Physically demanding work and cognitive impairment in late life: Results from the Brazilian longitudinal study of aging

Abstract

Background

Dementia is a major public health concern, especially in low- and middle-income countries. While structured exercise benefits cognition, occupational physical activity may not.

Objective

To investigate the association between lifetime occupational physical demand and cognitive impairment among older adults in Brazil.

Methods

Cross-sectional baseline data from the Brazilian Longitudinal Study of Aging (ELSI-Brazil) were analyzed (n = 9412). An algorithm was used to estimate the number of participants aged 60+ (n = 5432) with dementia and participants reported the physical demand of the job held for most of their life. Logistic regression models estimated the impact of physical demand on dementia status.

Results

After exclusions, 4924 participants were analyzed. Compared with ‘never worked’, intense physical effort was associated with higher odds of dementia (OR 2.52; p = 0.013). Other categories showed no associations. On sensitivity analyses using ‘intense physical effort’ as reference, lower demand categories were associated with less dementia, and this effect was only present among women.

Conclusion

Intense occupational physical demand was associated with greater odds of dementia. Given the cross-sectional design, reverse causation and residual confounding (such as job control) may explain these findings. Occupational physical activity differs from leisure-time exercise in psychosocial context, suggesting this association is unlikely to reflect physical effort alone and may instead be driven by unmeasured psychosocial job characteristics frequently linked with physical jobs. Therefore, solely reducing physical demands is insufficient without addressing job control and stress. Findings highlight the need for occupational health interventions addressing psychosocial risks in physically demanding jobs.