The search for a 77-year-old South Portland woman who was missing in the woods in Waterford for two days last week has highlighted a growing interest in a new technology that can help searchers locate people with memory or other cognitive problems who tend to wander and are at risk of getting lost.

Project Lifesaver allows police to locate a person by tracking the signal from a small radio beacon the person wears like a wristwatch.

“They say in the practical exercises they do, they’ve been able to locate within 30 minutes, which is certainly far better, maybe, than we could do today,” said Scarborough Police Chief Robert Moulton, whose department is evaluating whether to purchase the technology. Auburn and Ogunquit, which both launched Project Lifesaver programs last month, are the only communities in Maine that use the program.

The woman, Ruth Brennan, was found safe by a canine search team after two days in the woods.

But the search for 15-year-old Jaden Dremsa had tragically different results. After 10 days of searching, Dremsa, who had a mild form of autism, was found in Lake Arrowhead, not far from his home in North Waterboro. He had hit his head and drowned.

Samantha McDorr is lobbying for Brunswick to make the Project Lifesaver technology available to residents whose loved ones have cognitive impairment. Her daughter Sage, who will turn 9 in a few days, has autism and a tendency to wander.

“The world stops,” when McDorr and her husband can’t find Sage, despite security measures at their house, she said. “It’s a real safety concern for our family.”

McDorr said autistic children are of particular concern because they tend to be attracted to water and to avoid social interactions. Many are likely to run away from people who might be trying to help them, she said.

The Brunswick Police Department will raise the question of whether to use the program at the Town Council’s meeting Aug. 4, McDorr said.

A person at risk of wandering off who uses the Project Lifesaver technology wears a watch-like bracelet that emits a unique radio signal. Once notified that the wearer is missing, officers respond to the person’s last known location and use hand-held antennas to locate the direction of the signal.

Laurie Trenholm, executive director of the Maine chapter of the Alzheimer’s Association, said the Project Lifesaver system could be a huge benefit to people with Alzheimer’s and other dementia. The number of Maine residents ages 65 to 74 with cognitive impairment, now estimated at 12,390, is expected to increase by 77 percent by 2020.

“Wandering is definitely a major concern for folks with cognitive impairment and as it progresses through different stages of dementia,” Trenholm said. “This population can get confused and turned around and not use landmarks to find their way back … Anything we can do to help these people be connected to people who are looking out for them” is beneficial, she said.

The Maine Alzheimer’s chapter has supported use of MedicAlert’s Safe Return program, in which participants submit information to a central repository so that if they are lost, whoever finds them can call an 800 number to reunite them with their caregiver.

The Project Lifesaver program costs about $5,000 to launch in a community, plus money for training and additional wrist devices if needed. Auburn and Ogunquit were able to get grant funding to launch the program in their communities.

“It’s been received very well,” said Auburn Deputy Police Chief Jason Moen. “It kind of gives them a sense of comfort to know, should they wander off, there’s a better chance of finding them.” The city’s program gives them access to 10 bracelets. Officers visit participants once a month to change the batteries and make sure the device is working, he said. Participants are charged $50 a year to cover the cost of batteries.

Three people have signed up since the launch last month, he said.

In Brunswick, McDorr has been asking supporters to send donations directly to Project Lifesaver on behalf of the town of Brunswick.

Moulton said police agencies and towns need to weigh the benefits of the program against the cost.

“If you save one person, certainly it’s worth its weight in gold,” he said.

McDorr said even people who don’t have relatives who would benefit should consider supporting it.

“If you’re not touched by someone with autism or Alzheimer’s – it’s difficult not to be because they’re both so common – you could at least look at it from the standpoint of saving tax dollars,” she said. “The cost of a search and rescue for a lost person with cognitive disabilities is phenomenal.”

This article was updated at 8:53 a.m. Thursday, July 17 to correct the name of the town where Ruth Brennan was lost.