- Deep sleep is essential for clearing waste products from the brain, including the toxic protein beta-amyloid, which is implicated in Alzheimer’s disease.
- People who have disrupted breathing during sleep, which manifests as snoring and sleep apnea, may not get enough deep sleep.
- This results in reduced alertness and poor cognitive performance during waking hours, and experts associate it with an increased risk of Alzheimer’s disease.
- A pilot study suggests that a device that restores healthy breathing in sleep can improve cognitive performance of people in the early stages of Alzheimer’s disease.
During deep sleep, the brain flushes away its waste via a network of channels known as the glymphatic system.
The waste products include the toxic proteins alpha-synuclein and beta-amyloid, which are implicated in Parkinson’s disease and Alzheimer’s disease, respectively.
However, a condition that health experts call sleep-disordered breathing (SDB), in which the upper airway of the respiratory tract repeatedly collapses, can disrupt this cleansing process.
Mild SDB causes snoring, but a more severe form known as obstructive sleep apnea (OSA) halts respiration completely for several seconds at a time.
This prevents people from getting a restful sleep, which causes tiredness during waking hours, difficulty concentrating, and problems with memory.
OSA prevents the brain from entering the deepest phase of sleep, or slow wave sleep, which is when the brain’s waste disposal system is most active.
Buildup of toxic proteins
Studies have implicated OSA in the development of Alzheimer’s disease and Parkinson’s disease, possibly as a result of accumulated toxic proteins.
“There are a number of studies showing that sleep apnea increases one’s risk of developing Alzheimer’s disease,” said Jean-Paul Wiegand, Ph.D., preclinical program manager at the Center for Innovation in Brain Science at the University of Arizona Health Sciences in Tucson.
He told Medical News Today that there is also evidence that sleep disturbance can be an early symptom of Alzheimer’s disease.
“Sleep apnea is a multifaceted contributing factor to [Alzheimer’s disease], as it [affects both] sleep quality — and, subsequently, the long-term memory consolidation that occurs during restful sleep, as well as amyloid clearance — and cardiovascular health,” he said.
A 2014 study reports that a common treatment for sleep apnea known as continuous positive airway pressure can slow cognitive decline in people with Alzheimer’s disease.
A new study has found that another treatment, called myTAP, improves respiration patterns during sleep in people who snore.
There were hints in this small pilot study that the treatment may boost cognitive performance in people with mild cognitive impairment and Alzheimer’s disease.
Reduced snoring
myTAP is a customized oral appliance that snaps into place over the teeth. The device draws the lower jaw slightly forward, which facilitates breathing through the nose and reduces snoring.
Health experts believe that breathing through the nose promotes the type of brain activity that is needed to enter deep, or slow wave, sleep.
A team of researchers at the Center for BrainHealth, part of the University of Texas at Dallas and Texas A&M University, carried out a study involving people who snore. The participants were aged 50–85 years.
Of those who started the study, 14 were cognitively healthy, 14 had mild cognitive impairment, and nine had Alzheimer’s disease.
To obtain baseline data, the researchers asked the participants to sleep as normal at home while portable recorders measured their breathing rate, heart rate, and snoring.
During the daytime, clinicians assessed the participants’ memory, executive function, and attention.
The scientists discovered that respiration rate — which is the number of breaths per minute — during sleep fluctuated significantly more in the participants who were cognitively healthy than in those with Alzheimer’s disease.
Some of the participants went on to use the myTAP device at bedtime for 4 weeks. Of these, five were cognitively healthy, seven had mild cognitive impairment, and six had Alzheimer’s disease.
After 4 weeks of treatment, all the participants had a lower maximum breathing rate, which indicates that their quality of sleep had improved.
The improvement was greatest in those with Alzheimer’s disease, followed by those with mild cognitive impairment, then those who were cognitively healthy.
There were also improvements in breathing rate fluctuation, although these results were not statistically significant.
The researchers believe that if larger studies confirm their results, their device could help health professionals diagnose mild cognitive impairment and Alzheimer’s disease in people who snore.
“We saw three distinct patterns amongst the groups of people, meaning we can look for a breathing pattern that might predispose individuals to having dementia,” says Emet Schneiderman, Ph.D., one of the researchers who is a professor in the Department of Biomedical Sciences at Texas A&M University College of Dentistry.
Cognitive improvements
After 4 weeks of treatment, executive and memory function improved significantly in the participants with mild cognitive impairment and in some of the people with Alzheimer’s disease.
Overall, however, the study was too small to identify any statistically significant changes in cognitive performance in the participants with Alzheimer’s disease.
In addition, a longer period of treatment may be needed to see substantial improvements, the researchers believe.
“If we can make significant changes for individuals with mild cognitive impairment, we can slow the onset of Alzheimer’s disease,” says another of the researchers, Dr. Namrata Das, Ph.D., MPH, who is a postdoctoral fellow at McLean Hospital, Harvard Medical School, in Belmont, MA.
The results of the study appear in the journal Geriatrics.
More work needed
The researchers are seeking funding for a follow-up study that will incorporate MRI to detect possible structural changes in the brain with the treatment.
The study will also test for possible changes in the blood levels of beta-amyloid and tau, which are the toxic proteins health experts link with Alzheimer’s disease.
“We are in the process of applying to [the National Institute on Aging] for a larger study with submission in February 2022 and will integrate MRI scans and blood tests for amyloid beta and tau proteins,” said senior author Preetam Schramm, Ph.D., from Texas A&M University College of Dentistry, in an email to MNT.
“Treating poor sleep will serve to rescue immediate behavioral deficits of impaired memory consolidation at night, but it will take time to observe whether it alleviates amyloid buildup,” said Dr. Wiegand.
He concluded:
“I believe this study is a step in the right direction to attack one of the most pervasive and understudied contributing factors to [Alzheimer’s disease]. Applied early, the effect could be cumulatively beneficial.”
However, he cautioned that a combination of treatments will be needed to address all the underlying causes of Alzheimer’s disease in the brain.
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