Decreased driving ability in people with Parkinson's disease

BACKGROUND—Driving is a complex form of activityinvolving especially cognitive and psychomotor functions. Thesefunctions may be impaired by Parkinson's disease. The relation betweenParkinson's disease and driving ability is still obscure andclinicians have to make decisions concerning the driving ability oftheir patients based on insufficent information. Until now no studieshave compared different methods for evaluating the driving ability ofpatients with Parkinson's disease.
METHODS—The driving ability of 20 patients withidiopathic Parkinson's disease and 20 age and sex matched healthycontrol subjects was evaluated by a neurologist, psychologist,vocational rehabilitation counsellor, and driving instructor using astandard 10 point scale. The patients and controls also evaluated theirown driving ability. Cognitive and psychomotor laboratory tests and astructured on road driving test were used for evaluating the subjects'driving ability.
RESULTS—The patients with Parkinson's diseaseperformed worse than the controls both in the laboratory tests and inthe 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.