Working Life Psychosocial Conditions in Relation to Late-Life Cognitive Decline: A Population-Based Cohort Study

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.

Longitudinal associations of effort and reward at work with changes in cognitive function: evidence from a national study of U.S. workers

PURPOSE

This study aimed to examine longitudinal associations of workplace effort and reward with changes in cognitive function among United States workers.

METHODS

Data from the national, population-based Midlife in the United States (MIDUS) study with a 9-year follow-up were used. Validated workplace effort and reward scales were measured at baseline, and cognitive outcomes (including composite cognition, episodic memory, and executive functioning) were measured with the Brief Test of Adult Cognition by Telephone (BTACT) at baseline and follow-up. Multivariable linear regression analyses based on generalized estimating equations (GEE) examined the longitudinal associations under study.

RESULTS

Among this worker sample of 1,399, after accounting for demographics, socioeconomics, lifestyle behaviors, health conditions, and job control, high reward at baseline was associated with increased composite cognition (regression coefficient: 0.118 [95% CI: 0.049, 0.187]), episodic memory (0.106 [0.024, 0.188]), and executive functioning (0.123 [0.055, 0.191]) during follow-up. The joint exposure of 'high effort and high reward' was also associated with increased composite cognition (0.130 [0.030, 0.231]), episodic memory (0.131 [0.012, 0.250]), and executive functioning (0.117 [0.017, 0.216]), while the combination of 'low effort and high reward' was associated with increased composite cognition (0.106 [0.009, 0.204]) and executive functioning (0.139 [0.042, 0.235]).

CONCLUSION

Findings suggest that workplace high reward is related to improved cognitive scores among United States workers. Future research should investigate larger cohorts over longer timespans and expand into disease outcomes such as dementia. If these findings emerge as causal, relevant workplace rewards to promote worker cognitive health should be considered.

Association between psychosocial working conditions and well-being before retirement: a community-based study

Psychosocial working conditions have been linked to mental health outcomes, but their association with well-being is poorly studied. We aimed to investigate the association between psychosocial working conditions and well-being before retirement, and to explore the role of gender and leisure activities in the association. From the Swedish National Study on Aging and Care in Kungsholmen, 598 community dwellers aged 60-65 years were included in the cross-sectional study. Lifelong occupational history was obtained through an interview. Job demands and job control in the longest-held occupation were graded with job exposure matrices. Psychosocial working conditions were classified into high strain (high demands, low control), low strain (low demands, high control), passive job (low demands, low control), and active job (high demands, high control). Well-being was assessed with the 10-item version of positive and negative affect schedule, and scored using confirmatory factor analysis. Engagement in leisure activities was categorized as low, moderate, and high. Data were analyzed using linear regression. Both high job control and high job demands were dose-dependently associated with higher well-being. Overall, compared to active jobs, passive jobs were associated with lower well-being (β -0.19, 95% CI -0.35 to -0.02, P = 0.028). Passive (β -0.28, 95% CI -0.51 to -0.04, P = 0.020) and high strain (β -0.31, 95% CI -0.52 to -0.10, P = 0.004) jobs were associated with lower well-being in men, but not in women. The association between passive jobs and well-being was attenuated by high leisure activities, while the association between high strain and well-being was magnified by low leisure activities. In conclusion, negative psychosocial working conditions are associated with poor well-being, especially in men. Leisure activities may modulate the association. Our study highlights that promoting favorable working conditions can be a target to improve well-being among employees and active participation in leisure activities is encouraged to cope with work-related stress for better well-being.

Is the mental health of older adults receiving care from their children related to their children's dual burden of caregiving and work stress? A linked lives perspective

OBJECTIVES

Mental health problems are a major concern in the older population in Sweden, as is the growing number of older adults aging alone in their homes and in need of informal care. Using a linked lives perspective, this study explored if older parents' mental health is related to their children's dual burden of informal caregiving and job strain.

