For decades, clinicians have used electrical pulses to regulate abnormal brain activity in people with Parkinson’s disease. For some of the millions of people worldwide afflicted with Parkinson’s, the technology — known as deep brain stimulation — has helped ease their tremors, stiffness and slowed movements. But for others, deep brain stimulation carries too many side effects or is not effective.
A new, smarter version of the technology may help more patients. Like a cardiac pacemaker that responds to the rhythms of the heart, adaptive deep-brain stimulation (aDBS) uses a person’s individual brain signals to control the electric pulses it delivers. This makes it more personalized, precise and efficient than older DBS methods.
DBS and aDBS technologies employ electrodes connected to thin wires that are implanted into areas of the brain affected by Parkinson’s disease. The wires are attached to a small, battery-powered device implanted under the skin on the chest, similar to a cardiac pacemaker placement. The battery delivers trains of electric pulses through the wires and electrodes to the brain areas specifically affected in Parkinson’s.
Over the last decade, Helen Bronte-Stewart, MD, a professor of neurology and neurological sciences, has led research into how brain activity goes awry with Parkinson’s, how to sense irregular electrical brainwaves and how to correct them. Most recently, she led the large international, multicenter pivotal clinical trial of a new approach to deliver aDBS to people with Parkinson’s. Now, that technology has been approved by the U.S. Food and Drug Administration for use in people with Parkinson’s.
We asked Bronte-Stewart, the John E. Cahill Family Professor, about how the new technology was developed and why it could be game-changing for people with Parkinson’s. This interview has been edited for clarity and length.
What is deep-brain stimulation?
It’s like a pacemaker for the brain. The way a pacemaker in the heart provides electrical stimulation to keep the heart’s rhythm on track, deep-brain stimulation provides electrical stimulation to control the brain’s electrical rhythms.
The earliest cardiac pacemakers couldn’t sense a person’s heartbeat; they delivered one steady rhythm. At the time, that was big progress — these devices allowed people, who couldn’t otherwise, to stand up and walk. But they could also cause the heart to beat too quickly. The big leap came when pacemakers became adaptive; they started turning on only when a person’s heart rate dropped below a certain threshold.
That is the turning point we just reached with deep brain stimulation. Until recently, these stimulation devices delivered a one-size-fits-all train of electric pulses to the brain around the clock. They have helped some people but are a pretty blunt tool for trying to correct the brain arrythmias associated with Parkinson’s. Now, we have this adaptive technology that listens to brain activity and adjusts stimulation accordingly. It corrects brain rhythms only when needed and provides just the right degree of correction.
Why is adaptive deep-brain stimulation beneficial in Parkinson’s disease?
In Parkinson’s, brain circuits that coordinate movement begin to misfire, causing symptoms like tremors, stiffness and slow movements. One of the underlying causes is an abnormality in one type of electrical activity in the brain, called beta waves. Deep-brain stimulation sends an electrical signal that corrects the abnormal beta waves.
Traditional deep-brain stimulation suppressed the abnormal beta waves in the same way all the time. But with Parkinson’s, a patient’s levels of beta waves might vary, depending on how well other treatments are working, how the disease is progressing or what they’re doing at any given moment. The adaptive technology adjusts the stimulation based on these patterns, mimicking natural brain rhythms more closely and keeping beta rhythms in a stable range rather than constantly shut off.
How has your lab’s work paved the way for the development of this technology?
My lab has spent years developing ways to precisely measure movement. When we could record neural activity from implanted neurostimulations in people with Parkinson’s, this allowed us to determine which abnormal brain signals are most relevant to the impairment of movement seen in Parkinson’s.
We and others were then able to discover that there is abnormal neural activity that can be called a brain arrythmia and to describe the change in beta waves. We went on to establish that Parkinson’s drugs and deep-brain stimulation could partially correct these jammed signals and improve movement in patients.
My lab has been carrying out experiments on adaptive DBS since 2015. The earliest devices used a smartwatch to track changes in tremor and adapt DBS accordingly. Now, we have taken it a step further and are able to directly track beta waves in the brain and use that to control the DBS.
Where does adaptive deep-brain stimulation go from here?
The FDA approval is exciting because it means that everyone with Parkinson’s who has a compatible DBS device in the U.S. could use aDBS. We hope that patients and neurologists start looking into whether the technology can help them.
