New Blood Test Could Definitively Diagnose Alzheimer's Disease

We're all painfully aware that there isn't a cure for Alzheimer's. There isn't even a reliable way to diagnose it. But a new blood test, the first of its kind, indicates that we can hold out hope for a surefire diagnosis, one that might catch the disease earlier than the current battery of brain scans and cognitive tests.

A recent trial conducted by scientists at Saarland University and Siemens Healthcare compared and contrasted 140 microRNAs (non-coding genetic molecules) of a sample group of 202 people, made up of Alzheimer's patients and a healthy control group. The researchers found that 12 of the miRNA differed significantly between the Alzheimer's patients and the healthy group. By using those 12 as biomarkers, the technique accurately identified the presence of the Alzheimer's 93 percent of the time. It also distinguished Alzheimer's from similar neurodegenerative diseases, such as Parkinson's and early onset dementia.

This is important work. We still don't have a test that accurately detects Alzheimer's before symptoms hit. Brain scans look for the presence of beta-amyloid, a protein that has long been argued to be an indicator of Alzheimer's. (That, coupled with defective tau protein, yields an accurate post-mortem diagnosis.) But it's a hotly contested theory, and treatments that target beta-amyloid haven't been shown to be effective. This, of course, raises questions about its efficacy as a diagnostic tool—doubts that a definitive biomarker test could easily put to rest.

Of course, using biomarkers as a way to diagnose neurodegenerative disease isn't nearly as mature a field as traditional brain scans. There's still a lot to learn. To move forward here, researchers need to further ensure the accuracy of the biomarkers and get it approved for clinical use. If it's successful, this same technique could be used to detect cancers and other brain disorders. And being able to pinpoint cases and causes can only help nudge the search for cures along. But that's all well on down the line. For now, let's just hope this turns out to be the real deal for diagnosis. [Genome Biology via ScienceDaily, BBC]