Amyloid‐accumulating cortical regions show selectively greater longitudinal thinning in the presence of ARIA during anti‐amyloid therapy

These data show that presence of ARIA may play a role in observed brain parenchymal changes during anti-amyloid treatment. The specificity of the effects in amyloid-accumulating brain regions point to an interaction between amyloid clearance and the emergence of ARIA as confounding factors in measuring longitudinal change. While the underlying mechanism remains unclear, better characterization of such effects can help disentangle their influence on MRI-based measures of change and ultimately improve the usability of MRI as a marker for tracking potential treatment effects.