Onset and persistence of depression in older people--results from a 2-year community follow-up study.

BACKGROUND: baseline physical health, disability and social support have been shown to predict depression onset, but findings for persistence are inconsistent. For onset and persistence of depression, the effect of changes in these risk factors over time is unclear.
OBJECTIVE: to use baseline factors and change in factors over time to predict onset and persistence of depression over a 2-year period.
METHODS: a prospective cohort study with index assessment and 2-year follow-up of patients initially aged > or =65 years registered with two South London practices (n = 1,164). Depression was defined by a score >5/15 on the 15-item Geriatric Depression Scale. Associations between risk factors and onset and persistence of depression were analysed using multiple logistic regression.
RESULTS: the incidence of depression was 8.4%, while depression persisted amongst 61.2% of those depressed at baseline. Comparing onset and persistence suggested some common predictors: greater baseline depression score; and follow-up measures of poor general health and compromised social support. There was some evidence that pain and worsening disability were more important for depression onset. In contrast, low baseline belief in powerful others (health locus of control measure) predicted persistence only.
CONCLUSION: focusing on older people with increasing disability, pain, physical ill-health and compromised social support should help in both the prevention and recognition of onset of later-life depression. In older people with depression, those with the highest symptom scores and low belief in powerful others at baseline were more likely to develop chronic symptoms and could be targeted for more intensive treatment and support.