April 13, 2010, 12:50 pm
Driving While Demented
By PAULA SPAN
You might hope that when the American Academy of Neurology reviews and updates its decade-old guidelines on driving and dementia, the experts would come up with clear-cut recommendations: a specific score on a specific test means someone can head for the mall without much concern, or a particular behavior means it’s too risky to be on the road, so hand over the keys.
You might hope that, but on Monday, when an academy subcommittee presented its report at an annual meeting in Toronto, its findings demonstrated once more how complicated this question can be.
The report (here’s a news release that summarizes it) was systematic and thorough, analyzing 422 good-quality studies in an attempt to figure out how neurologists should handle this issue with their patients. And the findings tells us a lot about what experts still can’t (or won’t) say with authority.
Take the question of whether people with mild dementia — not just older drivers in general — should be behind the wheel at all. “Clinicians may present patients and their caregivers with the data showing that, as a group, patients with mild dementia . . . are at a substantially higher risk for unsafe driving, and thus should strongly consider discontinuing driving,” the report suggested.
Yet it also noted that several studies had shown that a considerable number of those with mild dementia — 41 percent to 76 percent, depending on the study — could pass an on-road driving test. Given that, in many parts of the country, not being able to drive can lead to isolation and a host of other real problems, should those people have to give up their cars?
“We don’t have a blood-alcohol level for dementia,” Dr. Gary Kennedy, director of geriatric psychiatry at Montefiore Medical Center in New York, said in an interview. “We don’t have that kind of standard.” But just as drivers who drink show some impairment, dementia accelerates the risks older drivers face from declining vision, hearing and reaction time, he pointed out.
In fact, the American Association for Geriatric Psychiatry, of which Dr. Kennedy is a past president, uses a stricter standard: “Our recommendation is that you stop driving once you have a dementia diagnosis.”
Less formally, he relies on “the grandchild rule”: If a patient’s children don’t want the grandchildren in the car when the patient is driving, he or she needs to relinquish the keys before hurting someone else’s grandchildren.
What the academy’s report does provide is a relative ranking of which factors most accurately identify an increased risk of unsafe driving. They include a higher rating on a test called the Clinical Dementia Rating, a history of crashes and traffic tickets in the past few years, and “aggressive or impulsive personality characteristics.” (Personally, I’d like those people off the highways even if they don’t have dementia, but being a hothead is not illegal.)
One of the more accurate predictors of trouble, the report emphasizes, is a caregiver’s assessment. If you report that your parent or other relative with dementia is driving unsafely, you’re likely to be correct. So stick to your guns.
“If I had written the report, I would emphasize to family members that you’re the best judge of when the risk is unacceptable, and you can ask the doctor to use his or her authority to say so,” Dr. Kennedy said. “We’re the ones who should take the heat.” He has written letters to patients telling them to stop driving when his advice during office visits proved ineffective; he also keeps the online forms handy to send to the state division of motor vehicles if a letter doesn’t work.
That’s because one of the decidedly unreliable factors, the report found, is a demented driver’s own judgment of his ability. It cited a study of patients with mild Alzheimer’s, 94 percent of whom rated themselves as safe drivers. Only 41 percent could pass a road test, however.
“A patient’s self-rating . . . is established as not useful for determining that the patient is safe to drive,” the report concluded. But you probably already knew that.