Main lifetime occupational skill and later‐life cognitive function among older adults in the United States, South Africa, India, and Mexico

Background Occupations are a potential source of later‐life cognitive reserve, but it is unknown how lifetime occupational skill level relates to cognitive function amongst older populations across diverse country contexts. We conducted a cross‐national comparison of the associations between main lifetime occupational skill and later‐life cognitive function among men and women living in four economically and socially distinct countries. Method Data were from population‐based studies of aging and their Harmonized Cognitive Assessment Protocol (HCAP) sub‐studies in the US, South Africa, India, and Mexico (N = 10,037). Main lifetime occupational skill was classified according to the International Standard Classification of Occupations (ISCO‐2008) in categories of never worked (reference); level 1 (manual labor occupations such as cleaner, construction worker, agricultural worker); level 2 (intermediate occupations such as secretaries, sales assistants, trades workers); and level 3 or 4 (professional or managerial occupations such as teachers, medical practitioners, business owners). Cognitive function was assessed from HCAP measures representing orientation, memory, language, and executive function, standardized to the US population distribution. Sampling‐weighted regression models adjusted for age, minority status, education, and parental education estimated country‐specific associations between main lifetime occupational skill and later‐life cognitive function in men and women. Result The mean (SD) age of participants ranged from 68.1 (9.0) years (Mexico) to 76.6 (7.5) years (US; Table 1). Lifetime occupational skill levels varied by country, with the proportion never having worked ranging from 4% (US) to 32% (India), and the proportion with a main lifetime occupation at skill levels 3 or 4 ranging from 6% (India) to 31% (US; Table 1). We observed positive gradients between increasing main lifetime occupational skill and later‐life cognitive function for men and women in the US and Mexico, a positive gradient for women but not men in India, and no association for men or women in South Africa (Table 2; Figure 1). Conclusion Main lifetime occupations may be a source of later‐life cognitive reserve, with heterogeneity in this association across countries. While further longitudinal research with more detail on occupations is needed, this study suggests that enriching occupational opportunities in low‐resource global settings may help to promote population cogn