Contingent negative variation and attention in schizophrenic and depressedpatients

Contingent negative variation (CNV) is supposed to be a psychophysiological indicator of attention and arousal. Both have been reported to be deterior ated in schizophrenic and depressed patients. Thirty-four patients with maj or depression, 43 patients with schizophrenia and 49 healthy subjects were investigated during acute illness with a complex three-stimulus go/no-go ta sk which requires different states of attention: trials consisted of three complex figures that were tachistoscopically presented. Three identical fig ures had to be confirmed by pressing a button (target condition). CNV was m easured: (1) after the first figure waiting for the second (baseline condit ion), (2) after two identical figures waiting for the third (response-relev ant condition), (3) after two different figures waiting for the third (resp onse-irrelevant condition). The response-relevant condition compared to bas eline significantly intensified CNV in healthy controls and to a minor exte nt in depressed patients but not in schizophrenics. In the response-relevan t conditions in healthy controls, CNV was significantly reduced compared to the response-relevant condition. This clear discrimination between respons e-relevant and response-irrelevant conditions was not observed in either gr oup of patients. Thus, the applied CNV paradigm was able to discriminate sc hizophrenic and depressed patients from healthy controls. Furthermore, subt le differences between schizophrenic and depressed patients were detected, reflected by the different CNV development across experimental conditions.