A public relations executive aged 67 years otherwise in good health was referred by her PCP to a geriatric psychiatrist for evaluation of an accelerating 6-month history of social withdrawal, professional apathy, insomnia with frequent awakenings, and anhedonia reflected by loss of interest in previously enjoyable activities. The psychiatrist suspected a diagnosis of mild cognitive impairment versus mild dementia and recommended a neurologic evaluation. Assessment included a brain MRI and a CSF amyloid beta (Aβ)42 and phospho-tau levels consistent with a diagnosis of mild AD, and the patient was heterozygous for ApoE ε4. At a consultation with the patient and her family, she expressed an interest in treatment, stating a preference for entering a clinical trial of an investigational anti-amyloid beta monoclonal antibody (anti-Aβ mAb). After 1 year of treatment, she and her family were gratified to note no progression of mild AD. However, a surveillance MRI was read as amyloid-related imaging abnormalities (ARIA)-E characterized by signal abnormalities less than 5 cm in diameter at a single site. She had no symptoms suggestive of ARIA.