Individuals with first-episode psychosis exhibit decreased beta and low gamma oscillations in electroencephalogram (EEG) readings, according to recent study results published in Schizophrenia Research. These deficits correlate with worse symptoms; early detection with transcranial magnetic stimulation (TMS)/EEG could result in better interventions.
This study included 16 participants with first-episode psychosis and 11 healthy control participants, all of whom were given TMS in the left primary motor cortex. This area was located by calculating the individual resting motor threshold. The T1 individual magnetic resonance imaging was also used to identify the frontal lobe’s precentral gyrus in the left primary motor cortex. To examine clustering analysis and significance of Gauss-Markov fading process, a nonparametric permutation test was used. Normality in the dataset was assessed using Pearson correlation analyses and the Shapiro-Wilk test, which compared scores in the Scale for the Assessment of the Positive and Negative Symptoms and measures from TMS.
Transcranial magnetic stimulation resulted in a number of EEG oscillations within the first 300 ms among both participants with first-episode psychosis and control participants. No significant difference was determined between groups in time of response to stimulation nor in EEG voltage; however, participants with first-episode psychosis displayed greater reduced beta and low gamma relative spectral power than did control participants, particularly in the 27- to 33-Hz range within the motor cortex (P =.01). Cumulative relative spectral power was also significantly lower among participants with first-episode psychosis than in control participants (P =.0004). Neurofeedback was lower among participants with first-episode psychosis (22.16±6.2) compared with control participants (27.45±5.9); P =.05.
Limitations in this study included the possibility of confounding differences between control participants and participants who used antipsychotic drugs; a lack of participant characteristic data; and possible underestimation of risk factors.
The study researchers concluded that “TMS/EEG recordings: 1) are feasible in acute, early-course [patients with psychosis]; and 2) reveal intrinsic oscillatory deficits at illness onset, which may help design more effective, which may help design more effective, early interventions in [schizophrenia].”
Ferrarelli F, Kaskie RE, Graziano B, Cardoso Reis C, Casali AG. Abnormalities in the evoked frontal oscillatory activity of first-episode psychosis: a TMS/EEG study [published online November 23, 2018]. J Schizophr Res. doi: 10.1016/j.schres.2018.11.008