BOSTON—Although attempts to reduce cognitive deficits by improving sleep have produced mixed results, some data indicate that this strategy may hold promise, according to research reported at the 26th Annual Meeting of the Associated Professional Sleep Societies. Further studies, including trials of sedatives/hypnotics, could clarify the relationship between sleep and cognition, said Donald Bliwise, PhD, Professor of Neurology at Emory University in Atlanta.
Sleep Loss and Protein Aggregation
David Holtzman, MD, Chair of Neurology at Washington University in St. Louis, and colleagues found that sleep deprivation raised levels of amyloid-β in the brains of vulnerable mice. “This is the same protein that tends to aggregate in Alzheimer’s disease,” said Dr. Bliwise. “It certainly is a provocative finding.”
When the researchers restricted animals’ sleep for 20 of 24 hours over 21 days, they found accumulations of amyloid-β throughout the brains. “This is fairly convincing data that sleep might be important here, particularly if an animal or human is deprived of it,” said Dr. Bliwise.
Hypoxia and Cognitive Impairment
Animal studies also have suggested a link between hypoxia, which often results from sleep-disordered breathing, and cognitive impairment. Michael J. Decker, PhD, Associate Professor of Neuroscience at Georgia State University in Atlanta, subjected rat pups to several hours of intermittent hypoxia per day for four days. When he sacrificed the animals 80 days later, he found various changes in their dopamine systems, including an upregulation of their dopamine transporters. The results suggest that hypoxia can impair neurotransmitter systems, said Dr. Bliwise.
David Gozal, MD, Chair of Pediatrics at the University of Chicago School of Medicine, exposed young and old animals to 12 hours of intermittent hypoxia per day for two weeks. The elderly animals experienced much more cell death than younger animals did, which indicates that sleep apnea could hasten degeneration, according to Dr. Bliwise.