Psychosocial work factors and dementia

Alzheimer's Disease Prevention and Treatment Based on Population-Based Approaches

The development of effective prevention and treatment strategies for Alzheimer's disease (AD) and dementia is hindered by limited knowledge of the underlying biological and environmental causes. While certain genetic factors have been associated with AD, and various lifestyle and environmental factors have been linked to dementia risk, the interactions between genes and the environment are not yet fully understood. To identify new avenues for dementia prevention, coordinated global efforts are needed to utilize existing cohorts and resources effectively and efficiently. This chapter provides an overview of current research on risk and protective factors for AD and dementia and discusses the opportunities and challenges associated with population-based approaches.

Impact of shift work on dementia: a systematic review and dose-response meta-analysis

OBJECTIVES

Although shift work has been reported as having a link to dementia, evidence remains inconsistent, and a comprehensive dose-response meta-analysis of the association is still lacking. We therefore conducted this meta-analysis to explore the association between shift work and the risk of dementia.

STUDY DESIGN

Systematic review and dose-response meta-analysis.

METHODS

PubMed, Embase, and Web of Science databases were systematically searched. Fixed or random-effects models were used to estimate the summary relative risks (RRs) and 95% confidence intervals (95% CIs). Generalized least squares regression was used to estimate dose-response associations, and restricted cubic splines were used to examine possible linear or non-linear associations.

RESULTS

Five articles (10 studies) with 72,999 participants and 23,067 cases were eventually included in the meta-analysis. The summary RRs and 95% CIs of dementia risk with shift work and night shift work versus daytime work were 1.13 (95% CI: 1.05-1.21, I2 = 46.70%) and 1.13 (95% CI: 1.03-1.24, I2 = 9.20%), respectively. The risk of dementia increased by 1% (RR = 1.01, 95% CI: 1.01-1.02, I2 = 41.3%) with each 1-year increase in the duration of shift work. We found a non-linear dose-response association between the duration of shift work and the risk of dementia (Pnon-linearity = 0.006). Though the shape of the curve was steeper with the duration of shift work <7 years, the increase was more gradual after 7 years.

CONCLUSION

Our findings suggest that shift work may be a risk factor for future dementia and that controlling the length of shift work is a feasible measure that may contribute to prevent dementia.

Psychosocial Risk Factors for Alzheimer's Disease in Patients with Down Syndrome and Their Association with Brain Changes: A Narrative Review

Several recent epidemiological studies attempted to identify risk factors for Alzheimer’s disease. Age, family history, genetic factors (APOE genotype, trisomy 21), physical activity, and a low level of schooling are significant risk factors. In this review, we summarize the known psychosocial risk factors for the development of Alzheimer’s disease in patients with Down syndrome and their association with neuroanatomical changes in the brains of people with Down syndrome. We completed a comprehensive review of the literature on PubMed, Google Scholar, and Web of Science about psychosocial risk factors for Alzheimer’s disease, for Alzheimer’s disease in Down syndrome, and Alzheimer’s disease in Down syndrome and their association with neuroanatomical changes in the brains of people with Down syndrome. Alzheimer’s disease causes early pathological changes in individuals with Down syndrome, especially in the hippocampus and corpus callosum. People with Down syndrome living with dementia showed reduced volumes of brain areas affected by Alzheimer’s disease as the hippocampus and corpus callosum in association with cognitive decline. These changes occur with increasing age, and the presence or absence of psychosocial risk factors impacts the degree of cognitive function. Correlating Alzheimer’s disease biomarkers in Down syndrome and cognitive function scores while considering the effect of psychosocial risk factors helps us identify the mechanisms leading to Alzheimer’s disease at an early age. Also, this approach enables us to create more sensitive and relevant clinical, memory, and reasoning assessments for people with Down syndrome.

Association of mental demands in the workplace with cognitive function in older adults at increased risk for dementia

Objectives

Growing evidence suggests a protective effect of high mental demands at work on cognitive function in later life. However, evidence on corresponding associations in older adults at increased risk for dementia is currently lacking. This study investigates the association between mental demands at work and cognitive functioning in the population of the AgeWell.de-trial.

Methods

Cross-sectional investigation of the association between global cognitive functioning (Montreal Cognitive Assessment) and mental demands at work in older individuals at increased risk for dementia (Cardiovascular Risk Factors, Aging, and Incidence of Dementia (CAIDE)score ≥ 9; n = 941, age: 60–77 years). Occupational information was matched to Occupational Information Network (O*NET)-descriptors. Associations between cognitive function and O*NET-indices executive, verbal and novelty were investigated using generalized linear models.

Results

Higher values of index verbal (b = .69, p = .002) were associated with better cognitive function when adjusting for covariates. No association was observed for indices executive (b = .37, p = .062) and novelty (b = .45, p = .119). Higher education, younger age, and employment were linked to better cognitive function, while preexisting medical conditions did not change the associations. Higher levels of depressive symptomatology were associated with worse cognitive function.

Conclusions

Higher levels of verbal demands at work were associated with better cognitive function for older adults with increased dementia risk. This suggests an advantage for older persons in jobs with high mental demands even after retirement and despite prevalent risk factors. Longitudinal studies are warranted to confirm these results and evaluate the potential of workplaces to prevent cognitive decline through increased mental demands.

Impact of chronic stress exposure on cognitive performance incorporating the active and healthy aging (AHA) concept within the cross-sectional Bern Cohort Study 2014 (BeCS-14)

Purpose

This study aims to verify that the mental-cognitive domain of the validated generic bio-functional status (BFS)/bio-functional age (BFA) assessment tool, incorporating the concept of Active and Healthy Ageing (AHA), reflects cognitive performance. In addition, the effects of chronic stress exposure on the mental-cognitive BFS/BFA should be investigated.

Methods

The study was carried out as a monocenter, cross-sectional, observational, non-interventional trial (Bern Cohort Study 2014, BeCS-14) with the participation of 147 non-pediatric, non-geriatric subjects. All participants followed a standardized battery of biopsychosocial assessments consisting of BFS/BFA, a validated cognitive performance test battery (Inventar zur Gedächtnisdiagnostik; IGD) and a validated questionnaire for the assessment of chronic stress (Trier Inventory for the assessment of Chronic Stress; TICS), respectively.

