Scientists discover new Alzheimer’s indicator in the blood

Despite researchers around the world investigating the causes of Alzheimer’s disease, there’s still many unknowns associated with the condition. Chief among them has been whether the build-up of amyloid plaques in the brain is a cause or symptom.

Further to this, scientists have remained puzzled as to why some people with these build-ups don’t go on to develop the neurodegenerative condition. Now, scientists at the University of Pittsburgh in the US believe they may have uncovered some answers.

They’ve found that individuals who go on to have Alzheimer’s have immune cells called astrocytes activated. These are picked up as indicators in the blood, which could also help to predict a person’s risk of developing the condition in the future.

Astrocytes are star-shaped cells that supply nutrients and oxygen to the brain and protect it from pathogens. When they’re activated, this can be detected via a simple blood test, which could work as an early warning system for those who may develop the most common form of dementia.

Dr Tharick Pascoal, associate professor of psychiatry and neurology at the university and senior author of the study, said: “This puts astrocytes at the centre as key regulators of disease progression, challenging the notion that amyloid is enough to trigger Alzheimer’s disease.”

More than 1,000 participants with good cognitive health were included in the research. Some had amyloid plaques in their brains and others didn’t, but all of their blood was tested and those exhibiting abnormal astrocyte activity were found to go on to develop Alzheimer’s.

The scientists have described the breakthrough as ‘critical’ in the search for treatments to prevent the disease’s progression. Assumptions that the accumulation of amyloid plaques and tau tangles are the cause of Alzheimer’s have led to drug manufacturers investing hugely in this area.

However, they’ve then failed to fully investigate the contribution of other brain processes, such as the neuroimmune system, to the disease. Heightened brain inflammation and other disruptors are now thought to be as significant as the amyloid plaques in the development of dementia.

Professor Pascoal added: “Our study argues that testing for the presence of brain amyloid along with blood biomarkers of astrocyte reactivity is the optimal screening to identify patients who are most at risk for progressing to Alzheimer's disease.”

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