METHODS

Data from a nationally representative Swedish survey, SWEOLD, were used. Mental health problems in older age (mean age 88) were measured with self-reported 'mild' or 'severe' anxiety and depressive symptoms. A primary caregiving adult child was linked to each older parent, and this child's occupation was matched with a job exposure matrix to assess job strain. Logistic regression analyses were conducted with an analytic sample of 334.

RESULTS

After adjusting for covariates, caregiving children's lower job control and greater job strain were each associated with mental health problems in their older parents (OR 2.52, p = 0.008 and OR 2.56, p = 0.044, respectively). No association was found between caregiving children's job demands and their older parents' mental health (OR 1.08, p = 0.799).

CONCLUSION

In line with the linked lives perspective, results highlight that the work-life balance of informal caregiving adult children may play a role in their older parent's mental health.

Work-Related Psychosocial Factors and Global Cognitive Function: Are Telomere Length and Low-Grade Inflammation Potential Mediators of This Association?

The identification of modifiable factors that could maintain cognitive function is a public health priority. It is thought that some work-related psychosocial factors help developing cognitive reserve through high intellectual complexity. However, they also have well-known adverse health effects and are considered to be chronic psychosocial stressors. Indeed, these stressors could increase low-grade inflammation and promote oxidative stress associated with accelerated telomere shortening. Both low-grade inflammation and shorter telomeres have been associated with a cognitive decline. This study aimed to evaluate the total, direct, and indirect effects of work-related psychosocial factors on global cognitive function overall and by sex, through telomere length and an inflammatory index. A random sample of 2219 participants followed over 17 years was included in this study, with blood samples and data with cognitive function drawn from a longitudinal study of 9188 white-collar workers (51% female). Work-related psychosocial factors were evaluated according to the Demand-Control-Support and the Effort-Reward Imbalance (ERI) models. Global cognitive function was evaluated with the validated Montreal Cognitive Assessment (MoCA). Telomere length and inflammatory biomarkers were measured using standardised protocols. The direct and indirect effects were estimated using a novel mediation analysis method developed for multiple correlated mediators. Associations were observed between passive work or low job control, and shorter telomeres among females, and between low social support at work, ERI or iso-strain, and a higher inflammatory index among males. An association was observed with higher cognitive performance for longer telomeres, but not for the inflammatory index. Passive work overall, and low reward were associated with lower cognitive performance in males; whereas, high psychological demand in both males and females and high job strain in females were associated with a higher cognitive performance. However, none of these associations were mediated by telomere length or the inflammatory index. This study suggests that some work-related psychosocial factors could be associated with shorter telomeres and low-grade inflammation, but these associations do not explain the relationship between work-related psychosocial factors and global cognitive function. A better understanding of the biological pathways, by which these factors affect cognitive function, could guide future preventive strategies to maintain cognitive function and promote healthy aging.

Psychosocial working conditions and cognitive and physical impairment in older age

BACKGROUND

Psychosocial working conditions are associated with cognitive and physical impairments. The aim of this study was to investigate the associations between mid-late life psychosocial working conditions and the combination of physical and cognitive impairment among older adults, and the potential sex differences in these associations.

METHODS

Data were derived from two Swedish nationally representative surveys (n = 839; follow-up: 20-24 years). Multinomial and binary logistic regressions assessed the associations between work stressors (job demand-control model), and a combination of cognitive and physical impairment.

RESULTS

Low control jobs were significantly associated with higher odds of cognitive (OR: 1.41, CI: 1.15-1.72) and physical impairment (OR: 1.23, CI: 1.02-1.47), and cognitive and physical impairment combined (OR: 1.50, CI: 1.19-1.89). Passive jobs (low control, low demand) were associated with higher odds of cognitive impairment (OR: 1.57, CI: 1.12-2.20), and combined cognitive and physical impairment (OR: 1.59, CI: 1.07-2.36). Active jobs (high control, high demand) were associated with lower odds of cognitive impairment (OR: 0.48, CI: 0.29-0.80). Sex-stratified analyses showed stronger associations among men; passive jobs were associated with both cognitive (OR: 2.18, CI: 1.31-3.63) and physical impairment (OR: 1.78, CI: 1.13-2.81), while low strain jobs were associated with less physical impairment (OR: 0.55, CI: 0.33-0.89). No significant associations between work stressors and impairment were found for women.

