A blood-based test could be used to predict the risk of Alzheimer’s disease up to 3.5 years before clinical diagnosis according to new research from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London.
The study, published on January 27 in the journal Brain, supports the idea that components in the human blood can modulate the formation of new brain cells, a process termed 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 study neurogenesis in its later stages through autopsies.
To understand the early changes, researchers collected blood samples over several years from 56 individuals with Mild Cognitive Impairment (MCI), a condition where someone will begin to experience a worsening of their memory or cognitive ability. While not everyone experiencing MCI goes on to develop Alzheimer’s disease, those with the condition progress to a diagnosis at a much higher rate 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 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 (the process by which cells are programmed to die). However, the researchers noted that these samples also increased the conversion of immature brain cells to hippocampal neurons.
While the underlying reasons for the increased neurogenesis remain unclear, the researchers theorise that it may be an early compensating mechanism for the neurodegeneration (loss of brain cells) 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.