Mayo Clinic Links Sleep and Dementia Risks

Researchers at the Mayo Clinic have found a link between a specific sleep disorder and men who later develop dementia with Lewy bodies -- the second more common form of age-related memory impairment after Alzheimer's Disease.

When most of us enter into a stage of sleep known as Rapid Eye Movement (REM), our bodies are still while our minds dream. But for some with a disorder called REM Sleep Behavior Disorder, their bodies actually move as if they are acting out their dream while they are asleep. And often those dreams are more like nightmares.
In the Mayo Clinic study, researchers looked at 75 patients with the sleep disorder and found those who acted out their dreams were more likely decades later to also develop symptoms associated with Lewy Body, including parkinsonisms and hallucinations. Those characteristics often help distinguish Lewy Body dementia from Alzheimer's.

From a U.S. News & World Report article:

"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," study lead investigator Melissa Murray, a neuroscientist at Mayo Clinic in Florida, said in a Mayo news release.

She said these findings could improve diagnosis and treatment of this type of dementia.

"Screening for the sleep disorder in a patient with dementia could help clinicians diagnose either dementia with Lewy bodies or Alzheimer's disease," Murray said. "It can sometimes be very difficult to tell the difference between these two dementias, especially in the early stages, but we have found that only 2 to 3 percent of patients with Alzheimer's disease have a history of this sleep disorder."