Precautions for Neurosurgeons in Administering Anti-Amyloid β Antibody Therapy.

In Japan, anti-amyloid β (Aβ) monoclonal antibodies, including lecanemab and donanemab, have recently been approved as disease-modifying therapies for early-stage Alzheimer's disease (AD). These drugs, developed based on the amyloid cascade hypothesis, target toxic Aβ aggregates: lecanemab selectively binds to soluble protofibrils, while donanemab targets Aβ plaques. The Ministry of Health, Labour and Welfare (MHLW) has issued Optimal Use Guidelines that specify criteria for administration: informed consent from both patients and caregivers; cognitive assessments (MMSE and CDR); confirmation of Aβ pathology via amyloid PET or cerebrospinal fluid (CSF) testing; and MRI screening to assess the risk of amyloid-related imaging abnormalities (ARIA). ARIA is a significant adverse event and requires regular MRI monitoring. Initial administration is limited to certified facilities staffed by experienced specialists and equipped with the necessary diagnostic infrastructure. After six months, treatment may be continued at collaborating institutions. The APOEε4 genotype is a known risk factor for ARIA but is not covered by insurance. Caution is advised when co-administering anticoagulants or antiplatelet agents. The guidelines also require the use of official treatment cards to inform healthcare providers. This article summarizes the clinical precautions, diagnostic requirements, and facility standards necessary for implementing anti-Aβ antibody therapy in accordance with current MHLW Guidelines in Japan.