According to the Société de l’assurance automobile du Québec, drivers aged 75 years and over are responsible for only 4% of accidents causing injury. This is relatively low compared to drivers aged 16 to 24 years, who cause 25% of this kind of accident. But when you look at it closer, the number of accidents is proportionally much higher for older drivers if you take into account the number of kilometres they drive each year. They cause from 1.6 to 2.4 times more accidents than drivers aged 25 to 64 years. And these are generally accidents involving more than one car. By comparison, young people have more accidents in high-speed zones, but their collisions usually involve only one car.

The most frequent mistakes among elderly drivers are failing to yield right of way and difficulties turning left at a corner,” notes Geneviève Daigneault, whose doctoral thesis in psychology, submitted recently at Université de Montréal, focussed on the elderly and driving. “To compensate for their impairments, the elderly often show excessive caution, and this causes them to reduce their speed. But their caution does not offset their slower reflexes or their difficulty in adapting to unforeseen situations.”

The neuropsychologist presents the conclusions of her work in two articles that appeared in the magazine Accident analysis and prevention and the Journal of Clinical and Experimental Neuropsychology in 2002. In the first article, she analyzes the relationship between previous infractions and accidents and potential risk of causing further accidents. In the second article, she presents the results of a study of 60 subjects, that compared cognitive function (measured with neuropsychological tests) with number of accidents and driving habits. Her study, directed by Jean-Yves Frigon, a Professor in the Department of Psychology, in conjunction with Pierre Joly, a researcher in the Transportation Research Centre, suggests that a subgroup of elderly drivers (drivers involved in three or more accidents in the previous 12 months) exhibit problems of judgment that cannot be compensated by safer attitudes on the highway.

In Québec, renewal of a driver’s licence for persons aged 75 and over is conditional upon passing an eye test and medical examination. But the doctor is not always able to diagnose impairment of executive function, i.e., mental faculties key to monitoring movements and making quick decisions. Severe impairment of these faculties is the cause of many accidents among the elderly.

For Geneviève Daigneault, it is a big concern. “We basically only test visual aptitudes, whereas driving a car is a complex task that requires both motor and cognitive abilities,” she says.

Researcher: Geneviève Daigneault
Telephone: (450) 771-3333, extension 4363
Funding: Société de l’assurance automobile du Québec