Significant brain atrophy in PSP can be observed over relatively short periods due to the rapid progression of the disease (Dutt, 2016). Significant volumetric changes can be observed on a time scale of 6-12 months. Höglinger et al. highlight the progressive nature of brain atrophy in PSP, showing measurable changes observed as early as the first year after symptom onset (Höglinger, 2017). Longitudinal studies over several years provide insights into the extensive brain atrophy observed in PSP, emphasizing the cumulative changes that become evident with disease progression (Josephs, 2006). Regular MRI assessments in clinical trials and clinical practice can effectively monitor these changes, thereby aiding in the evaluation of disease progression and treatment efficacy.