Although the precise causes of Alzheimer’s disease remain unknown, one hypothesis which has been under investigation for some time is that so-called tau proteins could play an important role.

Until recently, the only way to study tau protein levels in living patients involved sampling their cerebrospinal fluid.  However, in a new study reported in Science Translational Medicine, a research team from the Washington University in St. Louis was able to employ newly-developed PET imaging agents which bind to tau protein, allowing tau protein levels in the brain to be observed directly.

Higher levels of tau protein in the cerebrospinal fluid were found to correlate with the presence of tau protein deposits in the temporal lobe, which in turn were found to correlate more strongly with Alzheimer’s symptoms than ß-amyloid protein depoisits, which have also previously been implicated in Alzheimer’s disease.

Subject to replication and extension of this study, this could open the way to new, tau-protein-based diagnoses for Alzheimer’s disease based on non-invasive PET imaging and/or sampling of cerebrospinal fluid.

“When the team measured tau in the study participants’ CSF, it found that higher levels were specifically correlated with increased tau in the temporal lobe, a region involved in memory processing, Ances says. That’s important, he suggests, because it means that one could potentially use tau in CSF as a diagnostic tool.”

http://www.sciencemag.org/news/2016/05/tau-protein-not-amyloid-may-be-key-driver-alzheimer-s-symptoms