A comparative study of P 300 event-related potential in patients with bipolar affective disorder across its predominant polarity of presentation

Abstract

Background:P-300 is an event related potential (ERP) that is reflective of the cognitive status of a person. It has been seen to be deranged in patients with bipolar affective disorder (BPAD). Reliable approach to determine the predominant polarity (PP) in BPAD has been under focus. Past studies have found characteristic cognitive impairments in both manic and depressive PP. The current study investigated the differences in latency and amplitude of P-300 ERP between euthymic patients with manic and depressive PP in BPAD.

Methodology:Euthymic patients of BPAD recruited by purposive sampling were classified into depressive or manic PP on fulfilling the Barcelona proposal (two-third predominance of any episode). The auditory event related potentials were measured using the odd-ball paradigm. Evoked responses were analysed in terms of latencies and peak amplitude. A comparison of latency and amplitude of P300 in the two groups were done using Independent sample t-test.

Results:Overall, 22 patients were recruited in our study, of which 13 were of manic PP and 9 of depressive PP. It was found that there were no significant differences in latencies and peak amplitudeof P-300 between the two groups.

Conclusion:In our sample, manic and depressive PP could not be distinguished using the latency and amplitude of P-300. Small sample size was a limitation of the study. Further studies should be conducted using other parameters of ERP for further advancement.

Keywords: Bipolar disorder; Event related potential; Predominant Polarity; P-300; cognition