Occupational characteristics and cognitive performance among elderly male twins

The Mediating Effects of Education and Occupational Complexity Between Race and Longitudinal Change in Late Life Cognition in ACTIVE

This study examined educational and occupational inequality as two aspects of social determinants of health that might mediate the longitudinal relationship between racialization and late life cognitive level and change. Participants were 2371 individuals racialized as Black and White from the ACTIVE study who provided occupational data. Data were analyzed from baseline and five assessments over 10-years using structural equation modeling. Black/White race served as the predictor, occupational complexity (OC) and years of education as mediators, and cognitive (memory, reasoning, and speed of processing) intercept, linear slope, and quadratic slope as the dependent variables. Black/White race showed significant indirect associations through education and OC on level of performance in cognition, linear change in reasoning and memory, and quadratic change in reasoning. Education and OC accounted for 11-16% of the association between race and cognitive level and represent modifiable social determinants of health that are associated with disparities in cognitive aging.

Rural-Urban Differences in Cognition: Findings From the Advanced Cognitive Training for Independent and Vital Elderly Trial

ObjectivesWe examined associations between three geographic areas (urban, suburban, rural) and cognition (memory, reasoning, processing speed) over a 10-year period. Methods: Data were obtained from 2539 participants in the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) trial. Multilevel, mixed-effects linear regression was used to estimate cognitive trajectories by geographical areas over 10 years, after adjusting for social determinants of health. Results: Compared to urban and suburban participants, rural participants fared worse on all cognitive measures-memory (B = -1.17 (0.17)), reasoning (B = -1.55 (0.19)), and processing speed (B = 0.76 (0.19)) across the 10-year trajectory. Across geographic areas, greater economic stability, health care access and quality, and neighborhood resources were associated with better cognition over time. Discussion: Findings highlight the importance of geographical location when examining cognition later in life. More research examining place-based life experiences is needed to make the greatest impact on geographically diverse communities.

Predictors of cognitive functioning trajectories among older Americans: A new investigation covering 20 years of age- and non-age-related cognitive change

Despite the extensive study of predictors of cognitive decline in older age, a key uncertainty is how much these predictors explain both the intercept and age- and non-age-related change in cognitive functioning (CF). We examined the contribution of a broad range of life course determinants to CF trajectories. Data came from 7,068 participants in the 1996-2016 Health and Retirement Study. CF was measured as a summary score on a 27-point cognitive battery of items. We estimated multilevel growth curve models to examine the CF trajectories in individuals ages 54-85. We found that the variation in CF level at age 54 was three times as much as the variation in age slope. All the observed individual predictors explained 38% of the variation in CF at age 54. Personal education was the most important predictor (25%), followed by race, household wealth and income, parental education, occupation, and depression. The contributions of activity limitations, chronic diseases, health behaviors (obesity, smoking, vigorous activity), childhood conditions (childhood health, nutrition, financial situation), gender, marital status, and religion were rather small (<5%). Even though the age slope varied with many adulthood factors, they only explained 5.6% of the between-person variation in age slope. Moreover, age explained 23% of within-person variation in CF from age 54 to 85. The rest non-age-related within-person variation could not be explained by the observed time-varying factors. These findings suggest that future research is urgently needed to discover the main determinants of the slope of cognitive decline to slow down the progression of cognitive impairment and dementia.

Benefits of volunteerism for middle-aged and older adults: comparisons between types of volunteering activities

Volunteering is a popular activity among middle-aged and older adults as means to contribute to the society and to maintain personal health and wellbeing. While the benefits of volunteering have been well-documented in the current literature, it does not tend to distinguish between various types of volunteering activities. This cross-sectional study aims to compare the effects of instrumental (e.g. food preparation, fundraising) and cognitively demanding volunteering activities (e.g. befriending, mentoring) in a sample of 487 middle-aged and older Hong Kong Chinese adults. Participation in instrumental and cognitively demanding volunteering, life satisfaction, depressive symptoms, cognitive functioning and hand-grip strength were measured. The results of two-way between-subject robust analyses of variance demonstrated significant main effects of volunteering type and their interaction effect with age on life satisfaction and depressive symptoms. Comparisons among four volunteering groups (no volunteering, instrumental volunteering, cognitively demanding volunteering and both types) revealed that individuals engaging in instrumental volunteering exhibited lower life satisfaction and more depressive symptoms compared to those who engaged in cognitively demanding volunteering and those who did not volunteer at all. This detrimental pattern of instrumental volunteering was only seen in middle-aged adults, but not in older adults. Findings of this study revealed distinctive effects of two volunteering types, and provide valuable directions for designing future volunteering programmes.

