TORONTO — A new study suggests deep brain stimulation may help slow progression of Alzheimer’s disease in some patients.
The research is still in the very early stages and there is already evidence that it probably wouldn’t be useful in patients who slipped from mild cognitive impairment to the moderate stage of the disease.
But senior author Dr. Andres Lozano said there is enough evidence of benefit from the electrical pulses being given off by electrodes implanted deep in the brain that it’s worth conducting bigger and better-designed trials to investigate further.
“We have several pieces of data that suggest that there is indeed a signal (of efficacy),” said Lozano, who is a neurosurgeon.
A standard cognitive functioning test commonly known as the “mini-mental” showed that memory actually improved in two of six patients in the small trial. In another, the mini-mental score was the same after a year of deep brain stimulation. With an Alzheimer’s patient, one would have expected to see a decline.
But the test scores for two other patients declined by two points — the average decline for Alzheimer’s patients is about three points a year. And one patient’s score dropped by five points, though Lozano said that patient seemed to be what is called a rapid progressor.
The disease pattern in about 25 per cent Alzheimer’s patients is rapid, not the slow but steady decline seen in most.
One of the patients who appears to have benefited was Robert Linton, 64, of Brampton, who said he jumped at the chance of exploring something that might halt the progression of his disease.
“I’m sold,” he said. “For me it’s life changing.”
“It’s a horrible disease. It’s just frightening to think you’d have to go through it in a nursing home, withering away.”
Linton’s wife, Barb, said from her vantage point, her husband’s condition hasn’t improved but nor has it declined in the two years since he had the electrodes implanted.
The electrodes, which look like silver pieces of spaghetti, are linked to a pacemaker-like device implanted under the skin on the upper chest. Batteries for the unit last between four and five years, Lozano said, at which point they need to be replaced by cutting the unit out from under the skin.
Lozano and his team are building on a eureka moment that occurred several years ago. They were investigating deep brain stimulation as a possible treatment for obesity, using the technique on a patient who weighed more than 400 pounds. The man had tried diets, drugs, group therapy — nothing worked to curb his eating. And the deep brain stimulation didn’t either.
But when the team was trying to determine where in the brain to rest the electrodes, the man began to recount in detail events of a day roughly three decades earlier, when he was in a park with friends.
Linton had a similar memory phenomenon, recalling a day he spent fishing with his then four-year-old son. Lozano said those types of sharp and detailed memories only happened to some patients and only when the charge from the electrodes was set on high — seven on a dial that goes to 10. Day to day the charge is set at three, he said.
It took Lozano’s team 18 months to get ethics approval to conduct a small Phase 1 trial of deep brain stimulation in Alzheimer’s patients. He said they were only allowed to enrol one patient at a time to minimize risk.
Phase 1 trials are designed not to see if something works, but to determine that it is safe to test something — a procedure or a drug — in people. Phase 1 trials also are used to determine what a correct dose of a drug or therapy should be.
Phase 1 trials are always small. If something seems safe, researchers move to larger Phase 2 and Phase 3 trials; the latter provide data needed to get approval to bring a new drug to market, for instance.
Lozano would now like to proceed to Phase 2 and Phase 3 trials, which he estimated would take about three years apiece.
The study is being published in the journal Annals of Neurology.