Auditory evoked response potentials in somatization disorder

Event related potentials to frequently and infrequently occurring tones were recorded from 15 patients with somatization disorder, 10 patients with anxiety disorders and 15 normals. P3 component responses were of normal latency and amplitude in the somatizers, which suggests they had no apparent difficulty with certain aspects of processing novel, task-relevant stimuli. However, their N1 component responses to the frequent tones, which subjects had been instructed to ignore, were enhanced relative to each of the other groups. Moreover, there was no difference in N1 amplitude to the two types of tones among the somatizers, whereas each of the other groups had significantly larger N1 amplitudes to the infrequent tones. These preliminary results may suggest that somatization disorder is associated with an impaired ability to filter out and not respond to relatively meaningless afferent stimuli.