Investigators have discovered a new form of tau protein that becomes abnormal during the very early stages of Alzheimer disease (AD) before cognitive decline begins, according to a study published in Alzheimer’s and Dementia

AD is characterized by 2 pathological changes to brain tissue in the clumping of either the tau protein or the amyloid beta peptide. These clumps can progressively accumulate in specific areas of the brain.

Individual units of tau protein can aggregate into finely ordered fibrillar structures facilitated by a biochemical process known as phosphorylation. As the disease progresses, amyloid beta and phosphorylated tau (p-tau) are released from the brain and into cerebrospinal fluid. The amount released are reliable surrogate markers for the clinical diagnoses of AD. 

In the first of a series of studies, investigators discovered that approximately one-third of the 381 participants had brain evidence of AD without any cognitive problems related to late dementia stages. According to the study, this research can lead to new therapies for people in the early stages of AD. 

The investigators developed highly sensitive techniques to measure the changes of p-tau in the cerebral fluid, which are able to measure biomarkers that precede clinical signs by several years, according to the study.

"The remarkable findings reported in these publications show that the new highly sensitive tools capture the earliest Alzheimer disease changes in the brain in clinically normal people. These tools therefore have the potential to advance population screening and clinical trials,” said Thomas Karikari, PhD, an assistant professor at the University of Gothenburg, in a press release. 

One limitation of the study was the difficulty to recruit preclinical AD patients due to the difficulty of detecting these biomarkers. However, testing new therapies on people in the early stage of AD may help to improve treatment, according to the study. 

REFERENCE:
New tests identify early changes in Alzheimer’s disease before symptoms appear [News Release] December 1, 2020; Gothenburn, Sweden. Accessed December 4, 2020. https://www.sciencedaily.com/releases/2020/12/201201203937.htm.