Cerebrospinal Fluid Profile of Tau, Phosphorylated Tau, A₄₂, and A₄₀ in Probable Cerebral Amyloid Angiopathy

Background: There is no consensus regarding the diagnostic value of cerebrospinal fluid (CSF) Alzheimer's disease (AD) biomarkers in cerebral amyloid angiopathy (CAA). Objective: To describe the CSF levels of A beta(42), A beta(40), total protein Tau, and phosphorylated-Tau (p-Tau) in a large series of probable CAA patients and to compare with AD patients in order to identify a specific pattern in CAA but also to look for correlations with the neuroimaging profile. Methods: We retrospectively included from 2 French centers probable CAA patients according to modified Boston criteria who underwent lumbar puncture (LP) with CSF AD biomarker quantifications. Two neurologists independently analyzed all MRI sequences. A logistic regression and Spearman's correlation coefficient were used to identify correlation between MRI and CSF biomarkers in CAA. Results: We included 63 probable CAA and 27 AD patients. Among CAA 50.8% presented with decreased A beta(42) level associated with elevated p-Tau and/or Tau, 34.9% with isolated decreased A beta(42) level and 14.3% patients with normal A beta(42) level. Compared to AD, CAA showed lower levels of Tau (p = 0.008), p-Tau (p = 0.004), and A beta(40) (p = 0.001) but similar A beta(42) level (p = 0.07). No correlation between A beta(42) or A beta(40) levels and neuroimaging was found. Conclusion: CSF biomarkers may improve the accuracy of the modified Boston criteria with altered profile in 85% of the patients fulfilling revised Boston criteria for probable CAA. A beta(40) appears as an interesting selective biomarker in differential diagnosis.