in cognitive function was related to a reduced risk of death from all causes (HR 0.84; 95% CI 0.75 to 0.93) and cardiovascular disease (HR 0.78; 95% CI 0.64 to 0.95) but not from all cancers (HR 1.14; 95% CI 0.88 to 1.47) nor injury (HR 1.02; 95% CI 0.81 to 1.29). Adjustment for markers of socioeconomic status in middle age resulted in marked attenuation in the magnitude of these associations and statistical significance at conventional levels was lost in all analyses.

CONCLUSIONS

In the present study, the apparent link between increased cognition and mortality was mediated by socioeconomic status.

Cognitive decline and mortality among community-dwelling Chinese older people

BACKGROUND

Whether cognitive decline is related to a higher risk of death independent of the initial cognitive function is inconclusive. Evidence of the association between cognitive decline and mortality among Chinese older people is limited. We aimed to examine whether cognitive decline, assessed by the rate of decrease in the Mini-Mental State Examination (MMSE) score, was associated with mortality independent of initial cognitive function (baseline MMSE score) among Chinese older people.

METHODS

We established two successive and non-overlapping cohorts of older adults nested within the Chinese Longitudinal Healthy Longevity Survey (CLHLS), an ongoing, open, community-based cohort survey conducted every 2-3 years. Cognitive function was measured using the Chinese version of the MMSE. A total of 11,732 older adults who completed two consecutive cognitive function examinations were included and followed for 3 years. A Cox proportional hazards model was used to examine the association of cognitive decline with mortality after adjusting for sociodemographic characteristics, health behaviours, comorbidities and initial cognitive function.

RESULTS

The mean age was 82.5 years old, and 44.9% (5264/11732) of participants were men. After adjusting for baseline MMSE scores and other covariates, the rate of change in MMSE scores over 3 years was monotonically and positively associated with subsequent 3-year mortality. Compared to those with stable cognitive function, participants with rapid cognitive decline (decline faster than average, a reduction of MMSE scores > 1.62 points/year) had a 75% higher risk of death (hazard ratio = 1.75, 95% confidence interval 1.57-1.95). The association between cognitive decline and mortality was stronger among relatively younger Chinese older people (aged 65-79 years versus 80 years and over) and those with normal cognitive function at baseline (MMSE scores ≥ 24 versus < 24 points), respectively, but did not differ by cohort and sex.

CONCLUSION

Faster cognitive decline was associated with higher mortality independent of initial cognitive function, especially among those aged 65-79 years and those with normal cognitive function at baseline. The association was consistent across two successive cohorts. Our findings indicate the practical significance of monitoring cognitive change in older adults.

Is intraindividual reaction time variability an independent cognitive predictor of mortality in old age? Findings from the Sydney Memory and Ageing Study

Intraindividual variability of reaction time (IIV_RT), a proposed cognitive marker of neurobiological disturbance, increases in old age, and has been associated with dementia and mortality. The extent to which IIV_RT is an independent predictor of mortality, however, is unclear. This study investigated the association of IIV_RT and all-cause mortality while accounting for cognitive level, incident dementia and biomedical risk factors in 861 participants aged 70–90 from the Sydney Memory and Ageing Study. Participants completed two computerised reaction time (RT) tasks (76 trials in total) at baseline, and comprehensive medical and neuropsychological assessments every 2 years. Composite RT measures were derived from the two tasks—the mean RT and the IIV_RT measure computed from the intraindividual standard deviation of the RTs (with age and time-on-task effects partialled out). Consensus dementia diagnoses were made by an expert panel of clinicians using clinical criteria, and mortality data were obtained from a state registry. Cox proportional hazards models estimated the association of IIV_RT and mean RT with survival time over 8 years during which 191 (22.2%) participants died. Greater IIV_RT but not mean RT significantly predicted survival time after adjusting for age, sex, global cognition score, cardiovascular risk index and apolipoprotein ɛ4 status. After excluding incident dementia cases, the association of IIV_RT with mortality changed very little. Our findings suggest that greater IIV_RT uniquely predicts shorter time to death and that lower global cognition and prodromal dementia in older individuals do not explain this relationship.

