Kathleen Shields has had a few bad scares in the last year or so, when her husband Frank didn't return home at the expected time and she had to call police to go looking for him.

Frank Shields isn't a wayward husband: he has Alzheimer's disease, and the neurological condition has progressed to the point that he isn't always sure once he leaves the couple's Regina condo just how to make his way back home.

"I didn't think of this happening in any serious way until last summer when we were up at the lake and he disappeared one day and he didn't come back," says Kathleen Shields, 76, explaining that her husband had walked from the cottage north of Saskatoon to a nearby store, one he has visited for almost 50 years.

"He was bound and determined he was going by himself and you can't find out (if they can) unless you let them try," says Shields, a retired teacher and now full-time caregiver for her 80-year-old husband, who wears an Alzheimer's alert bracelet.

"He's in the woods, you know, and the lake is close by, and I was imagining all sorts of crazy things could happen," she says, adding that shortly after she called police to hunt for him, he walked in the door, tired and thirsty.

"He got home OK, but it scared me."

Wandering, as it's known, is a common phenomenon for people with Alzheimer's and other forms of dementia, primarily in their more advanced stages. It has spawned a whole series of devices -- from simple identification bracelets to high-tech GPS locators -- to help bring people disabled by dementia safely home.

In fact, Safely Home is the Alzheimer Society of Canada's national registry program aimed at preventing injury or death among those who stray and lose their way.

While wandering is the official term, it may be a bit of a misnomer, concedes Mary Schulz, senior manager of information support services at the Alzheimer Society. "The reason we're shying away from it a little bit is it suggests aimlessness. It suggests going out the door and just being in a fog and really having no clue what you're doing or where you're going."

But that's usually not the case, stresses Schulz. "There is a purpose to where they're going . . . They're often quite clear about what they're looking for. Someone might say, 'I have to get home and feed my children their lunch. They're on their way home from school.' This is someone who's 85. So in their mind, they're not wandering at all. They have a destination in mind."

As the dementia deepens, a person may be unable to recognize their environment - even their long-familiar home - as a safe and desirable place to be, she says. "They may misperceive that as a place of danger, they may perceive that the people around them are not people they know."

"And so they may feel very threatened and quite afraid . . . often the brain tricks them into thinking something that isn't true and that can cause them to want to leave."

Each year, there are reports of people with dementia who wandered from their residences and were found dead from exposure, says Schulz, adding that the society strongly encourages anyone with the condition (or the family) to register with Safely Home at a one-time cost of $35.

David Fost of Edmonton is among about 25,000 Canadians with dementia who have signed on to the registry and been provided with a numbered bracelet that directs anyone finding them to call police. An RCMP database allows local police units across Canada and the United States to tap in and contact a registrant's caregiver.

Fost, 63, is in the earlier stages of Alzheimer's, but he knows what's coming as the disease increasingly takes over his brain. So he supports any device that could help his wife Janet or others pinpoint his whereabouts should he go missing.

"For me, even if I hated it, I would say yes just because I wouldn't want Janet to worry."

There are a variety of tracking devices on the market, including those that use Global Positioning Satellite (GPS) technology, radio-frequency homing systems and special cellphone locators.

Another is an implantable microchip that identifies and carries medical information for a person with dementia. The chip can be scanned by hospital staff in the event a wandering person gets injured and is taken to hospital.

In Palm Beach, Fla., a care centre is teaming with VeriChip Corp. to study the effectiveness of the under-the-skin devices by implanting them in 200 residents with Alzheimer's. The decision has sparked outrage from an international rights group, which argues that patients are being treated like animals - and their privacy invaded without their consent.

But Dr. Michael Gordon, a physician at the Baycrest Centre for Geriatric Care and a clinical ethicist at the University of Toronto, believes the animal analogy is inappropriate - and that tracking devices in general may not only be useful but sometimes warranted.

"I don't look at this as a big ethical challenge in the usual construct of ethics," says Gordon. "You're trying to promote the person's autonomy as much as possible, even though they have a degree of impairment."

"You're trying to avoid harm while giving them the best independence, the best freedom, the best decision-making as possible. . . . A chip is just a technology to do that."

If someone with dementia is incapable of giving consent for such a tracking device, there is nothing wrong with a legally appointed surrogate making that decision for them, he suggests.

"It's no less ethical or more ethical than a surrogate deciding on life-saving heart surgery or putting in a pacemaker. If a chip turns out to be the safest way, you'd say: 'What's wrong with it? Is there anything intrinsically more wrong with it than other things we do?"'

Fost, who still drives his car and takes part in forums advising Alzheimer's patients and their families, says anyone newly diagnosed with dementia should start immediately planning for the future and letting their wishes be known to family members given power of decision-making.

"The first thing I would say is get all the information on the tracking devices you can," he says. "If there's some (discomfort with the notion) . . . it still probably would be to your advantage because it's not just you, it's also your caregiver. You have enough stress, but the caregiver also has a lot of stress."

Wearing a locating device could mean "saving your life," Fost tells those also afflicted with dementia, who may one day end up getting lost.

"And if you think, 'Well that's not important,"' he says, "your caregiver and your grandchildren would disagree."