Scientists think they have discovered the underlying origin of Alzheimer’s disease and that a straightforward blood test may now be used to diagnose the illness.
Although amyloid deposition in the brain has long been associated with the condition, it is unclear if the plaques are a cause of the illness or a symptom.
Why some people with amyloid clots in their brains never acquire Alzheimer’s disease is even more mysterious. The solution, according to a recent, ‘groundbreaking’ research from the University of Pittsburgh.
They discovered that individuals who acquire Alzheimer’s disease also have blood markers for the activation of immune cells known as astrocytes.
Scientists may have found the true cause of Alzheimer’s – and believe the condition can be detected with a simple blood test (stock image)
These star-shaped immune cells supply the brain with nutrients and oxygen and protect it from pathogens.
Dr. Tharick Pascoal, an associate professor of psychiatry and neurology at the university and senior author of the study, said: ‘This puts astrocytes at the center of attention as key regulators of disease progression, challenging the idea that amyloid is sufficient to cause Alzheimer’s disease. .
The research has been published in the journal Naturopathy.
The team tested the blood of more than 1,000 cognitively healthy older adults with and without amyloids in their brains.
They found that only those who had a combination of amyloid and blood markers of abnormal astrocyte activity would progress to symptomatic Alzheimer’s in the future.
They described it as a “critical” discovery for drug development to halt the progression.
Professor Pascoal said: ‘Our study argues that testing for the presence of brain amyloid together with blood biomarkers of astrocyte reactivity is the optimal screen to identify patients most at risk of developing Alzheimer’s disease.
The hallmark of Alzheimer’s disease is a buildup of amyloid plaques — protein aggregates that get stuck between nerve cells of the brain — and clumps of disordered protein fibers called tau tangles that form inside the neurons.
For years, brain scientists believed that a buildup of amyloid plaques and tau tangles is not only a sign of Alzheimer’s disease, but also the direct culprit.
The assumption also led drugmakers to invest heavily in molecules that target amyloid and tau, overlooking the contribution of other brain processes, such as the neuroimmune system.
Recent discoveries suggest that disrupting other brain processes, such as increased brain inflammation, may be just as crucial as the amyloid burden in starting the pathological cascade of neuronal death that causes rapid cognitive decline.
Now the research team has worked out that a blood test can predict cognitive impairment.
Professor Pascoal explained that astrocytes are specialized cells that are abundant in brain tissue. They support neuronal cells by supplying them with nutrients and oxygen and protecting them from pathogens.
But because they don’t conduct electricity and initially didn’t seem to play a direct role in how neurons communicate with each other, their role in health and disease has been overlooked until now.
Lead author of the study Dr. Bruna Bellaver said: ‘Astrocytes coordinate the amyloid and tau relationship in the brain like a conductor leading an orchestra.
“This could be a game-changer for the field, as glial biomarkers are generally not considered in any major disease model.”
The team tested blood samples from participants in three independent studies of cognitively unaffected elderly people for biomarkers of astrocyte reactivity along with the presence of pathological tau.
The study showed that only those positive for both amyloid and astrocyte reactivity showed evidence of progressive tau pathology, suggesting predisposition to clinical symptoms of Alzheimer’s disease.
Dr. Bellaver said the findings have direct implications for future clinical trials of Alzheimer’s drug candidates.
To halt disease progression faster, studies move to ever earlier stages of presymptomatic disease, making accurate early diagnosis of Alzheimer’s risk critical to success
She said the inclusion of astrocyte reactivity markers in tests will allow better selection of patients likely to progress to later stages of Alzheimer’s disease and therefore help refine patient selection for therapeutic interventions likely to benefit. .
Alzheimer’s can be detected using blood test, ‘game-changing’ study finds