The presence of a specific protein in the blood may be an early indicator of Alzheimer’s disease, researchers from Sweden’s Karolinska Institutet have found. The discovery could lead to earlier diagnoses of the condition via blood tests and increase the chance of slowing down its progression using preventative drugs.


Alzheimer’s disease is responsible for around 60 to 70 per cent of all dementia cases. It is caused by the proteins beta-amyloid and tau building up in the brain and damaging nerve cells. These build-ups can begin up to 25 years before they lead to noticeable symptoms such as memory loss and issues with speech.

The team analysed blood plasma samples from 75 patients, 33 that carried a genetic mutation that predisposes them to develop a rare inherited form of Alzheimer’s and 42 without the mutation.

They found that the presence of glial fibrillary acidic protein (GFAP) in star-shaped brain cells known as astrocytes was a potential early warning sign for those that went on to develop Alzheimer’s.

The levels of GFAP in the brain were seen to increase around ten years before the emergence of the first symptoms of the condition, followed by tau proteins and neurofilament light protein (NfL) – both compounds known to cause damage to neurons in those with Alzheimer’s.

“Our results suggest that GFAP, a presumed biomarker for activated immune cells in the brain, reflects changes in the brain due to Alzheimer's disease that occur before the accumulation of tau protein and measurable neuronal damage,” said lead researcher Charlotte Johansson, doctoral student at the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Sweden.

“In the future it could be used as a non-invasive biomarker for the early activation of immune cells such as astrocytes in the central nervous system, which can be valuable to the development of new drugs and to the diagnostics of cognitive diseases.”

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Jason Goodyer
Jason GoodyerCommissioning editor, BBC Science Focus

Jason is the commissioning editor for BBC Science Focus. He holds an MSc in physics and was named Section Editor of the Year by the British Society of Magazine Editors in 2019. He has been reporting on science and technology for more than a decade. During this time, he's walked the tunnels of the Large Hadron Collider, watched Stephen Hawking deliver his Reith Lecture on Black Holes and reported on everything from simulation universes to dancing cockatoos. He looks after the magazine’s and website’s news sections and makes regular appearances on the Instant Genius Podcast.