Auditory gamma oscillations predict global symptomatic outcome in the early stages of psychosis: a longitudinal investigation

Publication date: Available online 30 August 2018

Source: Clinical Neurophysiology

Author(s): Daisuke Koshiyama, Kenji Kirihara, Mariko Tada, Tatsuya Nagai, Mao Fujioka, Eriko Ichikawa, Kazusa Ohta, Motoko Tani, Maiko Tsuchiya, Akiko Kanehara, Kentaro Morita, Kingo Sawada, Jun Matsuoka, Yoshihiro Satomura, Shinsuke Koike, Motomu Suga, Tsuyoshi Araki, Kiyoto Kasai

Abstract

Objectives

The gamma-band auditory steady-state response (ASSR) is thought to reflect the function of parvalbumin-positive γ-aminobutyric acid (GABA)-ergic interneurons and may be a candidate biomarker in early psychosis. Although previous cross-sectional studies have shown that gamma-band ASSR is reduced in early psychosis, whether reduced gamma-band ASSR could be a predictor of the long-term prognosis remains unknown.

Methods

In this longitudinal study, we investigated the association between gamma-band ASSR reduction and future global symptomatic or functional outcome in early psychosis. We measured 40-Hz ASSR in 34 patients with recent-onset schizophrenia (ROSZ), 28 ultra-high risk (UHR) individuals, and 30 healthy controls (HCs) at baseline. After 1 to 2 years, we evaluated the global assessment of functioning (GAF) in the ROSZ (N = 20) and UHR (N = 20) groups.

Results

The 40-Hz ASSR was significantly reduced in the ROSZ and UHR groups. The attenuated 40-Hz ASSR was correlated with the future global symptomatic outcome in the ROSZ, but not in the UHR groups.

Conclusions

A reduction in the gamma-band ASSR after the onset of psychosis may predict symptomatic outcomes in early psychosis.

Significance

Gamma-band ASSR may be a potentially useful biomarker of the long-term prognosis in patients with recent-onset schizophrenia.

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