Major depressive disorder (MDD) often occurs during pegylated IFN-alpha2 (IFN-alpha) treatment. Identifying who is at risk for MDD in this population is essential, and epidemiological studies suggest that sleep may be related to depression risk. Controlling for pre-existing depression symptoms, we therefore examined whether sleep quality prior to IFN-alpha treatment would predict subsequent MDD incidence during IFN-alpha treatment. Adults with hepatitis C but without current clinical MDD (n=86) were evaluated prior to IFN-alpha treatment and then prospectively monitored during treatment using self-report measures of sleep quality (PSQI), depression (BDI), and anger and irritability (AIAQ), as well as with Structured Clinical Interviews for DSM-IV Axis I Disorders (SCID-I). During IFN-alpha treatment, 19% developed MDD, 19% developed subsyndromal depression with irritability, and one developed mania. Controlling for baseline depression symptoms and past history of depression, patients with worse sleep quality (PSQI > or = 10) prior to treatment had a significantly shorter time until they developed MDD or any severe psychiatric problem. These findings may have important implications for understanding, predicting, and possibly preventing depression, particularly in individuals treated with IFN-alpha.
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