Scientists from the University of California, Los Angeles (UCLA) have found that ongoing loss of cells from the brain’s breathing command center is the likely mechanism behind many deaths where people stop breathing during sleep.

The research, funded by the National Heart, Lung and Blood Institute, appeared in the online edition of the journal Nature Neuroscience on Sunday.

The UCLA scientists believe that many elderly deaths during sleep, normally attributed to heart attacks, might actually be due to age-related loss of brain cells known as preBötC neurons. The research could provide clues for future treatments.

“Sleep-disordered breathing is highly prevalent in elderly humans and in some patients with neurodegenerative disease,” wrote the researchers. “We propose that sleep-disordered breathing results from loss of preBötC neurons and could underlie death during sleep in these populations.”

PreBötC neurons are found in a region of the brainstem known as the preBötzinger complex, which acts as a breathing command center in mammals.

The UCLA scientists specifically destroyed preBötC neurons and studied the effects on the breathing rhythm of rats while they were wide awake and fast asleep.

Rat Dreams

As the rats cumulatively lost PreBötC neurons during the experiment, they seemed healthy while awake, but started having breathing problems during sleep. After a few days, the rats could no longer breathe during the “dreaming period of sleep,” known as REM (rapid eye movement).

“Breathing completely stopped when the rat entered REM sleep, forcing the rat to wake up in order to start breathing again," said Leanne McKay, postdoctoral fellow in neurobiology at UCLA.

Eventually, the breathing problems spread to other periods of sleep and then to when the rats were awake.

“Essentially, we sped up these cells’ aging process in the rats over several days instead of a lifetime,” said Jack Feldman, principal investigator and professor of neurobiology at UCLA’s David Geffen School of Medicine.

Mr. Feldman believes that we start life with a few thousand PreBötC neurons and slowly lose them as we grow older. He now plans to study the brains of people who have died from neurodegenerative diseases to look for signs of damage in their preBötzinger complexes.

The Pharmaceutical Research and Manufacturers of America (PhRMA), a pharmaceutical industry organization, lists five companies currently running clinical trials for sleep disorders.

These are Organon, of West Orange, New Jersey; Cephalon, of West Chester, Pennsylvania; Takeda Pharmaceuticals America, of Lincolnshire, Illinois; and the pharmaceutical giants Pfizer and Sanofi-Synthelabo, both based in New York City.