CONCLUSIONS

These results highlight the importance of psychosocial working conditions for late-life physical and cognitive impairment, especially among men. Jobs characterised by low control and low demands are associated with higher risk for impairments.

The influence of occupation type and complexity on cognitive performance in older adults

Sociodemographic factors, such as education and occupation, may influence the individual's cognitive reserve. We explored the extent to which the type and complexity of previous work activities influence cognitive performance (evaluated with Mini-Mental State Examination, MMSE, and the Animal Naming Test, ANT) in 799 older people with or without brain damage. The presence of cortical/subcortical ischemic brain lesions and right/left hippocampal atrophy was derived from magnetic resonance imaging. We found that individuals who had done intellectual work had better MMSE and ANT scores than their counterparts in the presence of brain lesions or hippocampal atrophy. Among the manual workers there were significant differences between the MMSE scores of individuals with and without brain damage (mean MMSE difference (2.09 [SD: 0.68], p=0.01), but not among the intellectuals (0.19 [SD: 0.29], p=0.36) nor the service providers (1.67 [SD: 0.55], p=0.21). Occupations involving more complex dealings with people were associated with better MMSE scores in the presence of brain lesions [β=-0.41, 95%CI: -0.72,-0.09] and hippocampal atrophy [β=-0.29, 95%CI:-0.58,-0.001]. These results indicate that in more cognitively stimulating work with greater social interaction may help older individuals preserve cognitive functions, even in the presence of brain damage.

Associations between combinations of job demands and job control among 6,16,818 people aged 55-64 in paid work with their labour market status 11 years later: a prospective cohort study

BACKGROUND

Given current discussions about extending working lives, more knowledge is needed on working conditions associated with labour market status in older age.

OBJECTIVE

To explore associations between combinations of job demands and job control among workers aged 55-64 years and their labour market status 11 years later.

METHODS

A population-based prospective cohort study using nationwide register data. The 616,818 individuals in Sweden aged 55-64 who in 2001 were in paid work were categorised using a job exposure matrix based on tertiles (reference = medium control/medium demands). Participants were followed up in 2012 regarding their main labour market status (paid work, old-age pension, no income/social assistance, sickness absence/disability pension, emigrated, dead; reference = old-age pension) using multinomial logistic regression for odds ratios (OR) and 95% confidence intervals (CI). The fully adjusted analyses included adjustment for sociodemographic factors and unemployment or sickness absence/disability pension for more than half the year in 2001.

RESULTS

Those in occupations with low job control at baseline were less likely to be in paid work at follow-up (OR low demands/low control 0.74, CI 0.71-0.78; high demands/low control 0.81, CI 0.75-0.87). Those in occupations with baseline high demands were less likely to have no income/social assistance at follow-up (OR high demands/low control 0.71, CI 0.52-0.96; high demands/high control 0.59, CI 0.47-0.75).

CONCLUSION

Job demands and control when aged 55-64 were associated with labour market status 11 years later: high control was associated with greater chance of being in paid work, and high demands were associated with lower risk of no income/social assistance.

Working life job strain status and cognitive aging in Europe: A 12-year follow-up study

BACKGROUND

To examine the association of job strain with cognitive ability and the influence of life-course job strain on later life cognitive decline.

METHODS

Data were derived from six waves of the Survey of Health, Aging, and Retirement in Europe. The study sample consists of 13349 participants aged 50 to 98 years at wave 2 and has been followed up for 12-years. Job strain status across working life was assessed using a short demand-control job strain model containing two core dimensions: job demands and job control collected in wave 3. Cognitive abilities concerning episodic memory was assessed by immediate recall and delayed recall tests, executive function was evaluated by verbal fluency test collected in all waves (waves 2-7) except wave 3. Mixed-effects model was used to estimate working life job strain and its cumulative effect on cognitive decline.

