Reduced P300 amplitude in adolescents with an at-risk mental state for psychosis

Poster C116, Saturday, October 22, 11:30 am - 1:00 pm, Le Baron

Tsubasa Morimoto1, Toyosaku Ota1, Kosuke Okazaki1, Yasuhiro Matsuda1, Yasunari Yamaguchi1, Yasuhiro Eto1, Junzo Iida2, Toshifumi Kishimoto1; 1Department of Psychiatry, Nara Medical University, 2Faculty of Nursing, Nara Medical University

The P300 is a late cognitive component of event-related potentials (ERPs), which is thought to reflect a working memory update of change and attention. In adults with an at-risk mental state (ARMS) for psychosis, P300 amplitude was found to be reduced compared with that of healthy control subjects. However, to the best of our knowledge, there are no reports on P300 components in treatment-naïve adolescents with ARMS compared with healthy control subjects. The aim of the present study is to investigate this assumption about P300 components in treatment-naïve adolescents with ARMS, as measured by ERP. Ten treatment-naïve participants (7 males and 3 females: mean age 16.5±2.92 years), diagnosed with ARMS according to the Criteria of Psychosis-Risk Syndromes, were compared with 10 age- sex- and IQ-matched healthy control subjects (7 males and 3 females: mean age 16.6±3.75 years). The adolescents with ARMS were evaluated with the Structured Interview for Prodromal Syndrome/Scale of Prodromal Symptoms. This study was approved by the Institutional Review Board at the Nara Medical University. Written informed consent was obtained from all participants and/or their parents prior to the study. Based on the guidelines for evoked potential measurement, the P300 was obtained by auditory odd-ball tasks. We found that the P300 amplitude in the Fz, Cz, Pz and C4 regions were significantly smaller in the ARMS group compared with the control group. There were no between-group differences in P300 latency. Therefore, reduction in the amplitude of the P300 is associated with an increased vulnerability to psychosis.

Topic Area: Ultra High Risk / Prodromal Research

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