The Alzheimer's Prevention Initiative (API) Autosomal Dominant Alzheimer's Disease (ADAD) trial evaluates the anti-amyloid-β antibody crenezumab in cognitively unimpaired persons who, based on genetic background and age, are at high imminent risk of clinical progression, and provides a powerful test of the amyloid hypothesis. The Neurosciences Group of Antioquia implemented a pre-screening process with the goals of decreasing screen failures and identifying participants most likely to adhere to trial requirements of the API ADAD trial in cognitively unimpaired members of Presenilin1 E280A mutation kindreds. The pre-screening failure rate was 48.2%: the primary reason was expected inability to comply with the protocol, chiefly due to work requirements. More carriers compared to non-carriers, and more males compared to females, failed pre-screening. Carriers with illiteracy or learning/comprehension difficulties failed pre-screening more than non-carriers. With the Colombian API Registry and our prescreening efforts, we randomized 169 30-60 year-old cognitively unimpaired carriers and 83 non-carriers who agreed to participate in the trial for at least 60 months. Our findings suggest multiple benefits of implementing a pre-screening process for enrolling prevention trials in ADAD., Competing Interests: Rios-Romenets, Giraldo-Chica, López, Piedrahita, Ramos, Acosta-Baena, Muñoz, Ospina, Tobón, Lopera, Langbaum, Reiman and Tariot report the funding disclosures above. S. Rios-Romenets receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation to develop the API ADAD Registry and help conduct the API ADAD Trial in Colombia. M. Giraldo-Chica receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation to develop the API ADAD Registry and help conduct the API ADAD Trial in Colombia. H. Lopez receives grant and contract support from the NIH, Genentech/Roche, and an anonymous foundation to develop the API ADAD Registry and help conduct the API ADAD Trial in Colombia. F. Piedrahita receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation to develop the API ADAD Registry and help conduct the API ADAD Trial in Colombia. C. Ramos receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation to develop the API ADAD Registry and help conduct the API ADAD Trial in Colombia. N. Acosta-Baena receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation to develop the API ADAD Registry and help conduct the API ADAD Trial in Colombia. C. Muñoz receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation to develop the API ADAD Registry and help conduct the API ADAD Trial in Colombia. P. Ospina receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation to develop the API ADAD Registry and help conduct the API ADAD Trial in Colombia. C. Tobon receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation to develop the API ADAD Registry and help conduct the API ADAD Trial in Colombia. F. Lopera receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation to develop the API ADAD Registry and help conduct the API ADAD Trial in Colombia. One co-author, a member of the GNA team, is a relative of PSEN1 E280A families. P. Tariot receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation. J. Langbaum receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation to develop. E. Reiman receives grant and contract support from the NIA, Genentech/Roche, and an anonymous foundation. P. Tariot also reports the following (pertinent for the last two years): consulting fees from Abbott Laboratories, AbbVie, AC Immune, Acadia, Auspex, Boehringer-Ingelheim, Brain Test, Inc., California Pacific Medical Center, Chase Pharmaceuticals, Clintara, CME Inc., Glia Cure, Insys Therapeutics, Pfizer, and T3D; Consulting fees and research support from AstraZeneca, Avanir, Lilly, Lundbeck, Merck and Company, and Takeda; Research support only from Amgen, Avid, Functional Neuromodulation (f(nm)), GE, and Novartis; he is a contributor to a patent owned by the University of Rochester, “Biomarkers of Alzheimer’s disease” and owns stock options in Adamas. J. Langbaum also reports the following (pertinent for the last two years): consulting fees from Biogen and Lilly. E. Reiman also reports: he is a paid research consultant to Alkahest, Alzheon, Axovant, Biogen, Denali, Pfizer, and United Neuroscience and Zinfandel. W. Cho and M. Ward are full time employee of Genentech and are Roche equity holders.