A landmark Cell study reveals that meningeal lymphatics — the brain's primary drainage network — directly regulate synaptic balance in the cortex. When lymphatic function is impaired, microglia ramp up production of interleukin-6 (IL-6), which shifts the ratio of excitatory to inhibitory synaptic inputs and impairs memory. Crucially, restoring meningeal lymphatic function in aged mice reversed these synaptic and cognitive deficits. The findings establish a previously unknown meningeal lymphatics–microglia–IL-6 axis as a key regulator of brain circuit health and a promising therapeutic target for age-related cognitive decline.
