REM sleep behaviour disorder and Parkinson’s

Preclinical and Diagnostic Biomarkers of Parkinson’s disease: MRI investigations in patients with REM sleep behaviour disorder and Parkinson’s disease

REM sleep behaviour disorder is a relatively uncommon condition during which people act out their dreams while asleep, sometimes injuring their partners or themselves. Up to 80 percent of people with this disorder later develop Parkinson’s disease, multiple systems atrophy or Lewy body dementia.

At Western University, Dr. Penny MacDonald, a neurologist, uses sophisticated Magnetic Resonance Imaging (MRI) technology to scan the brains of people with this sleep disorder. She’s checking for differences in the striatum region and sub-regions of the brain.

“One of the problems is that most therapies that we’ve tried to either slow, halt, or reverse Parkinson’s disease are not effective,” says MacDonald, the Canada Research Chair in Cognitive Neuroscience and Neuroimaging.

Part of the difficulty is that by the time people are diagnosed, researchers estimate they have already lost 60 to 80 percent of the dopamine-generating brain cells critical for motor control.

“If we could find a biomarker that predicts people who will develop PD, that would allow us to start trying therapies at an earlier disease stage when they might be more effective,” says MacDonald.

MacDonald suspects that her imaging studies will show that the caudal motor portion of the striatum in people with this sleep disorder is smaller and has fewer nerve endings that connect to other regions of the brain. If she is correct, then this structural difference in the striatum could serve as a biomarker.

By administering an MRI, doctors could then determine who is at risk for Parkinson’s and start treatment sooner.

“Maybe they (medications) would have greater efficacy before widespread loss of dopamine-producing cells occurs,” she says.

MacDonald earned a PhD in experimental psychology before she went to medical school to become a neurologist, because her first love was learning about the brain. But she thought research alone would not enable her to make a difference in this crucial field.

“I like to have the opportunity to apply the things that I know,” she says.

She now sees patients one day a week and spends the remainder of her time on research and teaching graduate and medical students.

“It gives me more freedom to do whatever research I want, because I know that at least one day a week I will be doing something very practical to help people, so I can be more adventurous in terms of the research that I pursue.”