Acute agitation in a young adult with suspected first-episode psychosis
A 24-year-old man is brought to the emergency department by police after he was found shouting at pedestrians and trying to climb a construction crane. He is dishevelled, sweating, and appears frightened. He says, 'The radio is sending messages that I must save the world.' He denies any drug use but his friends report he has been smoking cannabis daily for 2 years. He is agitated, pacing, and repeatedly clenches his fists. His heart rate is 118 bpm, blood pressure 145/90 mmHg, temperature 37.8°C, and pupils are dilated. He has no known medical history. He is refusing oral medication and attempts to leave. There is no collateral information available yet.
1. What is your immediate management plan, and what are the key diagnostic considerations?
Read the worked answer
Immediate management:
- Ensure safety of staff and patient; use verbal de-escalation first.
- If de-escalation fails and risk of harm is high, consider emergency sedation with intramuscular antipsychotic (e.g., haloperidol 5 mg + promethazine 25–50 mg) or benzodiazepine (e.g., lorazepam 2 mg) while monitoring vital signs. Avoid polypharmacy and consider ECG monitoring.
- Obtain urgent medical workup: vital signs, glucose, electrolytes, renal and liver function, urine toxicology, ECG (QTc), and consider neuroimaging if focal neurological signs or atypical presentation.
- Place in a quiet, low-stimulation area; involve security.
Diagnostic considerations:
- Differential includes: substance-induced psychosis (cannabis, stimulants, hallucinogens), first-episode schizophrenia, brief psychotic disorder, bipolar disorder with psychotic features, delirium secondary to medical condition (e.g., infection, metabolic), and other medical causes (e.g., thyrotoxicosis, encephalitis).
- The dilated pupils, tachycardia, and agitation raise suspicion for sympathomimetic intoxication (e.g., cocaine, amphetamines) despite denial.
- Collateral information from friends/family is crucial; urine toxicology will help but may be negative for cannabis if not recent.
- Observe over 24–48 hours; substance-induced psychosis often resolves with abstinence, while primary psychosis persists.
- Initiate antipsychotic treatment cautiously; avoid benzodiazepines alone if substance-induced psychosis is suspected? Actually benzodiazepines are first-line for stimulant intoxication.
Key point: Do not miss delirium; check for fluctuating consciousness, disorientation, and vital sign abnormalities.
2. How would you differentiate between a substance-induced psychosis and a primary psychotic disorder in this patient?
Read the worked answer
Differentiation relies on history, timeline, and observation:
- Temporal relationship: Substance-induced psychosis typically occurs during or shortly after intoxication or withdrawal (e.g., within 1 month of use). Primary psychosis may have a prodromal phase and persist beyond the expected duration of intoxication.
- Substance use history: Obtain detailed history from patient and informants about the type, amount, frequency, and last use. Cannabis can induce psychosis, especially with high-potency products (e.g., skunk). Stimulants like cocaine and amphetamines commonly cause paranoid psychosis.
- Symptom profile: Substance-induced psychosis often features prominent hallucinations (especially visual) and agitation, with less formal thought disorder and negative symptoms. Primary schizophrenia may have negative symptoms, disorganized behavior, and a chronic course.
- Course: Substance-induced psychosis usually resolves within days to weeks with abstinence; primary psychosis persists. Re-challenge or observation after detoxification can help.
- Family history: A family history of schizophrenia increases risk of primary psychosis.
- Response to treatment: Both respond to antipsychotics, but primary psychosis requires long-term treatment.
In this patient: The acute onset, agitation, dilated pupils, and tachycardia suggest possible stimulant use. However, daily cannabis use for 2 years also raises risk. A urine toxicology test and observation over 24–48 hours are essential. If symptoms persist beyond 4 weeks of abstinence, consider primary psychosis. Also, assess for bipolar disorder (manic episode with psychotic features).