The Generative Brain

Blood markers (neurofilament light and others)

Blood tests for CJD (plasma or serum neurofilament light and total tau) discriminate CJD from other dementias with an AUC of about 0.93 in one series, but they mark neuronal damage rather than prions; neurofilament light and tau were normal in asymptomatic carriers in the MGH cohort. Reviews call blood markers close to clinical use.

Key facts

  • Serum neurofilament light was sensitive and specific for genetic and sporadic CJD and might help predict onset (2016 cohort); no validated blood biomarker existed then.
  • Limits: Not prion-specific; changes in pre-symptomatic carriers were variable in the OBSERVE cohort.
  • What it asks of the person: Blood draw.
  • In 83 CJD patients compared with healthy controls and other neurological and dementia groups, plasma NfL and total tau both discriminated CJD from non-CJD dementias with an AUC of 0.93, NfL being more accurate than tau against rapidly progressive Alzheimer disease.
  • Plasma total tau emerged as a potential prognostic marker of disease duration.
  • A 2016 study found serum neurofilaments to be sensitive and specific for genetic and sporadic CJD and a promising tool to predict disease onset.
  • Among 27 pre-symptomatic carriers at MGH, NfL and tau were normal and RT-QuIC was positive in one carrier, so these markers may not serve as primary endpoints in pre-symptomatic trials.
  • A 2026 Lancet Neurology review states blood-based diagnostic biomarkers are close to clinical application and a biomarker-based staging system should be tested.
  • Goettingen papers in August and October 2026 report PrP profiles in blood and CSF and UCH-L1 as CSF and blood biomarkers.

Timeline

  1. 2016Serum neurofilament study published.
  2. 2021Plasma NfL and tau study published.
  3. 2026Lancet Neurology biomarker review.
  4. 2026UCH-L1 biomarker paper published.
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