Test can reveal if you're at risk of Alzheimer's YEARS before it develops: Key proteins seen in brain scans are an early indicator of the disease

For the first time, scientists have found a link between certain proteins found in the brain and the risk of people developing Alzheimer's.  

Using an advanced type of brain scanner, the researchers were able to detect two proteins called 'Tau' and 'amyloid' in the brains of patients. 

On their own, these proteins do not put people at risk. However, when they become 'tangled' together, the combination can cause the disease to develop. 

If this combination of proteins can be spotted in brain scans before typical symptoms of the disease develop, it could help doctors and patients prepare and manage the onset more effectively.  

Using a brain scanner, researchers have detected proteins that are thought to cause Alzheimer's. The left-hand scan shows low levels of these proteins, the middle scans show the brain of a person at risk from the disease and the right-hand scan shows what these levels look like in an Alzheimer's patient for comparison 

The test is the first time signs of the disease have been found in the living rather than on dead bodies.

Dr William Jagust, Professor of Neuroscience at Berkeley said the tests discovered the build-up of two kinds of proteins, amyloid and Tau protein which have been linked to getting Alzheimer's.

He said: 'Our study is the first to show the staging in people who are not only alive, but who have no signs of cognitive impairment.'

He added: 'We can now very reliably and with a great degree of accuracy say that there are changes in a person's brain that are very highly predictive that a person's going to get Alzheimer's.'

To test for Alzheimer's, Dr Jagust and colleagues carried out tests on 53 adults.

Five were young adults aged 20 and 26, 33 were cognitively healthy adults aged 64-90, and 15 were patients aged 53 and 77 who had been diagnosed with probable Alzheimer's dementia.

The researchers found that all ageing brains - in healthy patients and those with Alzheimer's - had more 'tangles' of Tau protein in an area called the medial temporal lobe, associated with memory.

The subjects were given memory tests.

Researchers found that the people with higher levels of Tau had worse memories – and it is now thought that it is the build-up of Tau which leads to people's memories worsening as they age.

The test is the first time signs of the disease have been found in the living rather than on dead bodies, using Positron emission tomography (PET). These scans are used to produce detailed 3D images of the inside of the body by detecting the radiation given off by a substance called a radiotracer as it collects in parts of the body

Researchers found people with higher levels of a protein call Tau (pictured in the brain of an Alzheimer patient) had worse memories. But having high levels of Tau protein alone was not linked to the severe dementia seen in Alzheimer's. It was only when Tau and amyloid were linked together, the declines in brain function were seen

But having high levels of Tau protein alone was not linked to the severe dementia seen in Alzheimer's.

At the same time, higher levels of amyloid alone did not get Alzheimer's.

But when the Tau and amyloid were linked together, the serious declines in brain function seen in Alzheimer's were found to be triggered, the researchers said.

Positron emission tomography (PET) scans are used to produce detailed 3D images of the inside of the body.

They work by detecting the radiation given off by a substance called a radiotracer as it collects in different parts of your body. 

By analysing the areas where the radiotracer does and doesn't build up, it's possible to work out how well certain body functions are working and identify any abnormalities. 

It is not yet known whether Tau leads to amyloid build up, or the other way round.

Dr Jagust said: 'Amyloid may somehow facilitate the spread of tau, or tau may initiate the deposition of amyloid. We don't know. We can't answer that at this point.

'All I can say is that when amyloid starts to show up, we start to see tau in other parts of the brain, and that is when real problems begin.

During the course of the disease, proteins build up in the brain to form structures called 'plaques' and 'tangles (examples pictured). This leads to the loss of connections between nerve cells, and eventually to the death of nerve cells and loss of brain tissue. In turn, this can lead to memory loss and problems with language

'We think that may be the beginning of symptomatic Alzheimer's disease.'

The build-up of the two proteins interferes with transmission of signals down nerves in the brain.

Dr Jagust added: 'If we can look at people before they get dementia, and we know how much amyloid is in the brain, and how much Tau is in the brain we might be able to get a sense of their stage or progression towards Alzheimer's disease.

'That may be crucially important when we give them certain kinds of medication. If this approach works, it will be very exciting, and we will, I hope have a therapeutic intervention for Alzheimer's.' Whether the drugs will need to target Tau or amyloid is still not yet known, he said.

Dr Simon Ridley, Director of Research at Alzheimer's Research UK, who was not involved in the study said: 'While the findings add to evidence that tau is a key mediator of damage in Alzheimer's, the results raise further questions about what triggers the most damaging events in the brain.

'Further research using PET scans to study tau will provide greater insight into how it interacts with amyloid and contributes to the disease, and whether this information could translate to meaningful improvements in diagnosis or treatments in the clinic.'