Organizational Justice and Cognitive Failures in Japanese Employees: A Cross-Sectional Study

OBJECTIVE

We examined the association of organizational justice (ie, procedural justice and interactional justice) with cognitive failures, and the mediation effect of psychological distress on this association in Japanese employees.

METHODS

A total of 189 men and 35 women from two sites of a manufacturing company in Japan were surveyed using a self-administered web-based questionnaire. A multiple mediation analysis was conducted.

RESULTS

A significant negative total effect of procedural justice on cognitive failures was observed (c = -0.180 [95% confidence interval: -0.315 to -0.044]). Furthermore, the mediation effect of psychological distress was significant (c-c' = -0.213 [95% confidence interval: -0.323 to -0.115]). Similar patterns were observed for interactional justice.

CONCLUSIONS

Employees may be more likely to experience cognitive failures in daily activities in work settings where organizational justice is lower, which seems to be explained by psychological distress.

Reproductive aging and executive functions in healthy women

The aim of this study was to analyze the influence of reproductive aging on executive functions. We assessed executive functions in three groups of healthy women in the premenopausal (n = 45, mean age = 30.89, SD = 10.5), perimenopausal (n = 31, mean age = 50.06, SD = 3.6) and postmenopausal (n = 24, mean age = 63.39, SD = 6.5) phase. No differences between groups were observed in working memory, verbal fluency, inhibitory control, planning, and cognitive flexibility. However, when the analyses were repeated with participants with occupations with lower intellectual demands, perimenopausal and postmenopausal women performed worse than premenopausal women in semantic verbal fluency. This study provides important evidence to understand the effects of reproductive aging on cognitive performance in healthy women. Our findings indicate that cognitive reserve-related factors may be important to understand the differences in executive functions associated with reproductive aging.

Complexity of Work and Incident Cognitive Impairment in Puerto Rican Older Adults

OBJECTIVE

We investigated complexity of work in main occupation in relation to incident cognitive impairment in older Puerto Ricans.

METHOD

A population-based sample of 1,673 adults age 60+ for the Puerto Rican Elderly: Health Conditions (PREHCO) study was used. Cognition was measured at baseline and 4 years later using the Mini-Mental Cabán (MMC), with scoring 1.5 SD below the MMC score adjusted for age, education, gender, and reading ability comprising cognitive impairment. Complexity scores were derived from the 1970 U.S. Census, 1977 and 2000 Dictionary of Occupational Titles, and 2001 O*Net.

RESULTS

Controlling for baseline age, gender, childhood economic hardship, adult money problems, depressive symptoms, and self-reported health, greater scores for most work complexity measures were associated with significantly lower risk of cognitive impairment (ps < .05), with significant odds ratios ranging between 0.74, reflecting 26% reduction in risk for every extra standard deviation of complexity, and 0.81. Controlling for education reduced these effects slightly but also reduced most associations to nonsignificant. The results were stronger for those with less childhood economic hardship or education (ps < .05).

DISCUSSION

Complexity of work may reduce risk of cognitive impairment in Puerto Rican older adults, especially when combined with favorable childhood economic conditions and higher educational attainment.

Concepts of Mental Demands at Work That Protect Against Cognitive Decline and Dementia: A Systematic Review

Objective:

Workplace-related mental demands (WPMDs) are considered to be protective factors for cognitive health in old age and are linked to delayed onset of dementia. Yet, what exactly is meant by WPMDs differs greatly between studies, putting an enormous challenge on researchers and practitioners. Aim of our study was thus to create a systematic overview on WPMD concepts and to depict their associations with dementia and cognitive decline. Thereby, we want to create a solid basis for further work and implementation.

Data Source:

PubMed, PsycINFO, Web of Science.

Inclusion/Exclusion Criteria:

We included observational studies with populations older than 18 that addressed the association between WPMDs and dementia/cognitive functioning and that were published as journal articles. We excluded studies with emotional and physical demands, stress, and organizational frameworks such as exposure variables and quality of life, depressive symptoms, burnout, and Parkinson as outcome. Furthermore, we excluded study populations younger than 18 and students.

Data Extraction:

Standardized search string.

Data Synthesis:

Based on theoretical concepts.

Results:

Thirty-four studies that employed concepts of WPMDs in 5 different categories: complexity with people/data/things, cognitive demands, job control, novelty, and mental workload.

Discussion:

Challenges associated with categorizing WPMDs as well as theoretical and measurement-related implications are discussed.

Conclusion:

This review helps to better understand how workplaces can contribute to later life cognitive fitness, and it offers a conceptual overview for practitioners that want to create more protective working environments or improve existing ones.

