About This Page
This is a clinician-written, evidence-based guide aligned to the MCC Examination Objectives. It is structured by clinical presentation — the way the MCCQE tests and the way patients actually present. Management reflects current Canadian guidelines (CMA, CFPC, CPS). Always cross-reference with institutional protocols and clinical judgment.
The Bottom Line
- Psychosis is a syndrome: distinguish primary psychotic disorder from delirium, substances, withdrawal, mood disorder, neurological disease, endocrine disease, and infection
- Delirium is the must-not-miss mimic: acute onset, fluctuating attention, altered consciousness, and abnormal vitals demand medical work-up
- First-episode psychosis requires safety assessment, collateral history, substance review, baseline labs, and early psychiatric intervention
- Assess risk: command hallucinations, persecutory delusions, access to weapons, self-neglect, suicide, violence, and vulnerability/exploitation
- Initial management prioritises de-escalation, treatment of medical causes, antipsychotic initiation when appropriate, and early psychosis services
Approach to the Presentation
The MCCQE1 approach to psychosis starts with medical safety, not diagnostic labelling. Check ABCs, vitals, glucose, level of consciousness, attention, intoxication/withdrawal signs, neurological signs, fever, and trauma. Clarify hallucination modality, delusional content, disorganisation, negative symptoms, mood symptoms, sleep, substance use, medications, cannabis potency, family history, trauma, and functional decline. Obtain collateral where possible because insight is often limited. Communicate non-confrontationally: do not argue with delusions, but acknowledge distress and focus on shared goals such as sleep, safety, and reducing fear.
Differential Diagnosis
| diagnosis | likelihood | key features | distinguishing test |
|---|---|---|---|
| Delirium / acute medical illness | must-not-miss | Acute fluctuating confusion, impaired attention, altered level of consciousness, visual hallucinations, fever, hypoxia, infection, metabolic disturbance, medication toxicity | CAM/4AT, vitals, glucose, CBC, electrolytes, renal/liver tests, urinalysis/CXR/CT as indicated |
| Substance-induced psychosis or withdrawal | must-not-miss | Cannabis, stimulants, cocaine, hallucinogens, steroids, anticholinergics, dopaminergic drugs; alcohol or benzodiazepine withdrawal may cause hallucinosis/delirium | Substance timeline, collateral, urine toxicology, withdrawal scales |
| Mania or mixed episode with psychosis | must-not-miss | Decreased need for sleep, increased energy, grandiosity, pressured speech, risky behaviour, irritability, mood-congruent or mood-incongruent psychosis | Mood episode history; collateral; mental status exam |
| Psychotic depression | must-not-miss | Severe depression with nihilistic, guilt, poverty, or somatic delusions; refusal to eat/drink; high suicide risk | Depression severity + psychosis content; urgent psychiatric assessment |
| First-episode schizophrenia-spectrum psychosis | common | Delusions, hallucinations, disorganised speech/behaviour, negative symptoms, functional decline over weeks-months | Clinical DSM-5-TR criteria, duration, collateral, exclusion of medical/substance causes |
| Brief psychotic disorder | less common | Psychosis lasting 1 day to 1 month, often stress-related, with eventual return to baseline | Longitudinal follow-up; diagnosis often provisional |
| Dementia-related psychosis / Lewy body dementia | less common | Older patient, cognitive decline, fluctuating cognition, visual hallucinations, parkinsonism, REM sleep behaviour disorder | Cognitive assessment, collateral, medication review, neuroimaging when indicated |
| Temporal lobe epilepsy / neurological lesion | rare | Olfactory hallucinations, episodic phenomena, automatisms, post-ictal confusion, focal neurological signs, new headache, seizures | EEG, MRI/CT brain, neurology assessment |
| Endocrine/autoimmune/infectious psychosis | rare | Atypical age/onset, neurological signs, autonomic instability, catatonia, thyroid disease, SLE, anti-NMDA receptor encephalitis, HIV, neurosyphilis | Targeted labs, CSF/EEG/MRI if encephalitis suspected |
Red Flags & Key History
Symptoms
Acute fluctuating attention, disorientation, or altered consciousness — delirium until proven otherwise
Fever, headache, meningism, seizure, focal neurological deficit, head trauma
Command hallucinations to harm self/others, persecutory delusions, access to weapons
Severe insomnia with increased energy and grandiosity — mania