Association of AKAP6 and MIR2113 with cognitive performance in a population-based sample of older adults

Genetic factors make a substantial contribution to inter-individual variability in cognitive function. A recent meta-analysis of genome-wide association studies identified two loci, AKAP6 and MIR2113, that are associated with general cognitive function. Here, we extend this previous research by investigating the association of MIR2113 and AKAP6 with baseline and longitudinal non-linear change across a broad spectrum of cognitive domains in a community-based cohort of older adults without dementia. Two single nucleotide polymorphisms (SNPs), MIR211-rs10457441 and AKAP6-rs17522122 were genotyped in 1570 non-demented older Australians of European ancestry, who were examined up to 4 times over 12 years. Linear mixed effects models were used to examine the association between AKAP6 and MIR2113 with cognitive performance in episodic memory, working memory, vocabulary, perceptual speed and reaction time at baseline and with linear and quadratic rates of change. AKAP6-rs17522122*T was associated with worse baseline performance in episodic memory, working memory, vocabulary and perceptual speed, but it was not associated with cognitive change in any domain. MIR2113-rs10457441*T was associated with accelerated decline in episodic memory. No other associations with baseline cognitive performance or with linear or quadratic rate or cognitive changes were observed for this SNP. These results confirm the previous finding that AKAP6 is associated with performance across multiple cognitive domains at baseline but not with cognitive decline, while MIR2113 primarily affects the rate at which memory declines over time.

Opportunities for longitudinal data linkage in Scotland

Scotland has existing data resources which are competitive internationally and available to researchers from elsewhere. The Scottish Informatics and Linkage Collaboration (SILC) was recently launched, allowing data sets to be linked within and between sectors (e.g. health to non-health). The purpose of this review article is to introduce and define key terms in data linkage, to describe the emerging data linkage resources available in Scotland and to describe the opportunities available in Scotland to researchers internationally. The review is aimed at researchers internationally who are interested in data linkage using Scottish data resources. The review makes particular reference to longitudinal health data but emphasises that linkage to non-health data allows research questions to be considered that were previously not answerable. The review is focused on longitudinal data resources (e.g. cohort studies and repeated measures designs), since they are usually the focus of data linkage research. The review concludes that any intended data linkage for research should be driven by a clear research question. The infrastructure already available and the launch of SILC will accelerate research in Scotland and generate new research questions that previously could not be considered.

Computer-based tools for assessing micro-longitudinal patterns of cognitive function in older adults

Patterns of cognitive change over micro-longitudinal timescales (i.e., ranging from hours to days) are associated with a wide range of age-related health and functional outcomes. However, practical issues of conducting high-frequency assessments make investigations of micro-longitudinal cognition costly and burdensome to run. One way of addressing this is to develop cognitive assessments that can be performed by older adults, in their own homes, without a researcher being present. Here, we address the question of whether reliable and valid cognitive data can be collected over micro-longitudinal timescales using unsupervised cognitive tests.In study 1, 48 older adults completed two touchscreen cognitive tests, on three occasions, in controlled conditions, alongside a battery of standard tests of cognitive functions. In study 2, 40 older adults completed the same two computerized tasks on multiple occasions, over three separate week-long periods, in their own homes, without a researcher present. Here, the tasks were incorporated into a wider touchscreen system (Novel Assessment of Nutrition and Ageing (NANA)) developed to assess multiple domains of health and behavior. Standard tests of cognitive function were also administered prior to participants using the NANA system.Performance on the two "NANA" cognitive tasks showed convergent validity with, and similar levels of reliability to, the standard cognitive battery in both studies. Completion and accuracy rates were also very high. These results show that reliable and valid cognitive data can be collected from older adults using unsupervised computerized tests, thus affording new opportunities for the investigation of cognitive.

Long-term Cognitive Trajectories and Mortality in Older Women

BACKGROUND

Few studies have examined whether change in cognition is linked to mortality. This study examined the relationship between cognitive trajectories in older age and risk of death.

METHODS

We studied community-dwelling, nondemented women aged 65+ (mean age = 71) enrolled in a prospective study of aging and followed up to 25 years. A modified Mini-Mental State Examination (mMMSE) and Trail Making Task Part B (TMTB) were administered at multiple visits during follow-up. We examined the association between cognitive trajectories (analyzed by quintiles) from baseline to age 80 (n = 7,477 for mMMSE and n = 6,503 for TMTB) and all-cause mortality after age 80 using Cox regression models, both unadjusted and adjusted for education, physical activity, alcohol, depression score, current smoking and history of hypertension and diabetes. Cause of death was determined from death certificates, classified as cardiovascular, cancer and other.

