A 26-year-old man is brought to the emergency department by his wife because of bizarre and agitated behavior for the last 6 weeks. He thinks that the NSA is spying on him and controlling his mind. His wife reports that the patient has become withdrawn and at times depressed for the past 3 months. He lost his job because he stopped going to work 4 weeks ago. Since then, he has been working on an invention that will block people from being able to control his mind. Physical and neurologic examinations show no abnormalities. On mental status examination, he is confused and suspicious with marked psychomotor agitation. His speech is disorganized and his affect is labile. Which of the following is the most likely diagnosis?

Schizotypal personality disorder

A 20-year-old male is involuntarily admitted to the county psychiatric unit for psychotic behavior over the past three months. The patient's mother explained to the psychiatrist that her son had withdrawn from family and friends, appeared to have no emotions, and had delusions that he was working for the CIA. When he spoke, his sentences did not always seem to have any connection with each other. The mother finally decided to admit her son after he began stating that he "revealed too much information to her and was going to be eliminated by the CIA." Which of the following diagnoses best fits this patient's presentation?

Schizotypal personality disorder

A 16-year-old boy is brought in to a psychiatrist's office by his mother for increasingly concerning erratic behavior. Her son has recently entered a new relationship, and he constantly voices beliefs that his girlfriend is cheating on him. He ended his last relationship after voicing the same beliefs about his last partner. During the visit, the patient reports that these beliefs are justified, since everyone at school is “out to get him.” He says that even his teachers are against him, based on their criticism of his schoolwork. His mother adds that her son has always held grudges against people and has always taken comments very personally. The patient has no psychiatric history and is in otherwise good health. What condition is this patient genetically predisposed for?

Antisocial personality disorder

A 31-year-old woman comes to the physician because she thinks that her “right wrist is broken.” She says that she has severe pain and that “the bone is sticking out.” She has not had any trauma to the wrist. Her medical records indicate that she was diagnosed with schizophrenia 2 years ago and treated with olanzapine; she has not filled any prescriptions over the past 4 months. Three weeks ago, she stopped going to work because she “did not feel like getting up” in the morning. Vital signs are within normal limits. Physical examination of the right wrist shows no visible injury; there is no warmth, swelling, or erythema. Range of motion is limited by pain. On mental status examination, she has a flat affect. Her speech is pressured and she frequently changes the topic. She has short- and long-term memory deficits. Attention and concentration are poor. There is no evidence of suicidal ideation. Urine toxicology screening is negative. An x-ray of the wrist shows no abnormalities. Which of the following is the most appropriate response to this patient's concerns?

“I cannot see any injury of your wrist and the physical exam as well as the x-ray don't show any injury. I imagine that feeling as if your wrist was broken may be very uncomfortable. Can you tell me more about what it feels like?”

“It seems as though you are having a schizophrenia relapse. If you don't follow my recommendations and take your medications, you will most likely have further and possibly more severe episodes.”

I understand your concerns; however, your symptoms seem to be psychological in nature. I would be happy to refer you to a mental health professional.

You are clearly distressed. However, your tests do not suggest a physical problem that can be addressed with medications or surgery. I suggest that we meet and evaluate your symptoms on a regular basis.

I can imagine that you are uncomfortable. That certainly looks painful. Let's take care of this injury first and then we should talk about your problems getting up in the morning.

A 24-year-old woman complains of intermittent fever and joint pain. She says that these symptoms have been present for the past month. Before that, she had no signs or symptoms and was completely healthy. She has also lost her appetite and some weight. A complete blood count (CBC) showed severe pancytopenia. What is the next best step in evaluating this patient?

Repeated CBCs for several weeks and reassess

Diagnostic criteria for delusional disorder — USMLE Lesson

Diagnostic Criteria - The Core Rules

Core diagnostic criteria based on DSM-5, outlining the essential features for a diagnosis of delusional disorder.

Delusion Presence: The patient must have one or more delusions.
Duration: These delusions must persist for a duration of ≥1 month.
Schizophrenia Exclusion: The individual has never met Criterion A for schizophrenia. Hallucinations, if present, are not prominent and are related to the delusional theme.
Functioning: Apart from the direct impact of the delusion(s), overall functioning is not markedly impaired, and behavior is not obviously bizarre or odd.
Mood Episode Exclusion: If manic or major depressive episodes have occurred, they have been brief in duration compared to the delusional periods.
Substance/Medical Exclusion: The disturbance is not caused by a substance, medication, or another medical condition.

⭐ Apart from the impact of the delusion(s), functioning is not markedly impaired, and behavior is not obviously bizarre or odd. This is a key feature distinguishing it from schizophrenia.

Delusion Flavors - Types & Specifiers

Delusion Type	Core Belief	Classic Example
Erotomanic	Someone is in love with the individual	"A famous actor is secretly in love with me and sends me coded messages."
Grandiose	Inflated worth, power, or identity	"I have a special relationship with the president and advise them on national security."
Jealous	Partner is unfaithful	"I know my spouse is cheating on me, even though there's no evidence."
Persecutory	Being conspired against or threatened	"My neighbors are plotting to poison my water supply."
Somatic	Involves bodily functions or sensations	"I am emitting a foul odor from my skin, despite reassurance from doctors."

Unspecified Type: The dominant delusional belief cannot be clearly determined.
Specifier: With bizarre content - Delusions are clearly implausible and not derived from ordinary life experiences (e.g., belief that an outsider has removed one's internal organs).

⭐ The persecutory type is the most common subtype of delusional disorder.

High-Yield Points - ⚡ Biggest Takeaways

Core feature: ≥1 delusion for ≥1 month.

Criterion A for schizophrenia has never been met; hallucinations, if present, are minimal and theme-related.

Functioning is not significantly impaired, and behavior is not overtly bizarre or odd.

Mood episodes, if they occur, are brief relative to the delusional period's duration.

The delusion is not due to a substance or another medical or neurological condition.

Remember to specify the delusional subtype (e.g., persecutory, jealous, grandiose).

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