Researchers from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London have developed a blood test that may be able to predict the risk of Alzheimer’s disease up to 3.5 years before clinical diagnosis. The study, which was published in the journal Brain, suggests that certain components in human blood can affect the formation of new brain cells, a process known as neurogenesis. This occurs in the hippocampus, a region of the brain that is vital for learning and memory.
Previous studies have only been able to study neurogenesis in the later stages of the disease through autopsies. To understand the early changes, the researchers collected blood samples over several years from 56 individuals with Mild Cognitive Impairment (MCI), a condition where someone begins to experience a worsening of their memory or cognitive abilities. While not everyone with MCI develops Alzheimer’s disease, those with MCI are much more likely to progress to a diagnosis than the general population.
The researchers studied how blood affected brain cells and made several key discoveries. The blood samples collected from participants who subsequently developed Alzheimer’s disease promoted a decrease in cell growth and division and an increase in apoptotic cell death. However, the researchers also observed that these samples increased the conversion of immature brain cells to hippocampal neurons.
The underlying reasons for the increased neurogenesis remain unclear, but the researchers theorize that it may be an early compensating mechanism for the neurodegeneration experienced by those developing Alzheimer’s disease.
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.
The researchers say that these findings could present an opportunity to further understand the changes the brain goes through at the earliest stages of Alzheimer’s disease. They also say that it is important to validate the findings in a bigger and more diverse group of people. If validated, this blood-based test could be used to help stratify individuals with memory problems for a clinical trial of disease-modifying drugs for Alzheimer’s.