New blood markers that reflect risk for Alzheimer’s disease (AD) are uncovering important modifiable risk factors to be aware of to dramatically reduce the likelihood of ever suffering from this cruel disease. The latest study shows that just one night of sleep disruption is associated with an increase in these blood markers.
The primary brain lesions of AD are the result of deposits of a substance known as beta-amyloid. Although the immune cells in the brain normally remove beta-amyloid and plaque, research is beginning to characterize a chronic and excessive inflammatory reaction to amyloid proteins in the brain in susceptible individuals that can promote AD. Blood measurements of a protein called tau that is formed from toxic beta-amyloid as well as a protein that acts as the internal skeleton of brain cells known neurofilament light chain (NfL) protein can predict neurodegeneration years before clinical symptoms appear in AD. When brain cells are damaged, tau and NfL are released into cerebrospinal fluid and then the blood.
Background Data:
Poor sleep quality is associated with a significant risk for Alzheimer’s disease. For example, researchers from the Washington University School of Medicine in St. Louis found that the inability to sleep through the night was associated with an increased risk the preclinical form of Alzheimer’s disease. Subjects who were the least efficient sleepers in the study were five times more likely to have preclinical form of Alzheimer’s. While researchers are exploring the formation of the beta-amyloid as being the cause of the poor sleep quality, a more likely explanation is that the poor sleep quality is actually the cause of the beta-amyloid formation.
During the deeper levels of sleep the repair mechanisms and antioxidant system of brain cells are heightened. Sleeping pills seem to exacerbate this situation. Use of sedative hypnotic drugs (sleeping pills) was associated with a whopping 230% increase risk of AD over an eight-year period in a study in France while in a study in the U.K., the risk was even greater over a 22-year follow up study– a dramatic 294% increase. The link between sleeping pill usage and the dramatic increased risk for AD may be the result of the fact that these drugs typically negatively impact the ability to achieve deeper levels of sleep.
New Data:
In a study conducted at Uppsala University in Sweden, researchers wanted to see whether acute sleep loss alters levels of the biomarkers that are associated with AD. Using a crossover design, 15 healthy young men participated in 2 standardized in-lab sessions with two different conditions — one night of normal sleep and one night of overnight sleep deprivation.
Levels of total tau and neurofilament light chain (NfL) were analyzed using ultrasensitive assays in plasma samples obtained in the evening prior to, and in the morning after, each intervention.
The biggest effect noted was an evening to morning increase in plasma levels of total tau following the acute sleep loss condition, while levels of total tau decreased in the normal sleep condition. No differences were found between the two conditions for the evening to morning change in plasma NfL levels. NfL is a marker of brain cell damage, while tau is a more preliminary finding.
The significance of the study was the fact that the increase in plasma tau was seen in just one night of overnight sleep loss.
Commentary:
One of the key underlying causes of poor sleep is faulty blood sugar control. Basically, most people with sleep maintenance issues are on the “blood sugar rollercoaster.” When blood sugar levels drop rapidly during the night it causes the release of cortisol and adrenaline leading to arousal and difficulty in getting back to sleep. Insulin resistance is the key factor in causing the blood sugar rollercoaster and is also a key risk factor for AD. In fact, AD is often popularly referred to as “diabetes of the brain” and even “type 3 diabetes.”
Obviously, taking a sleeping pill does not address the underlying cause of the poor sleep quality and looks like it makes the situation even worse. Instead the key focus should be on improving insulin sensitivity and stabilizing blood sugar levels.
Reference:
Brooks M. Acute Sleep Loss Increases Blood Levels of Alzheimer’s Biomarker. Medscape, June 11, 2019.