A 21-year-old unmarried man has near-daily intrusive thoughts that his neighbors knock on his door at night. He tells the PMHNP he knows this knocking is just his "imagination" because the neighbors work nights and are not home. However, he feels compelled to get out of bed and open the door, no matter what time it is. He opens and closes the door repeatedly for at least an hour, sometimes longer. He says he has had this problem "in the past" and did not seek help for it. This time it has been going on at least 6 months and is becoming "problematic." It is interfering with his ability to get a good night's sleep and he is having problems at work. His roommate is also very troubled by it. The PMHNP will diagnose him with which of the following?

Choice A reason: OCD is characterized by the presence of obsessions (intrusive, unwanted thoughts) and compulsions (repetitive behaviors performed to relieve anxiety). This patient exhibits clear obsessions about perceived knocking and compulsive checking behaviors, which interfere with daily functioning, consistent with a diagnosis of OCD. Choice B reason: Generalized anxiety disorder involves excessive worry about multiple domains, without specific compulsive behaviors or obsessions. The patient’s presentation is specific to obsessions and compulsions rather than generalized worry. Choice C reason: Schizophrenia involves psychotic symptoms such as hallucinations, delusions, or disorganized thinking. The patient demonstrates insight into the irrational nature of his thoughts, which is not consistent with psychosis. Choice D reason: Agoraphobia is the fear of being in situations where escape may be difficult or help unavailable. The patient’s symptoms are not triggered by situational avoidance but by intrusive thoughts, making agoraphobia an unlikely diagnosis.