New psychosis after age 40 or very abrupt onset — consider organic cause
Gradual social withdrawal, decline in school/work, odd beliefs, negative symptoms
Cannabis escalation, stimulant use, steroid prescription, or withdrawal state
Signs
Abnormal vitals, diaphoresis, tremor, mydriasis, dehydration, or autonomic instability
Catatonia: stupor, mutism, posturing, waxy flexibility, echolalia/echopraxia
Disorganised speech, responding to unseen stimuli, poor self-care
Neurological signs, parkinsonism, ataxia, abnormal movements
Extrapyramidal symptoms or akathisia after antipsychotic exposure
Approach to Investigation
First-line
Vitals, glucose, level of consciousness, attention assessmentDelirium and toxidromes must be identified early
Mental status exam and risk assessmentDocument appearance, behaviour, speech, mood/affect, thought form/content, perception, cognition, insight, judgement, and risk
Collateral historyBaseline function, onset, substances, medication changes, sleep, mood symptoms, and risk behaviours
Baseline labs and ECGCBC, electrolytes, creatinine, liver tests, TSH, glucose, pregnancy test when relevant, urine toxicology if useful; ECG before QT-prolonging antipsychotics when feasible
Second-line
CT/MRI brainIndicated for focal neurological signs, seizures, head trauma, atypical age/onset, immunosuppression, malignancy, severe headache, or concern for intracranial pathology
Infectious/autoimmune work-upHIV, syphilis, B12, inflammatory markers, ANA, CSF, EEG, autoimmune encephalitis testing when clinical features suggest
Metabolic baseline for antipsychoticsWeight/BMI, waist circumference, BP, fasting lipids, A1c/glucose, prolactin if symptoms, and movement disorder baseline
Specialist
Early psychosis intervention servicePreferred for first-episode psychosis; improves engagement, family support, relapse prevention, and functional recovery
Inpatient psychiatric admissionRequired for high risk, inability to care for self, severe disorganisation, catatonia, treatment refusal with risk, or need for diagnostic stabilisation
Management Principles
Canadian Schizophrenia Guidelines + CAMH clinical resources + DSM-5-TR1
Immediate safety and engagement
- Use calm, non-threatening communication; reduce stimulation; involve security only when necessary
- Do not challenge delusions directly. Acknowledge distress and focus on safety, sleep, food, hydration, and reducing fear
- Assess capacity and need for involuntary assessment when risk is substantial
2
Treat organic or substance-related causes
- Delirium: identify and treat infection, hypoxia, metabolic disorder, medication toxicity, pain, urinary retention, constipation, or withdrawal
- Substance-induced psychosis: supportive care and reassessment after sobriety; use benzodiazepines for stimulant agitation when appropriate
- Alcohol/benzodiazepine withdrawal psychosis or delirium requires benzodiazepine-based withdrawal management
3
First-episode psychosis
- Start antipsychotic when primary psychosis is likely and risk-benefit is discussed; use low dose and monitor metabolic/EPS/prolactin/QT effects
- Offer family education, psychoeducation, substance counselling, sleep stabilisation, and early psychosis intervention referral
- Avoid cannabis and stimulants because they increase relapse and persistence risk
Complications & Pitfalls
- Missing delirium: Visual hallucinations, fluctuating attention, and abnormal vitals point to medical illness, not primary schizophrenia.
- No collateral: Duration, functional decline, mood episodes, and substance use are often misjudged without collateral.
- Ignoring cannabis: High-potency cannabis can precipitate and perpetuate psychosis.
- Poor communication: Arguing with delusions destroys rapport; validate distress without endorsing false beliefs.
MCCQE1 Exam Tips
- 1In a psychosis stem, first separate delirium from primary psychiatric illness; impaired attention is the key clue
- 2First-episode psychosis needs medical/substance exclusion and early psychosis referral
- 3Mood symptoms determine diagnosis: psychosis only during mood episodes suggests mood disorder with psychotic features
- 4Command hallucinations, persecutory delusions, access to weapons, and self-neglect change disposition
- 5Do not confront delusions; use CanMEDS communication to acknowledge fear and assess safety
- 6Cannabis and stimulants are high-yield MCC distractors in young patients with hallucinations/paranoia
practicetest your knowledge on psychosis (hallucinations & delusions)Apply what you've learnt with MCCQE1-style questions from the iatroX Q-Bank — psychiatric and beyond.
open q-bank