Results

Mean cognitive performance was average and higher in younger or better educated individuals. The BFA of the participants was 7.8 ± 7.8 year-equivalents below their chronological age. The mental-cognitive BFS/BFA assessment correlated well with the validated questionnaire for cognition assessment, the IGD. Further, three TICS subdomains (work overload (r =  − 0.246, p = 0.003), work discontent (r =  − 0.299, p = 0.006) and pressure to succeed (r =  − 0.274, p < 0.001)), reflecting mainly work-related stress, showed a significant negative correlation with the mental-cognitive BFS/BFA.

Conclusions

Our study shows that the BFS/BFA assessment tool follows European Innovation Partnership on Active and Healthy Ageing (EIP-AHA) requirements. Further, we could demonstrate that higher levels of chronic work-related stress may be associated with poorer mental-cognitive performance and a pro-aging state indicating that cognitive impairments can be reduced by stress management interventions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00404-021-06289-z.

Association of Occupational Factors and Dementia or Cognitive Impairment: A Systematic Review and Meta-Analysis

BACKGROUND

Several existing studies have reported that occupational factors might play an important part in cognitive function with aging.

OBJECTIVE

We aim to explore the associations between modifiable occupational factors and risk of dementia or mild cognitive impairment (MCI).

METHODS

Adopting random-effect models, this study conducted primary analyses for all occupational factors and subgroup analyses for the effect of occupation type based on prospective cohort and case-control studies searched from PubMed and EMBASE databases up to March 2020.

RESULTS

Among the 38,111 identified literatures, 9 studies on occupation type, 4 studies on work complexity, and 30 studies on occupational exposure were included. In terms of occupation type, mental work conferred a 44% reduced risk (95% CI = 0.34-0.94, I² = 85.00%, p < 0.01) for MCI. In terms of work complexity, higher work complexity conferred a 5% reduced risk (95% CI = 0.91-1.00, I² = 57.00%, p < 0.01) for dementia. In terms of occupational exposure, high strain and passive job in the longest-held job conferred a 1.21- and 1.15-fold excess risk (95% CI = 1.05-1.39 I² = 62.00%, p < 0.05; 95% CI = 1.05-1.26 I² = 31.00%, p = 0.23; respectively) of cognitive decline. Besides, magnetic field exposure conferred a 1.26-fold excess risk (95% CI = 1.01-1.57, I² = 69.00%, p < 0.01) for dementia.

CONCLUSION

Novel prevention strategies based on occupational factors may hold promise against dementia and MCI.

Development of a protective mental work demands questionnaire

OBJECTIVES

Research shows that mental demands at work affect later-life cognitive functioning and dementia risk, but systematic assessment of protective mental work demands (PMWDs) is still missing. The goal of this research was to develop a questionnaire to assess PMWDs.

DESIGN

The instrument was developed in accordance with internationally recognized scientific standards comprising conceptualization, pretesting, and validation via confirmatory factor analysis (CFA), principal component analysis (PCA), and multiple regression analyses.

PARTICIPANTS

We included 346 participants, 72.3% female, with an average age of 56.3 years.

MEASUREMENT

Item pool, sociodemographic questions, and cognitive tests: Trail-Making Test A/B, Word List Recall, Verbal Fluency Test, Benton Visual Retention Test, Reading Minds in the Eyes Test.

RESULTS

CFAs of eight existing PMWD-concepts revealed weaker fit indices than PCA of the item pool that resulted in five concepts. We computed multivariate regression analyses with all 13 PMWD-concepts as predictors of cognitive functioning. After removing PMWD-concepts that predicted less than two cognitive test scores and excluding others due to overlapping items, the final questionnaire contained four PMWD-concepts: Mental Workload (three items, Cronbach's α = .58), Verbal Demands (four, Cronbach's α = .74), Information Load (six, Cronbach's α = .83), and Extended Job Control (six, Cronbach's α = .83).

CONCLUSIONS

The PMWD-Questionnaire intends to assess protective mental demands at the workplace. Information processing demands and job control make up the primary components emphasizing their relevance regarding cognitive health in old age. Long-term follow-up studies will need to validate construct validity with respect to dementia risk.

Impact of Shift Work and Long Working Hours on Worker Cognitive Functions: Current Evidence and Future Research Needs

Particular working conditions and/or organization of working time may cause important sleep disturbances that have been proposed to be predictive of cognitive decline. In this regard, circadian rhythm misalignment induced by exposure to night work or long working hours would be responsible for cognitive impairment. Nevertheless, evidence supporting this correlation is limited and several issues still need to be elucidated. In this regard, we conducted a systematic review to evaluate the association between shift/night work and cognitive impairment and address its main determinants. Information provided by the reviewed studies suggested that night work might have serious immediate negative effects especially on cognitive domains related to attention, memory and response inhibition. Furthermore, cognitive performance would progressively worsen over consecutive night shifts or following exposure to very long work shifts. Otherwise, conflicting results emerged regarding the possible etiological role that night work chronic exposure would have on cognitive impairment. Therefore, circadian rhythm desynchronization, lack of sleep and fatigue resulting from night work may negatively impact worker’s cognitive efficiency. However, in light of the considerable methodological variability of the reviewed studies, we proposed to develop a standardized research and evaluation strategy in order to obtain a better and comprehensive understanding of this topic.

Older Workers with Physically Demanding Jobs and their Cognitive Functioning

Although employment can provide older people with both financial and nonfinancial rewards, it is questionable whether those benefits extend to all older workers, particularly those with physically demanding jobs. This study aimed to examine whether the perceived level of physical demands placed on older workers 55 or older is significantly associated with their cognitive function. Using the Health and Retirement Study (HRS) 2010 wave, we analyzed two domains of cognition: verbal episodic memory and reasoning. After controlling for demographics and risk factors for age-related cognitive deterioration, the perceived level of physical demands placed on older workers was still significantly and negatively linked with both memory and reasoning domains of cognition. Older workers with more physically demanding jobs tended to have poorer cognitive function. Further longitudinal studies are needed to confirm this relationship.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12126-020-09404-8.

Does Midlife Forgetfulness Influence Positive and Negative Aspects of Social Relations at Work?: Results From the Danish Working Environment Cohort Study

OBJECTIVES

We investigated whether midlife forgetfulness was prospectively associated with changes in social relations at work (SRW) among occupationally active individuals in Denmark.

