Atypical waveform morphology in schizophrenia-visual evoked potential as a promising endophenotype

BACKGROUND: Electrophysiological research has provided measures of dysfunction of visual pathway in schizophrenia through the use of visual evoked potential (VEP) as the neurophysiologic tool. OBJECTIVE: The main objective of this study is to examine the morphology and topography of VEP responses in schizophrenic patients and to explore the potentiality of VEP as an endophenotype. MATERIALS AND METHODS: The study included 20 patients of schizophrenia who were recruited from the outpatient and inpatient department of psychiatry of a tertiary care rural hospital. The patients were assessed by tools such as Positive and Negative Symptoms Assessment Scale and Clinical Global Impression Scale for Severity. Transient Pattern Reversal VEP recordings were taken using an Evoked Potential Recorder (RMS EMG EP MARK II), and it was a cross-sectional study. RESULTS: The mean age of patients was 45.95 ± 10.14 years in the range of 35–60 years. Qualitative analysis of VEP waveforms in people with schizophrenia was performed. Abnormal waveform morphology was observed in 14/20 (70%) of the study population and all of them were the chronic and severe cases. Six out of 15 (40%) showed lack of differentiation of the evoked complex so that the three waves (negative–positive-negative [NPN] complex) could not be identified. In 5 of 15 (33.33%) VEP records, a distinct altered waveform with extinguished second negative component of NPN complex was obtained. CONCLUSION: Qualitative morphometric findings of this study in terms of pattern-reversal VEP waveform abnormalities emerged as a tool to provide evidence of relationship for emerging as first potential biomarker for diagnosing schizophrenia.