INTRODUCTION: Event related potentials are an objective parameter reflecting cognitive functions. Among the event related potentials, the P300 component is viewed as a measure of stimulus evaluation time and it can provide a rough estimate of the time required for perceptual processing. Impairment in cognitive processing, psychomotor retardation and abnormally amplitude and longer P300 latency have been found in depressive patients. METHODS: To evaluate the influence of visual and auditory stimuli on the P300 latency we studied 595 patients with major depression. The experimental tasks applied were, first, a series of 300 auditory stimuli: 85% were tones of 1,000 Hz, and 15% were tones of 2,000 Hz, and second, a series of 300 visual stimuli; 85% were black circles on a white background and 15% were black squares on a white background. RESULTS: The results shown an increase of P300 latency in depressive patients during auditory and visual tasks. DISCUSSION: These results are consistent with an impairment in brain function with cortical hypo activity in depressive patients that is associated with cognitive deficit processing. These results determine the clinical utility of P300 in patients with major depression.
INTRODUCTION: Event related potentials are an objective parameter reflecting cognitive functions. Among the event related potentials, the P300 component is viewed as a measure of stimulus evaluation time and it can provide a rough estimate of the time required for perceptual processing. Impairment in cognitive processing, psychomotor retardation and abnormally amplitude and longer P300 latency have been found in depressivepatients. METHODS: To evaluate the influence of visual and auditory stimuli on the P300 latency we studied 595 patients with major depression. The experimental tasks applied were, first, a series of 300 auditory stimuli: 85% were tones of 1,000 Hz, and 15% were tones of 2,000 Hz, and second, a series of 300 visual stimuli; 85% were black circles on a white background and 15% were black squares on a white background. RESULTS: The results shown an increase of P300 latency in depressivepatients during auditory and visual tasks. DISCUSSION: These results are consistent with an impairment in brain function with cortical hypo activity in depressivepatients that is associated with cognitive deficit processing. These results determine the clinical utility of P300 in patients with major depression.