Successful Memory Aging

For more than 50 years, psychologists, gerontologists, and, more recently, neuroscientists have considered the possibility of successful aging. How to define successful aging remains debated, but well-preserved age-sensitive cognitive functions, like episodic memory, is an often-suggested criterion. Evidence for successful memory aging comes from cross-sectional and longitudinal studies showing that some older individuals display high and stable levels of performance. Successful memory aging may be accomplished via multiple paths. One path is through brain maintenance, or relative lack of age-related brain pathology. Through another path, successful memory aging can be accomplished despite brain pathology by means of efficient compensatory and strategic processes. Genetic, epigenetic, and lifestyle factors influence memory aging via both paths. Some of these factors can be promoted throughout the life course, which, at the individual as well as the societal level, can positively impact successful memory aging.

Migration and cognitive function: a conceptual framework for Global Health Research

BACKGROUND

Migration is a fundamental demographic process that has been observed globally. It is suggested that migration is an issue of global health importance that can have an immediate and lasting impact on an individual's health and well-being. There is now an increasing body of evidence linking migration with cognitive function in older adults. In this paper, we synthesized the current evidence to develop a general conceptual framework to understand the factors contributing to the association between migration and cognitive function.

METHODS

A comprehensive review of the literature was conducted on the associations between migration and cognition among middle-aged and older adults.

RESULTS

Five potential mechanisms were identified from the literature: 1) socioeconomic status-including education, occupation, and income; 2) psychosocial factors-including social networks, social support, social stressors, and discrimination; 3) behavioral factors-including smoking, drinking, and health service utilization; 4) physical and psychological health status-including chronic conditions, physical function, and depression; and 5) environmental factors-including both physical and social environment. Several underlying factors were also identified-including early-life conditions, gender, and genetic factors.

CONCLUSIONS

The factors linking migration and cognitive function are multidimensional and complex. This conceptual framework highlights potential implications for global health policies and planning on healthy aging and migrant health. Additional studies are needed to further examine these mechanisms to extend and refine our general conceptual framework.

Occupational social and mental stimulation and cognitive decline with advancing age

Objective

this study investigates the role of social and mental occupational characteristics in cognitive decline after retirement.

Methods

the study included 1,048 subjects aged ≥65 years from the Three City cohort. Participants were evaluated at home at the initial visit and at 2-year intervals for a period of 12 years. The study includes detailed assessments of cognition, health and information about the subjects' main occupation. The four cognitive tests have been grouped into one latent factor. Three independent raters specialised in employment were asked to evaluate the level of social and intellectual stimulation for each occupation, which was then rated as low, medium and high.

Results

after controlling for potential confounding factors, no association was found between higher levels of social stimulation at work and baseline cognition (medium score, P = 0.440; high score, P = 0.700) as compared with a low level. While cognitive trajectories were initially similar between high and medium levels of social stimulation compared with that of a low level, with advancing age this association diverged whereby more social stimulation during work years was related to accelerated cognitive decline that further grew in magnitude with older age. For mental stimulation, differences were only observed at baseline, with greater levels of mental stimulation during work years being associated with better cognitive performance (medium score, β = 0.573, P = 0.015; and high score, β = 0.510; P = 0.090) compared with a low level of mental stimulation.

Conclusion

workers retiring from occupations characterised by high levels of social stimulation may be at risk of accelerated cognitive decline with advancing age.

Could High Mental Demands at Work Offset the Adverse Association Between Social Isolation and Cognitive Functioning? Results of the Population-Based LIFE-Adult-Study

OBJECTIVES

The study investigated whether high mental demands at work, which have shown to promote a good cognitive functioning in old age, could offset the adverse association between social isolation and cognitive functioning.

METHODS

Based on data from the population-based LIFE-Adult-Study, the association between cognitive functioning (Verbal Fluency Test, Trail Making Test B) and social isolation (Lubben Social Network Scale) as well as mental demands at work (O*NET database) was analyzed via linear regression analyses adjusted for age, sex, education, and sampling weights.

RESULTS

Cognitive functioning was significantly lower in socially isolated individuals and in individuals working in low mental demands jobs-even in old age after retirement and even after taking into account the educational level. An interaction effect suggested stronger effects of mental demands at work in socially isolated than nonisolated individuals.

CONCLUSIONS

The findings suggest that working in high mental-demand jobs could offset the adverse association between social isolation and cognitive functioning. Further research should evaluate how interventions that target social isolation and enhance mentally demanding activities promote a good cognitive functioning in old age.

Association between migration and cognitive status among middle-aged and older adults: a systematic review

Background

This study aimed to synthesize the current literature examining the association between migration and cognitive function among middle-aged and older adults.

Methods

We used the PRISMA as a guideline for this systematic review and searched the following databases: PubMed, CINAHL, EMBASE, and Global Health.

