The Link Between Sleep and Alzheimer’s

July 5, 2018

An estimated 1 in 3 Americans suffers from some sort of sleep deprivation – perhaps you’re one of them. Although lack of sleep is certainly a common struggle for many of us, it’s taken seriously in the medical community as a possible risk factor in everything from diabetes to depression to heart disease. Experts are now adding Alzheimer’s to that list, thanks to a growing collection of data connecting sleep deprivation not only with dementia, but also with the formulation of beta-amyloid plaque in the brain – the protein linked to Alzheimer’s disease.

There are three studies in particular that make a strong case that experts may be onto something. First, let’s look at one recently reported in the journal Neurology. Its authors tracked 321 participants in the famous Framingham Heart Study, all average age 61, over the course of a 12-year period. Researchers measured subjects’ sleep cycles, focusing on the REM phase – the deepest stage of sleep in which dream activity occurs and which usually takes an average of 90 minutes to reach. Over the course of their research, 32 people in their study group developed dementia; of that number, 24 were diagnosed with Alzheimer’s. Those participants who took longer than 90 minutes to reach REM were found more likely to develop dementia, and dreamed only 17% of their overall sleep cycle (the study average was 20%). No other sleep cycle was found to have any association with dementia onset.

Scientists at UC Berkeley took this research a step further, tracking the formation of beta-amyloid plaques in the brains of study subjects who lacked sufficient REM sleep. The study focused on 25 people aged 65 to 81 who had not been diagnosed with any form of dementia or sleep disorder. Those participants who struggled the most to achieve REM cycle exhibited the highest concentration of beta-amyloid proteins in their brain scans. One caveat:  since the mere presence of beta-amyloid plaques is known to inhibit sleep quality, there’s a bit of a chicken-and-egg aspect to their relationship with sleep cycles. Poor sleep seems to lead to these plaques forming, which in turn results in poor sleep. The authors noted this vicious cycle aspect as something to factor in, and as reason for additional research.

Finally, there’s one study that seems to indicate the damage that only a single night of disrupted sleep can cause. Scientists at the National Institutes of Health performed baseline PET scans on 20 healthy people, which they then repeated after one night of induced sleep deprivation. The follow up scans showed a significant increase in the levels of beta-amyloid plaques in the participants’ brains; even more notable were the locations of these increases – namely, the right hippocampus and the thalamus, regions largely associated with Alzheimer’s disease. But again, a caveat: NIH researchers point out that, because a decent night’s sleep serves to flush these harmful plaques out of the brain, further research is necessary to better understand the long-term cumulative affects of poor sleep on one’s risk for dementia.

There’s lots more happening on the topic that deserves our attention. As always, head to the Alzheimer’s Association website for all the latest news and updates.