Daytime sleepiness and Alzheimer’s risk: What you need to know

Kevin Lomangino is the managing editor of He tweets as @KLomangino.

Older adults who reported excessive daytime sleepiness were also more likely to have increasing levels of a protein called beta-amyloid in their brains over time, according to a study in JAMA Neurology.

Beta amyloid deposits are one of several pathologic signs of Alzheimer’s disease.

It’s an intriguing finding, and one that adds to a body of literature suggesting that sleep may be one of the many factors that could play a role in the development of the disease — or its prevention.

But it does not justify the misleading headlines that some news organizations slapped on their stories about the study, such as this one from CNN:

Why this is wrong: The study involved healthy older adults and did not try to assess whether the participants developed Alzheimer’s disease. So any claim that sleep disturbances increased the risk of this condition goes far beyond what the evidence can support.

What the researchers did assess was participant’s self-reported levels of excessive daytime sleepiness. They also performed scans that showed levels of beta-amyloid in participants’ brains over the course of the six-year study.

Results showed that excessively sleepy individuals were more likely to have a buildup of beta-amyloid than their counterparts who didn’t report excessive sleepiness.

Daytime sleepiness and Alzheimer’s risk

However, this does not mean that sleepiness caused the beta-amyloid to accumulate, says Harold DeMonaco, MS, a visiting scientist at the MIT Sloan School of Management and one of our expert story reviewers.

“There is a difference between association and causation. Daytime sleepiness may indeed be a cause of beta-amyloid accumulation or it may be the result of other factors that support accumulation. The chicken or the egg analogy is apt here. Suggesting that intervening in daytime sleepiness will lower the risk of the development of dementia is a bit of a stretch not supported by the study.”

We see this problem all the time with stories about Alzheimer’s disease, which often don’t acknowledge that beta amyloid isn’t proven to cause the condition, and that removing it won’t necessarily prevent or treat it.

Some people with extensive buildup of beta amyloid simply don’t develop Alzheimer’s disease. And some people with Alzheimer’s disease don’t have an excessive buildup of beta amyloid.

Moreover, it’s downright frightening to suggest that “daytime drowsiness” — something commonly experienced by both older and younger adults alike — could be a trigger for this terrible illness.

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