Determination of neurophysiological P300 and P50 in patients with schizophrenia at a tertiary hospital in Sokoto, Nigeria

Introduction: Schizophrenia is a severe and complex mental disorder. It currently lacks an objective biological diagnostic test. Neurophysiological markers like P300 and P50 event-related potentials have shown some diagnostic usefulness in previous studies. However, very few of these studies have been done among Africans. The objective of the study was to evaluate neurophysiological P300 and P50 eventrelated potentials in 70 schizophrenia patients and 70 healthy controls at a tertiary psychiatric hospital in Sokoto, Nigeria. Materials and Methods: The instruments used were the Electroencephalogram (EEG) machine, laptop with installed auditory P300 and P50 tones, headphones, Positive and Negative Syndrome Scale (PANSS). Results: Schizophrenia patients were significantly associated with higher amplitude of P300 and prolonged P300 peak latency auditory event-related potential compared to healthy controls (U = 1077.000, P=<0.001 and U= 1191.000, P=<0.001) respectively. Schizophrenia patients were also significantly more associated with higher P50 amplitude ratio (U= 1342.500, P=<0.001). The P300 event-related amplitude had the highest area under the curve of 0.78. P300 peak latency was the most specific (Specificity=0.93) while P50 ratio was most sensitive (Sensitivity=0.76). The determined cut-off points for P300 amplitude, P300 peak latency, and P50 ratio were 6.84μv, 445ms, and 0.89 respectively. There was a significant positive correlation between P50 ratio and age of participants among schizophrenia patients (rs=0.29, P=0.02). Conclusion: The study has determined the cut-off points for P300 and P50 neurophysiological markers in patients with schizophrenia. These will serve as an adjunct for diagnosis and for forensic purposes in these patients. Further studies including neuroimaging, biochemical, and genetic aspects are recommended in African countries.