There may be some truth behind all those jokes about grandma behind the wheel. Even healthy adults with a safe driving record tend to make more driving errors as they age, such as failing to check blind spots, according to a new study published by the American Psychological Association.
Most studies of older drivers have focused on people with dementia or other conditions that might impair their performance behind the wheel. This latest study was comprised of 266 volunteers ages 70 to 88 who showed no signs of dementia, lived independently and drove at least once a week.
Normal aging causes distinct declines in brain functioning that could hinder driving skills, including the ability to focus despite distractions on the road, make quick decisions and avoid other vehicles or pedestrians, the study found.
"All types of driving errors increased with age, and the errors weren't restricted to a small group of unsafe drivers or those with a history of crashes," said lead researcher Kaarin J. Anstey, Ph.D., a psychologist who directs the Aging Research Unit at Australian National University. "It is important to note that there is a large variation in cognitive ability, so some people still have a high level of functioning in later life even if they have suffered some cognitive declines related to normal aging."
Study participants completed a battery of cognitive tests and questionnaires about their driving history before they drove on a 12-mile route through city and suburban streets. A professional driving instructor rode in the car, which was equipped with an extra brake on the front passenger side for safety. An occupational therapist sat in the back seat and scored the drivers on various errors, including failure to check blind spots, speeding, sudden braking without cause, veering and tailgating.
Although men tend to think they are better drivers, they didn't fare any better on the tests than women. Blind spot errors were the most common mistake, followed by veering across lanes and failure to use turn signals. During the tests, 17 percent of the drivers made critical and potentially hazardous mistakes that required the driving instructor to hit the brake or grab the steering wheel.
The rate of critical errors during the driving test quadrupled from the youngest group, age 70 to 74, which had an average of less than one critical error, to the oldest group, age 85 to 89, with an average of almost four critical errors. There were no crashes during the tests, but participants who had reported an accident during the five years before the study also had a higher rate of critical errors.
The participants had their vision checked before the driving test, but Anstey said more research is needed to determine whether visual ability contributed to the high rate of blind spot errors.
There's no need to take the wheel away from grandma just yet, however. With training on checking blind spots and other driving skills, older drivers usually can remain safe on the roads longer.