A 45-Year-Old Man Arrives at the Clinic Complaining of Terrible

A 45-year-old man arrives at the clinic complaining of terrible sleeplessness. The patient is having difficulty sleeping because he thinks he has to stay attentive in order to defend himself from workers at a neighboring chemical factory. He claims they poison him by dumping poisonous garbage in his property at night. According to the patient's wife, "He's been this way for the past ten years. When pressed for proof, he becomes enraged, so he plans to install cameras the next week." She has never witnessed any strange activity in the backyard and claims that her husband has never been threatened or suffered physical violence. Over the years, he has ordered multiple soil toxicity tests, all of which have come back negative.   The patient started working as a taxi driver at age 21 and continues to work for the same company.  He has no history of psychiatric treatment.  Which of the following is the most likely diagnosis for this patient?

A) Delusional disorder
B) Major depressive disorder with psychotic features
C) Paranoid personality disorder
D) Schizophrenia
E) Schizophreniform disorder
F) Schizotypal personality disorder