Job strain and cognitive change: the Baltimore Epidemiologic Catchment Area follow-up study

Trajectories of occupational physical activity and risk of later-life mild cognitive impairment and dementia: the HUNT4 70+ study

Background

High levels of occupational physical activity (PA) have been linked to an increased risk of dementia. We assessed the association of trajectories of occupational PA at ages 33-65 with risk of dementia and mild cognitive impairment (MCI) at ages 70+.

Methods

We included 7005 participants (49.8% were women, 3488/7005) from the HUNT4 70+ Study. Group-based trajectory modelling was used to identify four trajectories of occupational PA based on national registry data from 1960 to 2014: stable low (30.9%, 2162/7005), increasing then decreasing (8.9%, 625/7005), stable intermediate (25.1%, 1755/7005), and stable high (35.2%, 2463/7005). Dementia and MCI were clinically assessed in 2017-2019. We performed adjusted multinomial regression to estimate relative risk ratios (RRR) with 95% confidence intervals (CI) for dementia and MCI.

Findings

902 participants were diagnosed with dementia and 2407 were diagnosed with MCI. Absolute unadjusted risks for dementia and MCI were 8.8% (95% CI: 7.6-10.0) and 27.4% (25.5-29.3), respectively, for those with a stable low PA trajectory, 8.2% (6.0-10.4) and 33.3% (29.6-37.0) for those with increasing, then decreasing PA; while they were 16.0% (14.3-17.7) and 35% (32.8-37.2) for those with stable intermediate, and 15.4% (14.0-16.8) and 40.2% (38.3-42.1) for those with stable high PA trajectories. In the adjusted model, participants with a stable high trajectory had a higher risk of dementia (RRR 1.34, 1.04-1.73) and MCI (1.80, 1.54-2.11), whereas participants with a stable intermediate trajectory had a higher risk of MCI (1.36, 1.15-1.61) compared to the stable low trajectory. While not statistically significant, participants with increasing then decreasing occupational PA had a 24% lower risk of dementia and 18% higher risk of MCI than the stable low PA group.

Interpretation

Consistently working in an occupation with intermediate or high occupational PA was linked to an increased risk of cognitive impairment, indicating the importance of developing strategies for individuals in physically demanding occupations to prevent cognitive impairment.

Funding

This work was supported by the National Institutes of Health (R01AG069109-01) and the Research Council of Norway (296297, 262700, 288083).

Manganese exposure and cognitive performance: A meta-analytical approach

Occupational manganese exposure is associated with serious health concerns, ultimately leading to an illness called manganism. Competing meta-analytic results were published over a decade ago, ranging from undetectable to serious effects on cognitive performance among working adults. Novel studies and findings about the relationship between occupational manganese and cognitive functions have been proposed since. First of all, a systematic literature search was carried out until October 2022 via multiple electronic databases investigating the relationship between occupational manganese exposure and cognitive functions. Differences between the exposure and control groups in cognitive testing were synthesized by effect size Hedge's g. A random effects model was deployed with a restricted likelihood estimator using Hedges' invariance weighting. Publication bias, p-hacking and exposure-effect relationships were investigated. We included 18 studies with 75 effect sizes comparing n = 888 controls and 1092 exposed participants. After exclusion of outliers, we found significantly lower performances in processing speed, attention, working memory, reaction time, cognitive control and visual attention in workers exposed to manganese. Regression analysis revealed an indication of exposure-effect relationships between manganese exposure and cognitive functioning in exposed workers. We provide results of impaired cognitive functions for working adults exposed to manganese in processing speed, attention, working memory, reaction time and visual attention. Indications of quadratic exposure-effect relationships are discussed. We provide several recommendations for further studies to investigate possible exposure effects in the context of occupational health and safety.

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.

Global cognitive function is associated with sex, educational level, occupation type, and speech recognition rate in older Chinese adults: a single-center, prospective, cross-sectional study

BACKGROUND

The development of cognitive impairment may be delayed if its risk factors are identified and detected, if its developmental trend can be predicted, and if early intervention can be performed. This study primarily aimed to investigate the association between global cognitive function and hearing loss, educational level, and occupation type and to determine any differences in such associations according to sex among older Chinese adults.

