Sleep and Alzheimer's

Alzheimer's disease and sleep disorders

Anna Kerman, XX2 century, based on ScienceDaily: Sleep, Alzheimer's link explained

A good sleep can restore strength – mental and physical. A bad one, according to a study conducted by scientists from Washington University in St. Louis, Radboud Universitair Medisch Centrum and Stanford University, may be associated with the development of Alzheimer's disease.

Healthy volunteers who did not complain of sleep disorders or cognitive problems took part in the work. But even after a single restless night, an increased concentration of beta-amyloid, a protein associated with the most common form of dementia, Alzheimer's disease, was found in their brains. And a week of poor sleep led to an increase in the level of tau protein – this compound is also associated with Alzheimer's disease and other neurological diseases.

"We have demonstrated that poor sleep is associated with an increase in the level of two proteins characteristic of Alzheimer's disease at once," the scientists say. "It is possible that poor sleep in adulthood may increase the risk of developing this disease in the later stages of life."

The results of the study were published on July 10 in the publication Brain (Ju et al., Slow wave sleep disruption increases cerebrospinal fluid amyloid-β levels).

Previous work conducted by the head of the new study, Dr. David Hotzman (David Hotzman) and his colleagues have shown that sleep disorders increase the risk of cognitive impairment. By "sleep disorders" the researchers meant various mental and somatic disorders that interfere with the natural sleep-wake cycle: bruxism (gnashing teeth in sleep), somnambulism (sleepwalking), restless legs syndrome and similar disorders. For example, in people suffering from sleep apnea (spontaneous short-term respiratory arrest during sleep), moderate thinking disorders develop, on average, 10 years earlier than in those who do not have apnea. It is also important that cognitive impairment itself may indicate the approach of Alzheimer's disease.

However, until today it was unclear exactly how sleep disorders damage the brain. To find the answer to this question, scientists selected 17 healthy volunteers aged 35 to 65 years. None of the participants suffered from sleep disorders or cognitive disorders. All volunteers wore a special bracelet on their arm for two weeks, which recorded the duration of sleep.

After five or more normal quiet nights, the participants visited a specially equipped "sleep room" – a small dark room with sound insulation. In this room, each of the volunteers spent the night – with electrodes attached to the head to assess brain activity.

Electroencephalogram of brain activity during sleep of various depths.
From top to bottom, from the lightest to the deepest.

Participants were randomly assigned to two subgroups. Those who were in the experimental subgroup were "woken up" every time as soon as the readings indicated that a person was sleeping a restful sleep without dreams. However, the word "woke up" is not taken in quotation marks by chance: the alarm clock beeping in the volunteers' headphones stopped exactly at the moment when sleep became superficial – it did not reach full awakening.

The next morning after a night in the "sleepy room", the participants of the experimental subgroup complained of fatigue and a feeling of exhaustion, although they slept as much as usual. On the same day, scientists took cerebrospinal fluid to analyze the level of beta-amyloid and tau protein.

A month later, the experiment was repeated, but this time the participants from different subgroups were swapped.

A comparison of protein concentrations showed that a single restless night leads to a 10% increase in beta-amyloid levels. It does not affect the concentration of tau protein. However, in those participants whose sleep quality left much to be desired and in the week preceding the night in the "sleepy room", there was also an increase in the level of tau protein.

Deep, or slow, sleep is necessary for a full rest – thanks to it, people wake up feeling rested. Sleep apnea disrupts slow sleep, so patients with this diagnosis often complain of lack of strength even after an eight-hour sleep.

However, according to the authors of the study, hardly a single "bad night" (or even a week of restless sleep) significantly increases the risk of developing Alzheimer's disease. But chronic sleep disorders can lead to a permanent increase in the level of tau protein and beta-amyloid, which, in turn, can result in the appearance of beta-amyloid plaques and the development of Alzheimer's disease.

Portal "Eternal youth" http://vechnayamolodost.ru  12.07.2017