A study of P300-event related evoked potential in the patients of major depression

Many studies involving various electrophysiological parameters have been conducted in psychiatric disorders like schizophrenia and dementia to assess their cognitive dysfunctions. Not much reports are available in major depression. The present study was conducted in 20 patients of major depression to evaluate their cognitive functions in terms of P300. P300 or P3 wave of auditory event related evoked potentials (ERPs) is usually seen around 300 msec of presenting of target stimulus, if the subject is responding to it. Auditory ERPs were recorded using the standard 'odd ball' paradigm. The latencies of various components of ERPs N1, N2, P1, P2, and P3 were recorded and compared with those of 20 normal age and sex matched controls. The latency of P300 was found to be significantly delayed in cases of major depression as compared to that of controls. Other waves were also delayed in cases of depression but the difference was not statistically significant. Our results suggest that P300 latency is longer in the patients of major depression disorders which could be due to constitutive altered 'cognitive neuronal pool' or a neurotransmitter/neuropeptide imbalance. Further studies involving larger populations are required to elucidate the diagnostic and predictive role of latency of P300 in the cases of depression.