A novel form of an Alzheimer’s protein found in the fluid that surrounds the brain and spinal cord indicates what stage of the disease a person is in, and tracks with tangles of tau protein in the brain, according to a study from researchers at Washington University School of Medicine in St. Louis. Tau tangles are thought to be toxic to neurons, and their spread through the brain foretells the death of brain tissue and cognitive decline. Tangles appear as the early, asymptomatic stage of Alzheimer’s develops into the symptomatic stage.

The discovery of so-called microtubule binding region tau (MTBR tau) in the cerebrospinal fluid could lead to a way to diagnose people in the earliest stages of Alzheimer’s disease, before they have symptoms or when their symptoms are still mild and easily misdiagnosed. It also could accelerate efforts to find treatments for the devastating disease, by providing a relatively simple way to gauge whether an experimental treatment slows or stops the spread of toxic tangles.