Ensuring restful, regular and quality sleep is precisely the key to healthy body and mind. In fact, a good, regular and restorative sleep is not only linked to the health of the immune system, our mood and our attention during the day, but also to the health of our brain in the years to come, representing a protection from neurodegenerative diseases such as Alzheimer's. This emerges from very recent scientific research published in the journal PLoS Genetics by an American team (Clark et al, PLoS Genetics, Feb 2022).
The link between Alzheimer's and circadian rhythm
Alzheimer's is a degenerative disease characterized by the simultaneous presence of neuroinflammation and accumulation of tau proteins and beta amyloids. Our brain has a defense system made up of macrophages, which are cells of the immune system, designed to remove protein aggregates that could be toxic to the brain. However, it can happen that this defense mechanism gets jammed and that there is an accumulation of beta amyloid proteins, thus paving the way for Alzheimer's. At the same time, a disruption of circadian rhythms was observed. Circadian rhythms are a biological clock inside our body that regulates the production of enzymes and hormones following the alternation between night and day. The circadian rhythm is what makes us sleepy in the evening when the light goes down and makes us get up in the morning full of energy when the light enters the room. At the same time, the circadian rhythm also regulates the immune system. Well, it has been hypothesized that the alteration of the circadian rhythm may be the factor that causes Alzheimer's, and not just a consequence of it.
This is why regular sleep is important
To further investigate this hypothesis, the researchers of the study we are talking about today performed a series of experiments in the laboratory. What emerged was that our body's ability to remove beta amyloid protein aggregates follows circadian oscillations. In particular, it was possible to observe that the circadian system stimulates or, on the contrary, inhibits, following the physiological oscillations during the day, the formation of particular proteins on the surface of macrophages. When these proteins are present on the surface of macrophages then their ability to remove beta amyloid proteins is inhibited. Conversely, when these proteins are not present, the ability to remove beta amyloid proteins is maximized. As a consequence, it appears clear that an alteration of the circadian rhythm leads to an alteration of the formation of this protein, which would result, in a mechanism still not well understood, more present, opening the way to a progressive accumulation of beta amyloid proteins and therefore of increased risk of Alzheimer's. It is important to emphasize that the alteration of the circadian rhythm and the sleep wake rhythm already begin years before any neurodegeneration appears.
Conclusions
This study is exciting and very promising and paves the way for a multi-disciplinary approach in the treatment of Alzheimer's. In the future, as the authors of the study point out, it will be possible to develop treatments to regulate the circadian rhythm and increase daily fluctuations, which tend to decrease with age. At the moment, waiting for science to take its course, it is certainly important to implement every strategy to preserve a correct alternation between sleep and wakefulness, linked to the circadian rhythm of release of enzymes and hormones. In fact, as we have seen, the destruction of this delicate internal clock system begins years before any neurodegeneration develops. It is therefore important to ensure a sleep-wake routine as stable as possible, avoid heavy meals in the evening, coffee and alcohol and to work late, concentrating activities and work during the daytime hours, if possible. Finally, try to do moderate physical activity, possibly outdoors during the day.
