Decreased Gamma Auditory Steady-State Response Is Associated With Impaired Real-World Functioning in Unmedicated Patients at Clinical High Risk for Psychosis.

Abstract

Deficits in synchronous, gamma-frequency neural oscillations may contribute to schizophrenia patients' real-world functional impairment and can be measured electroencephalographically using the auditory steady-state response (ASSR). Gamma ASSR deficits have been reported in schizophrenia patients and individuals at clinical high risk (CHR) for developing psychosis. We hypothesized that, in CHR patients, gamma ASSR would correlate with real-world functioning, consistent with a role for gamma synchrony deficits in functional impairment. A total of 35 CHR patients rated on Global Functioning: Social and Role scales had EEG recorded while listening to 1-ms, 93-dB clicks presented at 40 Hz in 500-ms trains, in response to which 40-Hz evoked power and intertrial phase-locking factor (PLF) were measured. In CHR patients, lower 40-Hz PLF correlated with lower social functioning. Gamma synchrony deficits may be a biomarker of real-world impairment at early stages of the schizophrenia disease trajectory.