Elevated levels of erythropoietin in cerebrospinal fluid of depressed patients.

To investigate the role of erythropoietin (EPO) in the central nervous systems, we assayed EPO concentrations in the cerebrospinal fluid (CSF) of patients with depression or old cerebrovascular injuries and controls. Concentrations of EPO in the CSF were significantly higher in 13 patients with depression (3.21+/-0.46 mU/mL) than in 10 patients with old cerebrovascular diseases (1.80+/-0.32 mU/mL, P < 0.01), and in 10 healthy controls (0.98+/-0.26 mU/mL, P < 0.01). Serum EPO concentrations did not differ among these three groups. In the patients with depression, 5 months of treatment with imipramine and/or nortriptyline significantly reduced EPO concentrations in the CSF (1.56+/-0.34 mU/ mL, P < 0.01). Results suggest that the brain of patients with depression may be in an hypoxic state, and that the increased EPO in the CSF may act to limit hypoxia-induced damage to neurons in these patients.