METHODS

We analyzed data of 2339 men and women participating in the first (1990) and second (1995) survey of the Danish Work Environment Cohort Study, responding to questions on working environment, SRW, and forgetfulness. We used multiple linear regression analysis while adjusting for potential confounders.

RESULTS

At baseline (1990), 517 (22.1%) study participants were categorized as forgetful. Forgetfulness was prospectively associated with a decline in one of the investigated items reflecting a negative aspect of SRW (experiencing teasing, regression coefficient = 0.07, 95% CI: 0.03 to 0.11), while no association was observed with positive aspects of SRW.

CONCLUSIONS

Our findings did not support the hypothesis that memory problems such as midlife forgetfulness negatively affect SRW.

Retirement and decline in episodic memory: analysis from a prospective study of adults in England

BACKGROUND

Work has been associated with cognitive health. We examined whether retirement from work is associated with a decrease in episodic memory and whether this effect differs when considering workers' occupational class.

METHODS

In this prospective study using the English Longitudinal Study of Ageing (ELSA), we examined 1629 persons aged 50-75 years who were in paid work at baseline. A two-slope random effects linear regression centred at retirement was used to study the effect of retirement on episodic memory. The potential effect modification by occupational class was examined.

RESULTS

While memory trajectories show slightly decreasing memory scores before and afterretirement, the decreasing rates for both periods were similar [episodic memory β2b-β2a= -0.03, 95% confidence interval (CI) -0.08, 0.02]. When stratifying by occupational class, there was also no substantial difference in episodic memory trajectories before and after retirement. However, the lower occupational class showed a clear decline in episodic memory with time (pre-retirement β2a = -0.11, 95% CI -0.19, -0.03; post-retirement β2b = -0.13, 95% CI -0.19, -0.07) which was not evident for the higher occupational classes.

CONCLUSIONS

Our results show no observable difference in trajectories of change in episodic memory before and after retirement. However, the steeper memory decline in workers belonging to the lower occupational class may limit their prospect of prolonging their working lives. Hence enrichment programmes for the prevention of memory decline for these workers should be considered.

Developing a Job Exposure Matrix of Work Organization Hazards in the United States: A Review on Methodological Issues and Research Protocol

Background

Most job exposure matrices (JEMs) have been developed for chemical and physical hazards in the United States (US). In addition, the overall validity of most JEMs of work organization hazards using self-reported data in the literature remains to be further tested due to several methodological weaknesses.

Methods

This paper aims to review important methodological issues with regard to a JEM of work organization hazards using self-report data and to present a research protocol for developing a four-axis (job titles, hazards, sex, and time) JEM of major work organization hazards using the US General Social Survey-Quality of Work-Life (GSS-QWL) data (2002–2018; N = 7,100 workers).

Results

Five methodological weaknesses in existing JEMs of work organization hazards using self-report data were identified: having only two axes (hazard and occupation), using psychometrically weak items and scales, including scales having little interoccupational variability, unresolved optimal minimum numbers of subjects per occupation, and low accessibility. The methodological weaknesses were successfully addressed in the proposed research protocol.

Conclusion

The work organization JEM to be developed will significantly facilitate and strengthen occupational epidemiological studies on work organization hazards and major health outcomes, improve national and occupational surveillance of work organization hazards, and promote interventions for a healthy work environment in the US.

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.

Socio-economic status and dementia onset among older Japanese: A 6-year prospective cohort study from the Japan Gerontological Evaluation Study

OBJECTIVES

Lower socio-economic status (SES) may be associated with dementia later in life, but there is inconsistent evidence supporting this claim. We aim to examine the association between three SESs (education, job, and income indicators) and dementia onset in older adults.

METHODS

Study design was a 6-year prospective cohort study. Participants included a total of 52 063 community-dwelling adults aged 65 years or older without long-term care needs from the Japan Gerontological Evaluation Study. Outcome variable was dementia onset. Explanatory variables were educational years, the longest job held, and equivalised household income. We performed Cox proportional hazard analysis by gender with multiple imputation.

RESULTS

During the follow-up period, 10.5% of participants acquired dementia. The adjusted risks of dementia incidence of the participants with less than 6 years of education were 1.34 times (95% confidence interval [CI], 1.04-1.73) in men and 1.21 (1.00-1.45) times in women higher than those with more than 13 years of education. Females with less than 1.99 million yen (hazard ratio = 0.83, 0.72-0.96) of equivalised income were less likely to acquire dementia than those with four million yen or higher.

CONCLUSIONS

Educational attainment had a robust impact on dementia onset compared with the other SES factors in both genders of older Japanese people. Securing an education for children could be crucial to prevent dementia later in life. The longest job held was less likely to be risks of dementia incidence, compared with the other two factors.

Social Relations at Work and Incident Dementia: 29-Years' Follow-Up of the Copenhagen Male Study

Objective:

We investigated whether social relations at work were associated with incident dementia in old age.

Methods:

One thousand five hundred seventy-two occupationally active men from the Copenhagen Male Study Cohort were followed from 1986 to 2014. Participants underwent a clinical examination at baseline and answered questionnaires on whether they (1) had possibilities to be in contact with coworkers, (2) could get along with coworkers, and (3) were satisfied with supervisor. Poisson regression was used to estimate incidence rate ratios (IRR).

Results:

Two hundred forty five (15.6%) men were diagnosed with dementia during an average of 15.8 years of follow-up. After adjusting for potential confounders, limited contact with coworkers was associated with a higher risk of dementia (IRR = 2.49, 95% confidence interval [CI] 1.14 to 5.44), but the other two measures were not.

Conclusions:

Our data partially support that social relations at work are associated with incident dementia.

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.

Night shift work, long working hours and dementia: a longitudinal study of the Danish Work Environment Cohort Study

OBJECTIVE

Shift work and long working hours are potential risk factors for dementia, but previous studies on shift work, long working hours and dementia are sparse and their findings are conflicting. Therefore, we investigated the effect of night shift work and long working hours on dementia.

DESIGN

A longitudinal study.

SETTING

Denmark.

PARTICIPANTS

3435 occupationally active men and women from the general working population.

METHODS

Work schedule covered day work (reference) and shift schedules without/with night work. Working hours covered <27, 28-36, 37 (reference), 38-44, and ≥45 hours/week. As the primary outcome, we used register-based information about dementia, and estimated incidence rate ratios (IRR) and 95% CI. Estimates were adjusted for gender, age, psychosocial work factors and cardiovascular risk factors.

