May 17, 2011

Older Adults More Likely To Make Driving Errors

As adults age, they tend to make more and more errors while driving, potentially dangerous mistakes, even if they are otherwise healthy adults with lifelong safe driving records, according to a recent Australian study.

While most studies of older drivers focus on people with dementia or other conditions that may impair driving, this study, published by the American Psychological Association, comprised 266 volunteers between the ages of 70 and 88 who showed no signs of dementia, lived independently and drove at least once per week.

Licensers and driving testers could significantly alter their training for older drivers based on the findings of this new study. The findings could also have implications for future design of roads, signs and even vehicles, the researchers said.

"We wanted to develop evidence-based measures for detecting unsafe older drivers and show how specific cognitive abilities relate to different types of driving errors," said lead researcher Kaarin J. Anstey, PhD, a psychologist who directs the Aging Research Unit at Australian National University.

Even normal aging causes various declines in brain functions and those unique changes could affect older persons' skills behind the wheel, including the ability to focus despite distractions on the road, make quick reflex decisions and avoid other vehicles or pedestrians, the study found.

Participants in the study completed a variety of cognitive tests and surveys about their driving history before they drove on a 12-mile route through city streets in Brisbane, Queensland. A driving instructor rode in the car, which was also equipped with an extra brake on the passenger side for safety precaution. An occupational therapist rode in the backseat and scored the drivers on various errors.

Among the top errors recorded were failure to check blind spots, speeding, sudden braking without reason, veering in to the opposite lanes and tailgating.

"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 Anstey. "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."

Although men usually think they are better drivers than women, the researchers found that men didn't fare any better on the tests performed than women did. Blind spot errors were the most common mistake in the tests.

During the tests, 17 percent of drivers made critical errors that were potentially hazardous. In those instances, the driving instructor was required to hit the brake or grab the steering wheel.

The rate of critical errors during the tests rose four-fold from the youngest group (age 70 to 74) to the oldest group (age 85 to 89). The youngest group had an average of less than one critical error, compared to an average of almost 4 critical errors in the oldest group.

While there were no accidents during the testing, those who reported they had an accident during the five years before the study also had a higher rate of critical errors.

Anstey said that older drivers could remain safe on the roads longer with proper training as they age. The participants had their vision checked before the driving test, but Anstey said more research is needed to determine if visual ability contributes to the high rate of blind spot errors.

Despite the results of the study, Anstey doesn't believe that driver's licenses should be restricted based on age alone. "In other research, we have shown that age-based restrictions reduce overall driving rates among older adults, but they don't reduce the rate of driving by those with cognitive impairments," she said.

"We need evidence-based driver screening tests along with training for older drivers and alternative transportation for those who can no longer drive safely," Anstey concluded.

Joanne Wood, PhD, a professor of optometry at Queensland University of Technology, co-authored the study, which is published in the APA journal, Neuropsychology.


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