Phenomenon linked to Parkinson’s, dementia, other serious neurodegenerative diseases
From the WashU School of Medicine News…
Picture this: A soccer referee, dreaming he’s on the pitch, flings his arm up with an imaginary red card and accidentally smacks his sleeping partner in the face. Funny? Maybe on TV. In real life, acting out dreams is not only bad for domestic harmony, it can be a warning sign of looming neurodegenerative disease.
A new study led by researchers at Washington University School of Medicine in St. Louis and the Mayo Clinic aims to understand a rare condition called REM sleep behavior disorder (RBD) that leads people to act out their dreams. The goal is to identify which people with the disorder will go on to develop neurodegenerative diseases such as Parkinson’s, and to lay the groundwork to test treatments aimed at preventing such diseases.
“When I evaluate patients with this disorder, I don’t know if they’re going to progress to a neurodegenerative disease or when it might happen or which specific condition they may develop,” said Yo-El Ju, MD, an assistant professor of neurology at the School of Medicine. “Investigational drugs in the pipeline will be ready for testing in two or three years, but before we can do a clinical trial, we need to figure out who may be most likely to benefit.”
REM sleep behavior disorder is a rare diagnosis that affects fewer than five people out of 1,000 in the United States. Cases that are associated with use of antidepressant medication, brain injuries or the sleep disorder narcolepsy are unlikely to develop into other serious neurological diseases. But of people diagnosed with REM sleep behavior disorder with no clear cause, more than half go on to develop Parkinson’s disease, Lewy body dementia or multiple systems atrophy – which is characterized by Parkinson’s-like symptoms, plus problems with balance, blood pressure regulation, and bladder control – within 10 years.
The sleep movements can be treated with melatonin or other medications. But while such treatment may make it easier to share a bed with someone with the disorder, it does nothing to forestall neurological decline.
The link between acting out dreams and neurodegeneration comes down to a brain protein known as alpha-synuclein that can form toxic clumps. Such clumps often first coalesce in a part of the brain that paralyzes the body during REM (or dreaming) sleep. As that area becomes damaged, people start thrashing around as they dream. Over time, synuclein clusters continue to accumulate and injure ever larger areas of the brain, causing neurodegenerative diseases.