Study suggests mechanism by which physical movement could be linked with brain's cleansing process

New Delhi, May 4 (PTI) A study has suggested a mechanism by which performing a physical behaviour can trigger a movement of the cerebrospinal fluid -- a clear liquid that circulates in the brain -- which may then carry away waste that can interfere with normal brain function.
    Functions of the cerebrospinal fluid include removing waste, cushioning the central nervous system from shocks, and delivering nutrients. The colourless fluid is part of the glymphatic system.
    "Our research explains how just moving around might serve as an important physiological mechanism promoting brain health," said author Patrick Drew, a professor of engineering science and mechanics, neurosurgery, biology, and biomedical engineering at The Pennsylvania State University in the US, said.
    Drew added, "In this study (in mice), we found that when the abdominal muscles contract, they push blood from the abdomen into the spinal cord, just like in a hydraulic system, applying pressure to the brain and making it move."
    "Simulations show that this gentle brain movement will drive fluid flow in and around the brain. It is thought the movement of fluid in the brain is important for removing waste and preventing neurodegenerative disorders. Our research shows that a little bit of motion is good, and it could be another reason why exercise is good for our brain health," the corresponding author of the study published in the journal Nature Neuroscience said.
    The researchers said even small actions, such as bracing your core before standing up or taking a step, can create the 'pumping' effect.
    An October 2025 research, published in the journal Alzheimer's and Dementia: The Journal of the Alzheimer's Association, suggested that problems with the brain's waste clearance due to an impaired movement of the cerebrospinal fluid could contribute towards developing dementia, a neurodegenerative disorder.
    The team observed moving mice and found that the brain shifted just before the animals moved, immediately after the abdominal muscles tightened to initiate motion.
    Further, they applied a gentle, controlled pressure to the abdomens of lightly anaesthetised mice.
    The level of pressure was lower than what a person experiences during a blood pressure test, yet it still caused the brain to move, the researchers said.
    "Importantly, the brain began moving back to its baseline position immediately upon relief of the abdominal pressure. This suggests that abdominal pressure can rapidly and significantly alter the position of the brain within the skull," Drew said.
    To understand how the brain's movement influences the flow of the cerebrospinal fluid, the team created computer simulations of fluid motion. They also developed imaging techniques for conducting experiments with live mice.
    The researchers treated the brain like a sponge and simulated how fluid travels through spaces of different sizes, similar to the folds of the brain or the pores of a sponge.
    "Keeping with the idea of the brain as a sponge, we also thought of it as a dirty sponge -- how do you clean a dirty sponge?" Francesco Costanzo, professor of engineering science and mechanics at The Pennsylvania State University, said.
    "You run it under a tap and squeeze it out. In our simulations, we were able to get a sense of how the brain moving from an abdominal contraction can help induce fluid flow over the brain to help clear waste products," Costanzo said.
    Drew noted that more research is needed to determine how the study's findings apply to humans.
    However, the results suggest that everyday movement may help circulate cerebrospinal fluid through the brain, aiding in the removal of waste and possibly lowering the risk of neurodegenerative diseases linked to waste buildup, Drew said.

(This story has not been edited by THE WEEK and is auto-generated from PTI)