METHODS

In this cross-sectional study, we prospectively recruited 219 individuals above 55 years old in an otolaryngology outpatient clinic who could write independently and had no severe vision impairment. Audiometric examinations included otoscopy, acoustic immittance, pure-tone audiometry, and speech audiometry for each ear. Cognitive function was evaluated by using the Chinese version of the Mini-Mental State Examination (MMSE). Multivariable linear regression analyses were performed to evaluate the relationship between variables and MMSE scores after adjusting for independent variables that were statistically significant in the univariable analyses.

RESULTS

We enrolled 219 individuals: 98 men (mean ± standard deviation age, 63.08 ± 6.64 years) and 121 women (62.64 ± 7.17 years). The overall MMSE scores of the normal hearing group and the mild, moderate, and severe-to-profound hearing loss groups were 24.00 (5.00), 24.00 (5.00), 23.00 (5.00), and 23.00 (13.00), respectively. MMSE scores were higher among participants with higher educational levels (p < 0.001) and were significantly correlated with occupation type (p < 0.001). MMSE scores were significantly higher in men than in women (p < 0.001). However, after the analysis of the five subdomains, significant differences were only observed for attention and calculation (p < 0.001) and language (p = 0.011). We further compared the distribution of educational levels between men and women by using the chi-square test; there was no significant difference in educational level between the sexes (p = 0.070).

CONCLUSIONS

We reported statistically significant relationships between global cognitive function and sex, educational level, and occupation type. Sex-specific strategies may be required to improve healthcare policies.

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.

Occupational class differences in outcomes after ischemic stroke: a prospective observational study

BACKGROUND

Occupational class is an integral part of socioeconomic status. The studies focused on the occupational difference in ischemic stroke outcome in a Chinese population are limited. We aimed to investigate the associations between occupational class and the prognosis of patients with ischemic stroke in China.

METHODS

We included 1484 ischemic stroke participants (mean age: 63.42 ± 11.26 years) from the prospective cohort study: Infectious Factors, Inflammatory Markers and Prognosis of Acute Ischemic Stroke (IIPAIS). Occupational class was categorized into white-collar workers, blue-collar workers and farmers in our study. Study outcomes were cardiovascular events and all-cause mortality within 12 months after ischemic stroke onset. We applied Cox proportional hazard model to evaluate the associations between the occupational class and study outcomes after ischemic stroke.

RESULTS

Within 12 months after ischemic stroke, there were 106 (7.5%) cardiovascular events and 69 (4.9%) all-cause deaths. The Kaplan-Meier plots showed that white-collar workers had highest risk of cardiovascular events after 12-month follow-up (Log-rank P = 0.02). Multivariate adjusted hazard ratio and 95% confidence intervals (CIs) of farmers versus white-collar workers was 0.43(0.20-0.91) for cardiovascular events. No significant difference showed in blue-collar workers versus white-collar workers, with fully adjusted hazard ratio 0.62(95% CIs, 0.23-1.67).

CONCLUSIONS

Compared with white-collar workers, farmers are associated with less risk of cardiovascular events at 12 months after ischemic stroke, while there are no significant differences in blue-collar workers.

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.

Long-term physical health outcomes of obsessive-compulsive personality disorder traits

BACKGROUND

Obsessive-compulsive personality disorder (OCPD) is characterized by pervasive and persistent traits including preoccupation with orderliness, perfectionism, and control. Relatively little is known about the potential relationship between OCPD traits and physical health.

METHODS

We investigated the association between OCPD traits and several self-reported medical conditions in 249 individuals followed prospectively from 1981 until 2004/2005 as part of the Epidemiological Catchment Area.

