Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for causing a stimulus presentation system to present content to a patient. Obtaining, from a brainwave sensor, electroencephalography (EEG) signals of the patient while the content is being presented to the patient. Identifying, from within the EEG signals of the patient, brainwave signals associated with a brain system of the patient, the brainwave signals representing a response by the patient to the content. Determining, based on providing the brainwave signals input features to a machine learning model, a likelihood that the patient will experience symptoms of anxiety within a period of time. Providing, for display on a user computing device, data indicating the likelihood that the patient will experience the symptoms of anxiety within the period of time.