WASHINGTON (November 17, 2009)--The Alzheimer's Association is adapting technology developed for monitoring prisoners to let caregivers track where their loved ones drive or walk and to alert them if they go beyond the virtual fences that each family can set.

The association's new Comfort Zone program uses a Web-based mapping service that works with multiple brands of tracking transmitters.

More than 5 million Americans are estimated to be living with Alzheimer's, as many as half in the disease's early stages.

Increasingly early diagnosis means many patients still have years of independent living ahead of them before they have to give up the car, and eventually give up going out alone at all.

At some point, nearly 60 percent of Alzheimer's patients will begin what's called wandering, requiring more intense supervision to keep them safe.