A Study to Evaluate the Safety and Biomarker Effects of RO7269162 in Participants at Risk for or at the Prodromal Stage of Alzheimer's Disease (AD)

Incidence of adverse events (AEs),Change from baseline in brain amyloid load, as measured by amyloid positron emission tomography ( PET) scan

This clinical trial is recruiting people who either are at risk of AD - have build-up of
 beta-amyloid, but have no clinical symptoms, or with a diagnosis of mild cognitive
 impairment. People can take part if they have a certain level of plaques (beta-amyloid) in
 the brain, shown by a positron emission tomography (PET) scan, a medical imaging technique in
 which tracers are injected to visualize specific pathological processes in the brain. People
 who take part in this clinical trial (participants) will be given RO7269162 OR placebo for up
 to about 1 and a half years. The clinical trial team will see them every 3 weeks in the first
 3 months and then every 6 weeks until the end of the trial. These hospital visits will
 include checks to see how the participant responds to the treatment and any side effects they
 may have. The total time of participation in the clinical trial will be 90 weeks.