Psychologists who treat patients with Alzheimer's disease must often respond to patient and family requests to gauge those patients' fitness to drive. Now, a meta-analysis in the January issue of APA's Neuropsychology (Vol. 18, No. 1) suggests that clinicians can use some cognitive tests--particularly tests of visuospatial skills--to help separate the safe drivers from the unsafe.
For the most part, clinicians advise patients with moderate or severe dementia not to drive. But assessing the driving abilities of patients in the early stages of Alzheimer's disease--who have only mild dementia--is more difficult, says lead researcher Mark Reger, PhD, of the University of Washington School of Medicine and the VA Puget Sound Health Care System.
Standard driving tests given by U.S. states are helpful, but they can't entirely answer questions of driving ability, says Reger. For example, state driving tests don't control for significant variables like lighting, weather conditions and specific driving situations, and they typically catch the types of mistakes made by inexperienced drivers, not experienced drivers with dementia. Moreover, many experts have worried about a lack of definitive evidence that cognitive testing--which is used by clinicians to try to fill the gap--can gauge driving fitness.
To address this concern, Reger and his colleagues reviewed 27 studies involving 132 cognitive tests linked to driving ability, as measured by on-road tests, paper tests, driving simulators and caregiver reports.
They divided the tests into six categories: general cognition, attention and concentration, visuospatial skills, memory, executive functions, and language.
Overall, they found a significant correlation between the cognitive indicators and driving skill. Visuospatial skills--like those that would be used to accurately position and maneuver a car or judge distances--had the highest correlation. Attention and concentration, executive functions, general cognition, and memory were also significantly related to driving skill.
"What this means for patients and families," says Reger, "is that neuropsychological evaluations are one more resource for them [besides driver interviews and road tests] if this is a concern of theirs."