Tau vs. Amyloid - An Alzheimer's Dilemma

For starters, this post is not about a sporting event, even though the title might lead one to think otherwise. The fact is there have been different approaches regarding research of the basic cause of Alzheimer's (AD), and hopefully, an eventual treatment and cure. The focus has been on protein changes in the brain.

The majority of the Alzheimer's research field has mainly focused on the protein ß-amyloid over the last 25 years. Brain scans performed over the last decade revealed that amyloid accumulated as AD progressed, so most Alzheimer's models are based on amyloid toxicity. (It has been found that amyloid can start accumulating in the brain by age 20).

The evidence however, left something to be desired. Even though studies have demonstrated that as a general rule, people with AD have far more ß-amyloid plaques in their brains than non AD people,  studies have also revealed a puzzle: roughly 30% of people without any signs of dementia have brains “chock-full” of ß-amyloid at autopsy, said neurologist Beau Ances at Washington University in St. Louis in Missouri. This finding has been well known for many years.

Could something else be the real cause of AD? Something like tau, which is a protein found in neurons (nerve cells)?

In an article published in Brain in 2015 researchers at the Mayo Clinics in Florida and Minnesota
concluded that tau is the culprit. The researchers were able to simultaneously look at the evolution of amyloid and tau using neuropathologic measures (over 3500 brain autopsies and scans).

The lead author, Melissa Murray, Ph.D., a neuroscientist at Mayo Clinic stated: "Imagine looking at the rings of a tree—you can identify patterns, like the changing seasons and the aging of the tree, when viewing the tree's cross-section...Studying brains at different stages of Alzheimer's gives us a perspective of the cognitive impact of a wide range of both amyloid and tau severity. Tau can be compared to railroad ties that stabilize a train track that brain cells use to transport food, messages and other vital cargo throughout neurons. In Alzheimer's, changes in the tau protein cause the tracks to become unstable in neurons of the hippocampus, the center of memory. The abnormal tau builds up in neurons, which eventually leads to the death of these neurons. Evidence suggests that abnormal tau then spreads from cell to cell, disseminating pathological tau in the brain's cortex. The cortex is the outer part of the brain that is involved in higher levels of thinking, planning, behavior and attention mirroring later behavioral changes in Alzheimer's patients"

She continued: "Our study shows that the accumulation of amyloid has a strong relationship with a decline in cognition. When you account for the severity of tau pathology, however, the relationship between amyloid and cognition disappears—which indicates tau is the driver of Alzheimer's."

Furthermore, Dr. Murray noted, "Our findings highlight the need to focus on tau for therapeutics, but it also still indicates that the current method of amyloid brain scanning offers valid insights into tracking Alzheimer's."

At the current time, there is not an accurate way to measure tau. Of particular interest is that large pharmaceutical firms, trying to find a treatment for AD, are spending hundreds of millions of dollars to develop drugs that try to stop or slow down amyloid deposits.

America....world...stay tuned.

Brain scans performed over the last decade revealed that amyloid accumulated as people progressed, so most Alzheimer's models were based on amyloid toxicity

Read more at: https://medicalxpress.com/news/2015-03-thousands-brains-reveals-tau-driver.html#jCp

Brain scans performed over the last decade revealed that amyloid accumulated as people progressed, so most Alzheimer's models were based on amyloid toxicity

Read more at: https://medicalxpress.com/news/2015-03-thousands-brains-reveals-tau-driver.html#jCp

Brain scans performed over the last decade revealed that amyloid accumulated as people progressed, so most Alzheimer's models were based on amyloid toxicity

Read more at: https://medicalxpress.com/news/2015-03-thousands-brains-reveals-tau-driver.html#jCp