Somewhere down the road, most of us will start to forget where we left our keys. We'll miss appointments here and there and struggle to find the words on the tip of our tongues. While this type of memory loss is part of normal aging, other cognitive changes – such as forgetting how to do routine tasks – may interfere with the ability to drive safely. The question is, how can licensing bureaus identify medically unfit drivers without discriminating based on age?
The "clock-drawing test" is proving to be a useful initial screening tool, said Brenda Vrkljan, associate professor of occupational therapy at McMaster University in Hamilton. This standard test is normally part of a battery of tests used to measure cognitive impairment in patients with signs of dementia. But studies have shown a link between difficulties in drawing a simple clock and one's ability to drive.
Evidence supporting the use of this test to detect potential driving problems is "moderate to strong," Vrkljan said. "If someone can't draw a clock, then I would want to do further testing."
Ontario adopted the clock-drawing test in 2014 as part of its mandatory education program for drivers of ages 80 and up. (The province is the only jurisdiction in the world to implement such a program for older drivers.) People taking the test are asked to draw the numbers and arms of a clock as they would appear at a certain time of day, such as 2:15 p.m.
Drawing a clock requires a higher level of brain function, researchers have found. The test can identify problems with visual perception, planning ability and short-term memory, Vrkljan said.
But if an Ontario driver cannot draw an adequate clock, a licence is not automatically taken away. Rather, a poor performance on the test signals the need for a closer look at the driver's physical and cognitive health, Vrkljan said. Many factors may result in a low test score, including infections, poor nutrition and depression. When an older adult shows cognitive difficulties, "automatically we go to Alzheimer's," she said, "but there could be other things happening."
Family members should not ask an older driver to draw a clock at home, she added. The person administering the test should be a health-care professional or trained personnel at a licensing bureau, she said. Performance on the test is based on nuances such as the order, spacing and placement of the numbers and clock hands. "There is a standardized approach to how you score it."
Moreover, cognitive changes do not necessarily mean a person shouldn't drive. Based on scientific evidence, "We know that people, even in the early stages of mild cognitive impairment, can still drive because it's so ingrained in terms of their abilities," Vrkljan said. "The key is for them to be tracked and followed, with regular check-ins with health-care professionals."
Vrkljan is the lead investigator in the McMaster-Candrive team conducting a long-term study of older drivers. Over the past five years, the national Candrive study has tracked the driving habits of 900 Canadians of ages 70 and up.
Adults of ages 65 and up are the fastest-growing cohort of drivers in Canada. Other than adolescents, those over the age of 70 have the highest car-collision rates when distance driving is considered, Vrkljan wrote in a post for McMaster University's Optimal Aging Portal.
But not all seniors are prone to car crashes, she pointed out. While driving safety is of chief concern, older adults with a car and driver's licence are more likely to participate in social activities linked to improved quality of life, she said. "Ideally, what we're trying to do as a society is help people stay mobile and healthy."