Parkinson’s trial targets inflammation before motor symptoms emerge

PRISMS is enrolling adults with REM sleep behavior disorder in US and Canada

Written by Andrea Lobo | Sept. 18, 2026

• PRISMS is testing whether targeting early inflammation can prevent or slow Parkinson’s before motor symptoms emerge.
• Participants are adults ages 50 to 80 with REM sleep behavior disorder and a reduced sense of smell.
• Researchers are testing adalimumab or placebo injections every two weeks for two years.

A new clinical trial led by scientists at the Yale School of Medicine is testing whether targeting inflammation in people at high risk of Parkinson’s disease can prevent or slow disease development.

In the PRISMS study (NCT06996652), which recently enrolled its first participant, researchers are testing adalimumab, an anti-inflammatory medication sold under the brand name Humira and approved for several autoimmune and inflammatory diseases.

RBD may offer an early window for intervention

The study is recruiting adults ages 50 to 80 with REM sleep behavior disorder (RBD) at several sites across the U.S. and Canada. RBD causes people to act out their dreams, sometimes violently, and can develop years before Parkinson’s disease or a related disorder.

“This is the first clinical trial of its kind to use an immunologically-based approach to try to slow the progression of Parkinson’s disease,” Jesse Cedarbaum, MD, professor at Yale School of Medicine and the study’s lead investigator, said in a university news story.

Parkinson’s disease is caused by the loss of nerve cells that produce dopamine, a chemical messenger that helps control movement. These cells are primarily located in a region of the brain called the substantia nigra. As these cells are lost and dopamine signaling is disrupted, motor symptoms such as tremor, rigidity, and slowed movements can develop.

Exactly what triggers the loss of these nerve cells is not fully understood, but several processes may contribute. These include abnormal clumping of a protein called alpha-synuclein and neuroinflammation, or inflammation in the brain.

Current treatments can ease Parkinson’s symptoms, but they do not stop the disease from progressing. That has increased interest in identifying Parkinson’s-related changes earlier, before substantial nerve cell loss has occurred, and testing treatments that could change the course of the disease. RBD may offer one such opportunity for earlier intervention.

“People who come to see their doctor for the first time with RBD are at high risk of developing Parkinson’s disease or a related disorder at a rate of 6% per year,” Cedarbaum said. “The transition can happen anytime over a span of 15 to 20 years.”