Job strain and cognitive decline: a prospective study of the framingham offspring cohort.

BACKGROUND: Workplace stress is known to be related with many behavioral and disease outcomes. However, little is known about its prospective relationship with measures of cognitive decline. OBJECTIVE: To investigate the association of job strain, psychological demands and job control on cognitive decline. METHODS: Participants from Framingham Offspring cohort (n=1429), were assessed on job strain, and received neuropsychological assessment approximately 15 years and 21 years afterwards. RESULTS: High job strain and low control were associated with decline in verbal learning and memory. Job strain was associated with decline in word recognition skills. Active job and passive job predicted decline in verbal learning and memory relative to low strain jobs in the younger subgroup. Active job and demands were positively associated with abstract reasoning skills. CONCLUSIONS: Job strain and job control may influence decline in cognitive performance.

The stress-disequilibrium theory: chronic disease development, low social control, and physiological de-regulation.

The Stress-Disequilibrium Theory is based on a new generalized analytic three-level model based on thermodynamics to describe the process of physiological risk development. This approach explains how low social control could cause chronic disease through chronic de-regulation of our highly integrated physiological systems. Could low external social control lead to low internal physiological control: i.e. compromised self-regulation--and then disease? The theory implicitly explores the evidence for the physiological causes of chronic diseases, including cardiovascular diseases, at a high level (i.e. a non-reductionist level) and in a unifying manner--to provide a potentially easier linkage to the broad social policy consequences implied by the global economy. Evidence from our own recent Heart Rate Variability monitoring and job strain research (5) is presented which assesses the effect of low control on autonomic regulation on the heart. The theory is consistent with the Demand/Control Model, and could be considered its underlying theoretical explanation.

Covariation between workplace physical and psychosocial stressors: evidence and implications for occupational health research and prevention.

There is increasing interest in distinguishing the effects of physical and psychosocial workplace stressors on the aetiology of work-related musculoskeletal disorders (MSD). Modest associations have been found between psychosocial stressors and MSD, such as intensive load, monotonous work and low job control. Interpretation of these results has been limited by likely covariation between physical and psychosocial stressors. This investigation examined exposure covariation among blue- and white-collar workers employed in a mass production manufacturing environment (N = 410). Physical stressors were assessed from questionnaire and accelerometry. Psychosocial stressors were assessed from questionnaire. Pearson and Spearman correlation coefficients were computed. An exploratory factor analysis procedure identified possible common factors linking specific physical and psychosocial stressors. Moderate to high correlations between some physical and psychosocial stressors showed evidence of covariation both across and within groups. Covariation was strongest among blue-collar production and low-status office workers. Factor analysis results showed considerable shared variance between some physical and psychosocial stressors, such as repetition and job control, suggesting that these disparate stressors manifest from common work organization factors that govern the structure of work. While recognizing the conceptual differences between physical and psychosocial stressors, these results call attention to the strong empirical relationships that can exist between some stressors in the workplace setting. To guard against ambiguous study findings that can occur when exposures are mixed, it is critical that future epidemiologic studies include information about the degree of association between task-level stressors. Future research on work organization determinants of task-level stressors, and their coincident occurrence in jobs with greater specialization, may provide promising new insights into the nature of risk for MSD and effective prevention strategies.

The Job Content Questionnaire (JCQ): an instrument for internationally comparative assessments of psychosocial job characteristics.

Part I discusses the Job Content Questionnaire (JCQ), designed to measure scales assessing psychological demands, decision latitude, social support, physical demands, and job insecurity. Part II describes the reliability of the JCQ scales in a cross-national context using 10,288 men and 6,313 women from 6 studies conducted in 4 countries. Substantial similarity in means, standard deviations, and correlations among the scales, and in correlations between scales and demographic variables, is found for both men and women in all studies. Reliability is good for most scales. Results suggest that psychological job characteristics are more similar across national boundaries than across occupations.

Current issues relating to psychosocial job strain and cardiovascular disease research.

