Plasma total tau predicts Alzheimer’s disease dementia

  • Pase MP & al.
  • JAMA Neurol
  • 4 Mar 2019

  • International Clinical Digest
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Takeaway

  • Plasma level of total tau showed a graded association with Alzheimer's disease (AD) risk, with a predictive capability at least as good as that of cerebrospinal fluid (CSF) level of total tau.

Why this matters

  • Attractiveness of blood-based biomarkers for dementia and its subtypes.

Key results

  • As plasma total tau level increased, so did adjusted risk for AD dementia (HR per standard deviation, 1.35; 95% CI, 1.10-1.67).
  • Adding plasma total tau to model including age and sex improved stratification for AD dementia risk (net reclassification improvement, 0.382; 95% CI, 0.030-0.716).
  • In replication cohort, plasma and CSF total tau levels weakly correlated (Spearman correlation coefficient, 0.16; P=.07).
  • But they similarly predicted adjusted AD dementia risk:
    • Log plasma total tau: HR, 2.33 (95% CI, 1.00-5.48).
    • Log CSF total tau: HR, 2.14 (95% CI, 1.33-3.44).

Study design

  • Dual prospective cohort study:
    • Base cohort: 1453 dementia-free participants in US Framingham Heart Study aged ≥65 years (median, 6-year follow-up).
    • Replication cohort: 367 participants in French multicenter Memento study of people with mild cognitive impairment or subjective cognitive complaints (median, 4-year follow-up).
  • Main outcome: dementia, AD dementia.
  • Funding: National Institute on Aging; others.

Limitations

  • Participants mainly white.
  • Subtypes largely based on clinical diagnosis.