Alzheimer’s disease and sleep apnea: better understood mechanisms


Until now, scientists have sought to understand the biological mechanisms that associate Alzheimer’s disease and poor quality sleep, which is undoubtedly known to have deleterious effects on the brain. These alterations caused by sleep apnea have been revealed, by various brain imaging techniques, in the brains of elderly people who are nevertheless healthy.

The syndrome obstructive apnea sleep is the most common sleep disorder, affecting more than 30% of the population after the age of 65. In subjects who have it, this pathology results in uncontrolled and repeated interruptions of breathing during sleep, linked to temporary obstruction of the upper airways in the throat. The sleep apnea are associated with many health problems, foremost among which are cardiovascular illnesses. However, this pathology remains silent for quite a long time, so that it is probably underestimated in the general population.

In recent years, scientific data has also accumulated showing a link between the quality of sleep, and in particular the presence of sleep apnea, and the development of Alzheimer’s disease. However, the biological mechanisms underlying this association remained to be elucidated.

To see more clearly, Inserm researcher Géraldine Rauchs conducted a study in the laboratory Physiopathology and Imaging of neurological diseases (Inserm / University of Caen-Normandie) in collaboration with the laboratory Neuropsychology and imaging of human memory (Inserm / University of Caen-Normandy / École Pratique des Hautes Etudes – PSL). In this work, published on March 23 in the journal JAMA Neurology, the researchers used several brain imaging techniques to map brain changes in people with untreated sleep apnea, both structurally and molecularly, but also functionally.

Notable changes seen in the brain

The researchers first recruited 127 participants over the age of 65. In good health, they presented no cognitive problems. Using a portable device making it possible to record their sleep and their breathing during the night at home, the researchers detected the presence of sleep apnea, with varying degrees of severity, in 75% of them. .

All participants were also subjected to a series of tests to assess their cognitive functioning, including memory and executive function. They responded to questionnaires on their perceptions of their cognitive functioning and the quality of their sleep. Several brain imaging tests were then performed to study their brain from all angles and identify possible changes that may be associated with the Alzheimer’s disease. Although no difference between the participants was observed with regard to their cognitive performance, brain imagery revealed several notable changes in the brains of people sleep apnea.

There are effective solutions to treat sleep apnea

Indeed, among these participants, the accumulation of protein beta-amyloid in the brain is more marked. Characteristic of the Alzheimer’s disease, this protein accumulates in the form of plaques which, depending on their distribution in the brain and their density, can lead to the appearance of clinical signs of the pathology. In addition, the researchers observed an increase in the mass of matter gray and consumption of glucose, suggesting the presence of inflammatory processes in the brain.

The links between Alzheimer’s disease and better understood quality of sleep

” AT the time when clinical tests aimed at testing treatments against Alzheimer’s disease are not yet successful, identification of risk factors and protection which researchers are increasingly interested in acting on. Thanks to the use of several brain imaging methods, this study allowed us to specify the mechanisms explaining the links between quality of sleep, risk of cognitive decline and Alzheimer’s disease, explains Géraldine Rauchs. This does not mean that these people will necessarily develop the disease, but they are at higher risk. In addition, there are effective solutions to treat sleep apnea. Detect sleeping troubles, in particular sleep apnea, and treating them would therefore be part of the means to promote successful aging ”.

To continue this work, the researcher and her team will now focus on the impact of apnea treatment on the development of brain damage and will also analyze the differences between the brains of men and women suffering from sleep apnea.

A sleep cure for Alzheimer’s?

A new study links sleep to the formation of senile plaques, structures found in abundance in the brains of people with Alzheimer’s. These results could lead to therapies aimed at improving the quality of the nights to limit the development of the disease.

Article by Agnès Roux, published on October 25, 2013

The Alzheimer’s disease is a form of dementia which is accompanied by a gradual decline in cognitive functions. Those affected are gradually losing their memory and have learning difficulties. They are no longer able to cope with daily life and generally need medical assistance. According to Inserm, 860,000 French people were affected by this pathology in 2010. This figure is constantly increasing and should reach two million in 2020.

The first description of the disease was made in 1906 by the German doctor Aloïs Alzheimer who observed suspicious plaques in the brain of one of her deceased patients. These structures were then called senile plaques, or amyloids, because they arise from the accumulation of a protein, beta-amyloid, between neurons. These clumps appear naturally with aging, but clump together in much greater quantities in patients withAlzheimer. The origin of this accelerated accumulation of beta-amyloids remains mysterious and is the subject of much research.

Who sleeps well protects his brain

Researchers from Johns-Hopkins University in Baltimore have just made progress on this subject. By going through a body of information, they realized that people with Alzheimer’s generally slept shorter and worse than others. They then wondered about the link between the sleep and the development of senile plaques. They were right: their study, published in the journal Jama Neurology, confirms this association.

For this study, the scientists selected 70 candidates in good health and an average age of 76 years. First, they asked them about their sleep habits: time tofalling asleep, number of night awakenings, difficulty falling asleep, early awakening, etc. Using several medical imaging technologies, they then observed the distribution and quantity of amyloid plaques in their brains.

Sleep therapy?

By compiling these data, the authors showed a link between the accumulation of senile plaques, the duration and the quality of the nights. However, the number of alarm clocks nocturnal does not appear to influence the formation of these clusters in the brain. These results are in line with a recent study showing that the brain got rid of his trash and toxins has a debit high during sleep. In particular, these researchers had shown that beta-amyloids were eliminated twice as quickly during sleep in mice.

All of these results reinforce the idea that it is important to spare his sleep to maintain a good balance of life. And Alzheimer’s disease is not the only reason. Studies have also shown a link between lack of sleep and other illnesses like diabetes, cardiovascular problems,obesity, depressive disorders and Parkinson disease. Sleeping would also promote the production of myelin in the brain and could decrease the progression of the multiple sclerosis. “We could develop therapies to improve sleep and reduce the risk of Alzheimer’s disease, and other pathologies associated with lack of sleep, concludes Adam Spira, lead author of the study.

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