RESULTS

Women with greater rate of decline were older, less educated, less physically active, had higher depression score and were more likely to have a history of hypertension and diabetes (all p < .01). Participants with the greatest decline (quintile 1) had an increased risk of death (mMMSE hazard ratio [HR] = 1.28; TMTB HR = 1.43] and those with the least decline (quintile 5) had a decreased risk of death (mMMSE HR = 0.73; TMTB HR = 0.61) compared with intermediate decliners (quintiles 2-4). Cognitive trajectories were associated with cardiovascular mortality and other causes of death, but not cancer deaths.

CONCLUSIONS

Our study suggests that greater decline in general cognition or executive function is associated with higher rates of mortality in oldest-old women.

Association of dementia with death after ischemic stroke: A two-year prospective study

The association between dementia and the risk of death after ischemic stroke was investigated. Neurological, neuropsychological and functional assessments were evaluated in 619 patients with acute ischemic stroke. Dementia was diagnosed at admission and at three months after stroke onset. The patients were scheduled for a two-year follow-up after the index stroke. The Kaplan-Meier survival and Cox proportional hazards regression analyses were used to estimate the cumulative proportion of survival, and the association between dementia and risk of death after stroke. In total, 146 patients (23.6%) were diagnosed with dementia after stroke. The cumulative proportion of surviving cases was 49.3% in patients with dementia after a median follow-up of 21.2±5.6 months, and 92.5% in patients without dementia. Multivariate analysis revealed that dementia (HR, 7.21; 95% CI, 3.85–13.49) was associated with death, independent of age, atrial fibrillation, previous stroke and NIH stroke scale. In conclusion, the mortality rate is increased in stroke patients with dementia. Dementia is an important risk factor for death after stroke, independent of age, atrial fibrillation, previous stroke, and the severity of the stroke.

A proposed panel of biomarkers of healthy ageing

BACKGROUND

There is no criterion reference for assessing healthy ageing and this creates difficulties when conducting and comparing research on ageing across studies. A cardinal feature of ageing is loss of function which translates into wide-ranging consequences for the individual and for family, carers and society. We undertook comprehensive reviews of the literature searching for biomarkers of ageing on five ageing-related domains including physical capability and cognitive, physiological and musculoskeletal, endocrine and immune functions. Where available, we used existing systematic reviews, meta-analyses and other authoritative reports such as the recently launched NIH Toolbox for assessment of neurological and behavioural function, which includes test batteries for cognitive and motor function (the latter described here as physical capability). We invited international experts to comment on our draft recommendations. In addition, we hosted an experts workshop in Newcastle, UK, on 22-23 October 2012, aiming to help capture the state-of-the-art in this complex area and to provide an opportunity for the wider ageing research community to critique the proposed panel of biomarkers.

DISCUSSION

Here we have identified important biomarkers of healthy ageing classified as subdomains of the main areas proposed. Cardiovascular and lung function, glucose metabolism and musculoskeletal function are key subdomains of physiological function. Strength, locomotion, balance and dexterity are key physical capability subdomains. Memory, processing speed and executive function emerged as key subdomains of cognitive function. Markers of the HPA-axis, sex hormones and growth hormones were important biomarkers of endocrine function. Finally, inflammatory factors were identified as important biomarkers of immune function. We present recommendations for a panel of biomarkers that address these major areas of function which decline during ageing. This biomarker panel may have utility in epidemiological studies of human ageing, in health surveys of older people and as outcomes in intervention studies that aim to promote healthy ageing. Further, the inclusion of the same common panel of measures of healthy ageing in diverse study designs and populations may enhance the value of those studies by allowing the harmonisation of surrogate endpoints or outcome measures, thus facilitating less equivocal comparisons between studies and the pooling of data across studies.

A proposed panel of biomarkers of healthy ageing

BACKGROUND

There is no criterion reference for assessing healthy ageing and this creates difficulties when conducting and comparing research on ageing across studies. A cardinal feature of ageing is loss of function which translates into wide-ranging consequences for the individual and for family, carers and society. We undertook comprehensive reviews of the literature searching for biomarkers of ageing on five ageing-related domains including physical capability and cognitive, physiological and musculoskeletal, endocrine and immune functions. Where available, we used existing systematic reviews, meta-analyses and other authoritative reports such as the recently launched NIH Toolbox for assessment of neurological and behavioural function, which includes test batteries for cognitive and motor function (the latter described here as physical capability). We invited international experts to comment on our draft recommendations. In addition, we hosted an experts workshop in Newcastle, UK, on 22-23 October 2012, aiming to help capture the state-of-the-art in this complex area and to provide an opportunity for the wider ageing research community to critique the proposed panel of biomarkers.

