Brain Pacemakers Used To Treat Alzheimer’s Disease
In an effort to alleviate the symptoms of a disease that has stubbornly resisted treatment, scientists are turning to a therapy that may appear more likely to be encountered on the sick bay of the starship Enterprise rather than in our real life clinics.
Scientists at the Ohio State University Wexner Medical Center have begun a trial to test whether or not a deep brain stimulation device – a “brain pacemaker” – can ward off the debilitating symptoms of Alzheimer’s disease. Their first patient, Kathy Sanford, received the implants last October. Prior to the surgery Sanford had been diagnosed with mild Alzheimer’s, and her symptoms were progressively getting worse. But after five months of continuous stimulation from the brain pacemaker her performance on cognitive tests have vastly improved. It’s still too early to know if the effects will last, but the doctors are hopeful.
“Basically, the pacemakers send tiny signals into the brain that regulate the abnormal activity of the brain and normalize it more,” Dr. Ali Rezai, a neurosurgeon and co-leader of the study said in a press release. “Right now, from what we’re seeing in our first patient, I think the results are encouraging, but this is research. We need to do more research to understand what’s going on.”
Unlike the Enterprise where all procedures seem to involve a few simple scans on an outpatient basis, implanting the brain pacemaker is major surgery. Two stimulating electrodes are inserted through holes drilled into the skull. A battery pack, implanted beneath the skin near the collarbone, powers the electrodes via wires that run up the neck and beneath the scalp.
So far doctors haven’t reported any adverse side effects from Sanford’s treatment. The trial is scheduled to conclude in 2015, by which time up to ten Alzheimer’s patients will have received the brain pacemaker.
Here’s a short video in which Sanford and her doctors discuss her treatment.
Deep brain stimulation (DBS) is already widely used to alleviate the symptoms of Parkinson’s disease and other disorders that interfere with movement. Between 85,000 and 100,000 worldwide have DBS implants for movement disorders, but Sanford is the first person to receive a permanent implant for Alzheimer’s, according to the surgical team. Dr. Rezai says the brain pacemaker could also one day help alleviate symptoms of other chronic brain disorders such as obsessive compulsive disorder, depression, chronic pain, and migraines.
The current study continues the work begun by Dr. Andres Lozano who, in 2003, serendipitously discovered the potential DBS held for Alzheimer’s patients. At the time he was treating a patient with obesity. By stimulating the fornix, a major nerve tract of the brain that connects to the hypothalamus, a key regulator of appetite, Dr. Lozano thought normalizing its activity through electrical shocks would suppress the patient’s appetite. But the fornix also connects to the hippocampus, the memory center of the brain. Unexpectedly, the stimulation caused the patient’s memory to improve.
Last May Dr. Lozano was involved in a phase I study to test the safety of DBS as a treatment for Alzheimer’s disease. One hallmark of Alzheimer’s disease is the decreased activity of neurons in affected brain areas such as the hippocampus and other areas of the temporal lobe. Because they aren’t working as much, these neurons also show a decrease in metabolic activity, measured by dropping levels of glucose metabolism. The study showed a metabolic increase: 15 to 20 percent over the course of a year of stimulation. The increase is greater than that which normally results from drug treatments. More importantly, the patients showed improvements in memory, cognitive abilities, and quality of life overall.
An estimated 35 million people worldwide suffer from Alzheimer’s disease. About 5 million of those are in the United States where one in eight Americans over the age of 65, and about half over 85, has Alzheimer’s. As Dr. Rezai mentioned, it’s still too early to tell. But if others respond to the brain pacemaker like Sanford did, it could be a way to greatly improve the lives of patients by treating the symptom while waiting for a cure.