Results

Twenty-five published studies were included. Twenty-two studies were focused on international migrants, while only 3 studied internal migrants. Fourteen studies were conducted in the United States, followed by UK (n = 2), Israel (n = 2), India (n = 2) and other countries like Canada and Australia. Some studies showed that middle-aged and older migrants demonstrated poorer cognitive function comparing to non-migrants in hosting places; while other studies indicated no association between migration and cognitive function. A higher level of acculturation was associated with better performance on cognitive function tests among migrants.

Conclusion

It is unclear how or whether migration and cognitive function are related. The quality of current literature suffered from methodological deficiencies. Additional research is needed to examine the linkages using more comprehensive measures of migration and cognitive function.

Occupation, retirement and cognitive functioning

The purpose of this paper is to examine the causal impact of the duration of retirement on the cognitive functioning of male elderly workers in Japan using data from the National Survey of Japanese Elderly. We explore how the complexity of a worker's longest served job affects cognitive functioning after retirement. In particular, we investigate eight dimensions of the longest served job using information listed in the United States Dictionary of Occupational Titles, namely physical demands, mathematical development, reasoning development, language development, the job's relationship to data, the job's relationship to people, the job's relationship to things and the specific vocational preparation required. Our estimator takes account of the potential endogeneity of the duration of retirement and the left-censoring of the duration of retirement. Our empirical evidence suggests that the duration of retirement has a negative and significant impact on cognitive functioning. Moreover, among the eight dimensions of job characteristics, high complexity in the job's relation to data is found to be an important job characteristic in delaying the deterioration of cognitive functioning after retirement.

Effects of Preretirement Work Complexity and Postretirement Leisure Activity on Cognitive Aging

OBJECTIVES

We examined the influence of postretirement leisure activity on longitudinal associations between work complexity in main lifetime occupation and trajectories of cognitive change before and after retirement.

METHODS

Information on complexity of work with data, people, and things, leisure activity participation in older adulthood, and four cognitive factors (verbal, spatial, memory, and speed) was available from 421 individuals in the longitudinal Swedish Adoption/Twin Study of Aging. Participants were followed for an average of 14.2 years (SD = 7.1 years) and up to 23 years across eight cognitive assessments. Most of the sample (88.6%) completed at least three cognitive assessments.

RESULTS

Results of growth curve analyses indicated that higher complexity of work with people significantly attenuated cognitive aging in verbal skills, memory, and speed of processing controlling for age, sex, and education. When leisure activity was added, greater cognitive and physical leisure activity was associated with reduced cognitive aging in verbal skills, speed of processing, and memory (for cognitive activity only).

DISCUSSION

Engagement in cognitive or physical leisure activities in older adulthood may compensate for cognitive disadvantage potentially imposed by working in occupations that offer fewer cognitive challenges. These results may provide a platform to encourage leisure activity participation in those retiring from less complex occupations.

Occupational complexity and lifetime cognitive abilities

Objective:

To examine associations between complexity of main lifetime occupation and cognitive performance in later life.

Methods:

Occupational complexity ratings for data, people, and things were collected from the Dictionary of Occupational Titles for 1,066 individuals (men = 534, women = 532) in the Lothian Birth Cohort 1936. IQ data were available from mean age 11 years. Cognitive ability data across the domains of general ability, processing speed, and memory were available at mean age 70 years.

Results:

General linear model analyses indicated that complexity of work with people and data were associated with better cognitive performance at age 70, after including age 11 IQ, years of education, and social deprivation.

Conclusions:

The current findings are supportive of the differential preservation hypotheses that more stimulating environments preserve cognitive ability in later life, although the continued effects into old age are still debated. Studies that have early-life cognitive ability measures are rare, and the current study offers interesting prospects for future research that may further the understanding of successful aging.

The role of midlife occupational complexity and leisure activity in late-life cognition

OBJECTIVE

To examine whether occupational complexity of working with data or people, and cognitive or social leisure activity at midlife predicted cognition in advanced old age.

METHODS

We used 810 eligible participants from Longitudinal Study of Living Conditions of the Oldest Old, a Swedish nationally representative study of individuals aged 77+ with cognitive assessments (an abridged version of the Mini-Mental State Exam) administered in 1992 and 2002 and linked to information about their midlife occupation and leisure activities collected in 1968 and 1981. A bootstrapping technique was applied to examine the direct and interactive associations of occupational complexity and leisure activity with late-life cognition.

RESULTS

Controlling for demographic and health-related factors from childhood, midlife, and late life, we found that greater work complexity, both with people and with data, and greater participation in cognitive or social leisure activities independently related to better late-life cognitive scores. The complexity-cognition link was moderated by leisure activity such that the cognitive benefit related to the complexity of work-especially complexity of working with people-was rendered insignificant when participation in leisure activities-especially social activities-was above average.

DISCUSSION

Results are discussed in terms of using work complexity to compensate for lack of leisure activity as well as in terms of promoting leisure engagement to compensate for long-term cognitive disadvantage imposed by working in less challenging occupations.

