Abnormal phase entrainment of low- and high-gamma-band auditory steady-state responses in schizophrenia.

Introduction: Gamma-band oscillatory deficits have attracted considerable attention as promising biomarkers of schizophrenia (SZ). Notably, a reduced auditory steady-state response (ASSR) in the low gamma band (40 Hz) is widely recognized as a robust finding among SZ patients. However, a comprehensive investigation into the potential utility of the high-gamma-band ASSR in detecting altered neural oscillations in SZ has not yet been conducted. Methods: The present study aimed to assess the ASSR using magnetoencephalography (MEG) data obtained during steady-state stimuli at frequencies of 20, 30, 40, and 80 Hz from 23 SZ patients and 21 healthy controls (HCs). To evaluate the ASSR, we examined the evoked power and phase-locking factor (PLF) in the time-frequency domain for both the primary and secondary auditory cortices. Furthermore, we calculated the phase-locking angle (PLA) to examine oscillatory phase lead or delay in SZ patients. Taking advantage of the high spatial resolution of MEG, we also focused on the hemispheric laterality of low- and high-gamma-band ASSR deficits in SZ. Results: We found abnormal phase delay in the 40 Hz ASSR within the bilateral auditory cortex of SZ patients. Regarding the 80 Hz ASSR, our investigation identified an aberrant phase lead in the left secondary auditory cortex in SZ, accompanied by reduced evoked power in both auditory cortices. Discussion: Given that abnormal phase lead on 80 Hz ASSR exhibited the highest discriminative power between HC and SZ, we propose that the examination of PLA in the 80 Hz ASSR holds significant promise as a robust candidate for identifying neurophysiological endophenotypes associated with SZ. Furthermore, the left-hemisphere phase lead observed in the deficits of 80 Hz PLA aligns with numerous prior studies, which have consistently proposed that SZ is characterized by left-lateralized brain dysfunctions.

[Adverse drug reactions of psychotropic agents: adverse drug reactions and safety monitoring of psychotropic agents].

Pharmacological treatments of psychiatric illness have been developed and many psychotropic drugs are now on the market. The body of safety information regarding psychotropic agents is so large that it is difficult for clinicians to consider all the details of possible adverse drug reactions(ADRs) in daily clinical practice. Although it is impossible to predict and prevent all occurrences of ADRs, many of them may be preventable. In this context, there is a strong need for compact manuals of diagnosis and treatment for ADRs arising from psychotropic agents that are likely to be used in daily practice. Under the auspices of the Japanese Society of Psychiatry and Neurology, a task force was convened to answer this need. This review focuses on the general considerations of ADRs with psychotropic agents, based on discussions of the task force. We also discuss the guidelines for drug safety monitoring, targeted towards specific psychiatric disorders or patients taking specific classes of drugs. Finally, we introduce the Adverse Drug Reactions Relief System in Japan.