Dementia patient Joan Warren was not wearing her electronic tracking bracelet when she went missing on Friday and family, friends, firefighters, police and volunteers all joined North Shore Search and Rescue in a huge search operation.
Warren's body was found two days later, off trail, near Lynn Canyon suspension bridge. She had died of hypothermia.
Warren's family say searchers did their best, but could she have been found sooner?
Robert J. Koester, a U.S. search and rescue expert based in Virginia, who spoke with Stephen Quinn on CBC Radio One's On The Coast, says dementia patients are the hardest subjects to find, and time is of the essence.
"The sooner you can get more eyes involved, the better. The more urban the area, the better the chance that somebody other than search and rescue is going to make the find," he said.
In a database he keeps, he's found that 22 per cent of cases of missing persons with dementia end with the patient found dead — a rate that is far too high — but Koester says he's identified patterns that can help searchers track what often seems like counter-intuitive behaviour.
Here are five search tips he shared with CBC Radio's On The Coast:
1. They'll go until they get stuck
"It's probably counter-intuitive that they go into some of the thickest, nastiest brush or briars," Koester said.
He said persons with severe cases of dementia will head out an exit door, keep going until a barrier or a bend in the road redirects them and, if not found soon enough, they will eventually head off into the brush or into a water feature, where they get stuck, and stay.
2. Water can be a draw
After fighting through brush and trees and other obstacles, some dementia patients will find a welcome relief when a pond, lake, stream, or river opens up in front of them: "My guess is, maybe finally they thought it was a flat place, like a nice sidewalk, to walk."
"I don't even know if they perceive water for what it is," Koester said.
3. Searchers may be ignored, or avoided
"They tend not to respond to searchers' shouts," he said. "They're living so much in the present, they can watch a search team walk right by them."
4. Look to the past
More moderate cases of dementia will see the patient trying to find their way around a neighbourhood, thinking they are in a different location from their past, and seeking out familiar-looking features.
5. Each case is unique, but always the same
"If you've met one dementia subject, you've met one dementia subject," Koester said.
But while there is no general pattern of behaviour that catches all cases, the inability to form short-term memories does guide a wanderer's path. Koester says the dementia patient is making all of his or her decisions based on what they can see right in front of them.
An area of thick brush that other people will avoid isn't as much of a barrier, if you can remember the easier terrain you just passed through. In a world with little or no short-term memory, there is little ability to remember to turn around.