A new test could detect Alzheimer’s disease three and a half years before it is diagnosed, a new study suggests. The new research from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London has established a blood-based test that could predict the risk of the condition.
The study supports the idea that components in human blood can influence the formation of new brain cells, a process called neurogenesis. This process occurs in a part of the brain called the hippocampus that is involved in learning and memory.
While Alzheimer’s affects the formation of new brain cells in the hippocampus during the early stages of the disease, previous research has only been able to study neurogenesis in its later stages through post-mortem examinations. In order to understand the early changes, over a number of years researchers collected blood samples from 56 people with mild cognitive impairment (MCI), a condition where someone will begin to experience a worsening of their memory or cognitive ability.
While not everyone with MCI will develop Alzheimer’s disease, those with the condition progress to a diagnosis at a much higher rate than the wider population. Thirty-six of the 56 people in the study went on to be diagnosed with Alzheimer’s.
When the researchers used only the blood samples collected furthest away from when someone was diagnosed with Alzheimer’s disease, they found that the changes in neurogenesis occurred 3.5 years before a clinical diagnosis.
Professor Sandrine Thuret, the study’s lead author from King’s IoPPN said, “Previous studies have shown that blood from young mice can have a rejuvenating effect on the cognition of older mice by improving hippocampal neurogenesis. This gave us the idea of modelling the process of neurogenesis in a dish using human brain cells and human blood.
“In our study, we aimed 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.”
According to the research, blood samples collected from people who went on to develop Alzheimer’s disease promoted a decrease in cell growth and division. They also promoted an increase in apoptotic cell death – the process by which cells are programmed to die, the study found.
While the reasons for the increased neurogenesis remain unclear, the researchers suggest it may be an early compensating mechanism for the loss of brain cells experienced by those developing Alzheimer’s disease.
Dr Edina Silajdzic, the study’s joint first author, added, “Our findings are extremely important, potentially allowing us to predict onset of Alzheimer’s early in a non-invasive fashion. This could complement other blood-based biomarkers that reflect the classical signs of the disease, such as the accumulation of amyloid and tau (the ‘flagship’ proteins of Alzheimer’s disease).”
The researchers say the findings, published in the journal Brain, could present an opportunity to further understand the changes the brain goes through at the earliest stages of Alzheimer’s.
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