Researchers reporting in Nature Medicine have identified circular RNAs (circRNAs) circulating in blood that show high predictive value for biomarker-confirmed early Alzheimer's disease. The strongest performance came not from the circRNAs alone but from combining them with an established marker, phosphorylated tau-217 (pTau217), suggesting the two carry partly different information about what is happening in the brain.
CircRNAs are a class of RNA molecules that form closed loops, and until now they have not featured in the blood tests being developed for Alzheimer's, which have centered on amyloid and tau proteins. The study's authors frame their findings as a potential additional layer for those panels rather than a replacement, one that could help pick out people who already carry early Alzheimer's biology or who face elevated risk of progressing.
The practical appeal is timing. Alzheimer's pathology builds up well before memory and thinking problems become obvious, and a blood test that flags that biology early would give clinicians a window for treatment decisions and planning that does not exist once symptoms are established. As therapies aimed at slowing progression become available, identifying the right patients early enough to benefit is the bottleneck.
The work is still early. The researchers themselves say the circRNA signature has to be validated in larger prospective clinical cohorts that include diverse populations before it could be considered for routine use. Until that happens, the finding is best read as a promising new direction for blood-based Alzheimer's diagnostics rather than a test available to patients.