Choose Your City
Change City

Deep brain stimulation for Alzheimer's? Maybe

TORONTO - Deep brain stimulation may help slow progression of Alzheimer's disease in some patients, a new study suggests.

TORONTO - Deep brain stimulation may help slow progression of Alzheimer's disease in some patients, a new study suggests.

The notion, while intriguing, is still very much in experimental territory. And it will likely be at least six years before the larger studies needed to flesh out these initial findings can be conducted and analyzed, admitted senior author Dr. Andres Lozano, a neurosurgeon at Toronto's University Health Network.

Lozano said the preliminary data already point to the likelihood that if deep brain stimulation works in Alzheimer's, it probably won't be useful in patients who have slipped from mild cognitive impairment to the moderate stage of the disease or beyond.

"Remember, this is the first time this has been done in human beings," said Lozano, who has also researched deep brain stimulation as a treatment tool for therapy-resistant depression and for Parkinson's disease.

"So to see anything is already great. I think it would be unreasonable to expect everyone to get better."

The data are drawn from a Phase 1 trial that Lozano and colleagues have been conducting for the past several years. The study was published Wednesday in the journal Annals of Neurology.

Phase 1 trials are the first in a series of at least three trials used whenever scientists want to test a new drug or treatment. Phase 1 trials are small — this one had only six participants — and are designed to ensure it's safe to proceed to the larger studies needed to determine if the drug or treatment works.

Still, Lozano and his team believe they've seen some signs the treatment may be beneficial in some patients.

Lozano implanted electrodes into the portion of the brain called the hippocampus, which is located behind the bridge of the nose. The hippocampus, which plays a key role in long-term memory, is hit early and hard by Alzheimer's disease, Lozano explained.

A result of the damage is that other parts of the brain which are downstream from the hippocampus and which are also involved in memory can't do their jobs, even though damage to them only occurs later in the disease.

Lozano said the implanted electrodes — which fire round the clock thanks to a pacemaker-like device implanted on the chest — seem to provide a work-around for those other parts of the brain. And the team has brain scans that suggest those areas actually do resume functioning.

PET scans show that those areas, which use progressively less glucose — brain fuel — as they shut down, start consuming it again after deep brain stimulation is commenced.

"The magnitude of this change is large and it is sustained," he said.

The director of the Mayo Clinic's Alzheimer disease research centre said that portion of the study adds weight to the hypothesis. But Dr. Ronald Petersen stressed that for the time being, this is still a theory.

"To say that deep brain stimulation is going to have any effect on that degenerative process is an interesting speculation, but clearly a leap of faith to say that that might be beneficial," said Petersen, a spokesperson for the American Academy of Neurology.

"I think this is an intriguing paper and warrants additional investigations," he said, while noting it remains to be seen whether deep brain stimulation stops progression of the disease or whether it, like Alzheimer's drugs, only modifies the symptoms of the disease.

Robert Linton is hoping Lozano is right.

Linton, 64, from Brampton, Ont., was one of the six patients in the Phase 1 trial and one of three in whom benefit seemed to be apparent.

A standard cognitive functioning test commonly known as the mini-mental state exam (or "the mini-mental" for short) showed that memory actually improved in Linton and another participant a year after they began treatment. A third person's mini-mental score was the same after a year of deep brain stimulation. With an Alzheimer's patient, one would have expected to see about a three-point decline.

But the test scores for two other patients dropped by two points. And one patient's score declined 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 of Alzheimer's patients is rapid, not the slow but steady decline seen in most.

Linton said he didn't hesitate when he was offered a chance to try something that might halt the progression of his disease. And he feels his memory is better than it was before the electrodes were implanted in his brain.

"For me it's life changing," he said. "It's a horrible disease. It's just frightening to think you'd have to go through it, be 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.

"I don't know that there's been an improvement, per se. ... But it certainly has stayed the same, for two years," she said.

"So we're pleased. We're very pleased."

The treatment costs between $15,000 and $20,000 per patient, Lozano said. Batteries for the pacemaker device last four to five years, Lozano said, after which the unit needs to be removed so the battery can be replaced.

The idea for using deep brain stimulation in Alzheimer's patients stems from a eureka moment Lozano and his team had 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 multiple other weight loss approaches. Nothing curbed 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 in vivid detail a day he spent fishing with his then four-year-old son.

"I could see that muskie coming right at me as I was sitting in the chair, in Technicolor," Linton said, mimicking the motion of reeling in a fish.

"So that's the power of touching a spot on your brain. So I'm sold on it."

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. The high setting helps Lozana figure out where to place the electrodes, but from day to day the charge is set at three.

Consider AlsoFurther Articles