A newly discovered biomarker in the blood could help detect Alzheimer’s disease at an earlier stage.
Researchers at the Karolinska Institutet in Sweden looked at a protein called glial fibrillary acidic protein, or GFAP, which may serve as a biomarker for very early stages of the disease.
They explain that the disease progresses slowly, with biological changes in the brain beginning 20 to 25 years before memory loss and other cognitive symptoms show.
Their study focused on a rare inherited form of Alzheimer’s disease, accounting for less than 1% of cases. Children of someone with this mutation-driven Alzheimer’s disease have a 50% risk of developing the disease.
Blood plasma samples from 33 carriers of the inherited mutation and 42 relatives without it were analysed.
Results appear in today’s *Brain* journal. They showed clear changes of several blood protein concentrations including GFAP in the mutation-carriers.
Professor Caroline Graff said: “The first change we observed was an increase in GFAP 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.”
First author, PhD student Charlotte Johansson, added: “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.”
Johansson, C. et al. Plasma biomarker profiles in autosomal dominant Alzheimer’s disease. *Brain* 11 January 2023; doi: 10.1093/brain/awac399
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