Diffusion weighted imaging abnormalities and cerebral ischemia in a cohort of patients on lecanemab.

INTRODUCTION: We evaluate the frequency of diffusion weighted imaging abnormalities consistent with stroke in patients on lecanemab, focusing on the association between amyloid-related imaging abnormalities (ARIAs) and stroke incidence. METHODS: For this retrospective cohort study, data were collected from time of lecanemab initiation to last follow-up. Descriptive statistics characterized demographic and clinical factors for patients who experienced interval stroke in contrast to individuals who did not experience stroke. Propensity score matching was performed to evaluate the association between ARIAs and stroke accounting for confounding factors. RESULTS: Of 261 patients, 11 (4.2%) were diagnosed with interval stroke. Stroke patients were older (80.1 vs. 74.3 years had lower median Montreal Cognitive Assessment cognitive scores (19 vs. 22) and higher prevalence of ARIAs (54.5% vs. 20.8%). A significant association (P = 0.011) was observed between ARIAs and stroke incidence after propensity score matching. Strokes were small, asymptomatic, and mostly cerebellar (36.4%) or cortical (36.4%). DISCUSSION: Diagnosis of an ARIA was significantly associated with increased stroke. Higher than expected rates of cerebellar and cortical stroke and relationship to ARIAs suggests a possible common, immune-mediated mechanism between these regions of restricted diffusion and ARIAs. Further study is warranted.