The most common cause of dementia is Alzheimer’s disease, which is difficult to treat. Deep brain stimulation, which is delivered by a kind of pacemaker, is one potential treatment.
A group of specialists at Charité – Universitätsmedizin Berlin has found that invigorating a particular network in the brain of Alzheimer’s patients decreases their symptoms.
The findings, which are published in Nature Communications, are expected to open the door for additional research.
In Germany, deep brain stimulation (DBS) is already approved for the treatment of neurological movement disorders like Parkinson’s disease and dystonia as well as neuropsychiatric conditions like obsessive-compulsive disorder. The patient’s brain is implanted with extremely thin electrodes that constantly deliver mild electrical pulses to a specific region.
A pacemaker-like device is implanted in the chest area, and the electrodes are connected to the brain via wires that run under the skin. The gadget is used to change the strength and recurrence of the electrical stimulation.
“Although DBS has been an established treatment for Parkinson’s disease for a good 20 years now, and the costs are covered by health insurance providers, it’s still not a very well-known therapy,” says Prof. Andreas Horn, head of a lab that explores network-based brain stimulation at the Department of Neurology and Experimental Neurology at Campus Charité Mitte, and at Brigham and Women’s Hospital and Massachusetts General Hospital, both affiliates of Harvard Medical School in Boston, USA.
“DBS works very well in patients with Parkinson’s,” he says. “It improves their quality of life significantly.”
It seems likely that DBS could also be used to treat Alzheimer’s, which is another neurodegenerative disease. Yet, protected, successful treatment is just conceivable assuming the exact brain regions that require stimulation are known.
A random observation made in a Canadian study served as the starting point for the current study, which the researchers carried out in close collaboration with numerous partners, including the University of Toronto in Canada.
“In one patient, who was being treated for obesity, deep brain stimulation caused flashbacks – sudden memories of their childhood and adolescence,” says Dr. Ana Sofía Ríos from the Department of Neurology and Experimental Neurology at Campus Charité Mitte, and the study’s lead author.
“This led the Canadian researchers to suspect that stimulating this brain region, which was located in the fornix, might also be suitable for treating Alzheimer’s.”
In a multicenter study, researchers at seven international centers implanted electrodes in the same area of the fornix in participants with mild Alzheimer’s disease to investigate this further.
“Unfortunately, most patients showed no improvement in their symptoms. But a handful of participants benefited considerably from the treatment,” says Dr. Ríos.
“In the present study, we wanted to find the root cause of these differences, so we compared the exact position of the electrodes in each participant.”
Prof. Horn’s research group has had some expertise in dissecting high-resolution magnetic resonance pictures of the brain and joining these with PC models to pinpoint the ideal areas for DBS exactly.
“One of the main challenges is that every brain is different – and that’s really important for accurately planting the electrodes,” says Prof. Horn.
“When electrodes are placed even a few millimeters off target, it could lead to a lack of benefit for the patient.”