Association between mental demands at work and cognitive functioning in the general population - results of the health study of the Leipzig research center for civilization diseases (LIFE)

Background

The level of mental demands in the workplace is rising. The present study investigated whether and how mental demands at work are associated with cognitive functioning in the general population.

Methods

The analysis is based on data of the Health Study of the Leipzig Research Centre for Civilization Disease (LIFE). 2,725 participants aged 40–80 years underwent cognitive testing (Trail-Making Test, Verbal Fluency Test) and provided information on their occupational situation. Participants over the age of 65 years additionally completed the Mini-Mental State Examination. Mental demands at work were rated by a standardized classification system (O*NET). The association between mental demands and cognitive functioning was analyzed using Generalized Linear Modeling (GENLIN) adjusted for age, gender, self-regulation, working hour status, education, and health-related factors.

Results

Univariate as well as multivariate analyses demonstrated significant and highly consistent effects of higher mental demands on better performance in cognitive testing. The results also indicated that the effects are independent of education and intelligence. Moreover, analyses of retired individuals implied a significant association between high mental demands at work of the job they once held and a better cognitive functioning in old age.

Conclusions

In sum, our findings suggest a significant association between high mental demands at work and better cognitive functioning. In this sense, higher levels of mental demands – as brought about by technological changes in the working environment – may also have beneficial effects for the society as they could increase cognitive capacity levels and might even delay cognitive decline in old age.

Cognitive activities and cognitive performance in middle-aged adults at risk for Alzheimer's disease

Cognitive activity is thought to provide some protection against dementia, but the mechanism and timing of these effects are unknown. Data for this study were drawn from the Wisconsin Registry for Alzheimer's Prevention (WRAP), an at-risk middle-aged sample (mean age = 54 years) enriched for parental family history of Alzheimer's disease (AD). We had two main aims: (a) to determine the relative contribution of three facets of cognitive activity-education, occupational complexity with data, and cognitive leisure activities-to WRAP participants' cognitive performance; and (b) to assess for interactions between genetic risk factors and cognitive activity in explaining cognitive performance. Results from mixed effects models indicate that some of the variance usually attributed to education may be more closely accounted for by cognitive activities later in life. Overall, our analyses suggest cautious optimism for cognitive activities, especially game playing, as a strategy for preserving cognitive strengths in midlife.

Mental work demands, retirement, and longitudinal trajectories of cognitive functioning

Age-related changes in cognitive abilities are well-documented, and a very important indicator of health, functioning, and decline in later life. However, less is known about the course of cognitive functioning before and after retirement and specifically whether job characteristics during one's time of employment (i.e., higher vs. lower levels of mental work demands) moderate how cognition changes both before and after the transition to retirement. We used data from n = 4,182 (50% women) individuals in the Health and Retirement Study, a nationally representative panel study in the United States, across an 18 year time span (1992-2010). Data were linked to the O*NET occupation codes to gather information about mental job demands to examine whether job characteristics during one's time of employment moderates level and rate of change in cognitive functioning (episodic memory and mental status) both before and after retirement. Results indicated that working in an occupation characterized by higher levels of mental demands was associated with higher levels of cognitive functioning before retirement, and a slower rate of cognitive decline after retirement. We controlled for a number of important covariates, including socioeconomic (education and income), demographic, and health variables. Our discussion focuses on pathways through which job characteristics may be associated with the course of cognitive functioning in relation to the important transition of retirement. Implications for job design as well as retirement are offered.

Enriched environment at work and the incidence of dementia: results of the Leipzig longitudinal study of the aged (LEILA 75+)

BACKGROUND

The high incidence of cognitive impairments in the aging population together with the challenges it imposes on health systems raise the question of what effect working life has on cognitive abilities. Animal models have demonstrated that so called enriched environments protect against neurodegenerative diseases, such as dementia. The aim was to investigate the impact of enriched environment at work on the incidence of dementia.

METHODS

The Leipzig Longitudinal Study of the Aged (LEILA 75+) is an ongoing representative population cohort study that examines cognitive functioning and dementia in individuals aged 75 years and older. The participants' occupational information was matched to O*NET SOC codes and the relevant job descriptors were used to create occupational context indices describing enriched environment at work.

RESULTS

Results of logistic regression modeling suggest that a higher level of the index Executive was associated with a lower risk of incident dementia (odds ratio  = 0.61, 95% confidence interval  = 0.47-0.79, p<0.001). Adjustment for various confounders did not alter the association. The cognitive stimulation indices were only significant in univariate analysis. The Novelty-index remained non-significant.

