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Difficulty: MediumSubstance-Related and Addictive Disorders

A 20-year-old man is brought to the emergency department by his roommates due to severe agitation and paranoia. Over the past 4 days, he has barricaded himself in his dorm room, claiming that the university administration has installed hidden cameras to steal his thoughts. He frequently yells at voices that no one else can hear. His roommates report that he has no prior psychiatric history but has been extremely stressed about upcoming final exams. Vital signs show a temperature of 37.9°C (100.2°F), blood pressure of 162/98 mm Hg, and pulse of 118/min. Physical examination reveals pronounced diaphoresis, bilateral mydriasis, and mild fine hand tremors. He is hypervigilant, oriented to person, place, and time, and admits to recently using a 'study aid' given to him by a friend to help him stay awake. Which of the following is the most likely diagnosis?

  1. Substance/medication-induced psychotic disorderAnswer
  2. B
    Brief psychotic disorder
  3. C
    Schizophreniform disorder
  4. D
    Schizophrenia
  5. E
    Delusional disorder

Answer

Substance/medication-induced psychotic disorder
The correct answer identifies that the patient's acute psychotic symptoms (paranoia, auditory hallucinations) are a direct physiological consequence of a substance. The patient's presentation of prominent autonomic hyperactivity (tachycardia, hypertension, diaphoresis, mydriasis) alongside the ingestion of an unknown 'study aid' is a classic presentation of psychostimulant (e.g., amphetamine) intoxication. According to DSM-5 criteria, a primary psychotic disorder cannot be diagnosed if the symptoms are attributable to the physiological effects of a substance.

Step-by-Step Solution

1
Identify the primary psychiatric symptoms.
The patient exhibits acute-onset paranoia, persecutory delusions, and auditory hallucinations lasting for 4 days.
Establishing the specific nature and temporal course of the psychotic symptoms is the first step in formulating a psychiatric differential diagnosis.
2
Analyze the patient's vital signs and physical examination findings.
The patient demonstrates significant autonomic hyperactivity, including tachycardia (118/min), hypertension (162/98 mm Hg), diaphoresis, and bilateral mydriasis.
Physical signs are crucial for distinguishing primary psychiatric conditions from secondary organic causes, such as medical illnesses or toxidromes.
3
Correlate the clinical presentation with the patient's history.
The combination of acute psychosis, a classic sympathetic toxidrome, and the recent use of an unknown 'study aid' strongly indicates psychostimulant (e.g., amphetamine) intoxication.
By strict DSM-5 criteria, a primary psychiatric diagnosis cannot be made if the symptoms are the direct physiological consequence of a substance or medication.
4
Exclude primary psychotic disorders based on duration and etiology.
Brief psychotic disorder is excluded because the symptoms are substance-induced. Schizophreniform disorder and schizophrenia are excluded due to both the substance etiology and the excessively short 4-day symptom duration.
Strict application of DSM-5 diagnostic criteria ensures accurate classification and guides appropriate acute management.

Key Concept

Differentiating substance-induced psychotic disorder from primary psychotic disorders based on clinical signs of intoxication and symptom duration.
Estimated Time:1m 0s
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Topics

Substance-Related and Addictive Disorders

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