Differential effects of reboxetine and citalopram on hand-motor function in patients suffering from major depression.

Abstract

Motor dysfunctions might be a more common side effect of serotonergic than noradrenergic antidepressants. However, the effects of antidepressants on motor function in depression have rarely been analyzed systematically. Computerized methods allow the objective registration of drug-induced motor dysfunction and were applied in this study. To examine the effects of a selective noradrenaline re-uptake inhibitor (NARI) (reboxetine) and a selective serotonin re-uptake inhibitor (SSRI) (citalopram) on hand-motor function in patients with major depression. Different types of hand movements (drawing of circles and handwriting probes) were recorded and analyzed in 16 acutely depressed inpatients receiving citalopram (30-60 mg/day) and 12 acutely depressed inpatients treated with reboxetine (4-8 mg/day), using a digitizing tablet for the analysis of movement dynamics. Both groups were comparable regarding mean age (42-43 years), gender, handedness (preponderance of right-handers) and the mean baseline HAMD score (about 27). Five kinematical parameters reflecting velocity, regularity and degree of automation of hand movements have been computed. Reboxetine had significantly more favorable effects on fine motor function (increased velocity of rapid hand movements) in depressed patients than citalopram. These differences became obvious when patients conducted more complex tasks and are not explained by differential antidepressant effects. Our findings are in line with the hypothesis that SSRI tend to have small, but more pronounced negative effects on motor function than NARI.