Years before tau tangles show up in brain scans of patients with Alzheimer’s disease, a biomarker test developed at the University of Pittsburgh School of Medicine can detect small amounts of the clumping-prone tau protein and its misfolded pathological forms that litter the brain, cerebrospinal fluid and potentially blood, new research published today in Nature Medicine suggests.

The cerebrospinal fluid biomarker test correlates with the severity of cognitive decline, independent of other factors, including brain amyloid deposition, thereby opening doors for early-stage disease diagnosis and intervention.

Since amyloid-beta pathology often precedes tau abnormalities in Alzheimer’s disease, most biomarker efforts have focused on early detection of amyloid-beta changes. However, the clumping of tau protein into well-ordered structures referred to by pathologists as “neurofibrillary tangles” is a more defining event for Alzheimer’s disease as it is more strongly associated with the cognitive changes seen in affected people.