RESULTS

We identified 85 dementia cases during a mean of 9.8 years of follow-up. We found a positive, but statistically insignificant association between night shift work and dementia (IRR=2.01; 95% CI: 0.87-4.65). Post hoc analyses indicated that this was only due to a higher risk in permanent night workers (IRR=3.25; 95% CI: 1.35-7.83). The dementia risk was also significantly higher among participants working 38-44 hours/week (IRR=2.08; 95% CI: 1.11-3.90) compared with those working 37 hours/week. We found no indications of a higher risk of dementia in participants working <37 hours/week or ≥45 hours/week.

CONCLUSION

We did not find arguments that night shift work or long working hours increased dementia risk in general. However, we found a higher risk of dementia in specific subgroups, that is, permanent night workers and employees with moderately longer weekly working hours than the standard.

The Protective Effect of Cantonese/Mandarin Bilingualism on the Onset of Alzheimer Disease

BACKGROUND

Several studies have found that bilingualism can delay the age of onset of Alz-heimer disease (AD). The interpretation of these findings is that switching between two languages can enhance cognitive reserve. However, some studies have provided inconsistent results. Diverse language pairs used by the bilinguals in different studies may contribute to the discrepancies. Cantonese and Mandarin are widely used in southern China, and regarded as bilingualism. The present study aims to determine if Cantonese/Mandarin bilingualism can delay the onset of AD.

METHODS

The data of 129 patients diagnosed with probable AD, including 48 Cantonese monolinguals, 20 Mandarin monolinguals, and 61 Cantonese/Mandarin bilinguals were analyzed.

RESULTS

Cantonese/Mandarin bilinguals were found to have an older age at AD onset, and older age at the first clinic visit than Mandarin monolinguals and Cantonese monolinguals. Both Mandarin monolinguals and Cantonese/Mandarin bilinguals had a higher education level and higher occupation status than the Cantonese monolinguals. Mandarin monolinguals did not differ from Cantonese/Mandarin bilinguals significantly in years of education and occupation status. The multiple linear regression analyses indicated that Cantonese/Mandarin bilingualism can delay the onset of AD independently.

CONCLUSION

Constantly speaking both Cantonese and Mandarin from at least early adulthood can delay the onset of AD.

Socioeconomic status, gender and dementia: The influence of work environment exposures and their interactions with APOE ɛ4

It is a well-established fact that unfavourable social and economic conditions have a negative impact on health and longevity. Recent findings suggest that this is also true of age-related dementias. Yet most common indicators of socioeconomic status (SES) say very little about the actual mechanisms at play in disease development. The present paper explores five work exposure characteristics, all of which have a clear social gradient, that could potentially shed further light on the relationship between SES and dementia. Specifically, it investigates whether these exposures could moderate the impact of a well-known genetic risk factor: the APOE ɛ4 allele. The empirical analyses are based on data from a Swedish population study (n = 1019). Main occupation was linked to The Job Exposure Matrix to estimate the individuals’ exposure to the following work environment factors: work control, support, psychological demands, physical demands and job hazards. All analyses were conducted using binary logistic regression and focused specifically on gene-work exposure interactions. A significant main effect of work control on dementia risk was detected for males (OR = 0.68; p< 0.05), but not for females. However, control was found to significantly moderate the effect of APOE ɛ4 in both genders, albeit in different ways. These findings do not only underscore the importance of considering interactions between social and genetic risk factors to better understanding multifactorial diseases such as dementia. They also propose that gender- and class-based inequities interact, and hence must be considered simultaneously, also in relation to this particular disease.

•

There are steep social gradients in exposure to various work environment conditions.

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Work control alters the effect of APOE ɛ4 in both genders, albeit in different ways.

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High work control protects male, but not female, APOE ɛ4-carriers.

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‘Male’ high control jobs differ greatly from ‘female’ high control jobs.

•

Gender- and class-based inequities interact also in the development of dementia.

Study of the validity of a job-exposure matrix for the job strain model factors: an update and a study of changes over time

OBJECTIVES

The objectives of the study were to construct a job-exposure matrix (JEM) for psychosocial work factors of the job strain model, to evaluate its validity, and to compare the results over time.

METHODS

The study was based on national representative data of the French working population with samples of 46,962 employees (2010 SUMER survey) and 24,486 employees (2003 SUMER survey). Psychosocial work factors included the job strain model factors (Job Content Questionnaire): psychological demands, decision latitude, social support, job strain and iso-strain. Job title was defined by three variables: occupation and economic activity coded using standard classifications, and company size. A JEM was constructed using a segmentation method (Classification and Regression Tree-CART) and cross-validation.

RESULTS

The best quality JEM was found using occupation and company size for social support. For decision latitude and psychological demands, there was not much difference using occupation and company size with or without economic activity. The validity of the JEM estimates was higher for decision latitude, job strain and iso-strain, and lower for social support and psychological demands. Differential changes over time were observed for psychosocial work factors according to occupation, economic activity and company size.

CONCLUSIONS

This study demonstrated that company size in addition to occupation may improve the validity of JEMs for psychosocial work factors. These matrices may be time-dependent and may need to be updated over time. More research is needed to assess the validity of JEMs given that these matrices may be able to provide exposure assessments to study a range of health outcomes.

Population-Based Approaches to Alzheimer's Disease Prevention

Progress in prevention and treatment of Alzheimer's disease (AD) and dementia is hampered by the restricted understanding of the biological and environmental causes underlying pathophysiology. It is widely accepted that certain genetic factors are associated with AD and a number of lifestyle and other environmental characteristics have also been linked to dementia risk. However, interactions between genes and the environment are not yet well understood, and coordinated global action is required to utilize existing cohorts and other resources effectively and efficiently to identify new avenues for dementia prevention. This chapter provides a brief summary of current research on risk and protective factors and opportunities and challenges in relation to population-based approaches are discussed.

Midlife Work-Related Stress Increases Dementia Risk in Later Life: The CAIDE 30-Year Study

Objective

To investigate the associations between midlife work-related stress and mild cognitive impairment (MCI), dementia, and Alzheimer's disease later in life, in a large representative population.

