Daytime Sleepiness a Possible Predictor of Alzheimer’s

Frequent daytime drowsiness in otherwise healthy adults may be a warning sign of Alzheimer’s later in life, according to a new study published in the journal Sleep. 

Researchers assessed 124 participants (mean age, 60.1 years) and asked them, “Do you often become drowsy or fall asleep during the daytime when you wish to be awake? (e.g. falling asleep while watching TV or reading)” and “Do you nap?” with response options of “daily,” “1–2 times/week,” “3–5 times/week,” and “rarely or never.” An average of 15.7 years after answering the questions, participants underwent a brain scan looking for β-amyloid (Aβ), the main component of the amyloid plaques found in the brains of Alzheimer’s patients. 

At baseline, 24.4% of participants reported excessive daytime sleepiness (EDS), and 28.5% said they nap during the day. There was no correlation between EDS and napping. 

When adjusting for confounding factors, those with EDS were 2.75 times more likely to have Aβ in the brain than those without it; in unadjusted analyses, the rate was 3.37. Nappers were 1.86 times as likely than non-nappers to have Aβ when adjusting for confounding factors, which the study authors called “nonsignificant,” and about twice as likely in unadjusted analyses, which they described as “trend-level.” 

“Factors like diet, exercise and cognitive activity have been widely recognized as important potential targets for Alzheimer’s disease prevention, but sleep hasn’t quite risen to that status — although that may well be changing,” said lead study author Dr. Adam P. Spira, an associate professor in the Department of Mental Health at the Johns Hopkins Bloomberg School of Public Health.  

“If disturbed sleep contributes to Alzheimer’s disease, we may be able to treat patients with sleep issues to avoid these negative outcomes,” he said. 

The study’s results bring up new questions for discussion. While researchers found a correlation between Aβ presence and EDS, the cause and effect remains less clear. Study authors took away four possible interpretations of their data: 

  1. EDS at baseline may have resulted directly from disturbed sleep that itself promotes Aβ deposition 
  2. Baseline EDS resulted indirectly from Aβ deposition 
  3. Rather than being a marker of risk for Aβ deposition, EDS actually promotes Aβ aggregation 
  4. Alterations in circadian rhythms may have played a role in all of the above scenarios 

Additional studies may more definitively identify the link between EDS and Alzheimer’s, which currently has no cure. If and when a cure is developed, prevention strategies will still be important, Spira noted. 

“There is no cure yet for Alzheimer’s disease, so we have to do our best to prevent it. Even if a cure is developed, prevention strategies should be emphasized,” he said. “Prioritizing sleep may be one way to help prevent or perhaps slow this condition.” 

Read about DTHR-ALZ, a product given Breakthrough Device designation created to treat Alzheimer’s. 

Read about how virtual reality helps Alzheimer’s patients. 

Read about the link between kidney hemodialysis and dementia. 

Sources: Sleep, Johns Hopkins Bloomberg School of Public Health