The intensity dependence of auditory evoked ERP components predicts responsiveness to reboxetine treatment in major depression.

Introduction: The intensity (loudness)-dependent amplitude change (IDAP) of auditory evoked event-related potential (ERP) components has been suggested as an indicator of central serotonergic neurotransmission. In patients with major depression, associations of high IDAP with favorable SSRI treatment outcome have been reported. This is the first study to assess the predictive value of the IDAP in SNRI treatment. Methods: We evaluated the pre-treatment intensity-dependent change of auditory evoked P1, N1, P2, and P1/N1 and N1/P2 peak-to-peak amplitudes in 14 inpatients with major depressive episode (DSM IV) in the course of 24 days of treatment with the SNRI reboxetine (6-12 mg/d). Results: Our data revealed a highly significant correlation between lower intensity-dependent N1 amplitude slopes prior to reboxetine treatment and stronger decrease of HDRS total score at Fz (r = 0.86, P < 0.001), Fcz (r = 0.91, P < 0.001), and Cz (r = 0.93, P < 0.001). Conclusion: This result corroborates the hypothesis of the IDAP as a differential indicator of serotonergic versus noradrenergic antidepressant psychopharmacotherapy.