Researchers at King’s College London have found that a blood test can help predict a person’s risks of Alzheimer’s disease years before a clinical diagnosis, by evaluating the body’s ability to form new brain cells.
In a study published in the journal Brain, researchers at the university’s Institute of Psychiatry, Psychology & Neuroscience said certain components in the bloodstream can help promote or slow down the processes of neurogenesis—where brain cells are fashioned within the hippocampus, the region associated with memory, and which are affected by the early phases of Alzheimer’s.
While previous studies have only been able to study neurogenesis in the disease’s later stages following an autopsy, the researchers hoped a non-invasive blood test could chart Alzheimer’s development by following these biomarkers.
Over a period of several years, they collected samples from 56 people with mild cognitive impairment; 36 of whom were eventually diagnosed with Alzheimer’s. The researchers then treated brain cells with the blood and observed how they responded as Alzheimer’s disease progressed.
They discovered that the blood from people who developed Alzheimer’s led to decreases in cell growth and division, and an increase in cell death. But at the same time, those samples also boosted the conversion of young, immature brain cells into hippocampal neurons.
“Previous studies have shown that blood from young mice can have a rejuvenating effect on the cognition of older mice by improving hippocampal neurogenesis. This gave us the idea of modeling the process of neurogenesis in a dish using human brain cells and human blood,” the study’s lead author, Professor Sandrine Thuret, said in a release.
Some of the earliest blood samples collected demonstrated effects on neurogenesis about three-and-a-half years before the person received a clinical Alzheimer’s diagnosis.
“Our findings are extremely important, potentially allowing us to predict onset of Alzheimer’s early in a non-invasive fashion,” said Edina Silajdžić, a postdoctoral research associate and one of the study’s joint first authors. “This could complement other blood-based biomarkers that reflect the classical signs of the disease, such as the accumulation of amyloid and tau (the ‘flagship’ proteins of Alzheimer’s disease).”
For development into a diagnostic test—or even a tool to organize the participants of a clinical trial for an Alzheimer’s treatment—the findings will have to be validated in a larger and more diverse group of people, the researchers said, and the underlying causes of neurogenesis still remain unclear.
Other blood tests have focused on becoming sensitive enough to detect the remnants of the aforementioned “flagship” brain proteins known as amyloid and tau. One test developed by C2N Diagnostics previously found that it could predict the presence of amyloid plaques on par with a PET scan. Meanwhile, a test from Roche compares a specific tau structure with the levels of another protein known as apolipoprotein e4; that approach earned a breakthrough designation from the FDA last year.
The agency cleared its first in vitro test for the early detection of Alzheimer’s in May 2022. The Lumipulse amyloid test, developed by Fujirebio Diagnostics, relies on samples of cerebrospinal fluid instead of blood.