Driving is a daily activity for most people in developed countries and is important in maintaining independence. Bipolar patients may have an impaired driving behavior because of the pathology itself, with psychomotor and cognitive disturbances. Additionally, adverse effects of pharmacologic treatment may be detrimental.

24 remitted bipolar outpatients diagnosed according to ICD-10 criteria were enrolled in the study, receiving either lithium (n = 12) or lamotrigine (n = 12). Participants were investigated under steady state plasma level conditions. According to the German Guidelines for road and traffic safety data were collected with the Wiener Testsystem (WTS) measuring visual perception, reactivity, stress tolerance, concentration and vigilance.

Psychopathologic symptoms were rated with the Montgomery-Asberg Depression Rating Scale (MADRS) and the Young Mania Rating Scale - Clinician rated (YMRS-C).

About 40% of patients were without clinically relevant psychomotor disturbances. In 40% of cases mild to moderate impairments could be seen, and 20% of the patients were considered as severely impaired. Data show that patients under lamotrigine had an altogether better test performance than patients treated with lithium. Especially in visual perception and stress tolerance differences were most pronounced.

About 20% of remitted bipolar outpatients treated with lithium or lamotrigine must be considered unfit to drive. In 40% of the cases it seems justified to counsel patients individually, taking into account compensational factors. Analysis of our data point to an advantage for bipolar patients treated with lamotrigine when compared with lithium. However causal relationships can not be drawn from our data.