Cerebrospinal fluid Aβ₄₂, tau, and F₂-isoprostane concentrations in patients with Alzheimer disease, other dementias, and in age-matched controls

Objective. - To test the hypothesis that quantification of cerebrospinal fluid (CSF) F₂-isoprostanes (F₂-IsoPs), in vivo biomarkers of free radical damage, along with CSF Aβ₄₂ and tau levels improves laboratory diagnostic accuracy for Alzheimer disease (AD). Participants. - Patients with probable AD (n = 19), dementias other than AD (n = 8), and age-matched controls (n = 10). Main Outcome Measures. - Cerebrospinal fluid concentrations of Aβ₄₂ and tau were determined by a commercially available test (Athena Diagnostics, Worcester, Mass). Cerebrospinal fluid F₂-IsoP levels were quantified by gas chromatography/mass spectrometry. Results. - Individuals were classified as AD or non-AD by a published method using CSF Aβ₄₂ and tau levels (95% sensitivity, 50% specificity), by CSF F₂-IsoP levels greater than 25 pg/mL and Aβ₄₂ concentrations less than 1125 pg/mL (90% sensitivity, 83% specificity), and by combined analysis using CSF F₂-IsoP, Aβ₄₂, and tau levels (84% sensitivity, 89% specificity). Conclusion. - Cerebrospinal fluid F₂-IsoP quantification may enhance the accuracy of the laboratory diagnosis of AD.