Sex Differences in Occupational Exposures and Cognitive Function in Later Life

Background/Purpose: Despite their longer life expectancies, women are more susceptible to cognitive decline and subsequent Alzheimer’s Disease and related dementias (ADRDs) than men. Although growing evidence has associated both enriching and hazardous occupational environments with cognitive function later in life, it is unclear whether sex differences in occupational exposures shape the sex differences in later-life cognitive function. Drawing from cognitive resilience theories, this study explores whether the association between occupational exposures and cognitive function is conditioned by sex and influenced by early life experiences.

Methods:

Data and Samples: The analysis includes longitudinal data among participants between 51-60 years at baseline (2004 to 2010) and at least 65 years old by 2016 with valid cognitive data from the Health and Retirement Study (HRS), a nationally representative study of older adults linked to the Occupational Information Network (O*NET) database (n=1,135).

Main Measures: Cognitive function estimates: a sex-adjusted continuous cognitive function estimate for HRS participants 65+ at their last wave of cognition data (available for the 2004 to 2016 waves). Baseline Occupational Complexity: Standardized sum of thinking creatively, freedom to make decisions, frequency of making decisions, making decisions and solving problems, coaching and developing others. Baseline Occupational Hazard: Standardized sum of hazardous equipment, exposure to high places, extremely bright or inadequate lighting, very hot or very cold temperatures, and cramped workspaces. Early life experiences (Retrospective): Include poor relationships with mother (0,1), self-rated low childhood SES (0,1), self-rated poor childhood health (0,1), and father with no high-school degrees (0,1). Scoring 1 indicates a corresponding stressor in early life. Sociodemographic controls: age, sex, race and ethnicity, marital status, baseline years, individual earnings, years of education, depressive symptoms, and baseline cognitive function.

Analysis: Ordinary least squares regression with robust standard error was used to evaluate occupational exposure on late-life cognitive function and differences based on sex, accounting for early-life exposures. Post-regression Wald test and marginal effect were also estimated to further interpret the sex difference in occupational exposure and cognitive health.

Results: On average, baseline cognitive complexity of work at baseline (β=0.08, p<0.01) was associated with better cognitive function whereas the occupational hazards (β= -0.05, p<0.01) were associated with poorer cognitive function at age 65 or older. Interaction effects suggest that the long-term cognitive impact of occupational complexity (β=-0.11, p<0.05) and hazards (β=0.07, p<0.05) depended on sex. Marginal effects of slope change further illustrated that older men—but not women—experienced significant cognitive benefits from occupational complexity (Δy/Δx=0.08, p=0.002) and cognitive detriments from occupational hazards (Δy/Δx=-0.05, p=0.003), with and without controlling for early life factors.

Conclusions and Implications: Besides confirming the existing literature regarding the cognitive impact of occupational complexity and hazards, our finding of older men’s higher sensitivity to occupational environments suggests that interventions designed to address hazardous exposures and enhance cognitive enrichment at work may be particularly important in protecting men’s cognitive function later in life. Further research is needed to determine whether differences in job activities and coping strategies between sexes explain why men's cognitive function is more susceptible to occupational exposures.