Slow-wave Sleep may instigate Alzheimer’s disease: Research

KARACHI- A study was recently carried out at the Washington University School of Medicine in the United States of America, regarding Alzheimer’s Disease and its correlation with Deep Sleep.

The findings of this study suggested that, poor quality sleep may deteriorate brain health during later years of life.

Researchers of this study mentioned that, Old age people who get less deep sleep have higher levels of a brain protein called ‘tau,’ which is an indicator cognitive decline and Alzheimer’s disease. According to them, slow-wave sleep is the deep sleep people need to consolidate memories and wake up feeling refreshed.

Assistant Prof. Brendan Lucey, Washington University School of Medicine discussed about the inverse relationship between decreased slow-wave sleep and an increase in tau protein.

She further stated that, “Reduced slow-wave activity may be a marker for the transition between normal and impaired. Measuring how people sleep may be a non-invasive way to screen for Alzheimer’s disease before or just as people begin to develop problems with memory and thinking.”

Alzheimer’s, a disease that affects an estimated 5.7 million Americans, progresses slowly and silently.

Up to 2 decades before the characteristic symptoms of memory loss and confusion appear, amyloid beta protein begins to form plaques in the brain, followed by tangles of tau protein, that leads to the atrophy of brain tissues. This is when people start showing unmistakable signs of cognitive decline.

The challenge faced by researchers is to finding people on track to develop Alzheimer’s before such brain changes, undermining their ability to think clearly. For that, sleep may be a handy marker.

Assistant Prof. Lucey, Prof. David Holtzman, alongside colleagues from Washington University studied 119 people, 60 years of age or older.

These participants were given a portable EEG monitor that was strapped to their foreheads to measure brain waves as they slept, as well as a wristwatch-like sensor that tracks body movement and were asked to keep sleep logs. Each participant produced at least 2 nights of data; some had as many as 6.

The researchers measured levels of amyloid beta and tau in the brain and in the cerebrospinal fluid that bathes the brain and spinal cord. 38 people underwent PET brain scans for the two proteins, and 104 people underwent spinal taps to provide cerebrospinal fluid for analysis. 27 participants did both.

After controlling factors such as sex, age and movements while sleeping; the researchers found that decreased slow-wave sleep coincided with increased levels of tau in the brain and a higher tau-to-amyloid ratio in the cerebrospinal fluid.

These findings lead to the conclusion that, the total amount of sleep wasn’t linked to tau but, it was the slow-wave sleep that reflected quality of sleep. It was noted that, people with increased tau pathology were noticed to be sleeping more at night and napping more in the day, but they weren’t getting quality sleep.