In Alzheimer's disease (AD), nonverbal aspects of communication become increasingly important in caregiver-patient interactions when the ability to communicate verbally is fading with progression of the disease. We therefore investigated the impact of cognitive deficits and neuropsychiatric symptoms, particularly apathy, on facial expression in AD. While overall neuropsychiatric symptoms were not associated with facial expression, apathy exhibited substantial correlations, even after controlling for cognitive deficits. Moreover, apathy appeared to moderate the influence of cognitive deficits: without considering apathy, cognitive deficits were associated with less specific facial expressions. After controlling for apathy, cognitive decline was related to increased facial expressiveness. In conclusion, apathetic symptoms appear to be specifically associated with facial expression in AD and thus could contribute to a disregard for patients' needs in everyday life.