Impact of psychosocial working conditions on health in older age

Abstract: Work takes up a large proportion of time in our adult lives, thus possibly making it an important determinant of health. This doctoral thesis aimed to investigate the impact of psychosocial working conditions on health in older age, including metabolic and cognitive health, and disability. Psychosocial working conditions were defined in accordance with the job demand-control model and classified into four scenarios: high strain (high demands, low control), low strain (low demands, high control), passive job (low demands, low control), and active job (high demands, high control). The four studies in this thesis were based on data from the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K). Study I. This study used six-year follow-up data and examined the association between work-related stress, characterized by high strain, and the risk of diabetes. High strain was related to an increased risk of diabetes among people aged 60 years at baseline, especially in women, but not in men. Having more than 14 years of work experience in high strain increased the risk of diabetes among women aged 60 years. Study II. The association between demand-control status and cognitive decline over the nine-year follow-up period was examined. Compared to active jobs, low strain, high strain, and passive jobs were all associated with faster cognitive decline. Longer duration of work in low strain, high strain, or passive jobs was associated with an accelerated rate of cognitive decline, whereas longer duration of active jobs was related to slower cognitive decline. Study III. This study examined the association of demand-control combinations with dementia using 12-year follow-up data. Passive jobs were associated with a higher risk of dementia among the younger-old individuals (aged ≤72 years), but not among the older-old (aged ≥78 years). Long work duration of more than ten years in passive jobs increased the risk of dementia among the younger-old. Study IV. The relationship between demand-control categories and disability trajectories over 12 years of follow-up was investigated. Compared to active jobs, low strain, high strain, and passive jobs were all related to a faster rate of disability progression. These associations were mediated 38% by cognitive decline and 18% by chronic disease accumulation. Conclusion. The findings from this thesis underscore the importance of psychosocial working conditions for health in older age. High strain increases the risk of diabetes among women in their early 60s; passive jobs increase the risk of dementia among the younger-old individuals. Having non-active jobs, including high strain, low strain, and passive jobs, accelerates the speed of cognitive decline and disability progression in later life. In addition, duration of work plays a role in the associations between psychosocial working conditions and health outcomes. Both cognitive decline and chronic disease accumulation can partially mediate the association between psychosocial working conditions and disability progression.