A clinician will order a blood test today to check the cholesterol or hemoglobin A1c levels of a patient — biomarkers that help predict the risk of cardiovascular disease or diabetes, respectively, for a person. But a blood test to predict the risk remains elusive amid decades of developments in the understanding of Alzheimer’s disease (AD). Imaging brain scans and lumbar punctures that collect cerebrospinal fluid can provide diagnosis, but for patients, such tests are costly and bulky.
Researchers documented the development of a blood test two years ago for a fragment of the protein tau, a hallmark of AD. In the Harvard Aging Brain Study (HABS), a cohort of cognitively normal, older adults who are closely monitored over time, the test for levels of N-terminal tau fragment (NT1) has now been assessed. Researchers are now documenting that baseline blood NT1 levels are highly predictive of the likelihood of cognitive impairment and AD dementia.