Method

Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study participants were randomly selected from independent population-based surveys (mean age 50 years). A random sample of 2,000 individuals was invited for two reexaminations including cognitive tests (at mean age 71 and mean age 78), and 1,511 subjects participated in at least one reexamination (mean follow-up 28.5 years). Work-related stress was measured using two questions on work demands that were administered in midlife. Analyses adjusted for important confounders.

Results

Higher levels of midlife work-related stress were associated with higher risk of MCI (odds ratio [OR], 1.38; 95% confidence interval [CI], 1.08-1.76), dementia (OR, 1.53; CI, 1.13-2.07), and Alzheimer's disease (OR, 1.55; CI, 1.19-2.36) at the first follow-up among the CAIDE participants. Results remained significant after adjusting for several possible confounders. Work-related stress was not associated with MCI and dementia during the extended follow-up.

Discussion

Midlife work-related stress increases the risk for MCI, dementia, and Alzheimer's disease in later life. The association was not seen after the extended follow-up possibly reflecting selective survival/participation, heterogeneity in dementia among the oldest old, and a critical time window for the effects of midlife stress.

Midlife work-related stress is associated with late-life cognition

To investigate the associations between midlife work-related stress and late-life cognition in individuals without dementia from the general population. The Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study population (n = 2000) was randomly selected from independent Finnish population-based surveys (baseline mean age 50 years). Participants underwent two re-examinations in late life (mean age 71 and 78 years, respectively). 1511 subjects participated in at least one re-examination (mean total follow-up 25 years). Work-related stress was measured using two questions on work demands administered in midlife. Multiple cognitive domains were assessed. Analyses were adjusted for several potential confounders. Higher levels of midlife work-related stress were associated with poorer performance on global cognition [β-coefficient, -0.02; 95% confidence interval (CI), -0.05 to -0.00], and processing speed [β -0.03, CI -0.05 to -0.01]. Results remained significant after adjusting for potential confounders. Work-related stress was not significantly associated with episodic memory, executive functioning, verbal fluency or manual dexterity. This study shows that global cognition and processing speed may be particularly susceptible to the effects of midlife work-related stress.

Low Control and High Demands at Work as Risk Factors for Suicide: An Australian National Population-Level Case-Control Study

OBJECTIVE

Previous research suggests that psychosocial job stressors may be plausible risk factors for suicide. This study assessed the relationship between psychosocial job stressors and suicide mortality across the Australian population.

METHODS

We developed a job exposure matrix to objectively measure job stressors across the working population. Suicide data came from a nationwide coronial register. Living controls were selected from a nationally representative cohort study. Incidence density sampling was used to ensure that controls were sampled at the time of death of each case. The period of observation for both cases and controls was 2001 to 2012. We used multilevel logistic regression to assess the odds of suicide in relation to 2 psychosocial job stressors (job control and job demands), after matching for age, sex, and year of death/survey and adjusting for socioeconomic status.

RESULTS

Across 9,010 cases and 14,007 matched controls, our results suggest that low job control (odds ratio [OR], 1.35; 95% confidence interval [CI], 1.26-1.44; p < .001) and high job demands (OR, 1.36; 95% CI, 1.26-1.46; p < .001) were associated with increased odds of male suicide after adjusting for socioeconomic status. High demands were associated with lower odds of female suicide (OR, 0.81; 95% CI, 0.72-0.92; p = .002).

CONCLUSIONS

It seems that adverse experiences at work are a risk factor for male suicide while not being associated with an elevated risk among females. Future studies on job stressors and suicide are needed, both to further understand the biobehavioral mechanisms explaining the link between job stress and suicide, and to inform targeted prevention initiatives.

Social class, dementia and the fourth age

Research addressing social class and dementia has largely focused on measures of socioeconomic status as causal risk factors for dementia and in observed differences in diagnosis, treatment and care. This large body of work has produced important insights but also contains numerous problems and weaknesses. Research needs to take account of the ways in which ageing and social class have been transformed in tandem with the economic, social and cultural coordinates of late modernity. These changes have particular consequences for individual identities and social relations. With this in mind this article adopts a critical gaze on research that considers interactions between dementia and social class in three key areas: (i) epidemiological approaches to inequalities in risk (ii) the role of social class in diagnosis and treatment and (iii) class in the framing of care and access to care. Following this, the article considers studies of dementia and social class that focus on lay understandings and biographical accounts. Sociological insights in this field come from the view that dementia and social class are embedded in social relations. Thus, forms of distinction based on class relations may still play an important role in the lived experience of dementia.

Sustaining people with dementia or mild cognitive impairment in employment: A systematic review of qualitative evidence

Introduction

The World Health Organization estimates that 10% of the 35.6 million people worldwide with dementia are aged under 65 years. In an ageing workforce this has implications for employers, employees, and statutory and third sector services. Limited research has been conducted into this emerging global issue.

Method

This systematic review, employing the methodology of the Joanna Briggs Institute, aimed to identify and synthesise the best available qualitative evidence regarding the needs, experiences and perspectives of people with early onset dementia or mild cognitive impairment who were either in employment or wished to gain employment.

Results

Of 69 studies identified, eight met the inclusion criteria. From these, four themes emerged: disease progression and recognition; the emotional impact of change; the employer’s management of the worker; and changes to the worker role.

Conclusion

There are health benefits to the individual with dementia or mild cognitive impairment of continuing to engage in meaningful occupation. Retirement policy changes have resulted in an ageing workforce with concurrent risk factors for dementia. A lack of understanding of reasonable adjustments and sheltered employment opportunities was evident from the literature. This review highlights the potential for occupational therapists to engage this client group in vocational rehabilitation.

Validity of a Job-Exposure Matrix for Psychosocial Job Stressors: Results from the Household Income and Labour Dynamics in Australia Survey

Introduction

A Job Exposure Matrix (JEM) for psychosocial job stressors allows assessment of these exposures at a population level. JEMs are particularly useful in situations when information on psychosocial job stressors were not collected individually and can help eliminate the biases that may be present in individual self-report accounts. This research paper describes the development of a JEM in the Australian context.

Methods

The Household Income Labour Dynamics in Australia (HILDA) survey was used to construct a JEM for job control, job demands and complexity, job insecurity, and fairness of pay. Population median values of these variables for all employed people (n = 20,428) were used to define individual exposures across the period 2001 to 2012. The JEM was calculated for the Australian and New Zealand Standard Classification of Occupations (ANZSCO) at the four-digit level, which represents 358 occupations. Both continuous and binary exposures to job stressors were calculated at the 4-digit level. We assessed concordance between the JEM-assigned and individually-reported exposures using the Kappa statistic, sensitivity and specificity assessments. We conducted regression analysis using mental health as an outcome measure.