CONCLUSIONS

The results suggest that occupational contexts enriched with independent planning/performance of work tasks might decrease the risk of developing dementia. A protective effect of enriched environment at work in general, namely high cognitive stimulation or confrontation with new tasks, could not be confirmed by the results.

Duke Twins Study of Memory in Aging in the NAS-NRC Twin Registry

The Duke Twins Study of Memory in Aging is an ongoing, longitudinal study of cognitive change and dementia in the population-based National Academy of Sciences-National Research Council (NAS-NRC) Twin Registry of World War II Male Veterans. The primary goal of this study has been to estimate the overall genetic and environmental contributions to dementia with a specific focus on Alzheimer's disease. An additional goal has been to examine specific genetic and environmental antecedents of cognitive decline and dementia. Since 1989, we have completed 4 waves of data collection. Each wave included a 2-phase telephone cognitive screening protocol, followed by an in-home standardized clinical assessment for those with suspected dementia. For many participants, we have obtained postmortem neuro-pathological confirmation of the diagnosis of dementia. In addition to data on cognition, we have also collected information on occupational history, medical history, medications and other lifetime experiences that may influence cognitive function in late life. We provide an overview of the study's methodology and describe the focus of recent research.

Relationship between occupation attributes and brain metabolism in frontotemporal dementia

Occupation has been associated with cognitive reserve in healthy aging and Alzheimer's disease. Here we assess the relationship between cerebral metabolic deficits in behavioral variant frontotemporal dementia (bvFTD) and occupation characteristics. Using factor analysis, we derived verbal, physical and visuospatial occupation scores from the US Department of Labor, Occupational Information Network and related these scores to regional cerebral metabolic rate of glucose utilization in 31 patients diagnosed with behavioral variant bvFTD, controlling for cognitive status (CERAD neuropsychological assessment battery), gender and education. Regression analyses showed a marked inverse association between glucose metabolism and (a) verbal occupation scores in left prefrontal cortex and, (b) physical occupation characteristics in right supplementary motor area. We concluded that, consistent with the cognitive reserve hypothesis, lifelong occupation characteristics are related to focal cerebral metabolic deficits in bvFTD. Specific occupation demands spanning decades may strengthen cognitive resistance to pathology.

Patterns of cognitive performance in healthy ageing in Northern Portugal: a cross-sectional analysis

BACKGROUND

The Minho Integrative Neuroscience Database (MIND)-Ageing project aims to identify predictors of healthy cognitive ageing, including socio-demographic factors. In this exploratory analysis we sought to establish baseline cohorts for longitudinal assessment of age-related changes in cognition.

METHODS

The population sample (472 individuals) was strictly a convenient one, but similar to the Portuguese population in the age profile. Participants older than 55 years of age were included if they did not present defined disabling pathologies or dementia. A standardized clinical interview was conducted to assess medical history and a battery of neuropsychological tests was administered to characterize global cognition (Mini Mental State Examination), memory and executive functions (Selective Reminding Test; Stroop Color and Word Test; and Block Design subtest of the Wechsler Adult Intelligence Scale). Cross-sectional analysis of the neuropsychological performance with individual characteristics such as age, gender, educational level and setting (retirement home, senior university, day care center or community), allowed the establishment of baseline clusters for subsequent longitudinal studies.

RESULTS

Based on different socio-demographic characteristics, four main clusters that group distinctive patterns of cognitive performance were identified. The type of institution where the elders were sampled from, together with the level of formal education, were the major hierarchal factors for individual distribution in the four clusters. Of notice, education seems to delay the cognitive decline that is associated with age in all clusters.

CONCLUSIONS

Social-inclusion/engagement and education seem to have a protective effect on mental ageing, although this effect may not be effective in the eldest elders.

Higher mental stimulation at work is associated with improved cognitive functioning in both young and older workers

The study examined whether mental stimulation received in the workplace positively affects cognitive functioning and rate of cognitive change. Data taken from the VISAT (ageing, health and work) longitudinal study concerned 3237 workers who were seen three times (in 1996, 2001 and 2006) and who were aged between 32 and 62 years at baseline. Measures of cognitive stimulation both at work and outside work were available at baseline. Cognitive efficiency was assessed on the three occasions through episodic verbal memory, attention and processing speed tests. Greater cognitive stimulation (at work and outside work) was associated with higher levels of cognitive functioning and a more favourable change over the 10-year follow-up. These results were obtained after adjustment for age, education, sex and a variety of medical, physical and psychosocial confounders. The study thus supports the hypothesis that exposure to jobs that are mentally demanding and that offer learning opportunities increases the level of cognitive functioning and possibly attenuates age-related decline. STATEMENT OF RELEVANCE: The effect of occupational activity on cognitive functioning is under-researched. This paper reports results from a substantive longitudinal study, with findings indicating that exposure to jobs that are mentally demanding are beneficial in increasing levels of cognitive functioning and possibly attenuating age-related decline.

