In a new study, researchers have shown that excessive sleepiness during the day time among elderly who had normal mental acuity and cognitive powers is associated with the buildup of amyloid plaques in the brain that is typical of Alzheimer’s disease.
The researchers explain that this deposit of the amyloid plaques within the brain is one of the preclinical stages of Alzheimer’s disease and may be seen much before any of the signs of dementia appear. The study was published in the latest issue of the journal JAMA Neurology.
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Study author Prashanthi Vemuri, an associate professor of radiology at the Mayo Clinic in Rochester, Minn., explained the study saying that it is known that sleep clears the toxins and beta amyloid proteins that buildup in the brain. It is also known that beta amyloid in the brain leads to sleep disruptions. He called this a “chicken and egg” problem. To understand exactly what was leading to what he said, they embarked upon this study to see if “excessive daytime sleepiness causes an increase of amyloid over time in people without dementia.” They found that this was indeed true.
For this study the team included 283 elderly individuals over the age of 70 years. The average age of the population was 77. These individuals were part of the Mayo Clinic Study of Aging conducted at Olmsted County, Minnesota. For this study they had to undergo a baseline scan and then again another one at a later stage. They were given a sleep quality questionnaire to fill up and were tested for any signs of dementia. The team looked at buildup of amyloid in the brains of these individuals with time.
Results revealed that those who complained of excessive drowsiness during the day were most likely to have increased amounts of amyloids in their brains over the two year study period. These amyloid deposits were most likely to occur in the regions of the brain that are responsible for memory recall, behavior and emotions viz. the anterior cingulate and cingulate precuneus. Overall 22 percent of the participants complained of excessive daytime sleepiness.
One of the limitations of the study was that it did not take into account the sleep problems at night such as insomnia or obstructive sleep apnea or restless legs syndrome etc that could be leading to daytime fatigue and drowsiness. These need to be taken into consideration say experts. Disrupted night sleep is a common problem affecting one third of Americans according to the US Centers for Disease Control and Prevention (CDC).
Bryce Mander of the University of California, Irvine and Joseph Winer of the University of California, Berkeley wrote an accompanying editorial with this study and they said that this study was the first to make this connection. More research is necessary say experts, but as of now increased daytime sleepiness could serve as a warning sign to get checked up for dementia as well as preclinical stages of Alzheimer’s disease along with other sleep related problems.