Blood Biomarker Test Could Detect Genetic Predisposition to Alzheimer’s
Posted on 18 Apr 2025
New medications for Alzheimer’s disease, the most common form of dementia, are now becoming available. These treatments, known as “amyloid antibodies,” work by promoting the removal of small deposits from the brain and can help delay the progression of the disease. However, these treatments are most effective when administered in the early stages of the disease, highlighting the growing importance of early diagnosis. Unfortunately, Alzheimer’s is typically diagnosed at a later stage, creating a need for improved diagnostic tools to fully capitalize on these new treatments. A new study has revealed that individuals genetically predisposed to Alzheimer’s disease exhibit altered blood levels that signal damage to neuronal connections as early as 11 years before the expected onset of dementia symptoms. This is reflected in the levels of the protein “beta-synuclein,” as detailed in findings published in Alzheimer’s & Dementia. The biomarker identified could potentially help detect neurodegeneration at an earlier stage, offering an optimal window for initiating treatment.
The study is based on data from DIAN, a global research network that includes researchers from the German Center for Neurodegenerative Diseases (DZNE, Göttingen, Germany). This network focuses on the hereditary form of Alzheimer’s disease, which is caused by genetic mutations. Beta-synuclein, a protein found primarily at synapses—the junctions through which neurons exchange signals—plays a critical role in the progression of Alzheimer’s. As these synapses deteriorate over time, beta-synuclein is released into the bloodstream, where it can be detected via a blood test. In the current study, the international team analyzed blood samples for beta-synuclein levels from over 100 adults with genetic mutations associated with Alzheimer’s disease. The participants, aged from their mid-30s to mid-40s, were also assessed for cognitive function. About one-third of the participants displayed signs of dementia, while the remaining individuals were symptom-free.
Some of the participants were further examined using cerebrospinal fluid samples and brain scans, with some even undergoing multiple assessments to track changes in their condition over time. This comprehensive data allowed the researchers to track how blood levels of beta-synuclein changed throughout the progression of Alzheimer’s. The study found that the concentration of beta-synuclein in the blood began to rise around 11 years prior to the expected appearance of dementia symptoms, indicating early synaptic degeneration. In contrast, the loss of brain mass and other pathological changes typical of Alzheimer’s occurred later. Moreover, after the onset of symptoms, the level of beta-synuclein in the blood was found to correlate with the severity of cognitive decline, with higher levels linked to greater impairment. This suggests that beta-synuclein serves as a biomarker reflecting the pathological changes occurring both in the pre-symptomatic and symptomatic stages of the disease. The researchers believe similar findings may apply to the sporadic form of Alzheimer’s disease, though this hypothesis requires further validation in subsequent studies.
“If confirmed, this biomarker could perhaps be applied in the context of extended diagnostics to confirm or rule out a suspected case of Alzheimer’s disease,” said DZNE researcher Dr. Patrick Öckl. “Besides early detection, this marker could possibly also be useful for assessing whether a therapy is taking effect, slowing synaptic loss and thus disease progression.”
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