The authors comment on recent reviews of cardiovascular job strain research by P. L. Schnall and P. A. Landsbergis (1994), and by T. S. Kristensen (1995), which conclude that job strain as defined by the demand-control model (the combination of contributions of low job decision latitudes and high psychological job demands) is confirmed as a risk factor for cardiovascular mortality in a large majority of studies. Lack of social support at work appears to further increase risk. Several still-unresolved research questions are examined in light of recent studies: (a) methodological issues related to use of occupational aggregate estimations and occupational career aggregate assessments, use of standard scales for job analysis and recall bias issues in self-reporting; (b) confounding factors and differential strengths of association by subgroups in job strain-cardiovascular disease analyses with respect to social class, gender, and working hours; and (c) review of results of monitoring job strain-blood pressure associations and associated methodological issues.

The relationship between 'job strain,' workplace diastolic blood pressure, and left ventricular mass index. Results of a case-control study.

To determine whether "job strain" (defined as high psychological demands and low decision latitude on the job) is associated with increased workplace diastolic blood pressure and the left ventricular mass index, we conducted a case-control study at seven urban work sites of 215 employed men aged 30 to 60 years without evidence of coronary heart disease. After comprehensive blood pressure screening of male employees (N = 2556) at the work site, 87 cases of hypertension and a random sample of 128 controls were studied. In a multiple logistic regression model, job strain was significantly related to hypertension, with an estimated odds ratio of 3.1, after adjusting for age, race, body-mass index, type A behavior, alcohol intake, smoking, work site, 24-hour urine sodium excretion, education, and physical demand level of the job. Controlling for the above variables in subjects aged 30 to 40 years with job strain, we found that the echocardiographically determined left ventricular mass index was, on average, 10.8 g/m2 greater than in subjects without job strain. We conclude that job strain may be a risk factor for both hypertension and structural changes of the heart in working men.

Job strain variations in relation to plasma testosterone fluctuations in working men--a longitudinal study.

Job strain, a high level of psychological demands combined with a low level of decision latitude, has been hypothesized to induce mobilization of energy and inhibition of anabolism. In the present project this hypothesis was tested using four repeated observations every third month in a group of 44 men working in six widely different occupations. On each occasion scores of self-reported demands and decision latitude were calculated for every participant. An earlier report has shown that systolic blood pressure during work hours--an indicator of mobilization of energy--increased with increasing job strain (ratio between demands and decision latitude). Blood samples were drawn in the morning at the work site. For each man the plasma testosterone levels--representing the general level of anabolic activity--on the two occasions with the worst strain (ratio between demands and decision latitude) were compared with the plasma testosterone levels on the two occasions with the least strain. The results indicated that total plasma testosterone (but not free testosterone) levels increased when strain diminished in sedentary but not in physically demanding work. Subjects with a family history of hypertension showed a greater decrease in testosterone levels than others when job strain increased.

The relation of psychosocial dimensions of work with coronary heart disease risk factors: a meta-analysis of five United States data bases.

The relation of job psychologic demands and decision latitude to four coronary heart disease risk factors (cholesterol, smoking, and systolic and diastolic blood pressures) was tested among 12,555 men in five investigations conducted in the United States during the period 1959-1980 (National Health and Nutrition Examination Surveys I and II, National Health Examination Survey, Western Collaborative Group Study, and Exercise Heart Survey). Using an imputation strategy, the authors attached measures of the two job characteristics above to persons in each data base by occupation. In 19 possible tests, decision latitude was related (p less than 0.05) to cholesterol and smoking in two instances in the predicted direction in the Exercise Heart Survey, when controlling for Type I error rate. Psychologic demands were not related to any of the risk factors. When a meta-analysis was performed across data bases, all relations were in the predicted direction except for the relation of psychologic demands to systolic pressure, and two of these were statistically significant (p less than 0.05): the relation of job decision latitude to smoking and to systolic pressure. The interaction of psychologic demands and decision latitude was not related to any of the risk factors when two common forms of an interaction were tested. These results indicate that psychosocial aspects of work, in particular the decision latitude of the job, may be related to some cardiovascular risk factors.

Occupational strain and the incidence of coronary heart disease.

