title: The intensity dependence of auditory ERP components in unmedicated patients with major depression and healthy controls. An analysis of group differences.
abstract: 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.
authors.affiliation: Clinic for Psychiatry and Psychotherapy, Rheinische Kliniken Essen, University of Duisburg-Essen, 45147 Essen, Germany. thomas.linka@uni-essen.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Linka
authors.forename: Gudrun
authors.initials: G
authors.lastname: Sartory
authors.forename: Stefan
authors.initials: S
authors.lastname: Bender
authors.forename: Markus
authors.initials: M
authors.lastname: Gastpar
authors.forename: Bernhard W
authors.initials: BW
authors.lastname: Müller
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D002540:Cerebral Cortex / Q000503:physiopathology; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008144:Loudness Perception / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010063:Ovum; D012016:Reference Values; D012701:Serotonin / Q000502:physiology; D013018:Sound Spectrography
chemical_list: D012701:Serotonin