A Study of a Potential Disease Modifying Treatment in Individuals at Risk for or With a Type of Early Onset AD Caused by a Genetic Mutation

The purpose of this research study is to test the study drug, referred to as remternetug, to determine its effectiveness for the study treatment of asymptomatic (at risk) Alzheimer disease in individuals with AD-causing mutations. This study will also investigate the effects of remternetug on biomarkers (measures of the disease including brain scans, blood and spinal fluid tests), examine safety data to identify any potential benefits or risks, and examine how well participants can tolerate remternetug. Stage 1 will determine if treatment with the study drug prevents or reverses amyloid beta (Aβ) accumulation compared with placebo in participants with dominantly inherited Alzheimer's disease (DIAD). Stage 2 will evaluate the effect of early anti-amyloid treatment on downstream biomarkers of AD in treated participants compared to external control groups.