Loretta Wales, left, shaves her husband, Alzheimer's patient Richard Wales, at the Greengables Villa elderly care home in Union City, Calif. Wales moved into the full-time care facility almost a year ago.

WALNUT CREEK, Calif. — Steven Williams, a San Francisco firefighter who lives in Oakland, Calif., had just finished a 24-hour shift when he returned home and told his mother’s caretaker she could take the rest of the day off.

His 88-year-old mother, Katherine Oppenheimer, was diagnosed with Alzheimer’s disease and requires constant supervision. Still, Williams thought he could get away with a 15-minute nap.

He awoke to find that she had wandered out of the home.

“It was one of the scariest experiences I’ve ever had,” he said. “I would rather run into a burning building than go through that again.”

This time, Williams’ harrowing moment ended well. He found his mother quickly, a few floors up in the same apartment building where she lives. But like a growing number of families coping with the devastating effects of Alzheimer’s disease, he fears a repeat episode.

Numbers on the rise

In 1980, about 2.8 million Americans had Alzheimer’s disease — the most common form of dementia. But with longer life expectancies and advanced treatment for other diseases such as cancer, that figure has nearly doubled in 2010, to 5.3 million, according to Elizabeth Edgerly, a chief program officer with the Alzheimer’s Association, a national advocacy group.

In all, 42 percent of people 85 and older will get Alzheimer’s, Edgerly said.

To deal with the increasing numbers, police agencies are training officers how to search for wanderers.

“The ability to recognize dementia has improved over the last 20 years,” said Rick Kovar, emergency services manager for the Contra Costa County Sheriff’s Office. “The science behind searching for people with Alzheimer’s has become efficient and scientific.”

Dementia affects the brain in several ways. People lose short-term memory, the ability to communicate, express emotions and follow a conversation.

They have severe mood shifts, and lose the ability to reason, problem-solve, sense danger and judge visual spacing.

“Wandering is one of the most common behaviors associated with dementia,” Edgerly said.

Sixty percent of people with dementia will wander at least once. Of those, 20 percent wander repeatedly.

“Those are the folks police departments and fire departments know of very well,” Edgerly said.

The Contra Costa County Sheriff’s Office trains its search-and-rescue team in scientific search strategies, department Emergency Services Manager Rick Kovar said.

The team studies “lost person behavior,” which is different for various groups of people who are lost. For example, an elderly person with dementia behaves differently than a missing hiker or child, Kovar said.

A straight line

A person with dementia may not recognize objects such as bodies of water or bushes, and walk right into them, Kovar said. They go until they become stuck. When they hit a barrier that blocks their way, they keep running into it until they find a way around, a phenomenon search professionals call “ping-pong.” They tend to travel in as straight a line as possible.

Another well-known characteristic is patients trying to return to a place that may no longer exist.

“A lot of times people with Alzheimer’s or dementia are stuck in an era of their life,” Kovar said.

That’s why the search-and-rescue team interviews family members to find out where — and when — the wanderers think they are. Then they search the area for similar-looking landmarks or former homes of the missing people.

Wanderers typically travel up to 2 miles away from their starting point, Kovar said, which is why the initial search perimeter starts at that distance and expands as needed.

Fremont, Calif., resident Loretta Wales’ 74-year-old husband, Richard, first wandered away from a day care facility where he was supposed to be supervised.

Her husband was diagnosed with Alzheimer’s in 1999 at age 63. By 2005, he would want to leave to search for his parents — who had been dead for 20 years — or to go to school.

Wanders 6 miles

In October 2008, she signed him up at a day care facility. On his third day there, he left and was missing for three hours.

“They were getting ready to put his picture on the six o’clock news when he was found,” she said.

Richard Wales walked six miles into Newark, Calif. He was found after people called police when he tried to break into a car that he thought was his.

After that he wandered away often and could not be left alone for more than a few minutes. Since September 2009, he has lived at Greengables Villa Home Care, an assisted living center in Union City, Calif.

Elderly dementia patients can wander away in any situation, be it from a car, a grocery store or their home, said Geri Degen, a social worker at Alzheimer’s Services of the East Bay.

“They don’t know where they live or who they live with,” she said. “When they leave, it’s usually because they think they are going home. There will be a pressing need to find something familiar.”