BACKGROUND—Driving is a complex form of activity involving especially cognitive and psychomotor functions. These functions may be impaired by Parkinson's disease. The relation between Parkinson's disease and driving ability is still obscure and clinicians have to make decisions concerning the driving ability of their patients based on insufficent information. Until now no studies have compared different methods for evaluating the driving ability of patients with Parkinson's disease. METHODS—The driving ability of 20 patients with idiopathic Parkinson's disease and 20 age and sex matched healthy control subjects was evaluated by a neurologist, psychologist, vocational rehabilitation counsellor, and driving instructor using a standard 10 point scale. The patients and controls also evaluated their own driving ability. Cognitive and psychomotor laboratory tests and a structured on road driving test were used for evaluating the subjects' driving ability. RESULTS—The patients with Parkinson's disease performed worse than the controls both in the laboratory tests and in the driving test. There was a high correlation between the laboratorytests and driving test both in the patient group and in the controlgroup. Disease indices were not associated with the driving test. The neurologist overestimated the ability of patients with Parkinson's disease to drive compared with the driving ability evaluated by thestructured on road driving test and with the driving related laboratorytests. Patients themselves were not capable of evaluating their ownability reliably. CONCLUSION—Driving ability is greatly decreased inpatients with even mild to moderate Parkinson's disease. Theevaluation of patients' driving ability is very difficult to carry outwithout psychological and psychomotor tests and/or a driving test.
