Non-REM sleep plays a primary role in the transfer of information from short- to long-term memory storage. Thus, age-related dementia may be sleep-deprived dementia. It might be hard to believe this, but scientists were confronted with Alzheimer’s paradox for decades.
About Alzheimer’s Disease
Alzheimer’s is a chronic neurodegenerative disease and the cause of 60–70% of cases of dementia. In 2015, there were approximately 29.8 million people worldwide diagnosed with Alzheimer’s.
The cause of Alzheimer’s disease is far from being completely understood. 70% of the risk is believed to be inherited from a person’s parents. Other risk factors include a history of head injuries, depression, and hypertension.
The disease process is associated with large numbers of senile plaques and neurofibrillary tangles in the brain. Senile plaques are extracellular deposits of amyloid-beta in the grey matter of the brain. They are primarily composed of amyloid-beta peptides. These polypeptides tend to aggregate and are believed to be neurotoxic.
The accumulation of amyloid plaques in Alzheimer’s patients is not building up in the expected area of the brain. Because Alzheimer’s is a memory deficiency, it should happen in the hippocampus, as it is the long-term hard-disk of the human brain. But it does not do so. It accumulates in mid-region of the frontal lobe. And this site of the brain is the sleep manager, especially the non-REM sleep.
About Sleep Disorders
It is known that sleep takes care of our memories. While we are awake, we only use short-term memory. It is during the night that our brain decides what is worth keeping in the long-term memory, and what goes to waste. Especially in the non-redundant eye movement stages of sleep.
Rapid eye movement sleep (REM) is a unique phase of sleep distinguishable by random/rapid movement of the eyes. During the four non-REM stages, there is usually little or no eye movement. According to studies, the mental activity that takes place during NREM sleep is believed to be thought-like, whereas REM sleep includes hallucinatory and bizarre content.
During the period of Non-REM sleep, the mindset of a person is more organized. The reported differences between the REM and NREM activity arise from differences in the memory stages that occur during the two types of sleep.
The New Study
About 60% of Alzheimer’s patients suffer from at least one severe sleep disorder, such as insomnia or sleep apnea. The scientists at UC Berkeley presumed that Alzheimer’s might be something else than a memory disability.
The elders involved in the study confirmed that their memory is strongly dependent on their sleeping behavior. Those experiencing sleep deprivation during the three non-REM stages had great difficulties in completing the simple memory tasks they were given.
PET scans of the patient’s amyloid buildup showed that sleep quality is correlated with memory performance. It looks like the amyloid plaque accumulation stirs the sleep deprivation that triggers poor memory performance. It is the other way around than previously thought: Alzheimer’s disease doesn’t directly impact memory. It does so via sleep.
The new study might indicate new ways to contain Alzheimer’s evolution. The new recommendations for Alzheimer’s patients might be the treatment of sleep disorders. A survey conducted on treating sleep apnea is already showing signs of improvement for Alzheimer’s patients. Their cognitive decline was reduced, just like it did for the patients using melatonin to improve their sleep.
This is an essential leap for curing Alzheimer’s. The impairment now seems to be that sleep disturbances appear several years before the onset of the disease. But maybe sleep issues could serve as an early-warning detector of the disease.