Many theories exist as to how misfolded tau protein impacts neuronal communication and promotes degeneration, but few have been empirically proven or replicated. Without this key factor, researchers only know what biomarker causes the degeneration (tau) and what impairment it causes, but not how. Unfortunately, without understanding how misfolded tau leads to impairment, it’s difficult to counteract the mechanism causing the impairment. Luckily, a recent study discovered a unique relationship between tau, nitric oxide (NO), and cerebral vasculature that occurs even before tau forms neurofibrillary tangles (NFTs).