Damage to the brain can occur 15 to 20 years before the clinical symptoms appear.
A disrupted body clock, leading to sleep problems, could be an early sign of Alzheimer’s, research finds.
Changes in the sleep cycle occur much earlier than memory problems or other symptoms of dementia.
The finding is an important sign because damage to the brain can occur 15 to 20 years before the clinical symptoms appear.
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Dr Erik S. Musiek, the study’s first author, said:
“It wasn’t that the people in the study were sleep-deprived.
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.”
Studies in people and animals have now linked poor sleep to higher levels of amyloid protein build-up in the brain.
Amyloid is thought to be a cause of Alzheimer’s.
Dr Musiek said:
“Over two months, mice with disrupted circadian rhythms developed considerably more amyloid plaques than mice with normal rhythms.
The mice also had changes in the normal, daily rhythms of amyloid protein in the brain. It’s the first data demonstrating that the disruption of circadian rhythms could be accelerating the deposition of plaques.”
For the study, 189 normal older adults with an average age of 66 were tracked.
50 of these turned out to have problems with sleep.
Dr Yo-El Ju, study co-author, said:
“In this new study, we found that people with preclinical Alzheimer’s disease had more fragmentation in their circadian activity patterns, with more periods of inactivity or sleep during the day and more periods of activity at night.”
It is not yet known if poor sleep is contributing to Alzheimer’s or whether it is a symptom of the disease’s early stages.
Dr Ju said:
“At the very least, these disruptions in circadian rhythms may serve as a biomarker for preclinical disease.
We want to bring back these subjects in the future to learn more about whether their sleep and circadian rhythm problems lead to increased Alzheimer’s risk or whether the Alzheimer’s disease brain changes cause sleep/wake cycle and circadian problems.”
The study was published in the journal JAMA Neurology (Musiek et al., 2018).
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