Objectives: To determine whether positive affect is associated with a lower incidence of frailty over 2 years in elderly community-dwelling women and to test the stress-buffering hypothesis by evaluating whether these associations differed in caregivers and noncaregivers.
Design: Prospective cohort study with three annual interviews conducted in four U.S. communities between 1999 and 2004.
Setting: Home-based interviews.
Participants: Three hundred thirty-seven caregiver and 617 noncaregiver participants from the Caregiver-Study of Osteoporotic Fractures (Caregiver-SOF) who were not frail at the baseline Caregiver-SOF interview.
Measurements: High and low positive affect and depressive symptoms were derived from the baseline 20-item Center for Epidemiologic Studies Depression Scale. Frailty was the development of three or more indicators (weight loss, exhaustion, slow walking speed, or weak grip strength) at the first or second follow-up interview.
Results: Respondents' mean age was 81.2. Caregivers and noncaregivers had similar levels of positive affect (56.3% vs 58.3%) and frailty incidence (15.4% vs 15.9%) but differed in perceived stress (mean Perceived Stress Scale score 16.7 vs 14.8, P<.001). Frailty risk was lower in respondents with high positive affect than in those with low positive affect in the total sample (adjusted hazard ratio (HR)=0.49, 95% confidence interval (CI)=0.35-0.70), caregivers (adjusted HR=0.44, 95% CI=0.24-0.80) and noncaregivers (adjusted HR=0.50, 95% CI=0.32-0.77).
Conclusion: These findings add to the evidence that positive affect protects against health decline in older adults, although it had no additional stress-buffering effect on health in elderly caregivers.