The neuropsychiatric symptoms of Alzheimer disease (AD) are a major source of caregiver burden, patient distress, and decreased quality of life. Symptoms such as agitation and aggression attract more attention and more therapeutic intervention as potential threats to patient and caregiver safety. But quieter symptoms, such as apathy, are far more common, particularly in the earlier stages of illness, and have an insidious and highly negative impact on clinical course. They have also been understudied, both in terms of their neurobiological underpinnings and the search for effective treatments.