Question: what mental illness makes you scream?
Answer: Klazomania. Klazomania (from the Greek κλάζω ("klazo")—to scream) refers to compulsive shouting; it has features resembling the complex tics such as echolalia, palilalia and coprolalia seen in tic disorders, but has been seen in people with encephalitis lethargica, alcohol abuse and carbon monoxide poisoning.