Research

What is ‘tau’ and what role does it play in dementia?

Dr Miguel Ramirez Moreno studies tau through his work as a postdoctoral researcher with Professor Amrit Mudher, through her AS funded project grant. Miguel has put together this helpful explainer on tau's function in dementia.

What is tau?

Tau is a protein naturally produced by our cells, helping them function properly. Its roles include supporting the internal structure of cells - by acting as a kind of strengthening scaffolding - to make them stronger.  

This is especially important for our neuron cells, as they need to be made up of strong and resilient parts, to communicate with each other, transporting everything from electric signals to vital nutrients

Good maintenance by proteins like tau keeps our bodies working efficiently. However, tau has gained a negative reputation because it is involved in several diseases that lead to dementia, including the most common one, Alzheimer’s disease.  

In the image above, we see a healthy neuron (top). tau acts normally across the structure of a neuron, but abnormal tau starts forming fibrous tangles (centre), that eventually are all what remains of the neuron (bottom).  

Did you know... We all have tau inside our brains – inside every one of our cells. And normally that is fine. The problem is not the protein itself, but its behaviour.

Untangling findings on tau and Alzheimer’s disease

Dementia is not a single disease, but a syndrome caused by many different conditions affecting the brain. Alzheimer’s disease is responsible for more than half of all the diagnosed cases of dementia.

The disease was first spotted over a century ago, by Alois Alzheimer. He described the strange clumps he’d seen inside of the brains of people affected - fibre-like structures, or “tangles”.  

As is often the case with major scientific breakthroughs, it took a collaborative effort to understand what these fibres actually were.

In 1975, a group at Princeton University (USA) discovered tau as a protein involved in protecting the internal structure of the cells. But it was not until 1988 that several scientists at Cambridge University (UK) found out that tau was making the tangles that Alzheimer described decades earlier.  

The mystery of the tangles Alois Alzheimer had seen was solved: Finding tau was present in a form it should not be in Alzheimer’s disease. But this opened up more questions for researchers of Alzheimer’s disease. what  Was this just an unusual presentation or something more? Could tau be responsible of for damaging our neurons getting hurt?  

How relevant is tau for dementia?  

Alzheimer’s disease is marked by the presence of abnormal tau tangles, alongside excessive depositions of amyloid beta – commonly known as senile plaques.

Scientists have discovered many ways in which these two proteins interact in the disease process. According to the amyloid cascade hypothesis, amyloid beta is disrupted first, which subsequently leads to changes in tau and other proteins. Abnormal tau is also linked to many other forms of dementia, either on its own or in combination with other proteins. This is why these conditions are collectively referred to as ‘tauopathies’. In each of these diseases, tau may be more or less important, but it is always involved.  

What do and don’t we know about tau?

When tau protein becomes abnormal, it stops doing its usual job of keeping brain cells healthy. This leaves the cells more vulnerable to damage. But it doesn’t just stop helping, it can start harming the brain. 

Scientists have found that abnormal tau can move from one neuron to another, which helps explain how the damage spreads across the brain in diseases like Alzheimer’s.

What research are Alzheimer's Society supporting into tau?

Research will beat dementia and will lead to improved diagnosis, effective treatments and the high-quality care that everyone living with dementia deserves. Learn more about some of the research we are funding to answer the outstanding questions about the tau protein, and how it could be targeted by future treatments.