Effect of dispositional optimism and pessimism on the relationship between stressful life events and late-life depression.

BACKGROUND: Dispositional optimism is associated with a lower risk of depression. Optimism may protect against depression by conferring resilience to stressful life events. This study aimed to investigate the effects of dispositional optimism, and the related trait of dispositional pessimism, on the relationship between stressors and depression in older adults. METHODS: This prospective cohort study used data from the ASPREE Longitudinal Study of Older Persons. Participants were aged ≥70 years and without known cardiovascular disease, dementia, independence-limiting physical disability and depression. Optimism and pessimism were measured using the Life Orientation Test-Revised. Incident depression was defined as a score ≥ 8 on the 10-item Center for Epidemiological Studies Depression Scale. The experience of 10 different types of stressors was assessed. FINDINGS: 10,791 participants were followed for a median (IQR) period of 3.5 (2.8-5.0) years. After adjusting for sociodemographic, lifestyle and medical factors and genetic predisposition to depression (using a polygenic score), optimism was associated with a lower risk of depression (HR, 0.92; 95% CI 0.90-0.93). Pessimism (HR, 1.07; 95% CI 1.06-1.08) and stressful life events (HR, 1.17; 95% CI 1.14-1.21) were associated with a higher depression risk. Neither optimism nor pessimism was associated with differences in the strength of the relationship between stressors and depression (p ≥ 0.499). CONCLUSIONS: Optimism was associated with a lower risk of late-life depression. However, it was not associated with lower vulnerability to the depressogenic effects of stressful life events. These findings raise questions regarding whether optimism confers resilience to stressors in older adults.