The P300 component decreases in a bimodal oddball task in individuals with depression: An event-related potentials study.

OBJECTIVE: In this study, we investigated auditory-visual stimulation-induced P300 and examined whether P300 was differentially modulated between individuals with clinical depression and healthy controls. We hypothesized that the P300 component would significantly differ between individuals with depression and healthy individuals Specifically, we predicted that the P300 component induced by the bimodal oddball task would be significantly different from that induced by the unimodal task.

METHODS: Forty-five individuals with depression and forty-five healthy controls participated in this study. All participants were instructed to complete three oddball tasks-auditory (A), visual (V), and bimodal (AV)-while their electroencephalographic signals were recorded.

RESULTS: Individuals with depression had a lower P300 amplitude and a longer latency than controls in the bimodal task. P300 amplitudes in the bimodal task were significantly higher than in the auditory or visual tasks in both groups. In the depression group, the P300 amplitude was negatively correlated with Hamilton Depression Rating Scale (HAM-D) scores in the bimodal task.

CONCLUSIONS: Our results, which agree with those reported previously, suggest that there is a heightened P300 amplitude sensitivity in the bimodal task in individuals with depression. Our data also suggest that P300 amplitudes in the bimodal task may reflect the severity of depression.

SIGNIFICANCE: The reduced task-related ERP response in individuals with depression suggests significant impairments in these individuals in stimulus integration and response functions.