Resting state quantitative electroencephalogram gamma power spectra in patients with first episode psychosis: An observational study.

Abstract

Electrophysiological abnormalities, especially in the gamma frequency range, have been well documented in schizophrenia. This study was aimed to investigate the gamma spectral power of the brain in patients with first episode psychosis, using high-resolution electroencephalography. Twenty-nine neuroleptic naïve/free male patients with non-affective psychosis as per ICD 10 DCR clinical criteria were compared with thirty age, sex, education and handedness matched healthy individuals as controls. All participants underwent 192-channel resting electroencephalography (EEG) recording. Gamma spectral power was calculated for low (31-50 Hz) and high-gamma (51-70 and 71-100 Hz) bands and compared between two groups using MANOVA and supplementary one-way ANOVA. Pearson correlation and linear regression analyses were conducted between spectral power parameters and various clinical variables. The gamma spectral power in 31-50 Hz and 51-70 Hz frequency bands was found to be significantly higher in patients in most brain regions. Duration of illness predicted the gamma spectral power in both right and left frontal regions of the brain in the frequency range 31-50 Hz and 71-100 Hz, as well as in the right temporal region in 71-100 Hz range, where it was negatively correlated. Patients with first episode psychosis have increased gamma spectral power, which might be indirectly related to the duration of illness.