People with early Alzheimer's disease were involved in more traffic crashes and performed worse on road tests than drivers without cognitive impairment, a new study finds.

The study included 84 people with early Alzheimer's and a control group of 44 age-matched people without cognitive impairment. Over two to three years, the participants' driving abilities were assessed through self-reports, family reports and a standardized road test.

People with Alzheimer's disease were involved in more crashes and had worse results on road tests than those in the control group. The study also found that people with mild dementia were much more likely to fail a road test than those with very mild dementia.

The study showed that people with mild dementia were almost four times more likely to fail a road test than those with very mild dementia, indicating that people with very mild dementia may be able to drive safely for longer periods of time.  The investigators also found that driving ability decline rapidly among patients with dementia, and therefore, they suggest regular follow-up assessments for people with very mild dementia. The American Academy of Neurology Guideline on Risk of Driving and Alzheimer's Disease recommend that people with very mild dementia who continue to drive should be re-assessed every six months.

The study also found that driving abilities could be affected by age as well as education levels. For each year after age 75, the odds of failing a road test increased by about 6 percent. And the risk of failing a road test increased 10 percent for each year a person lagged behind the average 14 years of education. Overall, the study results suggest that a regular driving assessment program may actually reduce the frequency of motor vehicle accidents in drivers with mild dementia by increasing awareness among drivers and caregivers.

The findings were published in the Jan. 23 issue of the journal Neurology.

-- Jeff Behar

SOURCE: Rhode Island Hospital, news release, Jan. 23, 2008