Given the progress in therapeutics for Alzheimer's disease (AD), including the recent approval of aducanumab – the first anti-amyloid immunotherapy approved by the FDA for the disease – there is a need for simple blood tests that could be used to ensure accurate diagnosis and assess therapeutic progress.
In a Perspective, Kaj Blennow highlights the progress made in developing blood tests for AD and the challenges that remain. AD is a progressive neurodegenerative disease that causes severe memory loss and cognitive decline. While much about AD is poorly understood, the progression of the disease is often characterized by the buildup of the proteins amyloid β (Aβ) and phosphorylated tau (pTau), which become plaques and neurofibrillary tangles in the brain.
These proteins are used as biomarkers to diagnose and track AD in patients using positron emission tomography (PET) imaging or by measuring Aβ and pTau concentrations in the cerebrospinal fluid. While these approaches allow for more reliable clinical diagnoses of AD, they are costly and highly invasive. Here, Blennow makes a case for widely accessible and inexpensive blood-based biomarker tests for AD. According to the author, these tests could be used to quickly and easily screen for and monitor AD progression in patients. They could also be used in clinical trials involving newly developed AD therapies to assess their therapeutic efficacy.
Although progress has been made toward achieving these goals, several hurdles need to be overcome, including identifying and classifying the most useful blood biomarkers for AD. However, Blennow notes that technological advances have enabled the measurement of very low amounts of brain-derived proteins in blood samples, suggesting that AD blood tests may soon be realized.
Blennow, K., (2021) Phenotyping Alzheimer's disease with blood tests. Science. doi.org/10.1126/science.abi5208.