INTRODUCTION: In this study of preclinical @entity195 ( @entity195 ) we assessed the added diagnostic value of using cerebrospinal fluid (CSF) Ab ratios rather than Ab42 in isolation for detecting individuals who are positive on amyloid positron emission tomography (PET). METHODS: Thirty-eight community-recruited cognitively intact older adults (mean age 73, range 65-80 years) underwent @entity62692 PET and CSF measurement of Ab1-42, Ab1-40, Ab1-38, and total tau (ttau). @entity62692 retention was quantified using standardized uptake value ratios in a composite cortical region (SUVRcomp) with reference to cerebellar grey matter. Based on a prior autopsy validation study, the SUVRcomp cut-off was 1.57. Sensitivities, specificities and cut-offs were defined based on receiver operating characteristic analysis with CSF analytes as variables of interest and @entity62692 positivity as the classifier. We also determined sensitivities and CSF cut-off values at fixed specificities of 90  % and 95  %. RESULTS: Seven out of 38 subjects (18  %) were positive on amyloid PET. Ab42/ttau, Ab42/Ab40, Ab42/Ab38, and Ab42 had the highest accuracy to identify amyloid-positive subjects (area under the curve (AUC)   >=    0.908). Ab40 and Ab38 had significantly lower discriminative power (AUC   =   0.571). When specificity was fixed at 90  % and 95  %, Ab42/ttau had the highest sensitivity among the different CSF markers (85.71  % and 71.43  %, respectively). Sensitivity of Ab42 alone was significantly lower under these conditions (57.14  % and 42.86  %, respectively). CONCLUSION: For the CSF-based definition of preclinical @entity195 , if a high specificity is required, our data support the use of Ab42/ttau rather than using Ab42 in isolation.

Diagnostic value of cerebrospinal fluid Ab ratios in preclinical XXXX .

@entity62692 :: ('MESH:C581552', 'Chemical') :: ['(18)F-flutemetamol'] @entity195 :: ('MESH:D000544', 'Disease') :: ['AD', "Alzheimer's disease"]
@entity195 :: (MESH:D000544,Disease) :: ['Alzheimer's disease']
