We might be on the precipice of a pivotal moment in Alzheimer’s disease research. In clinical trial data released this week, scientists have presented early evidence that it’s possible to delay symptoms in people genetically fated to develop Alzheimer’s at a young age.

Researchers at the Washington University School of Medicine led the study, which aimed to test whether an experimental anti-amyloid drug called gantenerumab could help people with an inherited form of Alzheimer’s. In a subset of patients treated the longest, the drug appeared to reduce their risk of developing symptoms as expected, by 50%. The findings will require a follow-up, but outside experts are cautiously optimistic about what this could mean for the future of treating Alzheimer’s.