Longevity & AgingBrain's Waste-Clearance Protein Fails Differently in Parkinson's and MSA
A postmortem study of 65 brains found that aquaporin-4 (AQP4), a protein critical for the brain's waste-clearance (glymphatic) system, is dysregulated in both Parkinson's disease and multiple system atrophy—but in strikingly different ways. In early PD, AQP4 is less recruited to astrocytic endfeet around blood vessels, yet recovers in late PD through enhanced polarization, mainly in superficial cortical layers. In MSA-parkinsonian type, AQP4 becomes depolarized, while the cerebellar variant is largely unaffected. Age-related neuritic plaques increase overall AQP4 abundance without disrupting its distribution. These distinct patterns suggest fundamentally different pathological mechanisms underlie glymphatic dysfunction in neuron-predominant versus oligodendrocyte-predominant synucleinopathies.
