Parkinson Disease Can Lead to Errors on Driving Test

People with Parkinson disease were more likely to make more safety mistakes during a driving test than people with no neurological disorders, according to a study published in the November 28, 2006, issue of Neurology, the scientific journal of the American Academy of Neurology.

The study involved an on-road driving test of 71 people with mild to moderate Parkinson disease who were current drivers and 147 people of similar age with no neurological disorders. While driving, the participants were given a verbal addition task that simulates the amount of distraction similar to having a conversation with a passenger or using a cell phone while driving.

While distracted, 28 percent of those with Parkinson disease made more driving safety mistakes than they did when they were not distracted, compared to 16 percent of those who did not have Parkinson disease. Those with Parkinson who made more safety mistakes and had poorer ability to control their speed and steering due to effects of distraction also did worse on tests of memory, vision and balance and the ability to switch attention between competing tasks, and were more likely to have excessive daytime sleepiness.

"The abilities of the people with Parkinson disease varied greatly, which in some ways is not surprising because this disease affects people very differently," said neurologist and principal investigator Ergun Uc, MD, of the University of Iowa and the Veterans Affairs Medical Center in Iowa City. "Clearly, Parkinson disease can affect the ability to drive, and that effect grows as the disease progresses. People with Parkinson disease should be aware of this potential decline in driving ability and their family and friends should also monitor it and then recheck periodically."

Uc noted that the well-known motor problems caused by the disease - tremors and difficulty with movement - had less effect on driving ability than lesser known aspects of the disease such as effects on mental functioning, vision and sleep.

Matthew Rizzo, MD (co-principal investigator), Steven W. Anderson, PhD, JonDavid Sparks, MS, Robert Rodnitzky, MD, and Jeffrey D. Dawson, ScD, also of the University of Iowa, strongly contributed to this study. The study was supported by the National Institute of Neurological Disorders and Stroke, the National Institute on Aging, and the University of Iowa-Carver College of Medicine New Investigator Research Award. The study is part of a longitudinal project using road tests, driving simulation and state crash records with the goal of developing a reliable and efficient method of predicting safety risk in drivers with Parkinson disease.

The American Academy of Neurology, an association of more than 19,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer's disease, epilepsy, Parkinson disease, and multiple sclerosis.