DISCUSSION

Here we have identified important biomarkers of healthy ageing classified as subdomains of the main areas proposed. Cardiovascular and lung function, glucose metabolism and musculoskeletal function are key subdomains of physiological function. Strength, locomotion, balance and dexterity are key physical capability subdomains. Memory, processing speed and executive function emerged as key subdomains of cognitive function. Markers of the HPA-axis, sex hormones and growth hormones were important biomarkers of endocrine function. Finally, inflammatory factors were identified as important biomarkers of immune function. We present recommendations for a panel of biomarkers that address these major areas of function which decline during ageing. This biomarker panel may have utility in epidemiological studies of human ageing, in health surveys of older people and as outcomes in intervention studies that aim to promote healthy ageing. Further, the inclusion of the same common panel of measures of healthy ageing in diverse study designs and populations may enhance the value of those studies by allowing the harmonisation of surrogate endpoints or outcome measures, thus facilitating less equivocal comparisons between studies and the pooling of data across studies.

Genetic contributions to variation in general cognitive function: a meta-analysis of genome-wide association studies in the CHARGE consortium (N=53949)

General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health- and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N=53,949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32 (best SNP and closest gene, respectively: rs10457441, P=3.93 × 10(-9), MIR2113; rs17522122, P=2.55 × 10(-8), AKAP6; rs10119, P=5.67 × 10(-9), APOE/TOMM40). We report one gene-based significant association with the HMGN1 gene located on chromosome 21 (P=1 × 10(-6)). These genes have previously been associated with neuropsychiatric phenotypes. Meta-analysis results are consistent with a polygenic model of inheritance. To estimate SNP-based heritability, the genome-wide complex trait analysis procedure was applied to two large cohorts, the Atherosclerosis Risk in Communities Study (N=6617) and the Health and Retirement Study (N=5976). The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e.=5%) and 28% (s.e.=7%), respectively. Using polygenic prediction analysis, ~1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N=5487; P=1.5 × 10(-17)). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer's disease: TOMM40, APOE, ABCG1 and MEF2C.

Cognitive impairment and risk of stroke: a systematic review and meta-analysis of prospective cohort studies

BACKGROUND AND PURPOSE

Cognitive impairment is linked to vascular risk factors and brain vascular pathologies. Several studies have tested whether subjects with cognitive impairment have higher risk for stroke. The aim of this study was to systematically review available evidence on the association between cognitive impairment and risk of stroke to obtain precise effect estimates of the association and to identify which cognitive domains associate most with incident stroke.

METHODS

PubMed, EMBASE, and Web of Science were searched from January 1, 1980, to October 1, 2013, without language restriction. Only prospective cohort studies were included. From each study, data on the association between cognitive impairment and stroke estimated with hazard ratios or relative risks with 95% confidence interval (CI) were extracted. For each study, risk of stroke per SD lower performance in various cognitive tests was calculated.

RESULTS

Twelve studies were included, comprising 82,899 participants of whom 3043 had an incident stroke. The pooled relative risk per SD lower global cognitive performance was 1.19 (95% CI, 1.12-1.27). Each SD lower score in executive function or attention was associated with 1.14-fold (95% CI, 1.06-1.24) higher risk of stroke. Lower scores in memory were associated with 1.07-fold (95% CI, 1.02-1.12) higher risk of stroke, and lower scores in language were associated with 1.08-fold (95% CI, 1.02-1.16) higher risk of stroke.

CONCLUSIONS

Cognitive impairment is associated with higher risk of stroke. The associations were not significantly different for executive function, memory, and language.

