The following are multiple choice questions (with answers) about medical knowledge.   **Question:** A 23-year-old man is brought to the emergency department by his mother because of a change in his personality. The mother reports that over the past 7 months her son has become increasingly withdrawn; he has not answered any phone calls or visited his family and friends. He had always been a quiet boy, who needed some time on his own, but he used to meet with friends at least once a week. The patient says that he cannot leave the house because aliens are watching him and “stealing his thoughts”. He does not drink alcohol. He used to smoke marijuana occasionally but quit 1 year ago. His vital signs are within normal limits. Physical examination shows no abnormalities. On mental status examination, it is impossible to follow the patient's sequence of thoughts. He is anxious and has a flat affect. Which of the following is the most likely diagnosis?   (A) Delusional disorder   (B) Mood disorder with psychotic features   (C) Schizoid personality disorder   (D) Schizophrenia
['(D) Schizophrenia <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Delusional disorder \n (B) Mood disorder with psychotic features \n (C) Schizoid personality disorder \n (D) Schizophrenia <> possible answers', "  A 23-year-old man is brought to the emergency department by his mother because of a change in his personality. The mother reports that over the past 7 months her son has become increasingly withdrawn; he has not answered any phone calls or visited his family and friends. He had always been a quiet boy, who needed some time on his own, but he used to meet with friends at least once a week. The patient says that he cannot leave the house because aliens are watching him and “stealing his thoughts”. He does not drink alcohol. He used to smoke marijuana occasionally but quit 1 year ago. His vital signs are within normal limits. Physical examination shows no abnormalities. On mental status examination, it is impossible to follow the patient's sequence of thoughts. He is anxious and has a flat affect. Which of the following is the most likely diagnosis? <> context@"]