Occupation attributes relate to location of atrophy in frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) often presents with asymmetric atrophy. We assessed whether premorbid occupations in FTLD patients were associated with these hemispheric asymmetries. In a multi-center chart review of 588 patients, occupation information was related to location of tissue loss or dysfunction. Patients with atrophy lateralized to the right had professions more dependent on verbal abilities than patients with left-lateralized or symmetrical atrophy. In a subgroup of 96 well-characterized patients with quantified neuroimaging data, the lateralization effect was localized to the temporal lobes and included verbal and mathematical ability. Patients whose professions placed high demands on language and mathematics had relatively preserved left temporal relative to right temporal volumes. Thus, occupation selection occurring in early adulthood is related to lateralized brain asymmetry in patients who develop FTLD decades later in the relatively deficient hemisphere. The finding suggests that verbal and mathematical occupations may have been pursued due to developmental right-lateralized functional impairment that precedes the neurodegenerative process. Alternatively, long-term engagement of activities associated with these occupations contributed to left-lateralized reserve, right-lateralized dysfunction, or both.

The role of occupational complexity in trajectories of cognitive aging before and after retirement

We examined the association between complexity of the main lifetime occupation and changes in cognitive ability in later life. Data on complexity of work with data, people, and things and on 4 cognitive factors (verbal, spatial, memory, and speed) were available from 462 individuals in the longitudinal Swedish Adoption/Twin Study of Aging. Mean age at the first measurement wave was 64.3 years (SD = 7.2), and 65% of the sample had participated in at least three waves of data collection. Occupational complexity with people and data were both correlated with cognitive performance. Individuals with more complex work demonstrated higher mean performance on the verbal, spatial, and speed factors. Latent growth curve analyses indicated that, after correcting for education, only complexity with people was associated with differences in cognitive performance and rate of cognitive change. Continued engagement as a result of occupational complexity with people helped to facilitate verbal function before retirement, whereas a previous high level of complexity of work with people was associated with faster decline after retirement on the spatial factor.

A biometric latent curve analysis of memory decline in older men of the NAS-NRC twin registry

Previous research has shown cognitive abilities to have different biometric patterns of age-changes. We examined the variation in episodic memory (word recall task) for over 6,000 twin pairs who were initially aged 59-75, and were subsequently re-assessed up to three more times over 12 years. In cross-sectional analyses, variation in the number of words recalled independent of age was explained largely by non-shared influences (65-72%), with clear additive genetic influences (12-32%), and marginal shared family influences (1-18%). The longitudinal phenotypic analysis of the word recall task showed systematic linear declines over age, but several nonlinear models with more dramatic changes at later ages, improved the overall fit. A two-part spline model for the longitudinal twin data with an optimal turning point at age 74 led to: (a) a separation of non-shared environmental influences and transient measurement error (~50%); (b) strong additive genetic components of this latent curve (~44% at age 60) with increases (over 50%) up to age 74, but with no additional genetic variation after age 74; (c) the smaller influences of shared family environment (~15% at age 74) were constant over all ages; (d) non-shared effects play an important role over most of the life-span but diminish after age 74.

Midlife activity predicts risk of dementia in older male twin pairs

BACKGROUND

This was a prospective study of dementia to elucidate mechanisms of disease risk factors amenable to modification and specifically to determine whether midlife cognitive and physical leisure activities are associated with delayed onset or reduced risk of dementia within older male twin pairs.

METHODS

The co-twin control design used prospectively collected exposure information to predict risk of dementia 20 to 40 years later. The subjects were community-dwelling and nursing home residents living throughout the continental United States. We studied 147 male twin-pairs who were discordant for dementia or age of dementia onset and were members of the National Academy of Sciences-National Research Council Twin Registry of World War II veterans and participants in the Duke Twins Study of Memory in Aging. The main outcome measure was diagnosed dementia by using a two-stage screen and full clinical evaluation. Conditional odds ratios were estimated for the association between midlife leisure activities and late-life dementia.

RESULTS

Greater midlife cognitive activity was associated with a 26% risk reduction for dementia onset. Protective effects were most robust in monozygotic twin pairs, where genetic and early-life influences were most tightly controlled, and for activities that were often cognitive and social in nature. Cognitive activity was particularly protective among monozygotic twin pairs carrying the apolipoprotein E epsilon4 allele, with a 30% risk reduction. Midlife physical activity did not modify dementia risk.

CONCLUSIONS

Participation in a range of cognitively and socially engaging activities in midlife reduced risk for dementia and AD in twins discordant for onset, particularly among twin pairs at elevated genetic risk, and might be indicative of an enriched environment.

