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D'Arcy Little MD CCFP FCFP FRCPC,

D’Arcy Little, MD, CCFP, FCFP, FRCPC, Medical Director, Journal of Current Clinical Care and www.healthplexus.net Radiologist, Orillia Soldiers’ Memorial Hospital, Assistant Professor, Department of Medical Imaging cross-appointed to Department of Family and Community Medicine, University of Toronto, University of Toronto, Toronto, ON.

CLINICAL TOOLS

Abstract:
Lecanemab (Leqembi®), approved by Health Canada in October 2025, represents Canada’s first disease-modifying therapy for Alzheimer’s disease. This guide reviews patient selection criteria, including mandatory APOE genotyping and amyloid biomarker confirmation, for adults with mild cognitive impairment or mild dementia due to Alzheimer’s disease. Key safety considerations include amyloid-related imaging abnormalities (ARIA), requiring rigorous MRI surveillance protocols. Family physicians play essential roles in early identification, coordinating pre-treatment workups, monitoring for adverse events, and providing collaborative care throughout treatment.

Key Words: Lecanemab, Alzheimer’s disease, amyloid-related imaging abnormalities (ARIA), APOE genotyping, disease-modifying therapy.
Patient Selection: Indicated for adults aged 50-90 with MCI or mild dementia due to Alzheimer’s disease, confirmed amyloid pathology (PET or CSF), and MMSE 22-30. APOE ε4 homozygotes excluded due to elevated ARIA risk.
Pre-Treatment Requirements: Mandatory APOE genotyping, amyloid confirmation, and baseline MRI. Patients with ≥5 microbleeds, macrohemorrhage, superficial siderosis, or anticoagulant use are excluded.
ARIA Monitoring: Imaging abnormalities occur in 13% (edema) and 17% (hemorrhage) of patients, mostly asymptomatic. MRI surveillance required at weeks 4, 8, 12, 26, and 52.
Clinical Efficacy: 27% relative reduction in cognitive decline at 18 months, representing approximately 4-5 months of delayed progression compared to placebo.
NO tPA with ARIA: Patients presenting with stroke-like symptoms should NOT receive thrombolytics until ARIA excluded by MRI. Always alert emergency personnel to lecanemab treatment status.
Anticoagulation Excludes Treatment: All anticoagulant therapy is contraindicated. Review antiplatelet medications during pre-treatment assessment.
ARIA is Usually Silent: 75-80% of cases are asymptomatic. Maintain high suspicion for headache, confusion, or visual changes in first 3 months when risk peaks.
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Related Terms: Radiology, Lecanemab, Alzheimer, amyloid-related imaging abnormalities (ARIA), APOE genotyping, disease-modifying therapy
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