Results

Kappa statistics indicate good agreement between individually-reported and JEM-assigned dichotomous measures for job demands and control, and moderate agreement for job insecurity and fairness of pay. Job control, job demands and security had the highest sensitivity, while specificity was relatively high for the four exposures. Regression analysis shows that most individually reported and JEM measures were significantly associated with mental health, and individually-reported exposures produced much stronger effects on mental health than the JEM-assigned exposures.

Discussion

These JEM-based estimates of stressors exposure provide a conservative proxy for individual-level data, and can be applied to a range of health and organisational outcomes.

Analysis of causal relationships by structural equation modeling to determine the factors influencing cognitive function in elderly people in Japan

The purpose of this study is to identify a potentiality factor that is a preventive factor for decline in cognitive function. Additionally, this study pursues to clarify the causal relationship between the each potential factor and its influence on cognitive function. Subjects were 366 elderly community residents (mean age 73.7 ± 6.4, male 51, female 315) who participated in the Taketoyo Project from 2007 to 2011. Factor analysis was conducted to identify groupings within mental, social, life, physical and cognitive functions. In order to detect clusters of 14 variables, the item scores were subjected to confirmatory factor analysis. We performed Structural Equation Modeling analysis to calculate the standardization coefficient and correlation coefficient for every factor. The cause and effect hypothesis model was used to gather two intervention theory hypotheses for dementia prevention (direct effect, indirect effect) in one system. Finally, we performed another Structural Equation Modeling analysis to calculate the standardization of the cause and effect hypothesis model. Social participation was found to be activated by the improvement of four factors, and in turn, activated "Social participation" acted on cognitive function.

Job strain and trajectories of change in episodic memory before and after retirement: results from the Health and Retirement Study

BACKGROUND

We examined indicators of job strain in relation to level and change in episodic memory in the years leading up to as well as following retirement.

METHODS

Our analyses centre on 3779 individuals from the nationally representative Health and Retirement Study (baseline age 57.3 years) who reported gainful employment in an occupation for 10+ years prior to retirement, and who were assessed for episodic memory performance over up to 20 years (median 8 waves over 16 years). We used ratings from the Occupational Information Network (O*Net) to score occupations for job control and job demands, and to measure job strain (job demands/job control).

RESULTS

Controlling for sociodemographic characteristics, depressive symptoms, and cardiovascular disease, less job control and greater job strain were not significantly associated with change in episodic memory in the period leading up to retirement, but were associated with significantly poorer episodic memory at retirement and an accelerated rate of decline in episodic memory following retirement. The results did not vary for men and women or by self-employment status.

CONCLUSIONS

Job strain expressed mainly as low job control is linked to poorer episodic memory at retirement and more decline after retirement. Job characteristics appear to have implications for cognitive ageing independent of relevant confounds.

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.

Delaying onset of dementia: are two languages enough?

There is an emerging literature suggesting that speaking two or more languages may significantly delay the onset of dementia. Although the mechanisms are unknown, it has been suggested that these may involve cognitive reserve, a concept that has been associated with factors such as higher levels of education, occupational status, social networks, and physical exercise. In the case of bilingualism, cognitive reserve may involve reorganization and strengthening of neural networks that enhance executive control. We review evidence for protective effects of bilingualism from a multicultural perspective involving studies in Toronto and Montreal, Canada, and Hyderabad, India. Reports from Toronto and Hyderabad showed a significant effect of speaking two or more languages in delaying onset of Alzheimer's disease by up to 5 years, whereas the Montreal study showed a significant protective effect of speaking at least four languages and a protective effect of speaking at least two languages in immigrants. Although there were differences in results across studies, a common theme was the significant effect of language use history as one of the factors in determining the onset of Alzheimer's disease. Moreover, the Hyderabad study extended the findings to frontotemporal dementia and vascular dementia.

Use of the Finnish Information System on Occupational Exposure (FINJEM) in epidemiologic, surveillance, and other applications

This paper reviews the use of the Finnish Information System on Occupational Exposure (Finnish job-exposure matrix, FINJEM) in different applications in Finland and other countries. We describe and discuss studies on FINJEM and studies utilizing FINJEM in regard to the validity of exposure estimates, occupational epidemiology, hazard surveillance and prevention, the assessment of health risks and the burden of disease, the assessment of exposure trends and future hazards, and the construction of job-exposure matrices (JEMs) in countries other than Finland. FINJEM can be used as an exposure assessment tool in occupational epidemiology, particularly in large register-based studies. It also provides information for hazard surveillance at the national level. It is able to identify occupations with high average exposures to chemical agents and can therefore serve the priority setting of prevention. However, it has only limited use at the workplace level due to the variability of exposure between workplaces. The national estimates of exposure and their temporal trends may contribute to the assessment of both the recent and future burden of work-related health outcomes. FINJEM has also proved to be useful in the construction of other national JEMs, for example in the Nordic Occupational Cancer study in the Nordic countries. FINJEM is a quantitative JEM, which can serve many purposes and its comprehensive documentation also makes it potentially useful in countries other than Finland.

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.

Occupational characteristics and cognitive aging in the Glostrup 1914 Cohort

OBJECTIVES

The effect of occupational characteristics on cognitive change over 20 years was examined.

METHOD

Occupational characteristics--intellectual challenge, physical hazards, and psychological demands--were assessed in the Glostrup 1914 Cohort when aged 60 years, and cognitive ability was assessed by 4 cognitive ability tests at ages 60, 70, and 80.

RESULTS

Individuals in more intellectually challenging occupations had higher cognitive ability (r = .27-.38, p < .01), whereas those in more physically hazardous occupations performed more poorly (r = -.12 and -.13 at ages 50 and 60, p < .05). In growth curve models, intellectual challenge continued to be associated with cognitive ability, controlling for sex, education, and social class. However, the association was reversed after accounting for cognitive ability at age 50; of 2 individuals with the same baseline level of cognitive ability, the one in the more intellectually challenging occupation had lower subsequent cognitive ability. The association of physical hazards with lower cognitive ability level did not remain after adjustment for the basic demographics, and none of the occupational characteristics were associated with cognitive change between age 60 and 80.

