The onset of psychiatric symptoms began with delusions of being in the presence of his deceased grandfather, but they remitted soon after treatment with risperidone (1 mg/day). Three months later, despite medication adherence, the patient abruptly developed visual illusions and hallucinations, soon followed by profound irritability and impulsive violence. A comprehensive evaluation at the UCLA Neuropsychiatric Hospital revealed no seizure activity, metabolic disturbances, intoxications, infections, or other acute medical etiology, although the possibility of a mixed manic episode could not be ruled out, given the patient's previous irritability. While zonisamide can induce psychosis, the patient's long and stable history made this a less likely culprit. He was discharged psychosis free and euthymic with prescriptions for risperidone (2 mg b.i.d.) and trazodone (50 mg every evening).