Mental exercise could prompt brain to remove waste

Researchers have discovered that the brain's waste disposal system, which involves cerebrospinal fluid (CSF), may be activated during intense neural activity, and may be possible to activate intentionally. Until recently, the system was thought to only activate during sleep, but researchers have now seen it ramping up in people after they watch flickering chequerboard patterns on a screen. The brain's waste disposal system involves CSF being pumped into the brain and leaving through a network of fine tubes called the glymphatic system, which was only discovered in 2012. Animal research suggests that the fluid flushes out waste products made by brain cells, including harmful compounds that may be involved in Alzheimer's disease and Parkinson's disease, such as beta-amyloid and alpha-synuclein. Researchers are still unclear on how the system functions in people and how boosting fluid flow could help improve brain health. The researchers used a new brain-scanning technique to highlight any CSF that has newly entered into the fourth ventricle of the brain, a cavity at the base of the head. They asked 20 volunteers to watch a screen inside the scanner that displayed a pattern known to cause high brain activity, and when the screen went dark, blood flow reduced and CSF flow into the brain increased. The brain-scanning technique couldn't reveal if the fluid left through the glymphatic vessels, nor if there was a reduction of waste products within the brain, but researchers are excited to understand the effect of these changes in fluid flow and how it intersects with brain health.