P300 and neuropsychological tests in schizophrenia and bipolar patients

INTRODUCTION: A smaller P300 amplitude has been found in schizophrenic patients in the majority of the studies done. And this occur in spite of treatment, sex, clinical stage and evolution time of the illness. It has been already described an association between this amplitude reduction and a poor result on the neuropsychological tests. But these changes in the P300 amplitude are not specific of the schizophrenic patients and they can be found in affective patients. OBJECTIVES: This study try to value the influence of the clinical stage and the cognitive results on the P300 values in the bipolar patients and to compare these results with the schizophrenic patients. PATIENTS AND METHODS: It has been evaluated the evoked potentials and the results of a neuropsychological battery of tests in three patient groups: schizophrenics in patients with acute symptomatology (n = 18), schizophrenic out patients without acute symptomatology (n = 15) and bipolar in patients during a maniac period (n = 16). RESULTS: It has not been found any differences between schizophrenic and maniac patients nor in the amplitude or in the latency of the P300. The results of the neuropsychological tests have not any relation with P300 amplitude and latency except for the verbal fluidity (VF) which has a good correlation with a longer P300 latency. At the same time this was the only test in which schizophrenic patients have smaller results than affective patients with a good correlation. CONCLUSIONS: These results suggest a similar pattern of neuropsychological and neurophysiological damage in schizophrenic and affective patients in acute period of mania.