Tau protein in the brain can help predict future Alzheimer’s

Measuring the levels of tau protein in the brain can help to predict the onset of Alzheimer’s symptoms, new research suggests. Scientists from the University of San Francisco Memory and Aging Center found build up of the protein could point towards atrophy for as much as one year in advance.

The research builds upon the understanding of two types of plaques - tau and amyloid beta - investigated in previous studies. These have been identified as a potential cause for Alzheimer’s, with the proteins clumping together and smothering neurons, resulting in memory loss.

While both are harmful to the brain, the scientists in the US found that only tau proteins could successfully be used to predict where future damage would occur as Alzheimer’s progressed. Researchers had a 40 per cent accuracy in these forecasts compared with three per cent when analysing amyloid beta proteins.

Dr Renaud La Joie, a postdoctoral researcher at the University of San Francisco, said: “No one doubts that amyloid plays a role in Alzheimer's disease. But more and more tau findings are beginning to shift how people think about what is actually driving the disease.”

Alzheimer’s disease affects approximately 44 million people worldwide, destroying their memory and making it more difficult for them to lead independent lives. There is currently no cure for the condition, but most treatments focus on preventing its progression.

Usually, an Alzheimer’s diagnosis only occurs once symptoms have set in and the resultant loss of cognition cannot be reclaimed. Predicting where Alzheimer’s may occur in the brain could help physicians to target preventative measures in these areas.

For the study, the US scientists looked at 32 participants who were all in the early stages of Alzheimer’s. They were each given a PET scan to evaluate the function of the organ and tissues. Two tracers were employed to measure the levels of amyloid and tau proteins.

From the results, the researchers discovered that the amount of tau in the brain at the start was indicative of degeneration for the coming year. Added to this, the build up of the protein could also predict atrophy in that area of the organ with 40 per cent accuracy.

This led the team to conclude that tau is an important factor in brain degeneration for patients with Alzheimer’s disease. It could help to inform treatment decisions in cases of the most common form of dementia in the future.

Dr Gil Rabinovici, a neurologist and leader of the PET imaging program at the UCSF Memory and Aging Center, commented on the findings. He said: “The match between the spread of tau and what happened to the brain in the following year was really striking.
“Tau PET imaging predicted not only how much atrophy we would see, but also where it would happen.”

It is hoped that drugs being developed to target tau protein could block the plaque and prevent it from causing brain atrophy. This would be a considerable step forward in the way that Alzheimer’s is treated and the outcome for patients.