-- Doris Clay is 89 years-old and has early Alzheimer's disease. She's driven herself through the streets of Hyde Park, N.Y. for most of her life, but for how much longer?
"I think we all have some misgivings about her driving," said Joann Wohlfahrt, Clay's stepdaughter. "But she said 'this is my last bit of independence; please don't take it away from me.'"
There are now more than 20 million drivers in the U.S. who are 70 years-of age or older. And according to American Automobile Association, the older these drivers are, the greater the risk of an accident. For every mile driven, collision rates for seniors 70 years-old and up is second only to teenagers.
So increasingly, families are turning to the "driving rehabilitation specialist" -- an occupational therapist, specifically trained to work with elderly drivers. The program gives drivers like Clay extensive testing on depth perception, peripheral vision, color vision, sign recognition and reaction time.
"I help them see their own strengths and weaknesses," said Mary Beth Meyer, a certified driving rehab specialist in Poughkeepsie, New York, one of about 300 nationwide. "My goal is to keep them on the road, if they're capable."
Meyer figures she can help about 30 percent of the senior drivers she sees. She says the biggest problem for families is identifying which drivers need help.
Warnings signs include: driving too slowly; failure to observe signs and signals; failure to yield; easily frustrated or confused and difficulty interpreting traffic situations.
Sometimes the solution is as simple as improving a senior's visibility in the car by adding wide-angle mirrors or cushions to position the driver more upright.
For 82 year-old Bill Emrich, it involved a refresher course on left-hand turns and full stops at intersections.
"I think it made a big difference," Emrich told ABC News. "I think I pay more attention to where I'm driving the car. She told me where to stop, how to turn, how to look before I turn."
As for Clay, it turned out, her failing memory was too much to overcome. But perhaps the greatest benefit of the program is that when it comes time to take away the car keys from an elderly driver, it's the driving rehab specialist who does it.
"I was the bad guy in this situation. The objective third party," Meyer told ABC News. "I think it helps the family tremendously because they don't have to be the ones to say 'Doris, you can't drive anymore.' The test, being objective, is something she can't argue with."
"It's better for the family. It's better for Doris and it's better for people who are on the roads," said Wohlfahrt.
Better and safer now that Clay is now driven as a passenger -- and not driving behind the wheel.