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, I-2 = 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, I-2 = 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 I-2 = 62.00%, p < 0.05; 95% CI = 1.05-1.26 I-2 = 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, I-2 = 69.00%, p < 0.01) for dementia. Conclusion: Novel prevention strategies based on occupational factors may hold promise against dementia and MCI.