Trouble with balance, weak lower limbs and poor neck flexibility were among the attributes Australian researchers linked to a higher risk of less-safe driving in The Journals of Gerontology: Series A.
"Although there has been a lot of research on the cognitive and visual predictors of driving performance and safety, very little work has so far looked at physical function and its relation to driving," said Philippe Lacherez, a post-doctoral fellow at Queensland University of Technology who led the study.
Lacherez and his colleagues gave 270 people between the ages of 70 and 88 a battery of physical tests to gauge their strength, flexibility, balance, reaction times and sensory perception. Next, the participants' driving performance was evaluated for safety.
About 17 percent of the participants made critical errors while driving in a test that was scored by a professional driving instructor and involved a range of traffic densities and complex or simple intersections.
In the physical abilities tests, the unsafe drivers tended to have a decreased ability to move the neck, slower reaction times, poor perception of vibration and lack of strength in the legs and feet. Factors that were not linked with driving safety included the ability to sense where the body or limbs are in space.
The results are preliminary but may open a new avenue to ways of ensuring that older drivers are safe to be on the road, researchers said.
"The study addresses an issue that is a big concern," said Sharon Brangman, chief of geriatrics at Upstate Medical University in Syracuse, New York. She was not involved in the study.
"We have so many (older) patients who are driving, and we don't have objective ways to determine who should stay on the road," Brangman said.
Some U.S. states, such as New Jersey, already have review programs in place that evaluate older adults and determine whether they should continue to drive. However, there is no standardized, nationwide approach used to evaluate driving safety.
"It would be good to have an objective way for physicians or others to quantify whether someone really is safe behind the wheel," said Brangman, who also noted the need for a change in national policy to better screen and guide older drivers.
As always, older patients and their families should talk to their doctors if they feel they or a loved one may be an unsafe driver. This study can serve as a way to initiate that discussion, Brangman told Reuters Health.
"It's a good way to start the conversation," she said. And in the future, results of studies such as this one "may provide some hard evidence that can be given to the patient or family that could justify stopping driving."