- Deep brain stimulation (DBS) is a surgical treatment to treat certain neurological conditions, such as Parkinson’s
- Researchers from Charité — Universitätsmedizin Berlin have found that DBS helps to alleviate the symptoms of Alzheimer’s patients.
- Although not all participants showed an improvement in symptoms, some “benefited significantly” from the treatment.
More than 160,000 people receive deep brain stimulation (DBS) treatment each year.
DBS is a surgical treatment for certain neurological disorders, including Parkinson’s disease, epilepsy, essential tremor, and dystonia.
Previous research has also investigated DBS as a treatment for certain psychiatric disorders, including treatment-resistant depression, obsessive-compulsive disorder (OCD), and addiction.
In a recent study, researchers from Charité — Universitätsmedizin Berlin found that DBS can help reduce symptoms in people with Alzheimer’s disease (AD).
The study was recently published in the journal Nature Communications.
What is deep brain stimulation?
DBS is a surgical procedure in which a doctor attaches electrodes to a specific area of a person’s brain. The electrodes in the brain are connected via cables to an electrical generator — similar to a pacemaker — which is implanted under a person’s collarbone.
The electrodes generate electrical impulses that interrupt abnormal signals that the brain may receive, leading to symptoms of illness such as tremors or difficulty moving.
“DBS disrupts the flow of information in the brain at the specific stimulation site,” Dr. Andreas Horn, Ph.D., associate professor of neurology and director of deep brain stimulation research at the Center for Brain Circuit Therapeutics in the Department of Neurology at Brigham & Women’s Hospital in Massachusetts and lead author of the study, explained to Medical News Today.
“That sounds negative, but we usually target circuits that are derailed and contain loud or nonsensical information,” he said.
Dr. Horn added that DBS is best understood in Parkinson’s disease, “where a sound signature in a specific frequency band can be observed in a specific circuit in the brain.”
He explained that the level of noise corresponds to the severity of symptoms such as bradykinesia (stiffness in the body).
“By injuring this circuit, we can reduce the sound signature and improve the symptoms. In fact, the lesion of the same sites that we “stimulate” with DBS results in similar improvements in symptoms. DBS has a similar effect — it dampens the aberrant “noise” in certain circuits in the brain. I believe that this way, other circuits are less distracted by the noise in the affected circuit and that meaningful information is not as prevented from flowing through those circuits.”
DBS and Alzheimer’s Disease
The new research began with an observation made during a Canadian study that examined the use of DBS to treat obesity.
Researchers found that DBS caused flashbacks of childhood memories in some study participants. Scientists then considered that the stimulation of exactly this site in
Fornix area of the brain could also help treat Alzheimer’s.
The fornix contains the white matter of the brain. Previous research links fornix neurodegeneration to Alzheimer’s disease.
Previous studies have also investigated the use of DBS to stimulate the brain’s fornix to treat dementia.
The present study further furthered research by analyzing data from electrodes implanted in the same area of the fornix in 46 people with mild Alzheimer’s disease.
After analysis, the researchers reported that most patients did not show any improvement in their symptoms. However, some participants “benefited significantly” from the treatment. In these test subjects, a specific circuit in the brain was stimulated and there were cognitive improvements after treatment.
Personalizing Alzheimer’s Treatment with DBS
According to Dr. Horn, who is also head of the Department of Movement Disorders and Neuromodulation in the Department of Neurology at Charité — Universitätsmedizin Berlin, the aim of this retrospective study is to examine the differences between participants for whom the treatment worked better than for others.
“We were able to prove that the electrodes were placed differently among the participants who reacted most frequently — in cases where a particular bundle was modulated in the brain, the treatment had the strongest effect,” he said.
This, according to Dr. Horn, is key to understanding that treating DBS is not the same procedure for all diseases.
“It is a focal stimulation that must be aimed at a specific brain structure in every disease. While we often target the so-called subthalamic nucleus in Parkinson’s disease, for example, a specific nucleus in the thalamus is the most frequently used target in tremor. Since the goal is decisive, an appropriate target must be defined to test this treatment for novel diseases. In theory, these goals could be derived from animal experiments, but the past shows us that they were mostly discovered through random events involving humans.”
— Dr. Andreas Horn, lead author of the study
Personalized targeting is the future, according to Dr. Jean-Philippe Langevin, neurosurgeon and director of the Pacific Neuroscience Institute’s Restorative Neurosurgery and Deep Brain Stimulation Program at Providence Saint John’s Health Center in Santa Monica, California.
“In the past, to place the electrodes in the brain, you simply looked at the rough anatomy of the brain on scans and placed an electrode in the intended target,” explained Dr. Langevin.
“But this type of research, where they’re looking at how the fibers move in each patient, should result in a personalization where the electrode is placed in the brain. You can take a closer look at the specific fibers and then choose exactly where the electrode should be located for that patient.”
Dr. Langevin added that personalized treatment that includes DBS could lead to improved outcomes.
“It will expand our knowledge about the brain and hopefully new treatment options, such as in the case of Alzheimer’s,” he said.
DBS treatment hurdles
DBS is already being used to treat neurological disorders such as Parkinson’s disease. So what prevented it from treating Alzheimer’s?
According to Dr. Langevin, there are two main reasons why DBS may not be widely accepted as a potential Alzheimer’s treatment. First, it is surgery, which is why it is considered a more invasive and riskier procedure compared to other treatments.
“Over time, we’ve worked to make the surgery more minimally invasive so that smaller incisions (and) less time are needed to recover,” he said.
The second issue is that DBS includes an implantable device that requires some adjustments, and sometimes practitioners aren’t comfortable with the programming devices, Dr. Langevin added.
Since then, manufacturers have improved the software and device programmers so that they are more intuitive and easy to use, he noted.
Next steps in DBS research
As improvements in DBS continue, it may be a while before treatment for Alzheimer’s is available.
“The adVANce II study is currently ongoing in several centers around the world,” stated Dr. Horn.
“In my opinion, if successful, FDA approval and a CE mark for the process would be very likely. And this in turn could make the treatment available to many patients who meet the criteria for which researchers have found DBS helpful.”
Nevertheless, Dr. Horn emphasized that DBS is not a curative treatment option for neurodegenerative diseases such as Parkinson’s or Alzheimer’s.
“Unfortunately, the disease will progress and the treatment will be symptomatic, i.e., at best, it will help improve some of the symptoms for some time,” he explained.
“In Parkinson’s disease, we have good evidence that this can lead to significantly longer periods of time with improved quality of life.”