A new study has revealed that people with obstructive sleep apnea or those who snore at night are more at risk of dementias and Alzheimer’s disease. It has been noted that these individuals may have a high accumulation of the toxic protein tau in their brains. The area involved in these depositions is usually the one which is vital for memory, time perception and navigation.
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The study was released early this week by the Mayo Clinic and is to be presented at the American Academy of Neurology's annual meeting in Philadelphia (between 4th and 10th of May this year).
This is one of the first studies that prove an association between dementia and disruption of sleep. Among patients with sleep apnea, there is repeated stopping of breathing during sleep. This leads to a night of interrupted sleep and is followed by a day of sleepiness.
Lead study author Dr. Diego Z. Carvalho, a neurology fellow at Mayo, in a statement said, “Our research results raise the possibility that sleep apnea affects tau accumulation.” He said, “Since tau accumulation is a hallmark of Alzheimer's disease, an increase in tau raises concern that sleep apnea could make [people] with sleep apnea more vulnerable to Alzheimer's.”
The researchers at the Mayo Clinic performed a Study of Aging and found 288 people aged 65 or more with no signs and symptoms of dementia. The participants were asked to track their snoring at night including number of times that they stopped breathing. Their brains were scanned and presence of a toxic protein called tau in the regions of entorhinal cortex of the brain was noted. This region is deep within the brain behind the nose. This area is normally susceptible to accumulation of tau protein in Alzheimer’s patients. Carvalho explains that this region of the brain is responsible for many function including time and visual perception and memory. If tangles of tau protein accumulate at this region, there is a risk of cognitive decline.
Results showed that 43 participants or 15 percent of the population suffered from sleep apnea as witnessed by their bed partners. Participants who were suffering from sleep apnea had 4.5 percent more tau in the entorhinal cortex than those who had a peaceful sleep. Several factors were accounted for to ensure that the association was clear. This included the participant’s age, gender, education, heart disease risk, other sleep problems etc.
Carvalho said that they noted that there is an association between sleep apnea and Alzheimer’s disease but it is a “chicken and egg problem.” “However, it is also possible that Alzheimer's disease could predispose people to sleep apnea or that there is a bidirectional relationship between sleep apnea and Alzheimer's disease,” Carvalho said. He calls for longer term studies to prove this association. Meanwhile, “people who have apneas during sleep should seek medical attention to confirm the diagnosis of sleep apnea and treat it, if indicated,” Carvalho said.
Rebecca Edelmayer, director of scientific engagement at the Alzheimer's Association, reviewed the study. She said, “These findings align with a lot of the data we've seen with sleep disturbances increasing the risk for cognitive impairment.”
The study was supported by the U.S. National Institutes of Health.