Statistical Analysis
Statistical analyses were performed between August 2020 and October 2022. We used linear mixed-effects models to estimate changes in MRI measures (FA, MD, WMLs, and CBF) for the treatment groups, with participant and MRI facility treated as random intercepts. Treatment group, intracranial volume, age, sex, and time since randomization (in days) were treated as fixed effects. For WMLs, an inverse hyperbolic sine transform—asinh: All statistical analyses were performed using R, version 3.6 (R Group for Statistical Computing).