We aim to examine the relationship between offspring sex and parental baseline level of cognition and rate of cognitive decline in older adults.

We analysed a cohort of 13,777 adults age ≥ 50 years from the US Health and Retirement Study. Offspring sex was classified as no boy vs. at least 1 boy in primary analysis and as number of boys (0 boys, 1 boy, 2 boys, 3 or more boys) and number of girls (0 girls, 1 girl, 2 girls, 3 or more girls) in secondary analysis. Cognition was assessed using a sum of scores from immediate and delayed 10-noun free recall tests, a serial 7s subtraction test, and a backwards counting test. Associations were evaluated using linear mixed-effects models, adjusting for 1) baseline age, sex, ethnicity, parity; 2) socioeconomic factors; and 3) health-related factors and marital status.

A total of 17.7% of respondents had no boy and 60.1% of respondents were female. Stratifying on parental sex, mothers and fathers of at least 1 boy had a significantly higher baseline cognition in comparison to those with no boy. Associations were attenuated in adjusted models. In secondary analysis, having 3 or more boys was associated with higher baseline cognition in fathers, there were no differences in mothers. We found a significant association of cognitive decline with number of boys, but not with number of girls.

Offspring sex was associated with cognitive aging among both mothers and fathers, suggesting interplay of biological and social influences.