Antidepressants and driving ability:: Results from a clinical study

Objective: Psychomotor disturbances can frequently be found in depressed patients and may have an important influence on the ability to drive. Additionally, effects of sedation, as seen with some antidepressants, probably impair driving performance. The present study was designed to evaluate the effects of antidepressant monotherapy on psychomotor functions related to cardriving skills in depressive patients in a routine clinical setting. Method: Inpatients (N = 100) who met the ICD-10 and DSM-IV criteria for major depressive disorder were tested under steady-state plasma level conditions prior to being discharged to outpatient treatment. The study ran from January 2004 through March 2005. All patients participated voluntarily and gave informed consent. According to the German guidelines for road and traffic safety, data were collected with the computerized Act & React Testsystem ART-90 and the Wiener Testsystem, measuring visual perception, reaction time, selective attention, vigilance, and stress tolerance. Psychopathologic symptoms were rated with the Hamilton Rating Scale for Depression. Results: Before discharge to outpatient treatment, 24% of the patients tested were without clinically relevant psychomotor disturbances. In 60% of the cases, mild to moderate impairments could be seen, and about 16% of the patients were considered as severely impaired in psychomotor functions related to car-driving abilities. Data show that patients treated with selective serotonin reuptake inhibitors (SSRIs) or the noradrenergic and specific serotonergic antidepressant (NaSSA) mirtazapine had an altogether better test performance in comparison with patients receiving tricyclic antidepressants (TCAs). Differences were most pronounced in measures of reactivity, stress tolerance, and selective attention. Statistically significant differences between patients treated with TCAs or the serotonin-norepinephrine reuptake inhibitor (SNRI) venlafaxine could not be found. Among the newer antidepressants there is an advantage for patients treated with mirtazapine, especially in tasks with high multi-channel perception and output demands. Conclusion: About 16% of depressive patients discharged from hospital to outpatient treatment must be considered unfit to drive. In 60% of the cases, patients performed at a questionable level of fitness for driving, and it seems justified to counsel patients individually, taking into account compensational factors. Data point to an advantage for patients treated with SSRIs or mirtazapine when compared with TCAs or venlafaxine. However, causal relationships cannot be drawn from our data.