Platelet serotonin (5-HT) levels in interferon-treated patients with hepatitis C and its possible association with interferon-induced depression

Background & Aims: Interferon-associated depression is a frequent side effect of antiviral therapy for chronic hepatitis C. The aim of the present study was to investigate the correlation between platelet serotonin (5-hydroxytryptamine, 5-HT) concentrations and IFN-induced depression. Methods: The study represents a secondary analysis of a previously published trial on the efficacy of SSRI medication in HCV patients on IFN therapy. Ninety-three patients were longitudinally assessed for depression and platelet serotonin. Evaluation time points were: prior to IFN therapy, at weeks 4, 12, and 24 of IFN treatment, and 4 weeks after antiviral treatment. Depression was assessed using the Hospital Anxiety and Depression Scale (HADS). Platelet serotonin concentrations were measured by ELISA. Results: Platelet serotonin concentrations were significantly decreased during interferon therapy (p = 0.001) in 74 of the 93 patients (79.6%). Clinically relevant depression occurred in 33.3% of patients - however, IFN-induced depression was not Significantly linked to either baseline 5-HT concentrations or kinetics. In the subgroup of patients with IFN-induced depression who received the selective serotonin reuptake inhibitor (SSRI) citalopram (20 mg daily, n = 17), serotonin levels declined further during anti-depressant medication, becoming statistically significant within the first 2 weeks (p < 0.001) of SSRI treatment. Conclusions: We demonstrate a significant impact of IFN and SSRI intake on platelet serotonin levels, suggesting a biochemical analogy between 5-HT metabolism in blood platelets and the CNS. Platelet 5-HT levels might serve as a surrogate marker for patient adherence to antiviral and anti-depressant medication. For the prediction of IFN-induced depression, however, platelet 5-HT measurements are not suitable. (C) 2009 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.