DISCUSSION

Notwithstanding the reversal of the effect of occupational intellectual challenge on cognitive ability level after accounting for pre-exiting cognitive differences, there was no evidence for long-term effects of occupational characteristics on cognitive change in old age.

Work-related stress may increase the risk of vascular dementia

OBJECTIVES

To examine job control, job demands, social support at work, and job strain (ratio of demands to control) in relation to risk of any dementia, Alzheimer's disease (AD), and vascular dementia (VaD).

DESIGN

Cohort study.

SETTING

The population-based Study of Dementia in Swedish Twins.

PARTICIPANTS

Two hundred fifty-seven people with dementia (167 AD, 46 VaD) and 9,849 without.

MEASUREMENTS

Dementia diagnoses were based on telephone screening for cognitive impairment followed by in-person clinical examination. An established job exposure matrix was matched to main occupation categories to measure work characteristics.

RESULTS

In generalized estimating equations (adjusted for the inclusion of complete twin pairs), lower job control was associated with greater risk of any dementia (odds ratio (OR) = 1.17, 95% confidence interval (CI) = 1.04-1.31) and VaD specifically (OR = 1.39, 95% CI = 1.07-1.81). Lower social support at work was associated with greater risk of dementia (OR = 1.15, 95% CI = 1.03-1.28), AD (OR = 1.14, 95% CI = 1.00-1.31), and VaD (OR = 1.28, 95% CI = 1.02-1.60). Greater job strain was associated with greater risk of VaD only (OR = 1.28, 95% CI = 1.02-1.60), especially in combination with low social support (OR = 1.35, 95% CI = 1.11-1.64). Age, sex, and education were controlled for. Work complexity, manual work, and vascular disease did not explain the results. No differences in work-related stress scores were observed in the 54 twin pairs discordant for dementia, although only two pairs included a twin with VaD.

CONCLUSION

Work-related stress, including low job control and low social support at work, may increase the risk of dementia, particularly VaD. Modification to work environment, including attention to social context and provision of meaningful roles for employees, may contribute to efforts to promote cognitive health.

Multilingualism (but not always bilingualism) delays the onset of Alzheimer disease: evidence from a bilingual community

A recent paper by Bialystok et al in Neuropsychologia (vol. 45, pgs. 459 to 464) suggested that early bilingualism produced a statistically significant 4.1-year delay in onset of memory loss symptoms in older individuals with Alzheimer disease, possibly reflecting an increase in the cognitive reserve of these individuals. That study focused on multilingual elderly patients of whom 90% were immigrants. Our memory clinic, in Montreal Canada, has the advantage of having a large set of individuals who are either multilingual immigrants to Canada, or who are nonimmigrants but raised in both official languages of Canada--French and English. We thus attempted to replicate the above findings using a larger cohort in a different setting. We examined age at diagnosis of Alzheimer disease and age at symptom onset for all unilingual versus multilingual participants, and then for those who were nonimmigrant English/French bilinguals. Overall, we found a small but significant protective effect of more than 2 languages spoken, but we found no significant benefit in bilinguals overall in relation to age at diagnosis or age at symptom onset. However, in the immigrant group, the results mirrored those of Bialystok et al with 2 or more languages delaying the diagnosis of Alzheimer disease by almost 5 years. A trend toward the same effect was also seen in nonimmigrants whose first language was French. In contrast, in nonimmigrants whose first language was English, no such effect was found. These results are discussed in relation to the earlier findings and the theory of cognitive reserve.

Psychosocial work environment and antidepressant medication: a prospective cohort study

Background

Adverse psychosocial work environments may lead to impaired mental health, but it is still a matter of conjecture if demonstrated associations are causal or biased. We aimed at verifying whether poor psychosocial working climate is related to increase of redeemed subscription of antidepressant medication.

Methods

Information on all antidepressant drugs (AD) purchased at pharmacies from 1995 through 2006 was obtained for a cohort of 21,129 Danish public service workers that participated in work climate surveys carried out during the period 2002–2005. Individual self-reports of psychosocial factors at work including satisfaction with the work climate and dimensions of the job strain model were obtained by self-administered questionnaires (response rate 77,2%). Each employee was assigned the average score value for all employees at his/her managerial work unit [1094 units with an average of 18 employees (range 3–120)]. The risk of first-time AD prescription during follow-up was examined according to level of satisfaction and psychosocial strain by Cox regression with adjustment for gender, age, marital status, occupational status and calendar year of the survey.

Results

The proportion of employees that received at least one prescription of ADs from 1995 through 2006 was 11.9% and prescriptions rose steadily from 1.50% in 1996 to the highest level 6.47% in 2006. ADs were prescribed more frequent among women, middle aged, employees with low occupational status and those living alone. None of the measured psychosocial work environment factors were consistently related to prescription of antidepressant drugs during the follow-up period.

Conclusion

The study does not indicate that a poor psychosocial work environment among public service employees is related to prescription of antidepressant pharmaceuticals. These findings need cautious interpretation because of lacking individual exposure assessments.

Construction of job-exposure matrices for the Nordic Occupational Cancer Study (NOCCA)

INTRODUCTION

The Nordic Occupational Cancer study (NOCCA) is a cohort study based on employed populations in one or more censuses in Denmark, Finland, Iceland, Norway and Sweden. The large size of the cohort allows us to study rare cancers and to identify even small risks by occupation and by specific occupational exposures. This paper describes principles and experiences of the construction of job-exposure matrices (JEMs), an instrument to transform the history of occupational titles into quantitative estimates of exposure to potential carcinogenic substances.

MATERIAL AND METHODS

For each Nordic country, a national JEM was constructed by a team of experts on the basis of the Finnish matrix (FINJEM) that has been used in similar national studies since the mid-1990s.

RESULTS

The structure of the Nordic JEMs is three-dimensional (over 300 occupations, over 20 agents, 4 periods covering 1945-1994). Exposure is characterised by estimates of the prevalence and level of exposure. Important differences between the Nordic countries were observed for several exposures.