Complex variation in measures of general intelligence and cognitive change

Combining information from multiple SNPs may capture a greater amount of genetic variation than from the sum of individual SNP effects and help identifying missing heritability. Regions may capture variation from multiple common variants of small effect, multiple rare variants or a combination of both. We describe regional heritability mapping of human cognition. Measures of crystallised (gc) and fluid intelligence (gf) in late adulthood (64-79 years) were available for 1806 individuals genotyped for 549,692 autosomal single nucleotide polymorphisms (SNPs). The same individuals were tested at age 11, enabling us the rare opportunity to measure cognitive change across most of their lifespan. 547,750 SNPs ranked by position are divided into 10, 908 overlapping regions of 101 SNPs to estimate the genetic variance each region explains, an approach that resembles classical linkage methods. We also estimate the genetic variation explained by individual autosomes and by SNPs within genes. Empirical significance thresholds are estimated separately for each trait from whole genome scans of 500 permutated data sets. The 5% significance threshold for the likelihood ratio test of a single region ranged from 17-17.5 for the three traits. This is the equivalent to nominal significance under the expectation of a chi-squared distribution (between 1 df and 0) of P<1.44×10(-5). These thresholds indicate that the distribution of the likelihood ratio test from this type of variance component analysis should be estimated empirically. Furthermore, we show that estimates of variation explained by these regions can be grossly overestimated. After applying permutation thresholds, a region for gf on chromosome 5 spanning the PRRC1 gene is significant at a genome-wide 10% empirical threshold. Analysis of gene methylation on the temporal cortex provides support for the association of PRRC1 and fluid intelligence (P = 0.004), and provides a prime candidate gene for high throughput sequencing of these uniquely informative cohorts.

Towards measurement of the Healthy Ageing Phenotype in lifestyle-based intervention studies

INTRODUCTION

Given the biological complexity of the ageing process, there is no single, simple and reliable measure of how healthily someone is ageing. Intervention studies need a panel of measures which capture key features of healthy ageing. To help guide our research in this area, we have adopted the concept of the "Healthy Ageing Phenotype" (HAP) and this study aimed to (i) identify the most important features of the HAP and (ii) identify/develop tools for measurement of those features.

METHODS

After a comprehensive assessment of the literature we selected the following domains: physiological and metabolic health, physical capability, cognitive function, social wellbeing, and psychological wellbeing which we hoped would provide a reasonably holistic characterisation of the HAP. We reviewed the literature and identified systematic reviews and/or meta-analysis of cohort studies, and clinical guidelines on outcome measures of these domains relevant to the HAP. Selection criteria for these measures included: frequent use in longitudinal studies of ageing; expected to change with age; evidence for strong association with/prediction of ageing-related phenotypes such as morbidity, mortality and lifespan; whenever possible, focus on studies measuring these outcomes in populations rather than on individuals selected on the basis of a particular disease; (bio)markers that respond to (lifestyle-based) intervention. Proposed markers were exposed to critique in a Workshop held in Newcastle, UK in October 2012.

RESULTS

We have selected a tentative panel of (bio)markers of physiological and metabolic health, physical capability, cognitive function, social wellbeing, and psychological wellbeing which we propose may be useful in characterising the HAP and which may have utility as outcome measures in intervention studies. In addition, we have identified a number of tools which could be applied in community-based intervention studies designed to enhance healthy ageing.

CONCLUSIONS

We have proposed, tentatively, a panel of outcome measures which could be deployed in community-based, lifestyle intervention studies. The evidence base for selection of measurement domains is less well developed in some areas e.g. social wellbeing (where the definition of the concept itself remains elusive) and this has implications for the identification of appropriate tools. Although we have developed this panel as potential outcomes for intervention studies, we recognise that broader agreement on the concept of the HAP and on tools for its measurement could have wider utility and e.g. could facilitate comparisons of healthy ageing across diverse study designs and populations.

Investigating terminal decline: results from a UK population-based study of aging

The terminal decline hypothesis states that in the proximity of death, an individual's decline in cognitive abilities accelerates. We aimed at estimating the onset of faster rate of decline in global cognition using Mini Mental State Examination (MMSE) scores from participants of the Cambridge City over 75 Cohort Study (CC75C), a U.K. population-based longitudinal study of aging where almost all participants have died. The random change point model fitted to MMSE scores structured as a function of distance to death allowed us to identify a potentially different onset of change in rate of decline before death for each individual in the sample. Differences in rate of change before and after the onset of change in rate of decline by sociodemographic variables were investigated. On average, the onset of a faster rate of change occurred about 7.7 years before death and varied across individuals. Our results show that most individuals experience a period of slight decline followed by a much sharper decline. Education, age at death, and cognitive impairment at study entry were identified as modifiers of rate of change before and after change in rate of decline. Gender differences were found in rate of decline in the final stages of life. Our study suggests that terminal decline is a heterogeneous process, with its onset varying between individuals.

