Stimulus-driven cerebrospinal fluid dynamics is impaired in glaucoma patients
Cerebrospinal fluid (CSF) dynamics, driven by sensory stimulation-induced neuronal activity, is crucial for maintaining homeostasis and clearing metabolic waste. However, it remains unclear whether such CSF flow is impaired in age-related neurodegenerative diseases of the visual system. This study addresses this gap by examining CSF flow during visual stimulation in glaucoma patients and healthy older adults using functional magnetic resonance imaging. The findings reveal that in glaucoma, CSF inflow becomes decoupled from visually evoked blood-oxygenation-level-dependent (BOLD) response. Furthermore, stimulus-locked CSF patterns, characterized by decreases following stimulus onset and increases after offset, diminish as glaucoma severity worsens. Mediation analysis suggests that this flattened CSF pattern is driven by a flatter BOLD slope, resulting in a shallower CSF trough and a reduced rebound. These findings unveil a novel pathophysiological mechanism underlying disrupted stimulation-driven CSF dynamics in glaucoma and highlight potential in vivo biomarkers for monitoring CSF in the glaucomatous brain.