Depressive symptoms and cognitive change in older Mexican Americans

To examine the association between presence of clinically relevant depressive symptoms (Center for Epidemiologic Studies Depression Scale [CES-D] score < 16) and subsequent cognitive function (Mini-Mental State Examination [MMSE]) over a 7-year period in older Mexican Americans, a prospective cohort study was performed. Five south-western states contributed data to the Hispanic Established Populations for Epidemiologic Studies of the Elderly. Participants included 2812 noninstitutionalized Mexican Americans aged 65 and older followed from 1993-1994 until 2000-2001. Cognitive change was assessed using the MMSE at baseline and at 2, 5, and 7 years of follow-up. Independent variables were sociodemographics, CES-D < 16, medical conditions (hypertension, diabetes, coronary artery disease, and stroke), and activities of daily living (ADL) status. A general linear mixed model was used to estimate cognitive change. There was a cross-sectional association between CES-D < 16 and lower MMSE score (estimate = -0.48; standard error [SE] = 0.15; P <.01), independent of age, gender, education, marital status, time of interview, ADL limitations, vision impairment, and medical conditions. In the fully adjusted longitudinal model, subjects with clinically relevant depressive symptoms had a greater decline in MMSE score over 7 years than those without clinically relevant depressive symptoms (estimate = -0.17; SE = 0.05; P <.001), adjusting for sociodemographics, ADL and medical conditions. Each point increase in the CES-D score was associated with a decline of 0.010 point in MMSE score per year (SE = 0.002; P < 0.0001), adjusting for relevant confounders. Presence of clinically relevant depressive symptoms was associated with subsequent decline in cognitive function over 7 years in older Mexican Americans, independent of demographic and health factors.