Predicting Driving Problems in Patients with Mild Dementia

Toronto, ON - Psychiatry researchers have for the first time provided findings that could help doctors identify patients whose driving ability will likely be impaired by dementia in the early stages.

“There is little information available on dementia and it’s association with driving cessation,” says Dr. Nathan Herrmann, principal investigator of the study and geriatric psychiatrist at Sunnybrook Health Sciences Centre. “Guidelines for primary care doctors are not specific enough, they need more guidance in determining when it is necessary for a patient to stop driving. Our research can help doctors predict which patients may be at risk in order to help them begin planning for alternatives to driving.”

It is well known that there is an association between the risk of being involved in a motor-vehicle collision and the severity and duration of one’s dementia. The study’s purpose therefore was to explore factors affecting the likelihood of driving cessation in a group of elderly people in the community with dementia.

The research found that increased mental and physical impairment and the presence of a greater number of behavioural disturbances all increased the likelihood of driving cessation over the years of the disease progression.

Apathy and hallucinations were significant predictors of driving cessation in patients with mild to moderate degree of dementia, which the authors believe may be because it led drivers to quit on their own or these behaviours may have alerted physicians and families to the severity of the disease and the need for the patient to quit driving. The presence of agitation or aggression on the other hand, showed an association with patients who continued to drive possibly because families and physicians might be more uncomfortable confronting such people with the need to stop driving.

The study also questions the various types of assessments that can be used including neurological, geriatric medical, or psychiatric assessments. “This study does not provide information on how to assess the safety risk, or which method of testing is best to predict collision risk, but the fact that cognitive impairment and behavioural disturbances - both easily measurable in the clinician’s office - are strong predictors of driving cessation suggests that measures already in use by doctors to monitor patients may also serve to warn of increases in the risks of driving as patients’ abilities decline”, says Dr. Herrmann, also a Professor in the Department of Psychiatry at the University of Toronto, and Head of the Division of Geriatric Psychiatry at Sunnybrook.

Patients at centres across Canada were studied over a three-year period. The study is published in the September 12, 2006 issue of the Canadian Medical Association Journal.

In 1992, approximately 316,500 Canadians over age 65 had dementia, with the risk of the disease doubling for every 5 years of age after 65. It is estimated that 500,000 Canadians will have dementia by 2021, and 750,000 by 2031.