Biomarkers are nature's indicators: measurable molecules that reflect processes happening inside our bodies. In Alzheimer's disease, brain imaging scans and cerebrospinal fluid (CSF) tests which measure the amyloid biomarker form part of the diagnostic pathway in several countries. Researchers have also spent many decades working on biomarkers for Alzheimer's disease that can be measured in blood samples, which can be easily obtained without undergoing invasive spinal tap procedures or costly PET scans.
In their new article, just published in the Alzheimer's and Dementia journal, and launched at the 2022 Alzheimer's Association International Conference (AAIC), the Alzheimer's Association Global Workgroup provides recommendations for the appropriate use of blood-based biomarkers in clinical practice and trials. Highlighting that 25-30% of patients with a clinical diagnosis of Alzheimer's dementia are misdiagnosed, and citing the lack of tools for predicting disease progression, the authors explain that blood-based biomarkers may be a feasible, cost-effective and accessible option for use in primary care.
However, they caution that most studies of blood-based biomarkers in Alzheimer's disease have been performed in the clinical research setting, which does not always capture the diversity present in wider society. As a result, the Workgroup calls for more studies on blood-based biomarkers in diverse, primary care populations prior to implementation in this setting, explaining that care must be taken to avoid doing more harm than good.
The article identifies a number of research priorities from the Workgroup, which span technical developments to more in-depth, longitudinal research on biomarkers; as well as work on implementation, interpretation of results, and communication of these to doctors and patients. Although blood-based biomarkers are not yet ready for use in primary care, the Workgroup recommend their use in clinical trial recruitment and screening, where they could help identify participants with Alzheimer's disease pathological changes who could benefit from trials of disease-modifying therapies. As a starting point towards implementing blood-based biomarkers in clinical practice, they recommend using them as part of the diagnostic progress in specialised memory clinics, alongside established methods such as brain PET imaging and/or analysis of CSF.
Prof Charlotte Teunissen (VUmc, the Netherlands), senior author of the article, explained: “The implementation of blood-based biomarkers in primary care will likely take a much longer time because there are very few relevant and high-quality research studies on Alzheimer’s-related biomarkers conducted in this setting - but more prospective studies are expected to launch in the coming years.”