REM sleep behavior disorder (RBD) is a condition that causes a person to physically act out their dreams and is a common in Lewy body dementia (LBD). RBD is a known risk factor in men for all Lewy body disorders, including LBD, Parkinson’s disease and multiple system atrophy; it is not as strongly associated with Lewy body disorders in women. New research indicates that the presence of RBD in men with dementia is a strong indicator of Lewy body dementia over Alzheimer’s disease.
Researchers at Mayo Clinic studied the medical histories of 75 individuals with autopsy-confirmed dementia with Lewy bodies (DLB). During the course of their lives, each individual underwent magnetic resonance imaging and were assessed for a history of RBD. Of those studied, 35 people had a history of RBD. Individuals with a history of RBD were found to have lower levels of Alzheimer’s pathology upon autopsy; during life, their MRI scans revealed higher volumes of brain matter in parts of the brain usually atrophied in Alzheimer’s disease. Those who did not have RBD had higher levels of Alzheimer’s pathology upon autopsy and more brain atrophy typical of Alzheimer’s disease during life compared to those with RBD.
The odds of a pathological diagnosis of DLB in men, was five times higher than Alzheimer’s for those with RBD, other features of DLB and preserved volume of the hippocampus. In fact, RBD was found to have increased the odds of a DLB pathological diagnosis more than Parkinsonism, cognitive fluctuations or visual hallucinations, the other differentiating symptoms of DLB.
This research suggests that RBD may play a more significant role in diagnosing DLB, compared to other DLB symptoms. Screening for RBD may be an effective way to determine the underlying cause of dementia, as only 2-3 percent of people with Alzheimer’s have a history of RBD.
“While it is, of course, true that not everyone who has this sleep disorder develops dementia with Lewy bodies, as many as 75 to 80 percent of men with dementia with Lewy bodies in our Mayo database did experience REM sleep behavior disorder. So it is a very powerful marker for the disease,” says lead author Melissa Murray, Ph.D., a neuroscientist at the Mayo Clinic in Jacksonville, Florida.
This research was presented at the American Academy of Neurology annual meeting in San Diego, CA in March. Principle investigator and the senior author of the study was Kejal Kantarci MD, MS. LBDA Scientific Advisory Council members who collaborated on this study included Tanis Ferman, Ph.D, Bradley Boeve, MD, and Dennis Dickson, MD. Funding for this research was provided by the National Institutes of Health, the Harry T. Mangurian, Jr. Foundation, and Robert and Clarice Smith and Abigail Van Buren Alzheimer's Disease Research Program.