Disabling a gene that is responsible for controlling our internal clocks leads to patterns of brain damage similar to that which is seen in Alzheimer's disease, according to a new study in mice.
Researchers say the findings shed some light on the link between sleep problems and Alzheimer's disease (Alzheimer's risk goes up with sleep loss, and disrupted sleep is considered a first sign of the disease).
"Normally in the hours leading up to midday, the brain increases its production of certain antioxidant enzymes, which help clean up free radicals," study researcher Erik Musiek, M.D., Ph.D., an assistant professor of neurology at the Washington University School of Medicine in St. Louis, explained in a statement. "When clock genes are disabled, though, this surge no longer occurs, and the free radicals may linger in the brain and cause more damage."
The study, published in The Journal of Clinical Investigation and conducted by researchers at the Washington University School of Medicine in St. Louis and the University of Pennsylvania, involved mice that were engineered to lack a gene called Bmal1, which controls the internal clock. Mice that have this gene naturally sleep during the day and stay awake at night, but mice that are missing this gene sleep a bit in both the day and the night.
Researchers found that as the mice got older, they had evidence of brain cell damage that looked similar to that seen in Alzheimer's disease, and the extent of the damage was greater than would be seen in normally aging mice.
"Many of the injuries appear to be caused by free radicals, which are byproducts of metabolism. If free radicals come into contact with brain cells or other tissue, they can cause damaging chemical reactions," Musiek said in the statement.