Spontaneous and Iatrogenic Amyloid-Related Imaging Abnormalities (ARIA): Clues for Immunotherapy in Alzheimer’s Disease

Amyloid-related imaging abnormalities or ARIA are an intriguing neuroimaging findings, present in a variable proportion of patients enrolled in immunotherapy trials for Alzheimer’s Disease (AD) but also in AD patients treated with placebo. ARIA is closely similar to inflammatory form of cerebral amyloid angiopathy (CAA) or CAA-related inflammation in both exudative (ARIA-E) and hemorrhagic (ARIA-H) components. As for CAA-related inflammation, its pathogenesis has not been fully elucidated and an immunological mechanism is highly probable, supported by the measurement of anti-amyloid beta antibodies in cerebrospinal fluid. The chapter presents the main clinical and neuroimaging features of ARIA and CAA-ri, including management issues and the potential impact on the natural history of the amyloid-related diseases in the brain.