One study reports that aerobic exercise increases levels of certain proteins that reduce inflammation in the brain and improve cognitive function.
It is well known that exercise produces many physiological changes that improve the function of multiple organs and contribute to improved health.
These benefits are particularly evident from a physical perspective (specifically improved cardiorespiratory capacity and muscle tone), but several studies have also shown that brain functions are also favorably influenced by physical activity.
It appears that exercise’s positive impact on cognitive function is due to an increase in neuronal plasticity and a reduction in inflammation in the hippocampus, the structure of the brain that plays a key role in memory (1).
blood factor
To determine whether these cognitive benefits of physical activity might be caused by factors released into the bloodstream after exercise, researchers at Stanford University in California compared the blood protein profile of physically active mice to that of sedentary mice (2).
They first observed that regular exercise caused a significant increase in the number of neurons (neurogenesis) in the brains of active mice compared to those of sedentary mice, consistent with several studies showing a protective effect of exercise on cognitive decline and neurodegeneration showed.
This neurogenesis appears to be induced by a factor present in the blood, since injecting blood plasma from active mice into sedentary mice caused an increase in the number of neurons in them, particularly in the hippocampus (the seat of memory) and an improvement in their cognitive abilities ( exiting a maze).
Anti-inflammatory proteins
To better understand this phenomenon, the scientists examined the activation level of thousands of genes in the hippocampus of sedentary mice, which received blood from the active mice.
Of the approximately 2,000 genes whose levels changed in response to plasma from active mice, 250 of them are known to be linked to inflammatory processes, suggesting that factors present in the blood of active mice reduce inflammation at the brain level.
Analysis of the blood of active mice suggests that this decrease in inflammation is caused by modulation of the complement system, a group of proteins involved in eliminating pathogens and controlling the inflammatory response.
One protein in this system in particular, clusterin, seems absolutely necessary to reduce neuroinflammation, since the specific elimination of this protein from the blood of active mice completely negates its beneficial effects on the brains of sedentary mice. The crucial role of this protein is also suggested by the observation that administration of purified clusterin to animals is sufficient to reduce inflammation in the brain.
Taken together, these results suggest that the beneficial effects of exercise on brain function would be linked to the production of certain proteins, particularly clusterin, that diffuse into the brain and reduce inflammation.
It’s likely that a similar phenomenon is at work in humans, as the researchers observed that a six-month exercise program caused a significant increase in this protein.
These results once again confirm how important exercise really is to staying physically and mentally healthy.
♦ (1) Gleeson M et coll. The anti-inflammatory effects of exercise: Mechanisms and implications for disease prevention and treatment. nat. Rev. Immunol. 2011 ; 11, 607-615.
♦ (2) De Miguel Z et al. Exercise plasma increases memory and suppresses brain inflammation via clusterin. nature 2021 ; 600: 494-499.