The body clock can show early Alzheimer's disease signs indicated through circadian rhythm disruptions before memory loss is experienced, according to a study earlier this year by Washington University School of Medicine in St. Louis.
The study's findings, which were published in January in the journal JAMA Neurology, could assist doctors in identifying people at the risk of Alzheimer's earlier than is currently possible, the Washington University statement said.
Alzheimer's damage can start in the brain some 15 to 20 years before clinical symptoms start to show, according to the statement.
"It wasn't that the people in the study were sleep-deprived," study coauthor Dr. Erik S. Musiek, an assistant professor of neurology at Washington University, said in the statement. "But their sleep tended to be fragmented. Sleeping for eight hours at night is very different from getting eight hours of sleep in one-hour increments during daytime naps."
The study, which was featured on Knowridge Science Report on July 15, tracked circadian rhythms in 189 cognitively normal, older adults with an average age of 66, the Washington University statement said. Of the participants, 139 had no evidence of the amyloid protein that signifies preclinical Alzheimer's. Most had normal sleep/wake cycles, although several had circadian disruptions that were linked to advanced age, sleep apnea or other causes.
The study stated, that among the other 50 subjects -- who either had abnormal brain scans or abnormal cerebrospinal fluid -- all experienced significant disruptions in their internal body clocks, determined by how much rest they got at night and how active they were during the day, the Washington University statement said.
The statement stated that researchers also conducted a separate study in mice, which was in The Journal of Experimental Medicine on Jan. 30, showing that similar circadian disruptions accelerate the development of amyloid plaques in the brain, which are linked to Alzheimer's.
In another study, the University Cambridge discovered that in fruit flies with Alzheimer's that their the biological clock remained functioning but had become uncoupled from the sleep-wake cycle it usually regulates, according to Alzheimer's and Dementia Weekly in April.
"We wanted to know whether people with Alzheimer's disease have a poor behavioral rhythm because they have a clock that's stopped ticking or they have stopped responding to the clock,"
Dr. Damian Crowther, of Cambridge's Department of Genetics, said about the study.
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