RESULTS

The OCPD trait score was inversely related to hypertension in males, in models unadjusted (OR = 0.66; 95% CI, 0.45-0.90) and adjusted (OR = 0.70; 95% CI, 0.47-0.95) for sociodemographic variables. Perfectionism was inversely related to hypertension in the unadjusted models for men (OR = 0.34; 95% CI, 0.12-0.89). Indecisiveness was positively associated with heart conditions in adjusted models for women (OR = 3.46; 95% CI, 1.11-10.52).

CONCLUSION

OCPD traits are associated with cardiovascular health in both sexes. Further studies are needed to understand the specificity of these relationships, as well as to determine the underlying mechanism.

Examining gender differentials in the association of low control work with cognitive performance in older workers

BACKGROUND

Limited workplace control, an important dimension of job strain, can reduce occupational opportunities for problem solving and learning. Women may have fewer professional resources to mitigate effects of low control, while conversely, gender-role norms may moderate the influence of occupational psychosocial risk factors. We therefore examined whether the links between control and cognitive function were similarly gendered.

METHODS

This observational, longitudinal study included respondents of the Survey of Health, Ageing and Retirement in Europe who were aged 50-64 years at entry, employed and provided at least two measurements of control and cognition (n = 6697). Relationships between control and cognition, quantified with standardized scores from verbal fluency, immediate and delayed word recall tests, were explored using linear fixed-effect and random-effect models with gender interactions.

RESULTS

Consistent trends of improved verbal fluency performance with high control were evident across analyses, equal to producing around three-quarters of a word more under high control conditions, with an effect size ∼0.1 SD units (fully adjusted models, range 0.077-0.104 SD), although associations with recall tests were inconsistent. We did not find evidence of clear gender differences in control-cognition relationships for any of the cognitive domains.

CONCLUSIONS

The cognitive health of older European workers may benefit from improved workplace control irrespective of gender. Possible sources of bias that could explain the lack of gender differences are discussed, particularly gender differences in labour force participation, response behaviour in job control ratings and implications of gender-role norms on the importance of occupational risk factors.

Occupational Physical Stress Is Negatively Associated With Hippocampal Volume and Memory in Older Adults

Our jobs can provide intellectually and socially enriched environments but also be the source of major psychological and physical stressors. As the average full-time worker spends >8 h at work per weekday and remains in the workforce for about 40 years, occupational experiences must be important factors in cognitive and brain aging. Therefore, we studied whether occupational complexity and stress are associated with hippocampal volume and cognitive ability in 99 cognitively normal older adults. We estimated occupational complexity, physical stress, and psychological stress using the Work Design Questionnaire (Morgeson and Humphrey, 2006), Quantitative Workload Inventory and Interpersonal Conflict at Work Scale (Spector and Jex, 1998). We found that physical stress, comprising physical demands and work conditions, was associated with smaller hippocampal volume and poorer memory performance. These associations were independent of age, gender, brain size, socioeconomic factors (education, income, and job title), duration of the job, employment status, leisure physical activity and general stress. This suggests that physical demands at work and leisure physical activity may have largely independent and opposite effects on brain and cognitive health. Our findings highlight the importance of considering midlife occupational experiences, such as work physical stress, in understanding individual trajectories of cognitive and brain aging.

Fatores de Risco e Riscos Psicossociais no Trabalho: Definição e Implicações

Resumo O objetivo deste artigo teórico é analisar os conceitos de fatores de risco e riscos psicossociais no trabalho, bem como discuti-los a partir de duas perspectivas teóricas proeminentes no campo: o Modelo Demanda-Controle e a Psicodinâmica do Trabalho. Além das definições, são apresentadas as relações entre antecessores - fatores de risco, e consequentes - riscos psicossociais, e as implicações teóricas e práticas decorrentes da definição mais acurada dos termos. As conclusões apresentadas apontam para importância de delimitação conceitual entre fatores de risco e riscos psicossociais no trabalho como passo indispensável para o desenvolvimento de estratégias eficazes de avaliação e intervenção nos contextos de trabalho, principalmente pela adoção de uma postura preventiva com foco na identificação e controle dos fatores de risco prioritariamente.