Physical activity affects neurodegenerative processes

The understanding of how physical activity affects cognitive longevity has received a new biomechanical explanation. A team of scientists led by Professor Patrick Drew has discovered that the brain has a much closer mechanical connection to the body than previously thought. This interaction is based on the functioning of the vertebral venous plexus, a network of blood vessels that connect the abdominal cavity and the spinal canal.

The mechanism of the process is triggered by the contraction of the abdominal muscles, which occurs even during minor movements such as preparing to walk or attempting to sit down. These contractions compress the blood vessels in the abdominal cavity, pushing blood towards the spine and skull. The resulting pressure leads to a slight but functionally significant displacement of the brain within the skull. This cyclic movement causes the surrounding cerebrospinal fluid (CSF) to circulate more intensively through the brain tissues. The cerebrospinal fluid acts as a solvent that washes away protein deposits and cellular debris, the accumulation of which correlates with Alzheimer’s disease and other forms of dementia.

To confirm this hypothesis, the researchers used a combination of imaging and modeling techniques. High-resolution two-photon microscopy was used to observe the displacement of the mouse brain during the contraction of the abdominal muscles that precedes movement. To eliminate the influence of other factors, the researchers conducted an experiment in which they applied controlled external pressure to the abdomen of mice that were under light anesthesia. The results confirmed that mechanical compression of the abdominal cavity is sufficient to change the position of the brain and then return it to its original position after the load is removed.

The mathematical part of the study, led by Professor Francesco Costanzo, focused on computer simulations of fluid dynamics. Since the brain’s structure is heterogeneous, a porous medium model was used for the simulations. This allowed researchers to calculate how external pressure and the movement of the brain’s soft “skeleton” contribute to the flow of fluid through its folds and microscopic pores. The modeling showed that even microscopic amplitudes of brain movement during walking create a sufficient hydrodynamic effect for effective tissue filtration.

The data obtained have a high clinical significance for preventive gerontology. Traditionally, it was believed that brain cleaning occurs mainly during sleep, but this study proves that wakefulness and physical activity provide an additional, dynamic cycle of washing out neural structures. This makes regular physical activity, including simple walking, an essential component of a strategy to protect the brain from pathological accumulation of proteins. In the future, scientists plan to study the optimal intensity of movements required to maintain the hydraulic function of the brain in people of different age groups.