The association of bone mineral density and depression in an older population

OBJECTIVE: To evaluate the association between bone mineral density (BMD) and measurements of depression in an older population. DESIGN: Population-based, cross-sectional study. SETTING: Study subjects were participants in the Cardiovascular Health Study (CHS), a longitudinal, long-term, follow-up study, at the University of California Davis (Sacramento, California) and the University of Pittsburgh (Pittsburgh, Pennsylvania) clinical centers. PARTICIPANTS: A random sample of 1,566 Medicare enrollees age 65 and older enrolled in the CHS. MEASUREMENTS: Total hip BMD, measured using dual energy x-ray absorptiometry (DEXA), after adjustment for multiple covariates, was compared with depression evaluated with the Center for Epidemiological Studies 10-item Depression Scale (CES-Dm). Risk factors for osteoporosis were compared in depressed and nondepressed participants. Potential correlates were entered into a regression model. Depression scores were compared in normal, osteopenic, and osteoporotic individuals. RESULTS: Sixteen percent of participants were clinically depressed; 9% had BMDs in the osteoporotic range. Mean BMD was 40 mg/cm² lower in those with clinical depression. High CES-Dm scores were associated with lower BMD (P < .001) when adjusted for body mass index (BMI), age, kilocalories of activity, estrogen use, gender, race, smoking and drinking. When stratified by race, this remained true for all Caucasians (P < .01), all African Americans (P < .05), and when stratified by race and gender the association remained only for all Caucasian women (P < .001). In women and Caucasian men there was an increase in depression scores among individuals with osteoporotic-range BMDs. CONCLUSIONS: A significant association was found between BMD and depressive symptoms after adjustment for osteoporosis risk factors. In Caucasians, depressive symptoms were associated with both osteoporotic and osteopenic levels of BMD. Causality cannot be ascribed, with only one measurement of BMD. We postulate that there may be an unmeasured third factor, such as an endogenous steroid, that is responsible for both low BMD and depression.