Daijiworld Media Network - New Delhi

New Delhi, May 31: People who physically act out their dreams while asleep may be experiencing an early sign of serious neurodegenerative diseases, including Parkinson’s disease and Lewy body dementia (LBD), according to a new study published in eBioMedicine.

The condition, known as Rapid Eye Movement (REM) sleep behavior disorder (RBD), is marked by vivid, sometimes violent dream enactment—such as punching, kicking, or shouting—during REM sleep. Unlike sleepwalking, which occurs in slow-wave sleep, RBD emerges during the dreaming phase and typically affects people around age 50.

“Normally, our muscles are paralyzed during dreams, but in RBD, this protective mechanism fails,” explained Dr. Shady Rahayel, a medical professor at Université de Montréal, Canada.

Researchers found that nearly 90 percent of people with RBD eventually develop Parkinson’s disease or LBD, a severe form of dementia second only to Alzheimer’s in prevalence.

“RBD is an early warning sign that certain brain mechanisms are no longer functioning properly,” said the study team. “Of those who progress to disease, about half will develop Parkinson’s, while the other half will develop LBD.”

LBD is characterized by cognitive decline, Parkinson’s-like symptoms, hallucinations, and fluctuating attention.

To explore how these disorders progress, researchers analyzed 1,276 MRI scans from patients with RBD, Parkinson’s, LBD, and healthy individuals.

They used machine learning to map patterns of brain atrophy: LBD often starts in the cortex and spreads inward, while Parkinson’s typically begins deep in the brain and progresses outward.

Future research will investigate factors that might influence this cortical deterioration, including vascular health, medications, and lifestyle factors.

“Now that we’ve mapped these patterns, our next step is to refine MRI-based diagnostics to identify patients at risk and guide treatment more effectively,” Rahayel added.