A blood test could be used to predict the risk of Alzheimer’s disease up to 3.5 years before clinical diagnosis. The key, according to a study published in the journal “Brain”, lies in identify brain cells in the blood who change their behavior as cognitive decline occurs.

Work done at King’s College London’s Institute of Psychiatry, Psychology and Neuroscience (IoPPN) supports the idea that components of human blood can modulate the formation of new brain cells, a process called neurogenesis. The neurogénesis it occurs in an important part of the brain called the hippocampus that is involved in learning and memory.

Although Alzheimer’s disease affects the formation of new brain cells in the hippocampus during the early stages of the disease, previous studies have only been able to study late-stage neurogenesis through autopsies.

To understand the early changes, the researchers collected blood samples over several years of 56 people with mild cognitive impairment (MCI), a condition in which there is impaired memory or cognitive ability.

While not all people who experience MCI develop Alzheimer’s disease, those with the condition progress to a diagnosis at a much higher rate than the general population.

Of the 56 study participants, 36 received a diagnosis of Alzheimer’s disease.

“In our study, we treated brain cells with blood taken from people with MCI, exploring how those cells changed in response to blood as Alzheimer’s disease progressed,” he explains. Aleksandra Maruszakone of the co-authors of the study.

By studying how blood affected brain cells, researchers made several key discoveries. Blood samples obtained from participants over the years who subsequently deteriorated and developed Alzheimer’s disease promoted a decrease in cell growth and division and an increase in cell death. apoptótica (the process by which cells are programmed to die). However, they found that these samples also increased the conversion of immature brain cells into hippocampal neurons.

Although the reasons for the increased neurogenesis are still unknown, researchers theorize that it may be an early compensatory mechanism for neurodegeneration (loss of brain cells) experienced by those who develop Alzheimer’s disease.

The findings allow us to predict the early onset of Alzheimer’s in a non-invasive way

“Previous studies have shown that blood from young mice may have a rejuvenating effect on cognition in older mice by enhancing hippocampal neurogenesis,” he explains. Sandrine Thuret, lead author of the study. This gave us the idea to model the process of neurogenesis. in a dish using human brain cells and human blood. In our study, the aim was to use this model to understand the process of neurogenesis and to use changes in this process to predict Alzheimer’s disease and we found the first evidence in humans that the body’s circulatory system may have an effect on the brain’s ability to form new cells».

When the researchers used only blood samples obtained before the time the participants were diagnosed with Alzheimer’s disease, they found that the changes in neurogenesis had occurred 3.5 years before the clinical diagnosis.

The data is an opportunity to better understand the changes that the brain goes through in the early stages of the disease.

Hyunah Lee

Kings College London

“Our findings are extremely important, as they potentially allow us to predict the early onset of Alzheimer’s disease in a non-invasive way. This could complement other blood biomarkers that reflect classic signs of the disease, such as amyloid and tau accumulation. (the ‘flagship’ proteins of Alzheimer’s disease)”, stresses Edina Silajdžić.

For Hyunah Lee, a joint co-author of the study, it is now “essential to validate these findings in a larger and more diverse group of people. We are excited about the possible applications of the blood-based test that we use. For example, it may help stratify people with memory problems for a clinical trial of Alzheimer’s disease-modifying drugs.”

The researchers conclude that these findings could be an opportunity to better understand the changes that the brain goes through in the early stages of Alzheimer’s disease.

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