RESULTS

Both passive and high strain jobs were associated with lower levels of cognitive ability (episodic memory and verbal fluency) in comparison with active job. Long exposure to active- or low strain-job was associated with higher cognitive ability whereas long exposure to passive job or moderate duration of high strain job was associated with lower cognitive ability. The rate of memory decline was positively related to moderate duration of passive job and negatively related to long-term exposure to low strain job.

LIMITATIONS

Information on working conditions was based on self-reported recollections.

CONCLUSIONS

Working life variation in job strain status and their duration may explain individual differences in cognitive ability in later life.

Job Strain and Trajectories of Cognitive Change Before and After Retirement

OBJECTIVES

We examined associations between job strain and trajectories of change in cognitive functioning (general cognitive ability plus verbal, spatial, memory, and speed domains) before and after retirement.

METHODS

Data on indicators of job strain, retirement age, and cognitive factors were available from 307 members of the Swedish Adoption/Twin Study of Aging. Participants were followed up for up to 27 years (mean = 15.4, SD = 8.5).

RESULTS

In growth curve analyses controlling for age, sex, education, depressive symptoms, cardiovascular health, and twinness, greater job strain was associated with general cognitive ability (estimate = -1.33, p = .002), worse memory (estimate = -1.22, p = .007), speed (estimate = -1.11, p = .012), and spatial ability (estimate = -0.96, p = .043) at retirement. Greater job strain was also associated with less improvement in general cognitive ability before retirement and a somewhat slower decline after retirement. The sex-stratified analyses showed that the smaller gains of general cognitive ability before retirement (estimate = -1.09, p = .005) were only observed in women. Domain-specific analyses revealed that greater job strain was associated with less improvement in spatial (estimate = -1.35, p = .010) and verbal (estimate = -0.64, p = .047) ability before retirement in women and a slower decline in memory after retirement in women (estimate = 0.85, p = .008) and men (estimate = 1.12, p = .013). Neither preretirement nor postretirement speed was affected significantly by job strain.

DISCUSSION

Greater job strain may have a negative influence on overall cognitive functioning prior to and at retirement, while interrupting exposure to job strain (postretirement) may slow the rate of cognitive aging. Reducing the level of stress at work should be seen as a potential target for intervention to improve cognitive aging outcomes.

Cumulative exposure to psychosocial stressors at work and global cognitive function: the PROspective Quebec Study on Work and Health

OBJECTIVES

Psychosocial stressors at work have been proposed as modifiable risk factors for mild cognitive impairment (MCI). This study aimed to evaluate the effect of cumulative exposure to psychosocial stressors at work on cognitive function.

METHODS

This study was conducted among 9188 white-collar workers recruited in 1991-1993 (T1), with follow-ups 8 (T2) and 24 years later (T3). After excluding death, losses to follow-up and retirees at T2, 5728 participants were included. Psychosocial stressors at work were measured according to the Karasek's questionnaire. Global cognitive function was measured with the Montreal Cognitive Assessment. Cumulative exposures to low psychological demand, low job control, passive job and high strain job were evaluated using marginal structural models including multiple imputation and inverse probability of censoring weighting.

RESULTS

In men, cumulative exposures (T1 and T2) to low psychological demand, low job control or passive job were associated with higher prevalences of more severe presentation of MCI (MSMCI) at T3 (Prevalence ratios (PRs) and 95% CIs of 1.50 (1.16 to 1.94); 1.38 (1.07 to 1.79) and 1.55 (1.20 to 2.00), respectively), but not with milder presentation of MCI. In women, only exposure to low psychological demand or passive job at T2 was associated with higher prevalences of MSMCI at T3 (PRs and 95% CI of 1.39 (0.97 to 1.99) and 1.29 (0.94 to 1.76), respectively).

CONCLUSIONS

These results support the deleterious effect of a low stimulating job on cognitive function and the cognitive reserve theory. Psychosocial stressors at work could be part of the effort for the primary prevention of cognitive decline.

