Psychosis assessment and antipsychotics

Schizophrenia, Acute Psychosis & Antipsychotic Management

Psychotic disorders represent profound disturbances in reality testing, thinking, perception, and behaviour. In Australian clinical practice, distinguishing between primary psychotic illnesses (such as schizophrenia and schizoaffective disorder) and secondary organic psychoses is a critical diagnostic competency assessed in the AMC examination. Prompt recognition of extrapyramidal movement disorders, metabolic complications, and medical emergencies such as Neuroleptic Malignant Syndrome (NMS) and clozapine-induced agranulocytosis is vital for patient safety.

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Diagnostic Framework: Schizophrenia and Psychotic Spectrum Disorders

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) categorizes psychotic disorders along a continuum defined by duration, symptom profile, and functional impairment.

DSM-5 Diagnostic Criteria for Schizophrenia

To establish a diagnosis of schizophrenia, the patient must fulfill three primary criteria:

1. Criterion A (Active-Phase Symptoms): Two (or more) of the following five symptoms present for a significant portion of time during a one-month period (or less if successfully treated). At least one symptom must be item 1, 2, or 3:
   • 1. Delusions: Fixed false beliefs impervious to contrary evidence (persecutory, grandiose, reference, somatic, or passivity/control).
   • 2. Hallucinations: Perceptual experiences without external sensory stimuli (auditory running commentary or voices conversing in the third person are classic).
   • 3. Disorganized Speech: Formal thought disorder reflected in speech (frequent derailment, loosening of associations, incoherence, neologisms).
   • 4. Grossly Disorganized or Catatonic Behaviour: Unpredictable agitation, catatonic stupor, waxy flexibility, posturing, or inappropriate bizarre actions.
   • 5. Negative Symptoms: Diminished emotional expression (blunted affect), avolition (lack of initiative), alogia (poverty of speech), anhedonia, and asociality.
2. Social and Occupational Dysfunction: Marked decline in one or more major areas of functioning (work, interpersonal relations, self-care) below the level achieved prior to onset.
3. Continuous Duration: Continuous signs of disturbance persisting for at least six months. This six-month window must include at least one month of active-phase symptoms (Criterion A), and may include prodromal or residual periods of attenuated symptoms.

Differential Diagnosis of Psychotic Disorders

• Brief Psychotic Disorder: Sudden onset of at least one psychotic symptom lasting at least one day but less than one month, with eventual full return to premorbid functioning. Frequently precipitated by severe psychological stressors.
• Schizophreniform Disorder: Fulfills Criterion A for schizophrenia, with the total duration of the illness (including prodromal, active, and residual phases) lasting at least one month but less than six months. If symptoms persist past six months, the diagnosis transitions to schizophrenia.
• Schizoaffective Disorder: An uninterrupted illness episode characterized by the concurrent presence of a major mood episode (major depressive episode or manic episode) alongside Criterion A of schizophrenia. Crucially, to differentiate schizoaffective disorder from a mood disorder with psychotic features, the patient must experience delusions or hallucinations for at least two consecutive weeks in the absence of prominent mood symptoms at some point during the lifetime course of the illness.
• Bipolar I Disorder with Psychotic Features: Psychotic symptoms occur exclusively during an acute manic or severe depressive episode. When the affective disturbance resolves, psychotic symptoms remit completely.
• Substance/Medication-Induced Psychotic Disorder: Psychosis developing during or immediately after substance intoxication (e.g., methamphetamine, synthetic cannabinoids, cocaine) or withdrawal, or following prescription medication (e.g., high-dose corticosteroids).

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Medical assessment in first-episode psychosis

Obtain a physical and neurological examination, observations and glucose; ask about medicines, substances, sleep and temporal course, with collateral where appropriate. Fluctuating attention suggests delirium. Seizures, focal signs, autonomic instability, abrupt cognitive deterioration or unusual age of onset warrant a targeted neurological/medical workup.

