A new study reveals why exercise protects against Alzheimer's disease, identifying the molecular mechanisms at work. Researchers from the University of California, San Francisco discovered that physical activity increases a protein called GPLD1 in the blood, which strengthens the brain's protective barrier.

This barrier, the blood-brain barrier, normally guards against inflammation and harmful substances. Over time, an enzyme called TNAP accumulates and weakens this barrier. The study found that GPLD1 'prunes' TNAP from brain tissue, maintaining barrier integrity and reducing cognitive decline.

The research showed that mice with increased GPLD1 or reduced TNAP levels had fewer amyloid beta protein clumps, hallmarks of Alzheimer's disease. This discovery opens possibilities for treatments that could mimic exercise's brain-protecting effects without physical activity.