Shared risk and protective factors between Alzheimer's disease and ischemic stroke: A population-based longitudinal study

INTRODUCTION

Stroke, especially ischemic stroke's (IS) link with Alzheimer's disease (AD) remains unclear.

METHODS

This prospective cohort study included 2459 AD- and cerebrovascular disease-free older adults at baseline (mean age 71.9 ± 10.3 years, Stockholm, Sweden). Using Cox regressions, shared risk factors (SRFs) and shared protective factors (SPFs) between AD and IS were recognized when their hazard ratios in both AD and IS models were significant and in the same direction.

RESULTS

During the follow-up period of up to 15 years, 132 AD and 260 IS mutually exclusive cases were identified. SRFs were low education, sedentary lifestyle, and heart diseases. High levels of psychological well-being, actively engaging in leisure activities, and a rich social network were SPFs. Having ≥1 SPF reduced 47% of AD and 28% of IS risk among people with a low risk profile (<2 SRFs), and 38% of AD and 31% of IS risk with a high risk profile (≥2 SRFs). In total, 57.8% of AD/IS cases could be prevented if individuals have ≥1 SPF and no SRF.

DISCUSSION

AD and IS share risk/protective profiles, and SPFs seem to counteract the adverse effects of SRFs on both AD and IS.

Prevention of dementia in an ageing world: Evidence and biological rationale

As the population ages, the number of people with dementia is expected to increase in the coming decades, with consequences at the societal and individual levels. In this narrative review, we provide a summary of the scientific evidence concerning dementia prevention, with a focus on the following three strategies: 1) Targeting the body to protect the brain, including prevention and treatment of cardiovascular morbidity; 2) Compensatory interventions to counteract brain ageing, including education and life-long engagement in cognitively and socially stimulating activities; and 3) Lifespan health promotion, such as a physically active lifestyle, smoking cessation, and a healthy and balanced diet. Next, we consider the biological mechanisms by which these strategies may act by taking into account the main pathways implicated in the development and progression of dementia: neurodegeneration, brain resilience, vascular damage, neuroinflammation, and oxidative stress. Based on the current evidence, and in line with the declining trends of dementia incidence in high-income countries, we conclude that timely multidomain preventive actions are promising strategies to reduce the dementia epidemic worldwide. There is still a considerable gap between the epidemiological evidence and its underlying biological mechanisms. Filling this gap will be crucial to move forward in dementia prevention worldwide.

The role of Apolipoprotein E epsilon4 in the association between psychosocial working conditions and dementia

In this population-based prospective study, we examined the association of job demand-control combinations with dementia, and explored the roles of Apolipoprotein E epsilon4 (APOE ɛ4) and work duration in this association. A total of 2,579 dementia-free individuals aged 60+ years from Sweden were followed over 12 years. Dementia diagnosis was made by physicians. Lifelong occupational experience was collected, and job demands and control were assessed using a psychosocial job-exposure matrix. Data were analyzed using multivariate Cox proportional hazard models. During the follow-up, 282 people developed dementia. Passive jobs (low control/low demands) were related to a higher risk of dementia compared with active jobs (high control/high demands) among the younger-old (aged ≤72 years), but not among the older-old (aged ≥78 years). Among the younger-old, compared to those with no passive job experience, those with 11+ years in passive jobs had a higher dementia risk. The joint-effect analyses showed that APOE ɛ4 carriers with passive jobs had an even higher risk of dementia compared to APOE ɛ4 non-carriers with active jobs. These findings suggest that passive jobs are related to a higher dementia risk among the younger-old. APOE ɛ4 and long work duration may amplify the impact of passive jobs on dementia.

Psychosocial working conditions, trajectories of disability, and the mediating role of cognitive decline and chronic diseases: A population-based cohort study

BACKGROUND

Unfavorable psychosocial working conditions have been associated with cognitive decline and chronic diseases, both of which may subsequently accelerate functional dependence. This study aimed to investigate the association between job demand-control-support combinations and trajectories of disability in later life and to further explore the role of cognitive decline and the co-occurrence of chronic diseases in mediating this association.

