Background: It is not known whether depression is a cause or consequence of progressive cognitive decline. We assessed the relationship between depressive symptoms and subsequent cognitive decline in the community-dwelling elderly population.
Methods: Data were from a population-based cohort study that enrolled 2812 noninstitutionalized elderly residents of New Haven, Conn, and followed them with in-home visits in 1982, 1985, 1988, and 1994. Cognitive function was assessed with the Short Portable Mental Status Questionnaire (SPMSQ). Response to the SPMSQ was scored as high, medium, and low, and cognitive decline was defined as a transition to a lower category. Depressive symptoms were measured with the Center for Epidemiological Studies Depression Scale.
Results: An elevated level of depressive symptoms was associated with an increased risk of incident cognitive decline among medium SPMSQ performers (3-year odds ratio [OR], 1.72; 95% confidence interval [CI], 1.04-2.82, P=.03; 6-year OR, 2.40; 95% CI, 1.33-4.34; P=.004; 12-year OR, 1.65; 95% CI, 0.62-4.38; P=.31) but not among high performers (3-year OR, 0.93; 95% CI, 0.62-1.39; P=.71; 6-year OR, 1.03; 95% CI, 0.67-1.58; P=.90; 12-year OR, 1.26; 95% CI, 0.59-2.71; P=.55), after adjustment for age, sex, race, education, income, housing type, functional disability, cardiovascular profile, and alcohol use.
Conclusions: Depressive symptoms, particularly dysphoric mood, presage future cognitive losses among elderly persons with moderate cognitive impairments. However, the data do not provide support for the hypothesis that depressive symptoms are associated with the onset or rate of cognitive decline among cognitively intact elderly persons.