BACKGROUND: The intensity dependent amplitude change (IDAP) of auditory evoked Event Related Potential (ERP) components has been found to correlate with the level of central serotonergic neurotransmission and to be associated with response to certain antidepressants. However, it is currently unknown whether there is a general abnormality of the IDAP in patients with major depression. Therefore, the purpose of the present study was to compare the IDAP in unmedicated depressed patients with that of healthy control subjects. METHODS: We report the results of a study evaluating the change of auditory evoked P1, N1, P2 as well as P1/N1 and N1/P2 peak to peak amplitudes in 34 in-patients with major depressive episode prior to antidepressant treatment, and 44 healthy control subjects. Clinical symptoms of depression were assessed by means of standardized psychiatric rating scales (CGI, HDRS, HAMA and BDI). RESULTS: In multivariate analyses of variance we found no group differences in the intensity dependent increase neither of the P1, N1, and P2 nor of the P1/N1 and N1/P2 peak to peak amplitudes between patients and controls. CONCLUSIONS: Our data revealed no general abnormality of the IDAP in patients with major depression in comparison to healthy control subjects. This result suggests that specific alterations of the IDAP are not to be expected in major depression in general, these may be confined to subgroups of depressed patients.
BACKGROUND: The intensity dependent amplitude change (IDAP) of auditory evoked Event Related Potential (ERP) components has been found to correlate with the level of central serotonergic neurotransmission and to be associated with response to certain antidepressants. However, it is currently unknown whether there is a general abnormality of the IDAP in patients with major depression. Therefore, the purpose of the present study was to compare the IDAP in unmedicated depressedpatients with that of healthy control subjects. METHODS: We report the results of a study evaluating the change of auditory evoked P1, N1, P2 as well as P1/N1 and N1/P2 peak to peak amplitudes in 34 in-patients with major depressive episode prior to antidepressant treatment, and 44 healthy control subjects. Clinical symptoms of depression were assessed by means of standardized psychiatric rating scales (CGI, HDRS, HAMA and BDI). RESULTS: In multivariate analyses of variance we found no group differences in the intensity dependent increase neither of the P1, N1, and P2 nor of the P1/N1 and N1/P2 peak to peak amplitudes between patients and controls. CONCLUSIONS: Our data revealed no general abnormality of the IDAP in patients with major depression in comparison to healthy control subjects. This result suggests that specific alterations of the IDAP are not to be expected in major depression in general, these may be confined to subgroups of depressedpatients.