Attention-related effects on somatosensory evoked potentials in college students at high risk for psychopathology.

Abstract

Attention directed to a stimulus elicits a late positive wave in the evoked potential, which has consistently been shown to be of lower than normal amplitude in schizophrenic patients. This study aimed to determine whether a similar deviation from normal occurs in nonpatient college students with extremely high scores on Chapman's Physical Anhedonia (AN) and Perceptual Aberration (PA) Scales. Individuals with such high scores have been shown to deviate from control subjects in ways analogous to schizophrenic patients and are considered to be at high risk for this disorder. Somatosensory evoked potentials (SEPs) were recorded from five scalp locations while subjects counted stimuli to one of four randomly stimulated fingers; SEPs to counted stimuli contained the attention-related late positive wave (P400). The AN (n = 10) and PA (n = 10) groups were compared with normal control subjects (n = 10); in addition, the AN group was compared with schizophrenic subjects (n = 7). P400 amplitudes of ANs were lower than those of normal control subjects matched for age and sex, whereas P400 amplitudes of PAs and their matched control subjects did not differ. P400 amplitudes of ANs did not differ significantly from those of the schizophrenic group, although AN means were somewhat higher. Measurements of SEP peaks preceding P400 yielded few consistent group differences with respect to attention-related changes. The results suggest that ANs, but not PAs, display a pattern of P400 deviation similar to that found in schizophrenic patients.