Psychiatrymiddle twist
A 25-year-old man has taken risperidone 4 mg at night for six months for schizophrenia, and his voices and persecutory beliefs have gone. His mother says he now sits in the same chair for hours, showers only when told, answers in three or four words and shows little expression. He denies feeling sad, sleeps seven hours, eats well and looks forward to his brother's visits. On examination his face is unlined, he blinks rarely, his arms do not swing when he walks, and there is increased tone at both wrists. Which one of the following best explains his current state?