Science Update

New study demonstrates the impact of sleep disturbance on cognitive decline

Alzheimer’s disease and related disorders (ADRD) are a group of conditions that cause mild cognitive impairment (MCI) or dementia. These conditions affect one’s ability to function socially, personally, and professionally. It’s important to recognize that Alzheimer’s disease begins long before symptoms start just like many other conditions. There is evidence that simple prevention strategies can reduce the risk of ADRD by as much as 50%.

According to a new study published last week, researchers demonstrate how sleep disruption increases amyloid beta and tau proteins, which are associated with ADRD.

This study consisted of 20 healthy individuals 22-72 years of age. Researchers measured human brain Aβ burden (ABB) using PET scans, assessing the impact of one night of sleep deprivation on Aβ clearance from the brain. These results were compared to baseline values from the same time of day but following a night of rested sleep.

As a result, increases in ABB after sleep deprivation were seen in the hippocampus and thalamus. The hippocampus is considered to be one of the most sensitive brain regions for Alzheimer’s disease pathology and the thalamus has increased Aβ in early stages of the disease.

Previous studies have shown that poor sleep increased the risk of cognitive problems.

I shared a study last July from the journal Brain in which researchers demonstrated how sleep disruption increases amyloid beta and tau proteins. In this study, 17 adults ages 35 to 65 with no sleep issues or cognitive impairment wore a sleep monitor for up to two weeks, tracking how much they slept each night.

After five or more nights of tracking their sleep, each participant went on site and had their brain waves monitored during sleep. Half the participants randomly had their sleep disrupted. These individuals reported feeling tired and unrefreshed even though they slept just as long as usual and rarely recalled being awakened during the night. Each person had a spinal tap to measure the levels of amyloid beta and tau in the CSF fluid.

After a month or so this process was repeated, except that those who had their sleep disrupted the first time slept undisturbed and those who had slept uninterrupted initially were disrupted when they began to enter deep slow-wave sleep. This is the time when neurons rest and the brain clears away the molecular byproducts of mental activity that accumulate during the day.

The researcher team then compared each individual’s amyloid beta and tau levels after the disrupted night to the levels after the uninterrupted night and found a 10% increase in amyloid beta levels after a single night of interrupted sleep but no increase in tau protein levels. However, individuals whose sleep monitors showed they had slept poorly at home for the week prior to the spinal tap showed a spike in tau levels. Amyloid levels normally change more quickly than tau, so this was not surprising.

It is highly unlikely that there is an overall increased risk of developing ADRD simply from a single bad night or a week of poor sleep.  Amyloid beta and tau protein levels will go back down after the next restful night of sleep; the main issue concerns those with chronic sleep issues. This can lead to chronically elevated amyloid levels, thus, leading to increased risk of ADRD.

It is important to address the environment to promote restful sleep. Limiting the use of screens at bedtime is critical, albeit very difficult to do in today’s society. If necessary, I would recommend using the Night Shift feature on smartphones and f.lux  on laptops. In addition, it is important to go to sleep around the same time every night. When the timing of your sleep is shifted (even if the duration of sleep is the same) the end result is not going to be as restorative. Since caffeine and other stimulants can keep you up and interfere with sleep, it is best to avoid these four to six hours before bedtime. Finally, workouts are best done earlier in the day. Exercise increases cortisol and can make it difficult to fall asleep. If this is not possible, consider phosphatidylserine  post-workout. Other nutrients to consider to help restore sleep include magnesium l-threonate, valerian root, passionflower, lemon balm, and melatonin.

By Michael Jurgelewicz, DC, DACBN, DCBCN, CNS


Source: Shokri-Kojori E, Wang GJ, et al. β-Amyloid accumulation in the human brain after one night of sleep deprivation. Proc Natl Acad Sci USA. 2018 Apr 9. pii: 201721694. doi: 10.1073/pnas.1721694115.