Dominic Walsh at Brigham and Women’s Hospital Boston has developed a plasma tau test that accurately distinguishes between Alzheimer’s disease cases and controls. To date reports Jessica Shugart of ALZFORUM, efforts to develop blood tests for cerebrospinal fluid tau, an established Alzheimer’s disease biomarker, have been hindered, due to substantially low concentrations of proteins there. But Walsh’s work may change this. His findings lead to the reality that there may be distinct forms of tau in the brain versus blood and point out that the minimally invasive blood test could prove useful for diagnosis and screening in clinical trials. It may be the case in the not-to-distant future that tau, like Aβ, could be tracked in the blood to provide insight into the CNS processing of tau.