Sex differences in cognitive aging and the role of socioeconomic status: Evidence from multi-cohort studies.

BACKGROUND

Sex differences exist in cognitive function, and socioeconomic status (SES) may play a role in changing these discrepancies. This study investigated the role of SES in contributing to sex differences in cognitive function.

METHODS

We conducted a pooled multi-cohort study on the basis of four comparative cohort studies from the UK, the US, Europe and China to assess sex differences and the role of SES in cognitive decline by birth cohort (1930-1938, 1939-1945, 1946-1968). Cognitive function was measured in three domains based on the mean and SD of the corresponding tests: episodic memory, working memory, and time orientation. SES was the summed scores of education and household wealth.

FINDINGS

61,019 individuals were involved. Cognitive function of women declined faster than those of men as growing old (particularly after 80 years old). As SES increased, cognitive function increased more for women than for men in most cases among later-born cohorts (1930-1938, 1939-1945, 1946-1968) (e.g., episodic memory scores at 60 years old: women exhibited an increase from -0.09 [95%CI -0.12, -0.07] in low SES to 0.89 [0.86, 0.92] in high SES; men from -0.16 [-0.19, -0.14] to 0.59 [0.56, 0.62]). However, sex-specific cognitive benefits were absent in the oldest birth cohort (1895-1929).

INTERPRETATION

These findings highlight the importance of considering the role of SES in the discrepancy of sex difference in cognitive aging.