How a ‘pacemaker’ for the brain fights off Parkinson’s
When Shawn Connolly was diagnosed with Parkinson’s disease nine
years ago, he was a 39-year-old daredevil on a skateboard, flipping and leaping
from walls, benches and dumpsters through the streets of San Francisco. He appeared
in videos and magazines, and had sponsorships from skateboard makers and shops.
But gradually, he began to notice that “things weren’t really working right” with his body.
Over time, he developed a common Parkinson’s pattern, fluctuating between periods of rapid involuntary movements and periods of calcified slowness when, he said, “I could barely move.” A couple of years ago, Connolly volunteered and became a participant in a study exploring an innovative approach to deep brain stimulation.
In the study, which was published on August 19 in the journal
Nature Medicine, researchers transformed deep brain stimulation — an
established treatment for Parkinson’s — into a personalised therapy that
tailored the amount of electrical stimulation to each patient’s individual
symptoms. The researchers found that for Connolly and the three other
participants, the individualised approach, called adaptive deep brain
stimulation, cut in half the time they experienced their most bothersome
symptom. The study also found that in most cases, patients’ perceived quality
of life improved. Although the study was small, it represents the strides being
made in using
brain implants and artificial intelligence to personalise treatment for neurological and psychiatric disorders — essentially developing pacemakers for the brain.
Recent experiments have begun individualising brain stimulation for depression, obsessive compulsive disorder and chronic pain. While much more research is needed, several experts predicted that some versions of brain pacemakers could be available within five or 10 years. Deep brain stimulation, which has been used for years for Parkinson’s, is typically introduced when patients have achieved what benefit they can from medications containing levodopa, a drug that combats the deficit of the hormone dopamine that drives Parkinson’s disease.
Under conventional deep brain stimulation, patients receive a
constant level of electrical pulses. While it helps most patients, many
eventually reach a plateau or, because it does not adjust to a patient’s
experience, the stimulation may be too much or too little and lead to drastic
swings between periods of rigidity and unbridled motion. In recent years,
neuroscientists have identified brain signals that correspond to phases of
stiffness, called bradykinesia, and phases of uncontrolled movement, called
dyskinesia. In the new study, researchers used methods derived from AI to
devise a personalised algorithm for each patient and a way to detect and
respond to brain activity as the patient’s symptoms fluctuated.
“The brain changes in its needs moment to moment, hour to hour, week to week,” said Dr Philip Starr, a professor of neurological surgery at the University of California, San Francisco, and a senior author of the study who has worked on deep brain stimulation for decades. “So it’s been a dream to make these stimulators self-regulating.”
The individualised system in the study reads signals from two separate brain areas and delivers more electrical stimulation when patients enter periods of stiffness and less when they begin phases of involuntary movement. The study’s participants were men in their 40s through 60s who had been diagnosed with Parkinson’s at least six years earlier. First, electrodes were implanted in their brains and they received conventional deep brain stimulation for months, until they had benefitted as much as they could from that.
Then researchers began developing personalised algorithms for the patients, primarily focusing on the symptom each patient found most bothersome. For three patients, including Connolly, that symptom was stiffness. For the fourth patient, it was involuntary spasms called dystonia. At intervals of two to seven days over a period of two months, the system would change to deliver either conventional stimulation or the personalised version.
Neither the patients nor most of the research team knew which type of stimulation was being delivered when.
Patients completed questionnaires daily, and wearable monitors
tracked how their movements changed. Most patients went from experiencing their
worst symptoms for about 25% of the day to about 12% of the day, Dr Starr said.
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