AbstractObjectiveTo examine whether 40-Hz Auditory Steady-State Responses (ASSRs) are impaired in participants at clinical high-risk for psychosis (CHR-P) and predict clinical outcomes.MethodMagnetoencephalography data were collected during a 40-Hz ASSR paradigm for a group of 116 CHR-P participants, 33 first-episode-psychosis patients (FEP, 15 antipsychotic-naïve), a psychosis-risk-negative group (CHR-N: n=38) and 49 healthy controls. Analysis of group differences of 40-Hz Inter-trial-phase-coherence (ITPC) and 40-Hz amplitude focused on right Heschl’s gyrus [RHES], superior temporal gyrus, hippocampus [RHIP], and thalamus [RTHA], after establishing significant activations during 40-Hz stimulation. Linear regression and linear discriminant analyses (LDA) were used to predict clinical outcomes, including transition to psychosis and persistence of attenuated psychotic symptoms (APS) in CHR-Ps.ResultsCHR-P and FEP-patients were impaired in 40-Hz amplitude in RTHA and RHIP. In addition, FEP-patients were impaired in 40-Hz amplitude in RHES and CHR-Ps in 40-Hz ITPC in RHES. 40-Hz ASSR deficits were pronounced in CHR-Ps who later transitioned to psychosis (n=13) or showed persistent APS (n=40). Importantly, both APS-persistence and transition to psychosis were predicted by 40-Hz ASSR impairments. Classification accuracy was 73.7% for non-persistent-APS and 72.5% for persistent-APS group (Area under the curve (AUC)=0.842). For transition risk to psychosis, classification accuracy was 76.7% and 53.8% for non-transitioned and transitioned CHR-P participants, respectively (AUC=0.810).ConclusionsOur data indicate that deficits in gamma entrainment in primary auditory cortex and subcortical areas constitute a potential biomarker for predicting clinical outcomes in CHR-P participants.
M73. Neuromagnetic 40 Hz Auditory Steady State Responses and Auditory Cortical GABA-Levels in Participants at Ultra-High Risk of Psychosis
