Biological and social predictors of long-term geriatric depression outcome

OBJECTIVE: In this study, we examined 204 older depressed individuals for up to 64 months to determine factors related to depression outcome. We hypothesized that both presence of vascular brain lesions seen on baseline magnetic resonance imaging (MRI) scans and lower baseline social support measures would be related to worse depression outcome. METHOD: At study entry, all subjects were at least 59 years old, had a diagnosis of major depression, and were free of other major psychiatric illness and primary neurological illness, including dementia and stroke. Depression was diagnosed via structured interview and clinical assessment by a geriatric psychiatrist who completed a Montgomery Asberg Depression Rating Scale (MADRS) to determine severity of depression. Subjects provided self-report data on social support variables and ability to perform basic and instrumental activities of daily living (ADL, IADL). All subjects agreed to have a baseline standardized MRI brain scan. Ratings of severity of hyperintensities were determined for the periventricular white matter, deep white matter, and subcortical gray matter by two readers who decided by consensus. Treatment was provided by geropsychiatrists following clinical guidelines. Using mixed models to analyze the data, we determined the effect of a variety of demographic, social and imaging variables on the trajectory of MADRS score, the outcome variable of interest. RESULTS: MADRS scores decreased steadily over time. In a final HLM model, in which time since entry, a baseline time indicator, age, gender, education and Mini-mental State Examination score were controlled, subjective social support, instrumental ADL impairment, subcortical gray matter severity, and the interactions of time with social network and with subcortical gray matter lesions remained significantly associated with MADRS score. CONCLUSIONS: Both social and biological factors at baseline are associated with longitudinal depression severity in geriatric depression.