Scientists have found a way to speed up brain recovery after a stroke

Scientists from the University of Rochester Medical Center have found that strengthening circadian rhythms can improve brain recovery after a stroke. In experiments on mice, this approach enhanced the glymphatic system, reduced inflammation, and helped restore motor function even when starting treatment three days after a stroke. About how the internal biological clock can affect the recovery of the brain — in the material "Izvestia".

Biological clock helped the brain recover after a stroke

The researchers studied the effects of stroke in mouse models and found out whether restoring normal circadian rhythms could affect the further state of the brain. Circadian rhythms regulate many processes in the body during an approximately 24-hour cycle, including sleep and wakefulness.

After a stroke, these rhythms are often disrupted. Such changes in sleep and wakefulness are associated with a more difficult recovery, depression and a decrease in the quality of life. Scientists have suggested that disruption of the internal clock may affect the brain's ability to get rid of the effects of damage.

In a study published in the Journal of Clinical Investigation (JCI), increased circadian rhythms in mice were accompanied by improved motor recovery, reduced brain damage, and decreased levels of inflammatory molecules.

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After a stroke, the brain is less cleansed of harmful substances.

One of the key objects of research was the glymphatic system, a network that helps move cerebrospinal fluid through brain tissues and remove metabolic products and other unnecessary substances from them.

Previously, scientists have established that the work of this system is especially active during sleep and depends not only on sleep itself, but also on circadian rhythms. After a stroke, its functioning is disrupted, which makes it more difficult for the brain to remove damage products and signaling molecules associated with inflammation.

According to the researchers, the problem after a stroke may lie not only in the excessive activity of inflammatory processes. A damaged brain can also be worse at getting rid of substances that support inflammation.

Scientists have restored the internal clock

To test the hypothesis, scientists have tested several ways to influence circadian rhythms. Among them were light exposure at certain times, melatonin, and time-limited nutrition.

First, the researchers tested whether these methods were able to enhance the glymphatic system in healthy animals. After that, time-limited nutrition was chosen as a promising approach for experiments with stroke.

Thus, the scientists did not directly affect inflammation, but the system that regulates the circadian rhythms of the body. It was assumed that restoring these rhythms would improve brain cleansing and thus affect the effects of damage.

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Treatment started three days after the stroke

The researchers paid special attention to the start time of the intervention. The mice were not treated immediately after the stroke — the scientists waited three days. This is much later than the period when many methods of emergency stroke therapy are used.

Despite this delay, the rodents that followed a time-limited diet recovered their motor function better. They also had a reduced volume of the damaged area of the brain and improved glymphatic flow.

At the same time, the level of inflammatory cytokines, signaling molecules involved in the inflammatory response, decreased in the brain. According to the researchers, the results may indicate not an effect on one specific inflammatory pathway, but a more effective removal of inflammatory signals from the brain.

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The new approach has so far been tested only on mice.

The authors of the work emphasize that the results obtained cannot yet be directly transferred to humans. The study was conducted on animal models, so it remains to be determined exactly how circadian rhythms, the glymphatic system and inflammation after stroke are related.

Separately, the scientists want to find out whether the increased glymphatic flow directly leads to better recovery. This will require additional experiments and further clinical studies involving humans.

Scientists consider time-limited nutrition to be one of the potentially convenient approaches: unlike some medical interventions, such a regimen can theoretically be used not only in the hospital, but also during rehabilitation at home. However, its effectiveness and safety specifically for stroke recovery have yet to be tested.