Alzheimer’s could be diagnosed more than a decade before symptoms appear with new blood biomarker

Newly found blood biomarkers could help diagnose Alzheimer’s disease more than a decade before symptoms start to emerge.

A world first study from researchers at Macquarie University identified a protein in the blood which could lead to low cost screening and quicker diagnosis in the future.

A person with Alzheimer's develops protein beta-amyloid forming ‘plaques’ outside the brain cells, and accumulation of the tau protein in ‘neurofibrillary tangles’ inside brain cells.

This build up gradually damages connections between brain cells, and it can be years before the damage is noticeable.

It was only in the last decade that this protein build-up could be identified using a brain imaging technique called positron emission tomography (PET) amyloid imaging, along with cerebrospinal fluid (CSF) tests.

This study is the first to compare the blood proteins associated with Alzheimer’s disease in a group of older people who had no behavioural signs of Alzheimer’s, but where some subjects had the early build-up of amyloid in the brain associated with the disease.

“We also found for the first time, that levels of GFAP and p-tau181 levels increased in pre-clinical Alzheimer’s patients over 12 months, but these didn’t increase in cognitively normal older people without Alzheimer’s-specific abnormal brain tissue changes,” said neurobiologist Professor Ralph Martins from Macquarie University’s Department of Biomedical Sciences.

Martins and his team have been working on a longitudinal Alzheimer's study, involving the collection of blood samples, neuroimaging and cognitive testing of more than 2000 people, some since 2006.

“We found that we could identify beta-amyloid in the brains of people up to 20 years before the onset of symptoms,” he says.

“Clinical trials are now starting much earlier, because we think the reason so many fail is that people’s brains have been severely compromised by the time drug treatments were being attempted."

The research involves an international team from around Australia, the UK, the USA, Sweden and Belgium, which is led by Martins.

“Our findings highlight promising biomarkers for use in early diagnostic and prognostic blood tests for Alzheimer’s disease, prior to symptoms,” said co-lead author Dr Pratishtha Chatterjee.

“These findings will allow more cost-effective screening and prognosis in clinical trials.”