Baseline blood tests commonly include FBC, electrolytes, kidney/liver function, calcium, thyroid function and metabolic measures before antipsychotic treatment. Select B12/folate, HIV/syphilis testing, toxicology and neuroimaging according to risks, findings and the local first-episode pathway, with appropriate consent. Do not label every conceivable test obligatory for every well young person.

Suspected encephalitis may require LP, EEG and CSF antibodies. Rapid psychiatric change with seizures and dysautonomia raises anti-NMDA receptor encephalitis, including an ovarian-teratoma association. A urine drug screen is only an adjunct: it may miss substances, remain positive after intoxication or have false positives. A primary psychiatric diagnosis requires a clinical longitudinal assessment, not simply a normal test panel.

Antipsychotic Pharmacotherapy: FGAs vs SGAs

Antipsychotic medications are the cornerstone of pharmacotherapy for schizophrenia. They are classified into first-generation (typical) and second-generation (atypical) antipsychotics based on their pharmacological receptor binding profiles.

Dopamine Pathways and Therapeutic Mechanism

• Mesolimbic Pathway: Hyperactivity of dopamine in this pathway mediates positive psychotic symptoms (delusions, hallucinations). Antipsychotics exert their therapeutic effect by blocking dopamine D2 receptors in this pathway.
• Mesocortical Pathway: Hypoactivity of dopamine here contributes to negative symptoms and cognitive deficits. Non-selective D2 blockade can inadvertently worsen negative symptoms.
• Nigrostriatal Pathway: Part of the extrapyramidal motor system. D2 receptor blockade here produces extrapyramidal side effects (EPSE).
• Tuberoinfundibular Pathway: Dopamine tonically inhibits prolactin release from the anterior pituitary. D2 blockade disinhibits prolactin release, causing hyperprolactinaemia.

First-Generation Antipsychotics (FGAs)

• Agents: Haloperidol, chlorpromazine, zuclopenthixol, flupentixol.
• Pharmacodynamics: High-affinity antagonism of dopamine D2 receptors. Highly effective against positive symptoms but carry a substantial risk of extrapyramidal movement disorders.
• Extrapyramidal Side Effects (EPSE) Spectrum:
  1. Acute Dystonic Reaction (Hours to Days): Sudden, painful, sustained spastic muscle contractions. Manifestations include torticollis (neck twisting), oculogyric crisis (involuntary upward gaze deviation), trismus (jaw clenching), and potentially fatal laryngeal dystonia. Treatment: Immediate anticholinergic medication—benztropine $1-2\text{ mg}$ IM or IV (or diphenhydramine), providing rapid relief within minutes.
  2. Akathisia (Days to Weeks): Intense subjective psychic restlessness accompanied by an objective compulsion to move (pacing, inability to sit still, rocking from foot to foot). Often misdiagnosed as worsening psychotic agitation. Treatment: Antipsychotic dose reduction, switching to an agent with lower liability (e.g., quetiapine), or adding a lipophilic beta-blocker (propranolol $10-40\text{ mg}$ bd/tds) or short-term benzodiazepine (clonazepam).
  3. Parkinsonism (Weeks to Months): Bradykinesia, cogwheel rigidity, masked facies, resting tremor, and festinating gait. Treatment: Dose reduction, switching to a second-generation agent, or temporary oral anticholinergic (benztropine $1-2\text{ mg}$ daily).
  4. Tardive Dyskinesia (TD) (Months to Years): Involuntary, repetitive, choreoathetoid movements predominantly affecting the tongue, lips, perioral muscles (lip-smacking, tongue-protrusion, chewing movements), and extremities. Pathophysiology involves postsynaptic D2 receptor upregulation and supersensitivity following prolonged dopamine blockade. Crucial Rule: Anticholinergic drugs (benztropine) worsen tardive dyskinesia and must be ceased. Management involves gradual tapering/cessation of the causative FGA, switching to clozapine, or treatment with vesicular monoamine transporter 2 (VMAT2) inhibitors (valbenazine, deutetrabenazine).

Primary references (checked 7 October 2026): Australian clozapine product information.