Quantitative resting state electroencephalography in patients with schizophrenia spectrum disorders treated with strict monotherapy using atypical antipsychotics
Takashi Ozaki 1, 2, Atsuhito Toyomaki 1, Naoki Hashimoto 1*, Ichiro Kusumi 1
1Department of Psychiatry, Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan, 2Koyogaoka Hospital
Received: June 27, 2020; Revised: August 12, 2020; Accepted: August 13, 2020; Published online: August 13, 2020.
© The Korean College of Neuropsychopharmacology. All rights reserved.

Objective: The effect of antipsychotic drugs on quantitative electroencephalography (EEG) has been mainly examined by the administration of a single test dose or among patients using combinations of other psychotropic drugs. We therefore investigated the effects of strict monotherapy with antipsychotic drugs on quantitative EEG among schizophrenia patients. 
Methods: Data from 2364 medical reports with EEG results from psychiatric patients admitted to the Hokkaido University Hospital were used. We extracted EEG records of patients who were diagnosed with schizophrenia spectrum disorders and who were either undergoing strict antipsychotic monotherapy or were completely free of psychotropic drugs. The spectral power was compared between drug-free patients and patients using antipsychotic drugs. We also performed multiple regression analysis to evaluate the relationship between spectral power and the chlorpromazine equivalent daily dose of antipsychotics in all the patients.
Results: We included 31 monotherapy and 20 drug-free patients. Compared with drug-free patients, patients receiving antipsychotic drugs demonstrated significant increases in theta, alpha and beta power. When patients taking different types of antipsychotics were compared with drug-free patients, we found no significant change in any spectrum power for the aripiprazole or blonanserin groups. Patients taking risperidone demonstrated significant increases in alpha and beta power. Patients taking clozapine and olanzapine demonstrated significant slow wave increases. Multiple regression analysis revealed that the chlorpromazine equivalent dose was positively associated with theta power.
Conclusion: Use of any antipsychotic drug by patients was associated with a dose-dependent increase in theta power. However, each type of antipsychotic demonstrated different spectral power changes.
Keywords: Atypical antipsychotics, Gamma oscillation, Monotherapy, Quantitative electroencephalography, Schizophrenia