Osteoprotegerin levels in patients with severe mental disorders.

BACKGROUND: Severe mental disorders are associated with elevated levels of inflammatory markers. In the present study, we investigated whether osteoprotegerin (OPG), a member of the tumour necrosis factor receptor family involved in calcification and inflammation, is elevated in patients with severe mental disorders. METHODS: We measured the plasma levels of OPG in patients with severe mental disorders (n = 312; 125 with bipolar disorder and 187 with schizophrenia) and healthy volunteers (n = 239). RESULTS: The mean plasma levels of OPG were significantly higher in patients than in controls (t531 = 2.6, p = 0.01), with the same pattern in bipolar disorder and schizophrenia. The increase was significant after adjustment for possible confounding variables, including age, sex, ethnic background, alcohol consumption, liver and kidney function, diabetes, cardiovascular disease, autoimmune diseases and levels of cholesterol, glucose and C-reactive protein. LIMITATIONS: Owing to the cross-sectional design, it is difficult to determine causality. CONCLUSION: Our results indicate that elevated OPG levels are associated with severe mental disorders and suggest that mechanisms related to calcification and inflammation may play a role in disease development.