In two papers in the July 8 issue of the journal Neurology, the team reports apparent links between deficits in brain chemistry and obstructive sleep apnea (OSA) and REM sleep behavior disorder (RBD). Both are relatively common sleep problems that disturb the slumber -- and daytime behavior -- of millions of Americans.
The new findings were made using two types of neurochemical brain scans and detailed sleep studies in 13 patients with multiple system atrophy (MSA), a rare and fatal degenerative neurological disease almost always accompanied by severe sleep disorders. Their results from the MSA patients, who all had both sleep apnea and REM behavior disorder, were very different from those of 27 healthy control subjects.
Specifically, the researchers found that MSA patients had a far lower density of certain brain cells, or neurons, that produce the key chemicals dopamine and acetylcholine. The greater their lack, the worse their sleep problems were.
The patients with the fewest dopamine-producing neurons in the striatum of their brains had the worst RBD symptoms of thrashing, talking and violent flailing while they slept. And patients with the lowest levels of acetylcholine-producing neurons in the brainstem had the most interruptions in their breathing during sleep.
And while the researchers are careful to note that their findings to date can only show a correlation, not causation, between brain chemistry and sleep disorders, they plan further research to explore the relationship.
"It's exciting to be able to show this major neurochemical deficit for the first time, and confirm what others have suspected," says lead author Sid Gilman, M.D., F.R.C.P., the William J. Herdman Prof
Contact: Kara Gavin
University of Michigan Health System