Heritability of neurocognitive functioning in the elderly: evidence from an Italian twin study

BACKGROUND

the genetic and environmental origins of individual differences in specific cognitive abilities in the elderly are poorly understood. One reason is the lack of studies performed in cohorts with normal cognitive functions.

OBJECTIVE

to estimate the relative contributions of genetic and environmental factors in determining inter-individual variation in neurocognitive abilities in the Italian population.

DESIGN

cross-sectional analysis of twin data.

SETTING

a sample of older twins with normal cognition from the population-based Italian Twin Registry (ITR).

SUBJECTS

twin pairs resident in Rome and born between 1926 and 1940, identified through the ITR in 2002. The final study population included 93 twin pairs.

METHODS

subjects underwent neuropsychological tests providing information about different cognitive domains. The contributions of genetic and environmental effects were assessed using standard univariate twin modelling based on linear structural equations.

RESULTS

the best-fitting model incorporated additive genetic (A) and unique environmental (E) sources of variance for the following tests: Mini-Mental State Examination (A = 55%), Raven (A = 56%), Attentional Matrices (A = 79%), Copying Drawings (A = 69%) and Story Recall (A = 54%). For Phonological and Semantic Verbal Fluency, the best model included non-additive (D) and unique environmental influences (D = 62 and 54%, respectively). Cigarette smoking was estimated to be negatively associated with the score of Phonological Verbal Fluency. For Token test, the inter-individual variance was entirely due to environmental factors not shared by the twins.

CONCLUSION

our data showed that most of the specific cognitive abilities are moderately to highly heritable, and that the environmental factors of relevance for these abilities are those causing within-family differences.

Trends in the prevalence and mortality of cognitive impairment in the United States: is there evidence of a compression of cognitive morbidity?

BACKGROUND

Recent medical, demographic, and social trends might have had an important impact on the cognitive health of older adults. To assess the impact of these multiple trends, we compared the prevalence and 2-year mortality of cognitive impairment (CI) consistent with dementia in the United States in 1993 to 1995 and 2002 to 2004.

METHODS

We used data from the Health and Retirement Study (HRS), a nationally representative population-based longitudinal survey of U.S. adults. Individuals aged 70 years or older from the 1993 (N = 7,406) and 2002 (N = 7,104) waves of the HRS were included. CI was determined by using a 35-point cognitive scale for self-respondents and assessments of memory and judgment for respondents represented by a proxy. Mortality was ascertained with HRS data verified by the National Death Index.

RESULTS

In 1993, 12.2% of those aged 70 or older had CI compared with 8.7% in 2002 (P < .001). CI was associated with a significantly higher risk of 2-year mortality in both years. The risk of death for those with moderate/severe CI was greater in 2002 compared with 1993 (unadjusted hazard ratio, 4.12 in 2002 vs 3.36 in 1993; P = .08; age- and sex-adjusted hazard ratio, 3.11 in 2002 vs 2.53 in 1993; P = .09). Education was protective against CI, but among those with CI, more education was associated with higher 2-year mortality.

CONCLUSIONS

These findings support the hypothesis of a compression of cognitive morbidity between 1993 and 2004, with fewer older Americans reaching a threshold of significant CI and a more rapid decline to death among those who did. Societal investment in building and maintaining cognitive reserve through formal education in childhood and continued cognitive stimulation during work and leisure in adulthood might help limit the burden of dementia among the growing number of older adults worldwide.

Associations of job demands and intelligence with cognitive performance among men in late life

OBJECTIVE

To examine the association of job characteristics and intelligence to cognitive status in members of the National Academy of Sciences-National Research Council Twins Registry of World War II veterans.

METHODS

Participants (n = 1,036) included individuals with an assessment of intelligence based on Armed Services testing in early adulthood. In late adulthood, these individuals completed the modified Telephone Interview for Cognitive Status (TICS-m) and occupational history as part of an epidemiologic study of aging and dementia. Occupational history was coded to produce a matrix of job characteristics. Based on factor analysis, job characteristics were interpreted as reflecting general intellectual demands (GI), human interaction and communication (HC), physical activity (PA), and visual attention (VA).

RESULTS

Based on regression analysis of TICS-m score covarying for age, intelligence, and years of education, higher levels of GI and HC were independently associated with higher TICS-m performance, whereas higher PA was independently associated with lower performance. There was an interaction of GI and intelligence, indicating that individuals at the lower range of intellectual aptitude in early adulthood derived greater cognitive benefit from intellectually demanding work.

CONCLUSIONS

Intellectually demanding work was associated with greater benefit to cognitive performance in later life independent of related factors like education and intelligence. The fact that individuals with lower intellectual aptitude demonstrated a stronger positive association between work and higher cognitive performance during retirement suggests that behavior may enhance intellectual reserve, perhaps even years after peak intellectual activity.