Sex differences in the association of physical function and cognitive function with life satisfaction in older age: The Rancho Bernardo Study

Objectives: This study examines the cross-sectional associations of cognitive and physical function with life satisfaction in middle-class, community-dwelling adults aged 60 and older.

Study design: Participants were 632 women and 410 men who had cognitive function tests (CFT) and physical function tasks (PFT) assessed at a clinic visit between 1988 and 1992, and who responded in 1992 to a mailed survey that included life satisfaction measures. Cognitive impairment was defined as ≤24 on MMSE, ≥132 on Trails B, ≤12 on Category Fluency, ≤13 on Buschke long-term recall, and ≤7 on Heaton immediate recall. Physical impairment was defined as participants' self-reported difficulty (yes/no) in performing 10 physical functions. Multiple linear regression examined associations between life satisfaction and impairment on ≥1 CFT or difficulty with ≥1 PFT.

Main outcome measures: The Satisfaction with Life Scale (SWLS; range:0-26) and Life Satisfaction Index-Z (LSI-Z; range:5-35).

Results: Participants' average age was 73.4 years (range=60-94). Categorically defined cognitive impairment was present in 40% of men and 47% of women. Additionally, 30% of men and 43% of women reported difficulty performing any PFT. Adjusting for age and impairment on ≥1 CFT, difficulty performing ≥1 PFT was associated with lower LSI-Z and SWLS scores in men (β=-1.73, -1.26, respectively, p<0.05) and women (β=-1.79, -1.93, respectively, p<0.01). However, impairment on ≥ 1 CFT was not associated with LSI-Z or SWLS score after adjusting for age and difficulty with ≥1 PFT.

Conclusions: Limited cognitive function was more common than limited physical function; however, limited physical function was more predictive of lower life satisfaction. Interventions to increase or maintain mobility among older adults may improve overall life satisfaction.