Chronic schizophrenics with positive symptomatology have shortened EEG microstate durations

In young, first-episode, never-treated schizophrenics compared with controls, (a) generally shorter durations of EEG microstates were reported (Koukkou et al., Brain Topogr 6 (1994) 251; Kinoshita et al., Psychiatry Res Neuroimaging 83 (1998) 58), and (b) specifically, shorter duration of a particular class of microstates (Koenig et al., Eur Arch Psychiatry Clin Neurosci 249 (1999) 205). We now examined whether older, chronic schizophrenic patients with positive symptomatology also show these characteristics.; Multichannel resting EEG (62.2 s/subject) from two subject groups, 14 patients (36.1+/-10.2 years old) and 13 controls (35.1+/-8.2 years old), all males, was analyzed into microstates using a global approach for microstate analysis that clustered the microstates into 4 classes (Koenig et al., 1999).; (a) Hypothesis testing of general microstate shortening supported a trend (P=0.064). (b) Two-way repeated measure ANOVA (two subject groupsx4 microstate classes) showed a significant group effect for microstate duration. Posthoc tests revealed that a microstate class with brain electric field orientation from left central to right central-posterior had significantly shorter microstates in patients than controls (68.5 vs. 76.1 ms, P=0.034).; The results were in line with the results from young, never-treated, productive patients, thus suggesting that in schizophrenic information processing, one class of mental operations might intermittently cause deviant mental constructs because of premature termination of processing.