Commentary—A New Test for Alzheimer Disease?

Alzheimer disease for a long time was diagnosed primarily on the basis of a doctor’s evaluation, including mental status testing. More recently, doctors have begun using tests such as spinal fluid analysis and positron emission tomography (PET) to help diagnose Alzheimer disease. However, these tests are expensive and cumbersome to carry out. Spinal fluid analysis requires a spinal tap (lumbar puncture) and PET scans are not easily available.

A fast, inexpensive, easy to carry out blood test would be ideal to detect Alzheimer disease, especially if the test could detect Alzheimer early. In addition to helping people with Alzheimer and their families plan for needed care, having a convenient test would make it easier for researchers to look for ways to prevent Alzheimer and to develop treatments.

In a recent issue of the journal Neurology, researchers reported on an experiment comparing a new blood test to the currently used diagnostic tests, PET scanning and spinal fluid analysis. The results of the experiment suggest that the abnormal amyloid protein that is a marker for Alzheimer disease may be detected in the blood even before the PET scan is abnormal. This preliminary finding suggests that eventually a blood test might be used as a screening test for people who are at risk of Alzheimer disease. Until the test is studied and proven more thoroughly, it will be useful mainly for researchers who are looking for ways to prevent and treat Alzheimer disease. Much additional experimentation is needed before such a blood test would be available to people who are experiencing memory loss.