Recent advancements in Alzheimer's disease (AD) focus on earlier detection and more effective treatments. New blood tests are being developed to identify AD before symptoms become severe, potentially replacing more invasive tests like spinal taps and brain scans. Excitingly, new drugs have been approved that target the disease's progression, with several more in clinical trials showing promise. These innovations offer hope for earlier diagnosis and better management of AD, making it a hopeful time for people living with a diagnosis of AD and their family members.

Although these recent achievements are promising, commercially available diagnostic tests using blood-based biomarkers (BBM) are still scratching the surface for early detection of AD. Researchers have found that p-tau 217 levels are elevated in individuals with AD and can be detected in both cerebrospinal fluid (CSF) and blood plasma. This biomarker best correlates with the presence of amyloid plaques in the brain, making it a promising tool for triaging and confirmation of amyloid pathology.

BBM tests serve two primary purposes: triaging and confirming amyloid pathology. When triaging, a negative test result indicates that individuals are unlikely to have amyloid pathology and should be assessed for other causes of cognitive impairment. A positive result suggests a higher likelihood of amyloid pathology, necessitating further accurate testing. Triaging tests are most suitable for people with a pre-test probability of amyloid positivity of 50% or less, as a negative result in this context provides high confidence that amyloid pathology is not present. However, when the pre-test probability exceeds 50%, a negative BBM result is less reliable for ruling out amyloid pathology. Clinicians must still consider Alzheimer's disease as a possible cause in people with negative BBM results but who show symptoms of AD.1