(300 WORDS MAX.) Alzheimer's disease (AD) is the most common form of dementia, accounting for 60% to 80% of cases with 46 million people reported to suffer from dementia in 2016. Currently, there are no efficient tools for the diagnosis of AD, where physicians rely on inaccurate clinical criteria and other invasive and costly analyses. Therefore, there is an urgent unmet medical need for the development of non-invasive, cost-effective methods for AD diagnosis. Biocross SL is proposing to develop a confirmatory tool for the diagnosis of AD through the statistical analysis of different factors detectable in a patient's blood, therefore providing a non-invasive and cost-effective test (ADD Test). The current stage of development consists of a test that has provided excellent diagnostic performance (88% accuracy) in a clinical study. Biocross' aim is to further refine its current product and to validate it in a different, independent clinical study in order to have the test available to a variety of populations. In Specific Aim #1 we will refine the current ADD Test using two different statistical approaches, to significantly reduce any possible statistical variations and to increase the chance of reproducibility in a different population. Only one approach will be advanced towards use in Specific Aim #2, which will consist of a clinical study where the test will be validated in a separate set of human subjects. In specific Aim #3 we aim to expand the use of the refined test by enabling the detection of earlier phases of AD. Overall, we expect to complete the proposed studies in two years and start marketing our product soon after, with the goal of implementing the test within the clinical routine of physicians, providing them with a better choice for AD diagnosis, instead of other current invasive or expensive techniques.