New research from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London has developed a blood test that could be used to predict the risk of Alzheimer’s disease up to 3.5 years before the onset of clinical diagnosis.
The study, published in the journal Brain, supports the idea that components of human blood can modulate the formation of new brain cells, a process called neurogenesis. Neurogenesis occurs in an important part of the brain called the hippocampus which is involved in learning and memory.
While 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 investigate neurogenesis in its later stages through autopsies.
To understand the early changes, the researchers took blood samples over several years from 56 people with mild cognitive impairment (MCI), a condition in which a person will begin to experience worsening of their memory or cognitive abilities. Although not everyone with MCI develops Alzheimer’s disease, those with it progress to a diagnosis at a much higher rate than the general population. Of the 56 study participants, 36 were subsequently diagnosed with Alzheimer’s disease.
Dr. Aleksandra Maruszak, one of the first co-authors of the King’s IoPPN study, explains: “In our study, we treated brain cells with blood taken from people with MCI, exploring how these cells changed in response to blood as Alzheimer’s disease progressed.
By studying how blood affects brain cells, researchers made several key discoveries. Blood samples taken over the years from participants who later deteriorated and developed Alzheimer’s disease promoted decreased cell growth and division and increased apoptotic cell death (the process by which cells are programmed to die). However, the researchers noted that these samples also increased the conversion of immature brain cells into hippocampal neurons.
Although the underlying reasons for increased neurogenesis remain unclear, researchers hypothesize that it may be an early compensatory mechanism for neurodegeneration (loss of brain cells) experienced by people developing Alzheimer’s disease.
Professor Sandrine Thuret, lead author of the King’s IoPPN study, said: “Previous studies have shown that the blood of young mice can have a rejuvenating effect on the cognition of older mice by enhancing hippocampal neurogenesis. This gave us the idea to model the process of neurogenesis. in a dish using human brain cells and human blood In our study, we sought to use this model to understand the process of neurogenesis and to use changes in this process to predict Alzheimer’s disease and found the first evidence in humans that the body’s circulatory system can have an effect on the brain’s ability to form new cells. »
When researchers used only blood samples taken furthest from when participants were diagnosed with Alzheimer’s disease, they found changes in neurogenesis occurred 3.5 years before a clinical diagnosis. .
Dr Edina Silajdži?, co-first author of the study, added: “Our results 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 Alzheimer’s disease. disease, such as the accumulation of amyloid and tau (the “flagship” proteins of Alzheimer’s disease). »
Dr Hyunah Lee, co-lead author of the study, said: “It is now essential to validate these results with a larger and more diverse group of people. We are excited about the potential applications of the blood test we used. For example, it can help stratify people with memory problems for a clinical trial of Alzheimer’s disease-modifying drugs. »
The researchers say these findings could provide an opportunity to better understand the changes the brain undergoes in the early stages of Alzheimer’s disease.
This study was made possible by funding from the John and Lucille van Geest Foundation, the Medical Research Council UK, the Cohen Charitable Trust, the Galen and Hilary Weston Foundation and the Rhodes Trust.