Driving is a source of independence for many seniors, so determining when they should hang up the keys requires careful consideration, an expert says.

"Driving retirement is a normal part of aging, and should be carefully considered and discussed openly," said Dr. Ericka Tung, an internist and geriatrician at the Mayo Clinic in Rochester, Minn.

"Primary care providers are uniquely poised to counsel patients about driving safety because they understand their patients' health conditions, capacities, challenges and goals," Tung said in a clinic news release. She is lead author of a paper in the journal Mayo Clinic Proceedingsthat examines the issue.

There's no single test to determine whether an older person should continue driving, but health care providers can look at several areas of physical and mental functioning to assess a senior's driving fitness.

Those areas are vision, including depth perception and visual fields; thinking skills, including changes in memory, attention or language; mobility and physical function, including range of motion and coordination of the neck, upper body and lower body; health conditions that could affect the ability to safely operate a vehicle; and medications that could impair alertness.

Another key factor is input from family members or other care providers, according to Tung and her colleagues.

These people can provide information about the senior's driving performance, ability to do daily basic tasks of living, or their history of falls. All can help determine if the senior needs a driver safety refresher course or should stop driving.

Because driving gives many seniors a sense of independence and control, any decision about hanging up their car keys must be communicated clearly and with compassion, the authors said.

It's critical that seniors stop driving at the appropriate time — not after they've had a crash.

"Open dialogue is encouraged between patients, families and primary care teams to ensure safety on the road," Tung said.