Equivalence of plasma p‐tau217 with cerebrospinal fluid in the diagnosis of Alzheimer's disease

p-tau₂₁₇ in plasma performed equivalent to p-tau₂₁₇ in CSF for the diagnosis of AD, suggesting the increased accessibility of plasma p-tau₂₁₇ is not offset by lower accuracy. p-tau biomarkers in plasma had lower mean fold-changes between amyloid-PET negative and positive groups than p-tau biomarkers in CSF. CSF p-tau biomarkers had greater effect sizes than plasma p-tau biomarkers when differentiating between amyloid-PET positive and negative groups. Plasma p-tau₁₈₁ and plasma p-tau₂₃₁ performed worse than p-tau₁₈₁ and p-tau₂₃₁ in CSF for AD diagnosis.