Although conflicting results have been obtained regarding P300 amplitude and latency in major depressive patients, most studies have reported that major depressive patients have smaller P300 amplitudes and longer latencies than healthy people. This study aimed to investigate the relationship between P300 and treatment response in major depressive disorder patients. Twenty-eight patients suffering from major depression who completed 12 weeks of follow-up appointments and 28 healthy people, whose

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... age and gender were matched with patients, were included in the study. Event-related potentials (P300) were recorded for patients before and after treatment with sertraline (50-200 mg/day) for 12 weeks. Treatment response was defined as a 50% or greater decrease in a given patient's total Hamilton Depression Rating Scale score. Pre-treatment and post-treatment P300 amplitude and latency values were compared for responders (n=18), non-responders (n=10) and healthy subjects. No significant difference was found between the P300 amplitude values of responders, non-responders and healthy subjects before or after treatment. Pre-treatment P300 latencies of non-responders were significantly longer than latencies of responders and healthy subjects. After treatment for depression, P300 latency values of responders were normalized, but non-responders still maintained longer P300 latencies than responders and healthy subjects. These findings suggest that delayed P300 latency may be related to a non-response to sertraline treatment. No relation was found between P300 amplitude and treatment response.