METHODS AND FINDINGS

In this cohort study, 2,937 community dwellers aged 60+ years (mean age 73 ± 10.6; 62.9% female) residing in the Kungsholmen District of Stockholm, Sweden, participated in the baseline survey (2001-2004) and were followed up to 12 years. Lifelong occupational history was obtained through a standardized interview; job demands, job control, and social support at work in the longest-held occupation were graded with a psychosocial job-exposure matrix. Job control, demands, and social support were dichotomized using the median values from the matrix, respectively, to further generate demand-control-support combinations. Disability was measured by summing the number of impaired basic and instrumental activities of daily living. Global cognitive function was assessed by Mini-Mental State Examination. Chronic conditions were ascertained by clinical examinations, medical history, and patient clinical records; the total number of chronic diseases was summed. Data were analyzed using linear mixed-effects models and mediation analysis. Age, sex, education, alcohol consumption, smoking, leisure activity engagement, early-life socioeconomic status, occupational characteristic and physical demands, and baseline cognitive function and number of chronic diseases were adjusted for in the analyses. Compared with active jobs (high control/high demands; n = 1,807), high strain (low control/high demands; n = 328), low strain (high control/low demands; n = 495), and passive jobs (low control/low demands; n = 307) were all associated with a faster rate of disability progression (β = 0.07, 95% CI 0.02-0.13, p = 0.01; β = 0.10, 95% CI 0.06-0.15, p < 0.001; β = 0.11, 95% CI 0.05-0.18, p < 0.001). The association between high strain and disability progression was only shown in people with low social support at work (β = 0.13, 95% CI 0.07-0.19, p < 0.001), but not in those with high social support (β = 0.004, 95% CI -0.09 to 0.10, p = 0.93). Moreover, we estimated that the association between demand-control status and disability trajectories was mediated 38.5% by cognitive decline and 18.4% by accumulation of chronic diseases during the follow-up period. The limitations of this study include unmeasured confounding, self-reported work experience, and the reliance on a psychosocial job-exposure matrix that does not consider variabilities in individuals' perception on working conditions or job characteristics within occupations.

CONCLUSIONS

Our findings suggest that negative psychosocial working conditions during working life may accelerate disability progression in later life. Notably, social support at work may buffer the detrimental effect of high strain on disability progression. Cognitive decline and chronic-disease accumulation, and especially the former, partially mediate the association of psychosocial working conditions with trajectories of disability. Further studies are required to explore more mechanisms that underlie the association between psychosocial working conditions and disability trajectories.

Job demands and control and sickness absence, disability pension and unemployment among 2,194,692 individuals in Sweden

Background: Knowledge is needed on associations between job demands and job control and long-term sickness absence (SA) and unemployment. We explored associations of job demands and job control with SA/disability pension (DP) and unemployment among women and men in paid work. Methods: We included all 2,194,694 individuals living in Sweden in 2001, aged 30–54 years, and in paid work. The Swedish Job Exposure Matrix (JEM) was used to ascertain levels of job demands and job control. Individuals were categorized into nine groups based on combinations of high, medium, or low values on both demands and control. Using multinomial logistic regression, we estimated odds ratios (OR) with 95% confidence intervals (CI) for the association of job demands and job control with risk of long-term SA/DP (>183 net days) and long-term unemployment (>183 days). Results: Regarding SA/DP, among women the risk was highest for those in occupations with low demands and low control (OR=1.32; 95% CI: 1.28–1.36), whereas among men the risk was highest among those in occupations with high demands and low control (OR=1.22; 1.11–1.34). Regarding unemployment, among women the risk was highest among those in occupations with low demands and medium control (OR=1.30; 1.24–1.37), whereas among men the risk was highest for those in occupations with low demands and high control (OR=1.54; 1.46–1.62). Conclusions: Using a JEM among all in a population rather than for specific occupations gives a more comprehensive view of the associations between job demands/job control and long-term SA/DP and unemployment, respectively.