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University of Iowa News Release

Sept. 14, 2004

UI Study: Drivers With Mild Alzheimer's Disease Make More Errors

People with mild Alzheimer's disease make more mistakes on a driving test than older people with no cognitive problems, according to a University of Iowa study published in the Sept. 14 issue of Neurology, the scientific journal of the American Academy of Neurology.

The study involved an on-road driving test with 32 people with mild Alzheimer's disease and 136 people with no neurological disorders. The people with Alzheimer's disease were still driving, although some had reduced their driving due to restrictions imposed by themselves or their families.

The 45-minute test included "on-task" time when the drivers were given verbal instructions to follow a route, as well as time when the drivers were not "on task," or were not asked to remember and follow instructions. The driving test was conducted aboard an instrumented vehicle known as ARGOS (Automobile for Research in Ergonomics and Safety), a mid-sized car with hidden instrumentation and sensors.

The people with Alzheimer's were more likely to make driving errors during the route-following task than those people without Alzheimer's. For example, more than 70 percent of the people with Alzheimer's made at least one wrong turn while following the route, while about 20 percent of those without Alzheimer's made at least one wrong turn. Also, nearly 70 percent of those with Alzheimer's made two or more safety errors, such as erratic steering or going onto the shoulder, while following the route, compared to about 20 percent of those without Alzheimer's.

Performing the task accentuated the safety gap between the two groups compared to when drivers were not asked to follow specific instructions.

"There was no difference in the basic control of the vehicle for the people with Alzheimer's," said study author Matthew Rizzo, M.D., professor of neurology in the UI Roy J. and Lucille A. Carver College of Medicine. "This leads us to believe that the mental demands of following verbal instructions and navigating a new route can compete with drivers' cognitive resources and potentially impair their driving abilities."

People with Alzheimer's who were familiar with the area of town where the test was conducted did not get lost during the test, although those with Alzheimer's who were unfamiliar with the area were likely to get lost during the test.

"Drivers with early Alzheimer's may have trouble learning new routes but continue to navigate accurately on familiar routes," Rizzo said. "This suggests that drivers' license policies could be considered that would allow driving only in familiar neighborhoods for people with mild dementia."

Rizzo also noted that some of the people with Alzheimer's did not make any errors or get lost and drove safely. "This suggests that some people with mild Alzheimer's remain fit drivers and should be allowed to continue to drive," he said.

The study concluded that the driving ability of people with mild cognitive impairment should be assessed with driving tests that include tasks that check their memory and attention skills.

Contributors to the study included Ergun Uc, M.D. UI assistant professor of neurology; Steven Anderson, Ph.D., UI associate professor of neurology; Jeffrey Dawson, Sc.D., associate professor of biostatistics in the UI College of Public Health; and Qian Shi, a research assistant in neurology and a doctoral student in biostastics.

The study was supported by grants from the National Institute on Aging.

University of Iowa Health Care describes the partnership between the UI Roy J. and Lucille A. Carver College of Medicine and UI Hospitals and Clinics and the patient care, medical education and research programs and services they provide. Visit UI Health Care online at

NOTE TO EDITORS: This news release was adapted from a release issued by the American Academy of Neurology

STORY SOURCE: University of Iowa Health Science Relations, 5139 Westlawn, Iowa City, Iowa 52242-1178

MEDIA CONTACT: David Pedersen, (319) 335-8032,