Fully 15 years after implantation, brain stimulation devices for Parkinson’s disease continue to have a positive effect on patients’ motor symptoms and reduce the need for medication, a new study by neurologists has found. 

Brain implants deliver electrical stimulation to targeted areas of the brain. This disrupts the abnormal activity caused by both Parkinson’s disease and its first line treatment drug levodopa, and can lessen the motor symptoms such as tremor, head bobbing and swaying.

Whether the effects last beyond 15 years was previously unknown, according to researchers from Grenoble Alpes University Hospital, in France. The researchers identified 51 people who had a deep brain stimulation device implanted an average of 17 years ago at the hospital. Their average age for diagnosis of Parkinson’s disease was 40.

After reviewing data on movement problems, quality of life, medication and measures of severity and progression of Parkinson’s disease, they found that:

  • The amount of time participants experienced dyskinesia caused by the Parkinson’s drug levodopa was reduced by 75% when comparing the time before device implantation to data 15 years afterward; 
  • The amount of time spent in an “off” state — when medication was no longer working well — was reduced by 59%; 
  • The use of medications to control dopamine levels was reduced by 51%; and
  • Side effects of having the stimulation for 15 years were few and mostly manageable.

“Despite the natural progression of Parkinson’s disease and the worsening of some symptoms that become resistant to medications over the years, participants still maintained an overall improvement in quality of life,” concluded senior author Elena Moro, M.D., Ph.D., and colleagues.

One limitation of the study was that some patients were not available to be studied 15 years post-implant, Moro and colleagues noted. “It is possible that the people in the study may have been healthier than those not included, meaning the results may not fully reflect the experience of all people using deep brain stimulation,” they explained.

Full findings were published in the journal Neurology.