DISCUSSION

The selection of priority agent-occupation combinations and the adoption of general principles in the beginning of the work were necessary because of the high number of estimates to be evaluated (over 50 000/country). The selective modification of an existing JEM for use in other countries was a feasible, albeit challenging task, because exposure data and information about the use of chemicals in the past was scanty. As compared to the use of FINJEM for all Nordic countries, the modification process will probably increase the validity of dose-response and risk estimates of occupational cancer which is to be expected soon as the main outcome of the NOCCA project.

Mentally stimulating activities at work during midlife and dementia risk after age 75: follow-up study from the Kungsholmen Project

OBJECTIVES

Previous research has suggested that mental stimulation in different life periods may protect against dementia or delay disease onset. This study aimed to explore the association between work complexity factors at midlife and dementia risk in late life under the hypothesis that high work complexity may modulate the increased dementia risk due to low education.

DESIGN

Population-based follow-up study.

SETTING

Urban.

PARTICIPANTS

A cohort of 931 nondemented subjects, aged 75+ years from the Kungsholmen Project, Stockholm, examined twice over 6 years.

MEASUREMENTS

Incident dementia cases were identified using Diagnostic and Statistical Manual of Mental Disorders, 3rd-Edition Revised criteria. Primary occupations were assigned into categories according to the Nordic Occupational Classification and matched to the 1970 U.S. Census to score the level of work complexity with data, people, and things by using a preformed matrix.

RESULTS

Lower dementia risk was associated with complexity of work with both data (age and gender adjusted relative risk [aRR]: 0.85, 95% confidence interval [CI]: 0.75-0.95) and with people (aRR: 0.88, 95% CI: 0.80-0.97). Adjusting for education led to similar results, although no longer statistically significant. Further, the highest degrees of complexity of work with data that involves analyzing, coordinating, and synthesizing data were associated with lower dementia risk even among lower educated subjects (relative risk: 0.52, 95% CI: 0.29-0.95). No gender differences were detected.

CONCLUSIONS

This study suggests that work complexity with data and people is related to lower risk of dementia and that the highest levels of work complexity may modulate the higher dementia risk due to low education.

Psychosocial working conditions and the risk of depression and anxiety disorders in the Danish workforce

Background

To examine the risk of depressive and anxiety disorders according to psychosocial working conditions in a large population-based sample.

Methods

Job Exposure Matrix was applied to assess psychosocial working conditions in a population-based nested case-control study of 14,166 psychiatric patients, diagnosed with depressive or anxiety disorders during 1995–1998 selected from The Danish Psychiatric Central Research Register, compared with 58,060 controls drawn from Statistics Denmark's Integrated Database for Labour Market Research.

Results

Low job control was associated with an increased risk of anxiety disorders in men (IRR 1.40, 95% CI 1.24–1.58).

In women an elevated risk of depression was related to high emotional demands (IRR 1.39, 95%CI 1.22–1.58) and to working with people (IRR 1.15, 95% CI 1.01–1.30). In both sexes high demands were associated with a decreased risk of anxiety disorders. There was a weak association between job strain and anxiety disorders in men (IRR 1.13, 95%, CI 1.02–1.25)

Conclusion

Psychosocial work exposures related to the risk of depressive and anxiety disorders differ as between the sexes. The pattern of risks is inconsistent. The results give rise to rethinking both study designs and possible causal links between work exposures and mental health.

Do work-related stress and reactivity to stress predict dementia more than 30 years later?

The purpose of this study was to examine associations for work-related stress, reactivity to stress, and subsequent risk of dementia. The sample consisted of members of the population-based Swedish Twin Registry who were participants in the HARMONY study (n=2,049). We used case control and cotwin control designs, with information on work-related stress and reactivity to stress collected as part of a questionnaire completed in 1967. Dementia was diagnosed approximately 30 years later using a 2-stage procedure-screening for cognitive impairment followed by full clinical evaluation. We found that measures of work-related stress (job dissatisfaction and high job demands) were not associated with dementia risk. Greater reactivity to stress predicted higher risk of dementia controlling for age, education, sex, occupational status, alcohol use, and smoking status (odds ratio=1.57, 95% confidence interval 1.08-2.31). Cotwin control analyses also showed that dementia probands were more likely to report high reactivity to stress than their nondemented cotwins. We did not find evidence of an interaction between work stress and reactivity in predicting dementia. Overall, indicators of stress due to environment (ie, work) were not associated with dementia, whereas the individual characteristic of reactivity to stress predicted dementia risk.

Bilingualism as a protection against the onset of symptoms of dementia

This study examined the effect of lifelong bilingualism on maintaining cognitive functioning and delaying the onset of symptoms of dementia in old age. The sample was selected from the records of 228 patients referred to a Memory Clinic with cognitive complaints. The final sample consisted of 184 patients diagnosed with dementia, 51% of whom were bilingual. The bilinguals showed symptoms of dementia 4 years later than monolinguals, all other measures being equivalent. Additionally, the rate of decline in Mini-Mental State Examination (MMSE) scores over the 4 years subsequent to the diagnosis was the same for a subset of patients in the two groups, suggesting a shift in onset age with no change in rate of progression.

Occupational exposure to low frequency magnetic fields and dementia: a case-control study

BACKGROUND

Several studies point to a potential aetiological relevance to dementia of exposure to low-frequency magnetic fields, but the evidence is inconclusive.

OBJECTIVE

To further examine the relationship between low frequency magnetic fields and dementia.

METHODS

From 23 general practices, 195 patients with dementia were recruited. Of these, 108 had possible Alzheimer's disease, 59 had possible vascular dementia and 28 had secondary or unclassified dementia. A total of 229 controls were recruited: 122 population controls and 107 ambulatory patients free from dementia. Data were gathered in a structured personal interview; in cases, the interview was administered to the next of kin. Exposure to low-frequency electromagnetic fields was assessed by expert rating. To identify occupations suspected to be associated with dementia, major occupations were a priori formed. Odds ratios were calculated using logistic regression, to control for age, region, sex, dementia in parents and smoking.

RESULTS

Exposure to magnetic fields was not significantly associated with dementia; restriction of the analysis to cases with possible Alzheimer's disease or possible vascular dementia did not lead to statistically significant results. We found an increased risk of dementia in blue-collar occupations (electrical and electronics workers, metal workers, construction workers, food and beverage processors and labourers).

CONCLUSIONS

Our study does not support a strong association between occupational exposure to low-frequency magnetic fields and dementia. Further studies should consider the relationship between blue-collar work and the late development of dementia.