Key points:
- A blood-based test could predict the risk of Alzheimer’s disease up to 3.5 years ahead of diagnosis.
- The study focused on formation of new brain cells in the hippocampus during the early stages of the disease.
- The findings might help scientists understand changes the brain goes through in the early stages of Alzheimer’s.
Researchers at King’s College London have demonstrated a blood-based test that can predict the risk of Alzheimer’s disease up to 3.5 years ahead of clinical diagnosis
The study, published in Brain, supports the idea that components in the human blood can modulate the formation of new brain cells, a process called neurogenesis. Neurogenesis occurs in the hippocampus, the part of the brain involved in learning and memory. The majority of studies have focused on studying neurogenesis in its later stages through autopsies, but Alzheimer’s disease affects the formation of new brain cells in the hippocampus during the early stages of the disease.
To understand the early changes, researchers collected blood samples over several years from 56 individuals with mild cognitive impairment. While those experiencing mild cognitive impairment don’t always go on to develop Alzheimer’s disease, those displaying the condition are at a higher risk than the wider population. Of the 56 participants in the study, 36 went on to receive a diagnosis of Alzheimer’s disease.
In studying how blood affected the brain cells, the researchers made several key discoveries. The blood samples collected 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 apoptotic cell death. However, the researchers noted that these samples also increased the conversion of immature brain cells to hippocampal neurons.
When the researchers used only the blood samples collected furthest away from when the participants were diagnosed with Alzheimer’s disease, they found that the changes in neurogenesis occurred 3.5 years prior to a clinical diagnosis.
While the underlying reasons for the increased neurogenesis remain unclear, the researchers theorize that those developing Alzheimer’s disease may undergo early compensating mechanisms for the neurodegeneration.
“It is now essential to validate these findings in a bigger and more diverse group of people. We are excited about the potential applications of the blood-based test we used. For example, it can help stratify individuals with memory problems for a clinical trial of disease-modifying drugs for Alzheimer’s,” said co-first author Hyunah Lee.