Scientists know that many proteins and pathways are involved in the development and progression of neurodegenerative conditions such as Alzheimer’s disease, Parkinson’s disease and frontotemporal dementia (FTD), and that these proteins can be detected in the plasma of people with the conditions.

But it hasn’t been clear exactly which proteins are distinct to one disease vs. shared among two or more of them, adding to the difficulty both of diagnosing these complex diseases from blood samples and of developing effective treatments.

A new study by Washington University School of Medicine in St. Louis researchers, published in Nature Medicine, provides some answers. Led by Carlos Cruchaga, the Barbara Burton & Reuben Morriss III Professor in the Department of Psychiatry and director of the NeuroGenomics and Informatics Center at WashU Medicine, the researchers analyzed protein activity in more than 10,500 blood plasma samples from patients with Alzheimer’s disease, Parkinson’s disease or FTD.