A very simple blood test could one day diagnose a rare inherited form of Alzheimer’s disease, decades before symptoms of loss of memory even show up.
Researchers in Europe and the United Kingdom have finally proven that cases of early-onset Alzheimer’s are connected with increasing levels of a biomarker in blood plasma.
Alzheimer’s is a generalized term for forms of dementia which have a wide variety of basic reasons, a lot of which we’re still working out.
One form, called autosomal dominant familial Alzheimer’s disease (ADAD), is identified by the presence of mutations in one of several specific genes.
While it covers less than 1 percent of all Alzheimer’s cases, symptoms develop significantly sooner in life than with other forms, which makes it a major problem for those at risk.
Presently, you will find 3 recognized single gene mutations associated with early-onset ADAD. As a predominant trait passed down on non-sex chromosomes, a kid has a fifty percent chance of inheriting the mutated version of the gene if one parent has got the illness.
Genetic testing for the disorder can be expensive and challenging for many to access, therefore a person whose parent had ADAD frequently must wait and see if they develop the condition themselves.
A blood test which can cheaply and easily diagnose ADAD might put many minds at ease, while simultaneously letting early treatment to stall the further advancement of the disease just where it is recognized.
Alzheimer’s disease currently does not have any known cure or cause, and that’s a part of what makes it very tough to diagnose. Biological changes ramp up in the background for a long time before they’ve any distinct physiological effects.
Researchers all over the world have been trying to produce a good diagnostic test, but knowing precisely what to focus on for a definite diagnosis isn’t straight forward. Because Alzheimer’s is not always caused by an individual biological pathway, we would need a lot of different tests for different biomarkers to cover all of the bases.
The brand new research from Sweden provides evidence of a new emerging biomarker. The findings are based on a study in Sweden which followed 33 genetic mutation carriers at risk of ADAD from 1994 to 2018.
In comparison to 42 of their relatives without a mutation, the writers noticed 3 biomarkers which were closely connected with ADAD: plasma phosphorylated tau (P-tau181), neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP).
All three are potential biomarkers of the disease, but the changes to GFAP were noticed in blood plasma well before P-tau181 or NfL, aproximatelly ten years before any symptoms were believed to begin.
What’s more, GFAP showed up in blood plasma samples well before clumps of tau proteins did, along with these are a significant hallmark of the illness, thought to be existing from the very earliest stages. In past times, tau proteins have been employed to foresee the risk of developing Alzheimer’s disease with ninety % accuracy.
“This is the very first report hinting that plasma GFAP is among the earliest blood-based biomarkers in ADAD to our knowledge,” the writers of the study write.
“Our results claim that plasma GFAP might reflect Alzheimer’s disease pathology upstream to buildup of tangles and neurodegeneration.”
The findings will need to be replicated among larger cohorts, but the authors believe there’s a link between plasma GFAP and brain inflammation.
GFAP is a protein for a kind of neuron called an astrocyte, which releases pro-inflammatory molecules when it encounters amyloid beta plaques in the brain.
Amyloid beta (Aβ) proteins which fold into plaques are one key hallmark of some forms of Alzheimer’s disease. In fact, preliminary blood tests used poisonous precursors of Aβ proteins to accurately diagnose the disease years before its first symptoms emerge.
Perhaps GFAP is another route that shows up even earlier in some cases. Maybe the presence of the protein is able to activate astrocyte activity, researchers suggest, leading to more Aβ plaques.
To be clear, Aβ plaques and tau clumps by themselves may not be toxic. That said, they could be a sign of underlying poisonous behavior along with other particles, like GFAP.
The better we get to the root of the illness, the better chance we’ve of diagnosing Alzheimer’s the second it shows up, as opposed to after death, and that is presently the one conclusive way.
“Our results claim that GFAP, a presumed biomarker for activated immune cells in the human brain, reflects changes in the brain as a result of Alzheimer disease that happen before the accumulation of tau protein and measurable neuronal damage,” says neurobiologist Charlotte Johansson from the Karolinska Institutet in Sweden.
“In the future it might be utilized as a non invasive biomarker for the first activation of immune cells such as astrocytes in the central nervous system, which may be valuable to the development of new drugs and also to the diagnostics of cognitive diseases.”
The study was published in Brain.