A new study shows that excessive daytime sleepiness in cognitively normal elderly people leads to a build-up of a plaque in the brain called amyloid, which is linked to Alzheimer’s.
Deposited amyloid in brain tissue is the first known preclinical stage of Alzheimer's and happens well before any obvious symptoms of dementia begin.
The researchers were motivated to look at the relationship between excessive daytime sleepiness – defined for the study as "difficulty in maintaining desired wakefulness or as a complaint of an excessive amount of sleep" – and neurodegenerative disease due to several links found by previous studies.
The researchers analysed data from 283 participants aged 70 or older who had been recruited through the Mayo Clinic. None of the participants had an existing diagnosis of dementia. At recruitment, everyone completed surveys reporting their degree of daytime sleepiness.
Participants also agreed to undergo at least two consecutive positron emission tomography (PET) brain scans between 2009 and 2016.
The scientists found that 63 participants qualified as experiencing excessive daytime sleepiness. In these people, this state was also associated with increased levels of beta-amyloid in two relevant regions of the brain.
"Our study showed," they say, "that [excessive daytime sleepiness] in elderly persons without dementia may be associated with longitudinal [beta-amyloid] accumulation."
They continue, saying, "This finding supports previous literature suggesting that [excessive daytime sleepiness] is a risk factor for cognitive decline or dementia."
However, they admit that the study has some limitations, including the fact that it lacked "objective measures of sleep disturbance", and that it did not assess exactly how much sleep the participants were getting per night.
Do you find yourself getting sleepier throughout the day? Are you worried about these findings?
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