Patients With Mild Alzheimer's May Still Drive Safely

NEW YORK -- Patients with mild forms of Alzheimer's disease can usually still drive safely, with crash rates similar to other older drivers, results of a small study suggest.

"Although road test studies have shown a clear decline in average driving ability with increasing severity of dementia," note researchers at Washington University in St. Louis, Mo., "some drivers are still judged to be safe who are in the very mild or mild stages of the disease."

The researchers, led by Dr. David B. Carr, looked at the state motor vehicle accident records of 34 patients with very mild dementia of the Alzheimer's type, 29 with mild Alzheimer's disease, and 58 without dementia. Participants had an average age of 77, and had been driving for at least 10 years.

All participants kept a driving journal for a week, completed a questionnaire about their driving history, and took a road test as part of the study. For each participant, another adult who knew him or her well also filled out a questionnaire.

The researchers found that patients with mild Alzheimer's disease drove less than the other two groups. Overall, crash rates were low for all three groups, with 80 percent driving accident-free for 5 years. Writing in the January issue of the Journal of the American Geriatrics Society, Carr and his team note that most studies of demented drivers report more car crashes among this group. They add that they would have needed at least 300 participants in their study to identify differences among the groups, given the overall low number of crashes these participants had.

On the other hand, the authors write that participants with dementia were slightly more likely to have crashes in which they were at fault, and more that were due to inattention or failure to yield. Carr's group calls for more research with larger numbers of participants, especially looking for ways to assess driving competence.

In an editorial in the same issue, Dr. Richard A. Marottoli of the VA Connecticut Healthcare System in West Haven, notes that clearer guidelines need to be developed for physician reporting of patients whose dementia may impair their driving. Marottoli concludes that we need a system that can "determine which individuals are truly at increased risk" for causing traffic accidents.