Applying electrical pulses directly into targeted areas of the brain appears to reverse some of the damage caused by Alzheimer’s disease and may even improve cognitive function and memory, according to Dr Andres M. Lozano and his team at Toronto Western Hospital in Ontario, Canada, who carried out a small study into the effects of deep brain stimulation on patients with early signs of the disease.
The team reported early results of their phase 1 safety trial of deep brain stimulation in six Ontario patients with early stage Alzheimer’s disease last year in the Annals of Neurology. These latest results on the potential effectiveness of the method were presented at a Society for Neuroscience annual meeting in Washington DC earlier this November, but they have not yet been published in a scientific journal.
Lozano and colleagues applied deep brain stimulation to the fornix, a part of the brain that sends messages to and from the hippocampus, one of the first parts of the brain to shrink in patients with Alzheimer’s disease.
The hippocampus works like a communications housekeeper, encoding short term memory into long-term memory. It sits in the temporal lobe, along with another region called the posterior cingulate, which is also important for memory. In Alzheimer’s disease, both these regions use less glucose than normal, another indicator that cells are shutting down. Early symptoms of the disease, such as disorientation and memory problems, are the result of damage in these regions.
The electrodes were put in place under local anasthetic and hooked up to a tiny battery placed under the skin near the collar bone. The patients were able to leave hospital within 2 to 3 days of surgery, after which their brains continued to receive tiny electrical pulses at 130 times per second. They also continued to participate in regular follow-up assessments of their thinking and memory skills.
Lozano told the media one would normally expect the hippocampus of a person with Alzheimer’s disease to shrink by about 5% a year on average. However, after one year of deep brain stimulation, they saw the expected shrinkage in four of the participants, but were astonished to find the hippocampus had grown in the other two: by 5% in one and 8% in the other.
Tests also showed that these two participants appeared to have improved cognitive function, and the other four did not.
Lozano said they had never seen the hippocampus grow in anyone with Alzheimer’s. He told the BBC:
“How big a deal is 8%? It is huge.”
“It was an amazing finding for all of us,” he said.
The researchers are not exactly sure how the method works but Lozano said animal studies suggest it can generate new brain cells, and it can also trigger the production of proteins that stimulate the formation of new connections between brain cells.
He said it was still too early to say for sure that the method works: this was just a small study with a handful of patients. He and his team now want to move to a larger trial with 50 patients with mild Alzheimer’s. They will all have the electrodes implanted but only half of them, the controls, will receive the pulses.
Deep brain stimulation has already been used in about 90,000 patients with Parkinson’s disease worldwide.
Written by Catharine Paddock PhD