Neuroticism combined with slower and more variable reaction time: synergistic risk factors for 7-year cognitive decline in females

OBJECTIVE

Among adults, slower and more variable reaction times are associated with worse cognitive function and increased mortality risk. Therefore, it is important to elucidate risk factors for reaction time change over the life course. Method. Data from the Health and Lifestyle Survey (HALS) were used to examine predictors of 7-year decline in reaction time (N = 4,260). Regression-derived factor scores were used to summarize general change across 4 reaction time variables: simple mean, 4-choice mean, simple variability, and 4-choice variability (53.52% of variance).

RESULTS

Age (B = .02, p < .001) and HALS1 baseline reaction time (B = -.10, p = .001) were significant risk factors for males (N = 1,899). In addition to these variables, in females (N = 2,361), neuroticism was significant and interacted synergistically with baseline reaction time (B = .06, p = .04). Adjustment for physiological variables explained the interaction with neuroticism, suggesting that candidate mechanisms had been identified. Discussion. A priority for future research is to replicate interactions between personality and reaction time in other samples and find specific mechanisms. Stratification of population data on cognitive health by personality and reaction time could improve strategies for identifying those at greater risk of cognitive decline.

Social origin, schooling and individual change in intelligence during childhood influence long-term mortality: a 68-year follow-up study

Background Intelligence at a single time-point has been linked to health outcomes. An individual's IQ increases with longer schooling, but the validity of such increase is unclear. In this study, we assess the hypothesis that individual change in the performance on IQ tests between ages 10 and 20 years is associated with mortality later in life.

Methods The analyses are based on a cohort of Swedish boys born in 1928 (n = 610) for whom social background data were collected in 1937, IQ tests were carried out in 1938 and 1948 and own education and mortality were recorded up to 2006. Structural equation models were used to estimate the extent to which two latent intelligence scores, at ages 10 and 20 years, manifested by results on the IQ tests, are related to paternal and own education, and how all these variables are linked to all-cause mortality.

Results Intelligence at the age of 20 years was associated with lower mortality in adulthood, after controlling for intelligence at the age of 10 years. The increases in intelligence partly mediated the link between longer schooling and lower mortality. Social background differences in adult intelligence (and consequently in mortality) were partly explained by the tendency for sons of more educated fathers to receive longer schooling, even when initial intelligence levels had been accounted for.

Conclusions The results are consistent with a causal link from change in intelligence to mortality, and further, that schooling-induced changes in IQ scores are true and bring about lasting changes in intelligence. In addition, if both these interpretations are correct, social differences in access to longer schooling have consequences for social differences in both adult intelligence and adult health.

A novel clinical test of recognition reaction time in healthy adults

We evaluated a clinical "go/no-go" reaction time test (recognition RTclin) that is portable and does not require a computer, and used it to quantify the effect of age on recognition RTclin test scores. Fifty-two healthy adults 19-83 years old completed simple and recognition RTclin testing. Simple RTclin was measured as the elapsed time from initial release of a suspended vertical shaft by the examiner until its arrest by participant pinch grip. Recognition RTclin was similar except that a light on the apparatus randomly illuminated in 50% of the trials to signal the participant to arrest the device. To help interpret the RTclin results, we partitioned them into premovement time (PMT) and movement time (MT) using an optoelectronic camera system that is not ordinarily part of the RTclin test. Recognition RTclin scores were significantly slower than simple RTclin scores, with 71% of the prolongation attributable to PMT. While simple RTclin test scores correlated with age, recognition RTclin scores did not. A strong negative association between recognition RTclin accuracy and age was found. Recognition RTclin is feasible to measure in healthy adults and appears to represent a portable, computer-independent measure of cognitive processing speed and inhibitory capacity. Potential applications include assessment of brain injury, dementing illness, medication side effects, fall risk, and safe driving.

