Does Sleep Apnea Increase the Risk for Alzheimer Disease?
According to a new study, apneas are significantly associated with elevated tau levels, thus raising the possibility that sleep apnea has an impact on tau accumulation.1
The study, which was authored by Diego Z. Carvalho, MD, and colleagues at the Mayo Clinic, will be presented at the American Academy of Neurology’s 71st Annual Meeting in May.
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To assess whether witnessed apneas in elderly people who are not cognitively impaired are associated with higher levels of tau, the researchers identified 288 participants aged 65 years or older from the population-based Mayo Clinic Study of Aging. All participants had both tau- and amyloid-positron emission tomography scans.
The number of witnessed apneas during sleep were gathered through questionnaires that the participants’ bed partners completed.
To evaluate for any association between tau levels and apneas, the researchers analyzed the entorhinal cortex because of its high susceptibility to tau accumulation, as well as the cerebellum crus as a reference region.
In all, bed partners reported having witnessed apneas during 43 of the participants’ sleep.
After controlling for factors such as body mass index, hypertension, reduced sleep, and global amyloid, the researchers determined that the apneas were significantly associated with tau in the entorhinal cortex. In fact, the 15% of participants who had had apneas had, on average, 4.5% higher levels of tau in the entorhinal cortex than those who did not have apneas.
“Our research results raise the possibility that sleep apnea affects tau accumulation,” said Carvalho. “But it is also possible that higher levels of tau in other regions may predispose a person to sleep apnea, so longer studies are now needed to solve this chicken and egg problem.”2
—Colleen Murphy
References:
1. Carvalho D, St. Louis E, Boeve B, et al. Witnessed apneas during sleep are associated with elevated tau-PET signal in the entorhinal cortex in cognitively unimpaired elderly [published online March 3, 2019]. https://www.aan.com/PressRoom/Home/GetDigitalAsset/12894.
2. Sleep apnea may be linked to higher levels of Alzheimer’s biomarker in brain [press release]. Minneapolis, MN: American Academy of Neurology; May 4-10, 2019. https://www.aan.com/PressRoom/Home/PressRelease/2699. Accessed March 4, 2019.