New biomarkers of algorithms may improve the diagnostic accuracy of cerebrospinal fluid (CSF) for Alzheimer’s disease (AD. The present study aimed to determine whether Aβ42/Aβ40 and Aβ42/Aβ38 ratios improve the diagnostic accuracy of AD during predementia and dementia stages in comparison to CSF Aβ42 alone. The study included three different cohorts comprising a total of