Influence of biopsychosocial factors on the survival of the elderly in northeast Brazil-a prospective study

Background. Identifying the risk factors peculiar to each population has a great relevance, because it enables health policy formulators to analyze information accurately and by doing so, define objectives and action programs aimed at a qualitative and economically feasible solution to the problem. Thus, this study aimed at identifying the risk factors for survival in elderly in a city in the state of Rio Grande do Norte (RN), Brazil. Methods. A prospective study was carried out, where 310 elderly persons were selected to form a baseline. The follow-up was 53 months. The predictive variables were divided into sociodemographic, physical health, neuropsychiatric and functional capacity. Statistical analysis was performed using bivariate analysis, survival analysis, followed by Cox regression in the multivariate analysis. Results. A total of 60 (19.3%) elderly individuals died during the follow-up. The survival mean was 24.8 months. In the Cox analysis, dependence in basic activities of daily living (HR = 3.55), cognitive deficit (HR = 4.22) and stroke (HR = 3.35) continued as independent risk factors for death. Discussion. The risk factors found in the study can be interpreted as the primary predictors for death among elderly members of the community.

Cognition and incident coronary heart disease in late midlife: The Whitehall II study

The purpose of this study was to investigate whether cognitive function in midlife predicts incident coronary heart disease (CHD), followed up over 6 years. Data on 5292 (28% women, mean age 55) individuals free from CHD at baseline were drawn from the British Whitehall II study. We used Cox regression to model the association between cognition and CHD in analyses adjusted for socio-demographic variables, cardiovascular risk factors and health behaviors. The results show a one standard deviation lower score on the "general" cognitive measure and measures of reasoning and vocabulary to be associated with elevated CHD risk. There was some evidence that these effects differed between high and low socioeconomic status (SES) groups with associations only seen in the low SES group. These results were not explained by threshold effects or by the different SES groups representing different parts of the cognitive test score distribution. Three other possible explanations of these results are discussed: sub clinical vascular disease drives the observed association but no effect is observed in the high SES group due to compensation provided by greater cognitive reserve, cognition is a marker of overall bodily integrity particularly in low-SES groups, and SES is a moderator of the association between cognition and CHD, because it marks a range of other risk factors.

[Impact of cognitive deficit on survival among elderly residents in the community]

OBJECTIVE

To analyze cognitive deficit as a risk factor for death in elderly residents in the community and its relationship with variables related to sociodemographic factors, physical health, and functional capacity.

MATERIAL AND METHODS

A prospective study was carried out in the city of Santa Cruz, Brazil, in 310 randomly selected elderly individuals who were followed-up for 53 months. Predictive factors were sociodemographic and neuropsychiatric variables, physical health, and functional capacity. The statistical methods used were bivariate analysis (survival analysis), and Cox regression (multivariate analysis) with respective hazard ratios (HR). A value of P<.05 was considered statistically significant and 95% confidence intervals (CI) were calculated.

RESULTS

A total of 60 (20.5%) elderly residents died during the study. The main cause of death was cardiovascular disease. The mean time until death was approximately 24.8 months. The main risk factors identified in Cox analysis were cognitive deficit (HR=4.22), stroke (HR=3.08) and dependency for basic activities of daily living (HR=3.55).

CONCLUSIONS

Cognitive deficit is an independent risk factor for death. The results of the present study could be useful in formulating future health policies aiming to reduce mortality in the elderly.

Is retaining the youthful functional anatomy underlying speed of information processing a signature of successful cognitive ageing? An event-related fMRI study of inspection time performance

It has been hypothesized that individual differences in cognitive ageing might in part be based on the relative preservation of speed of information processing. However, the biological foundations of processing speed are not understood. Here we compared two groups of non-demented older people who had relatively similar IQs at age 11 but differed markedly in non-verbal reasoning ability at age 70: 'cognitive sustainers' (n=25), and 'cognitive decliners' (n=15). Using an event-related fMRI design, we studied the BOLD response while they performed an inspection time task. Inspection time is a two-alternative forced choice, backward masking test of the speed of the early stages of visual information processing. Inspection time has a well-established, significant association with higher cognitive abilities. The group of cognitive sustainers showed a pattern of BOLD activation-deactivation in response to inspection time stimulus duration differences that was similar to a healthy young sample [Deary, I.J., Simonotto, E., Meyer, M., Marshall, A., Marshall, I., Goddard, N., Watdlaw, J.M., 2004a. The functional anatomy of inspection time: an event-related fMRI study. NeuroImage 22, 1466-1479]. The group of cognitive decliners lacked these clear neural networks. The relative preservation of complex reasoning skills in old age may be associated with the preservation of the neural networks that underpin fundamental information processing in youth.