Depression in anorexia nervosa: A risk factor for osteoporosis

Context: Both anorexia nervosa (AN) and depression are associated with osteoporosis. We hypothesized that adolescent girls with AN and depression will have lower bone mineral density (BMD) than anorexic girls without depression. Objective: The objective of this study was to investigate whether depression is an independent risk factor for osteoporosis in anorexic adolescent girls. Design: This study was cross-sectional. Setting: This study was conducted at the University Children's Hospital (Bialystok, Poland) from October 2002 through September 2003. Participants: Forty-five Caucasian anorexic girls aged 13-23 yr, matched by age, Tanner stage, weight, height, calcium intake, and duration of AN, were studied, including 14 with comorbid depression (based on Hamilton Depression Rating Scale and Montgomery-Asberg Depression Rating Scale) and 31 anorexic girls without depression. Main Outcome Measures: Total body and lumbar spine (LS) BMD, fat mass, and lean mass assessed using dual-energy x-ray absorptiometry were compared between AN girls with and without depression. Results: BMD was reduced in both groups, relative to reference data, but girls with AN and depression had lower BMD than those with AN alone (LS Z-scores, -2.6±0.3 vs. -1.7±0.3; P=0.02) (mean±SEM). Quantitative assessment of depression correlated independently with total body BMD (r = -0.4; P < 0.05) and LS BMD (r = -0.6; P < 0.001). Conclusion: Anorexic girls with depression are at higher risk of osteoporosis than those without depression. The mechanisms responsible for decreased BMD in depression are not known. Independent treatment of the depressive disorder in AN may partly alleviate the bone fragility.