A simple blood test could spot Alzheimer's a decade before a person starts to display symptoms, scientists have discovered.
Researchers at Karolinska Institutet, Sweden, found that a type of protein called GFAP could be used as a possible blood-marker for the 'very early' signs of the illness - meaning that it could be identified during a quick blood test.
It often takes years for Alzheimer's symptoms such as memory loss to show up after a person develops the disease. However, diagnosing it earlier on may help slow down the illness with drugs and other medication.
The discovery of GFAP as a potential blood-marker could allow experts to prompt an early immune response.
At the moment, Alzheimer disease causes 60 to 70 percent of all dementia cases, according to the Swedish Brain Foundation.
Around 20 to 25 years before a person starts to experience symptoms like memory loss, the person's brain begins to change. The earlier they're diagnosed, the faster they can access treatment.
Proteins beta-amyloid and tau begin to form abnormally, causing the nerves in the brain to degenerate. As more brain neurons are damaged, sufferers begin to lose cognitive functions such as memory and speech.
The study's first author Charlotte Johansson, doctoral student at the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Sweden, said: "Our results suggest that GFAP, a presumed biomarker for activated immune cells in the brain, reflects changes in the brain due to Alzheimer disease that occur before the accumulation of tau protein and measurable neuronal damage.
"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."
The team of scientists searched biomarkers in the blood for very early changes in a rare and inherited form of Alzheimers, where those who have a parent with the disease have a 50 percent chance of developing it.
They analysed 164 blood plasma samples from 33 mutation carriers, and 42 relatives without the inherited chance of getting Alzheimers taken between 1994 and 2018.
They found distinct changes of several blood protein concentrations in the mutation-carriers.
Writing in the journal Brain, study author Caroline Graff, professor at the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet: "The first change we observed was an increase in GFAP (glial fibrillary acidic protein) approximately ten years before the first disease symptoms.
"This was followed by increased concentrations of P-tau181 and, later, NfL (neurofilament light protein), which we already know is directly associated with the extent of neuronal damage in the Alzheimer brain.
"This finding about GFAP improves the chances of early diagnosis."
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