Hints Deep Brain Stimulation Could Ease Alzheimer’s Symptoms

By Amy Norton HealthDay Reporter

THURSDAY, Dec. 22, 2022 (HealthDay News) — Researchers are studying whether deep brain stimulation could help people with Alzheimer’s disease retain their memories longer, and now a new discovery could help refine the approach.

Deep brain stimulation (DBS) is an established treatment for several medical conditions, including epilepsy, Parkinson’s disease, and obsessive-compulsive disorder. It involves implanting electrodes in certain areas of the brain to deliver electrical impulses that disrupt abnormal brain activity.

Researchers have also begun to study DBS as a possible way to help people with Alzheimer’s disease.

The hope is that when given in the early stages of Alzheimer’s disease, DBS may slow the progression of memory loss.

So far, studies have tested the effects of stimulating an area of ​​the brain called the fornix, a bundle of nerve fibers that is a key part of the brain’s memory circuitry. Research has shown that the fornix is ​​damaged in people with milder Alzheimer’s disease, and it is thought that DBS may improve the functioning of this faulty circuit.

The results, however, were mixed: some patients in the study showed evidence of slowing memory loss, while others did not.

One question is whether this could be at least partly due to variances in the specific placement of the DBS electrodes.

So for the new study, the researchers looked at data from 46 patients who had participated in an early trial of DBS for mild Alzheimer’s disease. They wanted to see if there were any correlations between particular sites of DBS stimulation and the likelihood of patients responding to treatment.

Searcher Dr Andreas Horn said that upon entering he was skeptical whether they would find any interesting places.

But it turned out there was. The researchers found, for example, that better responses to treatment were correlated with DBS at the interface between the fornix and what is called the bed nucleus of the stria terminalis – a band of fibers involved in emotional responses. and behavioral.

The researchers then checked their results by focusing on 18 patients they had left out in the initial analysis. They found they were able to predict how these patients responded to DBS based on where the electrodes were placed in their brains.

The goal, Horn said, is to refine DBS targeting in the brain — from a “fuzzy” area to more precise sites.

“We’re not suggesting a new treatment strategy. We’re suggesting a more refined one,” said Horn, who is based at the Center for Brain Circuit Therapeutics at Brigham and Women’s Hospital in Boston.

He pointed out, however, that no matter how refined DBS might become in the future, it will not cure Alzheimer’s disease.

“We want to extend the period when people have a better quality of life,” Horn said.

And for now, he added, DBS remains “very experimental” as a treatment for Alzheimer’s disease. This means that patients must be enrolled in a study to receive it.

A larger clinical trial, called ADVANCE IIis underway to test the effects of one year of DBS therapy for patients with mild Alzheimer’s disease.

Dr. Gabriel de Erausquin is a physician/researcher at the University of Texas Health Sciences Center at San Antonio, one of the medical centers involved in this trial.

He agreed that the new findings could be used to better target the DBS approach. “It’s actually a nice study,” said de Erausquin, who was not involved in the research.

If the results can ultimately help improve the effectiveness of DBS for Alzheimer’s disease patients, de Erausquin said, “that would be huge.”

DBS technology involves different parties. Electrodes implanted in the brain are connected to a pulse generator via wires placed under the skin. This pulse generator, a device similar to a pacemaker, is implanted under the skin of the upper chest and programmed to automatically deliver electrical impulses to electrodes in the brain.

DBS has been used since the 1990s to treat Parkinson’s disease, and it’s considered a generally safe therapy, de Erausquin said. But the surgery itself has some risks, and over time parts of the DBS system can move or break.

Like Horn, de Erausquin pointed out that DBS will not offer a cure. The usual course of Alzheimer’s disease, he noted, is a steady loss of function, and the hope is to halt that progression.

“We are exploring using established technology as a way to do this,” de Erausquin said. “Because right now there is nothing.”

SOURCES: Andreas Horn, MD, PhD, Center for Brain Circuit Therapeutics, Brigham and Women’s Hospital, Boston; Gabriel de Erausquin, MD, PhD, MSc, Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health Sciences Center, San Antonio; Nature Communication, December 14, 2022, online

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