DIFFERENCES IN THE EEG PROFILES OF EARLY AND LATE RESPONDERS TO ANTIPSYCHOTIC TREATMENT IN FIRST-EPISODE, DRUG-NAIVE PSYCHOTIC-PATIENTS

The aim of this study was to search for differences ir. the EEG of fir st-episode, drug-naive patients having a schizophrenic syndrome which presented different time courses in response to antipsychotic treatmen t. Thirteen patients who fulfilled DSM-IV diagnosis for schizophrenia or schizophreniform disorder participated in this study. Before beginn ing antipsychotic treatment, the EEG was recorded. On the same day psy chopathological ratings were assessed using the AMDP system, and again after 7 and 28 days of treatment. The resting EEG (19 leads) was subj ect to spectral analysis involving power values for six frequency band s. The score for the schizophrenic syndrome was used to divide the pat ients into two groups: those who displayed a clinically meaningful imp rovement of this syndrome (reduction of more than 30%) after 7 days of treatment (early responders, ER) and those who showed this improvemen t after 75 days (late responders, LR). Analysis of variance for repeat ed measures between ER, LR and their matched controls with the 19 EEG leads yielded highly significant differences for the factor group in t he alpha2 and beta2 frequency band. No difference was found between th e slow-wave frequency bands. Compared to controls the LR group showed significantly higher alpha2 and beta2 power and in comparison to the E R group, significantly higher alpha2 power. There were no significant differences between the ER and the control group. These findings point to differences in brain physiology between ER and LR. The implication s for diagnosis and treatment are discussed. (C) 1998 Elsevier Science B.V.