A blood test built around circular RNAs is making Alzheimer’s research more predictive, but the distance between a good biomarker and a routine clinical test remains substantial. The Nature Medicine study analyzed blood data from 1,221 people and identified 34 circRNAs associated with Alzheimer’s status. [1][4]

Strong discrimination is not diagnosis

The circRNA model reached an area under the curve (AUC) of 0.945 for biomarker-confirmed Alzheimer’s status, compared with 0.877 for pTau217. An integrated model combining signals reached 0.977. These are discrimination metrics: they describe how well a model separates groups in the study, not how every patient will fare in a clinic. [1][4]

The study also reported a hazard ratio of 2.92 for circRNA levels predicting progression to symptomatic disease in the Knight-ADRC discovery cohort, versus 1.81 for pTau217. In plain language, the signal was associated with a higher rate of future progression; it does not tell an individual when symptoms will begin. [1]

The missing step is prospective care

NIH said additional experiments suggested circRNA levels diverged from normal roughly two to four years before symptoms and that the findings replicated in two independent cohorts. WashU Medicine described the work as an AI-assisted diagnostic approach, while stressing that clinical implementation remains ahead. That is encouraging, but a real screening programme would need prospective validation across ages, ancestries, comorbidities and care settings. [2][3]

The authors disclose patent licensing and advisory or industry relationships. That is not evidence of wrongdoing; it is a reason to keep replication and implementation visible. The educational takeaway is to separate three questions: does a marker correlate, does it predict, and does using it improve decisions? The study answers the first two more strongly than the third.

Production note: This briefing was researched and drafted with AI assistance by Anayati and was not reviewed by a human.

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References

Nature Medicine1 Jul 2026Blood-based circular RNAs for early diagnosis of Alzheimer’s disease National Institutes of Health1 Jul 2026New Alzheimer’s blood test may tell when symptoms are around the corner WashU Medicine1 Jul 2026Blood test powered by AI could transform diagnosis of dementia PubMed1 Jul 2026Blood-based circular RNAs for early diagnosis of Alzheimer’s disease (PubMed record)