Role of previous parity in the relationship between lifetime physical activity and later life cognition: The Rancho...

BackgroundParity history influences dementia risk and cognitive aging, and recent evidence suggests it may also influence the association between physical activity and cognition in later life.ObjectiveTo examine associations between total lifetime and life-stage-specific physical activity and later life cognition in postmenopausal females with differing parity histories.MethodsThis cross-sectional analysis using data from the Rancho Bernardo Study included 867 postmenopausal females with complete data, categorized into three parity groups (number of pregnancies >6-months): nulliparous, 1-2 pregnancies, and grand-multiparous (≥3 pregnancies). Cognitive outcomes included executive functions and memory. Physical activity was assessed using a self-report questionnaire capturing retrospective activity during adolescence, age 30, age 50, and current activity in later life. Covariates included age, education, health composite score, body mass index, and hysterectomy status. Linear models examined associations between physical activity and domain-specific later life cognitive outcomes stratified by parity.ResultsGreater total lifetime physical activity was associated with higher executive functions in nulliparous and grand-multiparous females. Moderate activity in nulliparous females and high activity in grand-multiparous females during adolescence and at age 30 were associated with higher executive functions. High physical activity at age 50 and currently was associated with higher executive functions in nulliparous females.ConclusionsThe findings suggest the relationship between self-reported physical activity and cognition was strongest in the two groups at greater risk for cognitive decline and Alzheimer's disease, the nulliparous and grand-multiparous groups. Further research is needed to understand the mechanisms driving parity differences.