Despite the assumption that the EEG parameters in schizophrenia may be predictive for the treatment outcome, there are only a small number of such studies present. We hypothesised that the characteristics of the changes in EEG rhythms during cognitive load might differ in the first episode of psychosis and remission being dependent on the stage of the illness.

The EEG rhyths spectral power (SP) in the resting state and their changes during the performance of spatial logical task in 25 first-episode psychosis patients (FEP) and same patients in remission (REM) after 6–18 months were analysed. Control group included healthy subjects matched with patient group by gender, age and years of education.

The resting state SP values did not differ in FEP and REM. When performing a task, FEP theta SP was decreased compared to the resting state values in F7, F8, P3, T6 sites (P<0.05), while gamma2 SP was increased in Fz (P<0.001) and Pz (P<0.01). REM theta, alpha, and beta1 SP was decreased in the same way as in norm in all sites (P<0.05). Gamma2 SP increase was found in sites Fp1, F8, Fz (P<0.05). FEP theta and beta1 SP changes during cognitive load positively correlated with the PANSS scales (delusions, thought disorders, hallucinations). REM did not have significant correlations between SP and PANSS parameters.

The analysed REM EEG characteristics differ less from the norm than the FEP. Based on the results, the performance of the task is related to the stage of the illness.