Plasma amyloid beta predicts conversion to dementia in subjects with mild cognitive impairment: The BALTAZAR study.

Abstract

Blood-based biomarkers are the next challenge for Alzheimer's disease (AD) diagnosis and prognosis. Mild cognitive impairment (MCI) participants (N=485) of the BALTAZAR study, a large-scale longitudinal multicenter cohort, were followed-up for 3 years. A total of 165 of them converted to dementia (95% AD). Associations of conversion and plasma amyloid beta (Aβ)1-42 , Aβ1-40 , Aβ1-42 /Aβ1-40 ratio were analyzed with logistic and Cox models. Converters to dementia had lower level of plasma Aβ1-42 (37.1 pg/mL [12.5] vs. 39.2 [11.1] , P value=.03) and lower Aβ1-42 /Aβ1-40 ratio than non-converters (0.148 [0.125] vs. 0.154 [0.076], P value=.02). MCI participants in the highest quartile of Aβ1-42 /Aβ1-40 ratio (>0.169) had a significant lower risk of conversion (hazard ratio adjusted for age, sex, education, apolipoprotein E ε4, hippocampus atrophy=0.52 (95% confidence interval [0.31-0.86], P value=.01). In this large cohort of MCI subjects we identified a threshold for plasma Aβ1-42 /Aβ1-40 ratio that may detect patients with a low risk of conversion to dementia within 3 years.