Phosphorylation of one particular tau protein residue measured in cerebrospinal fluid (CSF) correlated with the distinct biological stages of Alzheimer's disease, researchers reported here.
Among people in the Dominantly Inherited Alzheimer Network (DIAN) -- a group in which Alzheimer's disease progression is relatively predictable -- phosphorylated tau started increasing in CSF as early as 2 decades before the estimated age of symptom onset and 2 years before signs of Alzheimer's disease were seen on brain imaging, Nicolas Barthelemy, PhD, of Washington University at St. Louis, and colleagues reported at the 2018 American Neurological Association Annual Meeting.
"Our study demonstrates unambiguously the hyperphosphorylation of CSF tau in familial Alzheimer's disease," Barthelemy told MedPage Today.
"Surprisingly, one of the phosphorylated tau sites -- T217 -- has a nearly total association with brain amyloid," he added. "The modification of this site can be detected more than 20 years before the symptom onset at a time when amyloid plaques become detectable, when no tau aggregates are expected in the brain, and when CSF tau levels are normal. This suggests amyloid plaque deposition impacts tau metabolism at an early stage of the disease."
Learn more: Molecular P-Tau Status May Track Alzheimer Pathology, Symptoms