Mild Alzheimer's Patients Can Drive Safely

From the WebMD Archives

Jan. 4, 2000 (Washington) -- A controversial new study shows that elderly patients with a mild form of Alzheimer's disease are just as safe on the road as their unimpaired counterparts, at least by one crucial measure. The study compared the crash rates of 63 patients suffering from dementia of the Alzheimer's type (DAT) with those of 58 healthy drivers, looking back at state driving records over a five-year period.

"We found no difference in crash rates between drivers with DAT and controls," write David Carr, MD, and his colleagues from the division of geriatrics and gerontology at Washington University in St. Louis, in an article appearing in the January issue of the Journal of the American Geriatrics Society.

The surprising research comes in the wake of other findings that document a doubling in the rate of DAT every five years in those older than 65 and a tendency for patients with DAT to drive dangerously. "We know that some of these people are safe drivers, at least at this stage," study co-author John Morris, MD, tells WebMD. Morris, director of the memory and aging project at Washington University, emphasizes that these patients are at the very earliest stage of DAT, and their symptoms may be barely detectable.

"We want to allow people to maintain their driving independence as long as they're safe but have them stop just before they demonstrate that they are unsafe," says Morris. For example, he says that mildly impaired patients should be evaluated every six months to see if their driving skills have deteriorated. One predictor might be the ability to execute a left-turn safely. According to Morris, a loss of driving privilege can lead to isolation and a quicker decline in these patients.

In fact, while there were relatively few crashes in the study overall, the accident rate was slightly higher (0.07 per year) for the non-demented group than for those with DAT (0.06 per year for patients with the mild form and 0.04 per year for patients with very mild disease). Even though the results are not statistically significant and those with mild DAT didn't drive as much as the others in the study, the researchers say the data show a trend.

"[T]his finding is further evidence not to suspend driving privileges based on diagnosis alone," write the authors. Contrary to the views of some experts, the study indicates that having mild or very mild Alzheimer's disease doesn't predict a decline in driving ability, at least for the first couple of years.

The patients were from the Alzheimer's Disease Research Center. Participants of this registry are enrolled in studies of healthy aging and dementia and return each year for an evaluation.

In order to enroll in the study, patients had to take a driving test, and the severity of their disease was determined by a clinical evaluation consisting of a 90-minute interview and physical and neurological exams by experienced clinicians. However, Dan Foley, MS, an epidemiologist at the National Institute on Aging, says that the study is flawed because the researchers picked only those individuals who were most likely to have good driving records.

"I don't think this population is representative of all drivers with dementia. I think it was a rather robust group who was conscious of the fact that they were driving with dementia and probably would need to quit," Foley tells WebMD. Foley agrees that it's possible to drive safely with Alzheimer's disease, but not for long.

"For me, a patient with Alzheimer's disease is an accident on the way to happen. Well, how do you prevent that ...? You have the person stop driving," says Foley. Morris acknowledges that those in the study may represent a pro-driving bias, but he says more research needs to be done to see how the positive finding applies to a larger population of Alzheimer's patients.

The study does show that those with DAT tended to more often be involved in crashes where they were at fault or where injuries were involved. "What particular cognitive abilities need to be affected, how severely, and whether drivers with dementia are more likely to be involved in at-fault or injurious crashes ... remain to be determined," writes accompanying editorial author Richard Marottoli, MD, of the VA Connecticut Healthcare System.

Vital Information:

  • The rate of dementia of the Alzheimer's type doubles every five years in the population over age 65.
  • A new study shows that patients with this mild form of Alzheimer's disease can drive just as safely as their healthy counterparts.
  • Critics say the study is flawed because individuals likely to have the best driving records were selected for the study.