CSF biomarkers for Alzheimer disease correlate with cortical brain biopsy findings

Objective: To assess the relationship between Alzheimer disease (AD)-related pathologic changes in frontal cortical brain biopsy and AD biomarkers in ventricular vs lumbar CSF, and to evaluate the relationships of AD biomarkers in CSF and cortical biopsy with the final clinical diagnosis of AD. Methods: In 182 patients with presumed normal pressure hydrocephalus (152 with known APOE carrier status), A beta plaques and tau in the cortical brain biopsies were correlated with the ventricular and lumbar CSF A beta 42, total tau, and p-tau levels measured by ELISA. In a median follow-up of 2.0 years, 51 patients developed AD dementia. Results: The patients with A beta 42 plaques in the cortical biopsy had lower (p = 0.009) CSF A beta 42 levels than those with no A beta plaques. The patients with tau in the cortical biopsy had lower (p = 0.014) A beta 42 but higher (p = 0.015) p-tau 181 in CSF as compared to those with no tau in the cortical biopsy. The patients with amyloid + tau + biopsies had the lowest A beta 42 and highest tau and p-tau 181 levels in CSF. The A beta 42 levels were lower and the tau and p-tau 181 higher in the ventricular vs corresponding lumbar CSF samples. In multivariate analysis, the presence of cortical A beta was independently predicted by the APOE epsilon 4 carrier status and age but not by CSF A beta 42 or tau levels. Conclusions: Amyloid plaques and hyperphosphorylated tau in cortical brain biopsies are reflected by low CSF A beta 42 and high CSF tau and p-tau levels, respectively. Neurology (R) 2012;78:1568-1575