APOE and early-onset autosomal dominant Alzheimer disease: <h4>Importance</h4>Alzheimer disease (AD) biomarker and genetic testing results are increasingly disclosed to cognitively unimpaired adults in research and could in the future inform clinical treatment decisions in this population.<h4>Objectives</h4>To assess psychological outcomes after returning 3 categories of amyloid biomarker results as well as apolipoprotein E (APOE) genotypes.<h4>Design, setting, and participants</h4>This cohort study was a secondary analysis of data collected as part of screening for the multisite AHEAD preclinical AD trial.