The hypothesis that men in high "strain" occupations have an increased risk of developing coronary heart disease was tested during an 18-year follow-up study from 1965-1983 of a cohort of 8,006 men of Japanese ancestry in Hawaii. There were no significant associations between the incidence of coronary heart disease and the individual job components of high psychologic demands and low job control or for the high strain interaction of these two characteristics. There were, in fact, trends of associations opposite to that predicted by the job strain model which were of borderline significance in multivariate analyses. Stratified analyses by level of acculturation showed similar inverse associations of job strain and coronary heart disease for the more Westernized men and no association for the more traditional men. There were also no significant associations among the various job characteristics and the major risk factors for coronary heart disease in this cohort. The disagreement of these results with those from other studies may be due to methodologic differences of using men whose usual and current occupations were the same in this study compared with using only current occupation in the other studies, the use of different methods of measuring job strain, or the possibility that men in this cohort perceive or react to occupational strain differently.

The political implications of psychosocial work redesign: a model of the psychosocial class structure.

The goal of this article is to further illuminate the poorly understood distribution of psychosocial well-being at the national population level (the distribution of conventional economic well-being is, of course, well understood). After reviewing psychosocial phenomena that cannot be predicted by the "conventional" class structure, the author introduces a new definition of production output value (New Value), more closely related to psychosocial well-being. A psychosocial class structure model is presented based on nine occupational subgroups in four status levels, representing both conventional and New Value-based status differences. An empirical analysis of 38 occupations in the U.S. work force (U.S. Quality of Employment Surveys 1969, 1972, 1977) uses psychosocial job dimensions of decision latitude, psychological demands, physical exertion, and social support. The author reviews job redesign strategies for three New Value "impoverished" groups with routinized, bureaucratized, and commercialized jobs, and the conditions for economic stability and political participation related to the psychosocial class structure model. Conflicts arising between conventional and New Value-based policies are discussed.

A procedure for linking psychosocial job characteristics data to health surveys.

A system is presented for linking information about psychosocial characteristics of job situations to national health surveys. Job information can be imputed to individuals on surveys that contain three-digit US Census occupation codes. Occupational mean scores on psychosocial job characteristics-control over task situation (decision latitude), psychological work load, physical exertion, and other measures-for the linkage system are derived from US national surveys of working conditions (Quality of Employment Surveys 1969, 1972, and 1977). This paper discusses a new method for reducing the biases in multivariate analyses that are likely to arise when utilizing linkage systems based on mean scores. Such biases are reduced by modifying the linkage system to adjust imputed individual scores for demographic factors such as age, education, race, marital status and, implicitly, sex (since men and women have separate linkage data bases). Statistics on the linkage system's efficiency and reliability are reported. All dimensions have high inter-survey reproducibility. Despite their psychosocial nature, decision latitude and physical exertion can be more efficiently imputed with the linkage system than earnings (a non-psychosocial job characteristic). The linkage system presented here is a useful tool for initial epidemiological studies of the consequences of psychosocial job characteristics and constitutes the methodological basis for the subsequent paper.

Job characteristics in relation to the prevalence of myocardial infarction in the US Health Examination Survey (HES) and the Health and Nutrition Examination Survey (HANES).

Associations between psychosocial job characteristics and past myocardial infarction (MI) prevalence for employed males were tested with the Health Examination Survey (HES) 1960-61, N = 2,409, and the Health and Nutrition Examination Survey (HANES) 1971-75, N = 2,424. A new estimation method is used which imputes to census occupation codes, job characteristic information from national surveys of job characteristics (US Department of Labor, Quality of Employment Surveys). Controlling for age, we find that employed males with jobs which are simultaneously low in decision latitude and high in psychological work load (a multiplicative product term isolating 20 per cent of the population) have a higher prevalence of myocardial infarction in both data bases. In a logistic regression analysis, using job measures adjusted for demographic factors and controlling for age, race, education, systolic blood pressure, serum cholesterol, smoking (HANES only), and physical exertion, we find a low decision latitude/high psychological demand multiplicative product term associated with MI in both data bases. Additional multiple logistic regressions show that low decision latitude is associated with increased prevalence of MI in both the HES and the HANES. Psychological workload and physical exertion are significant only in the HANES.