The U.S. Food and Drug Administration (FDA) has given the go-ahead for research trials to determine whether deep brain stimulation (DBS)—a procedure involving the implantation in the brain of a pacemaker-like device—can halt or slow the progression of Alzheimer’s disease (AD). The technique has been used with success in the treatment of symptoms of Parkinson’s disease (PD), and preliminary studies involving small groups of AD patients have been encouraging. Up to 50 people with early signs of AD will be recruited to participate in the AD trials, known as the ADvance Study, at seven different sites in the U.S. and Canada.
DBS for AD patients involves the implantation of a battery pack underneath the skin of the chest which delivers low-grade electrical impulses through a subcutaneous wire to an electrode positioned in an important memory pathway in the brain called the fornix. In preliminary studies, electrical stimulation of the fornix appeared to increase neuronal activity in that region, and was linked to improved cognition and slower cognitive decline in many patients.
WHAT YOU CAN DO
Contact one of these trial sites for more information on the ADvance Study:
- Johns Hopkins Bayview Medical Center in Baltimore, MD (410) 550-4258
- Toronto Western Hospital in
Ontario, Canada (416) 603-5800 Ext.3304
- Banner Sun Health Research Institute in Sun City, AZ (623) 832-6512
- Banner Alzheimer’s Institute in
Phoenix, AZ (866) 840-5838
- University of Pennsylvania in
Philadelphia, PA (215) 662-4379
- Brown University-affiliated Butler Hospital and Rhode Island Hospital in
Providence, RI (401) 455-6403
- University of Florida Center for Movement Disorders and Neurorestoration in
Gainesville, FL (352) 273-5614
“In the natural history of AD, memory decays over time, but these trials suggest that DBS may prevent or slow this decay in many patients, and that’s very exciting,” says Michael D. Fox, MD, PhD, an Instructor in Neurology at Harvard Medical School and a neurologist with the Division of Movement Disorders at MGH. “At this time, most AD patients are treated with drugs such as Aricept. However, among many experts there is increasing recognition that treating neurological diseases with focal interventions such as DBS that are applied directly to brain circuits may be more effective than drugs.”
How DBS Works
The ADvance Study is intended to add to scientific understanding of the precise mechanism by which electrical stimulation brings about brain changes. Half of the participants will be fitted with active pacemakers, and half with placebo pacemakers that provide no stimulation. Researchers will compare the two groups over a 12-month period, and then activate the DBS system in the placebo group. All participants will undergo periodic psychological, physiological, and cognitive assessments, and brain scans will be performed to measure glucose metabolism and changes in brain structure in memory regions.
“It’s possible that the electricity from the DBS electrode creates a functional lesion inhibiting brain activity at the stimulation site and brings about beneficial changes as the brain reacts,” says Dr. Fox. “It’s also possible that the electrical pulses stimulate white matter fibers that pass near the electrodes on their way to the adjacent hippocampus, a key memory center.”
Other hypotheses that might explain the positive brain effects of DBS in stimulated regions include:
- An increase in glucose metabolism that boosts activity levels in brain cells, or neurons
- Increases in neurogenesis, the birth of new brain cells
- Increases in connectivity among neurons
- Increases in blood or oxygen delivery to nourish brain cells
“We don’t know about the variability of DBS for AD,” Dr. Fox cautions. “Its success may depend on factors such as the brain area affected by the stimulation, the exact placement of an electrode, the strength or frequency of electrical pulses, and the severity and characteristics of an individual participant’s dis-ease. We may find that DBS works for a subset of AD patients, but not for others.”
Many of the sites collaborating on the ADvance Study (see What You Can Do) are in the process of recruiting study participants. Applicants for the trial must be in good general health and diagnosed with early-stage AD, between 55 and 80 years of age, live at home, have been on a stable dose for at least two months of an FDA-approved drug for AD (Aricept, Razadyne, or Exelon), and have a reliable spouse, relative, or caregiver who agrees to cooperate with the study.