CPT performance in major depressive disorder before and after treatment with imipramine or fluvoxamine

Numerous neuropsychological studies have reported deficits in cognitive and attentional functioning in depressed patients. However, there are limited data available about unmedicated depressed patients and the effects of antidepressant treatment on attentional performance. In this study, a Continuous Performance Test (CPT) was employed to evaluate the attentional performance of depressed inpatients during a drugfree period (n = 52) in comparison to healthy control subjects (n = 73). After 4 weeks of double-blind treatment with imipramine (TCA) or fluvoxamine (SSRI) at adequate plasma levels the CPT performance was studied again. We found that the unmedicated patients had a significantly impaired performance on all CPT parameters (reaction time, omission errors and commission errors) in comparison to the controls. None of the CPT parameters correlated with the severity of the depression or the level of psychomotor retardation. However, the CPT performance in the patient group was significantly related to subjective mood state (depression, tension). Double-blind treatment with imipramine or fluvoxamine resulted in an improvement of the CPT performance. In the imipramine treatment group the mean reaction time decreased significantly, and after treatment with fluvoxamine a significant decrease of the mean reaction time and the number of omission errors was detected. Both antidepressants induced a significant improvement of clinical state, but we did not find a relationship between the altered CPT performance and the changes on the clinical scales. Future studies should investigate other mechanisms underlying the improved attentional performance after treatment.