The authors of this paper note that various clinical trials are investigating active or passive immunotherapeutic approaches to reduce cerebral amyloid-β burden as treatments for Alzheimer’s disease. A certain number of these studies have reported treatment-related abnormalities in brain images, however, the reason for these changes is uncertain. Amyloid-related imaging abnormalities (ARIA) have been reported in patients with Alzheimer's disease treated with bapineuzumab, a humanised monoclonal antibody against amyloid-β.

The authors aimed to investigate the incidence of ARIA during treatment with bapineuzumab. They conducted a systematic, central review of all MRI data from studies (two phase 2 and one ongoing open label) to assess the incidence of ARIA during bapineuzumab treatment, and their associated risk factors and clinical characteristics. The results of the analysis found that ARIA was detected in 36 of 210 (17%) patients treated with bapineuzumab and most cases were clinically silent. The authors conclude, “The increased risk of ARIA among APOE ɛ4 carriers, its association with high bapineuzumab dose, and its timecourse in relation to dosing suggest an association between ARIA and alterations in vascular amyloid burden.” They note that their findings have important implications for elucidation of the mechanisms underlying ARIA and warrant the close monitoring of ARIA in the development of anti-amyloid therapies for Alzheimer’s disease.