PMHNP psychosis: schizophrenia, antipsychotic prescribing, and EPS management

DSM-5 schizophrenia: ≥2 of the following, each present for significant portion of 1-month period (≥1 must be positive symptoms 1–3): (1) delusions, (2) hallucinations, (3) disorganised speech, (4) grossly disorganised/catatonic behaviour, (5) negative symptoms. Continuous signs for ≥6 months. Significant social/occupational dysfunction.

Positive symptoms: Delusions (fixed false beliefs — persecutory, referential, grandiose, somatic), hallucinations (auditory most common in schizophrenia — command, commentary, or conversing voices), disorganised thinking/speech, grossly disorganised behaviour. Respond better to antipsychotics.

Negative symptoms: Affective flattening, alogia (poverty of speech), avolition (lack of motivation), anhedonia, asociality. Respond poorly to antipsychotics. Associated with greater functional impairment and worse long-term outcomes.

First-episode psychosis: Evaluate and rule out medical causes: temporal lobe epilepsy, autoimmune encephalitis (anti-NMDA receptor), substance-induced psychosis (cannabis, stimulants), CNS lesion, thyroid disease, metabolic disorders. Brain MRI + lab workup for first episode.

First-generation antipsychotics (FGAs — "typicals"): Primarily D2 receptor blockade. High-potency (haloperidol, fluphenazine): high EPS risk, low sedation/anticholinergic. Low-potency (chlorpromazine, thioridazine): lower EPS, more sedation/anticholinergic/hypotension. Long-acting injectable (LAI) forms available (haloperidol decanoate, fluphenazine decanoate) — improve adherence for patients with insight problems.

Second-generation antipsychotics (SGAs — "atypicals"): D2 + 5-HT2A blockade (plus variable additional receptor effects). Less EPS, more metabolic effects. Key differences:

• Clozapine: Most effective for treatment-resistant schizophrenia (failure of ≥2 antipsychotics). Unique risk: agranulocytosis (absolute neutrophil count must be monitored — REMS program, weekly CBC initially, then monthly). Also: weight gain, T2DM, sialorrhoea, sedation, seizure (dose-dependent), myocarditis.
• Olanzapine: Highest metabolic risk — weight gain, T2DM, hyperlipidaemia. Effective for mania and schizophrenia.
• Risperidone: Most typical-like SGA — D2 blockade predominates at higher doses → EPS risk. Most elevated prolactin of SGAs. LAI form (Risperdal Consta, Perseris) available.
• Quetiapine: Most sedating, minimal EPS, moderate metabolic risk. Used for sleep (off-label) — caution as QTc-prolonging effect.
• Aripiprazole/brexpiprazole/cariprazine: D2 partial agonists — minimal metabolic effects, minimal EPS, minimal prolactin elevation. Aripiprazole can be activating.
• Ziprasidone: QTc prolongation — baseline and monitoring ECG. Must be taken with food (significant food effect on absorption).

Extrapyramidal syndromes (EPS) — onset and management:

• Acute dystonia: Hours to days after initiation — sustained muscle contraction (torticollis, oculogyric crisis, laryngospasm). Treatment: benztropine IM/IV or diphenhydramine IM/IV — immediate relief. Prophylactic benztropine can prevent recurrence.
• Akathisia: Days to weeks — motor restlessness, unable to sit still, must move. Subjectively distressing. Often misidentified as anxiety. Treatment: lower dose, switch antipsychotic, add propranolol or mirtazapine (not benztropine — doesn't help).
• Parkinsonism: Weeks to months — bradykinesia, rigidity, tremor (like Parkinson disease). Treatment: reduce dose, switch, add benztropine/trihexyphenidyl.
• Tardive dyskinesia (TD): Months to years — involuntary rhythmic movements (oral-lingual: lip smacking, tongue protrusion; limbs; trunk). Persists after stopping antipsychotic. Treatment: VMAT2 inhibitors — valbenazine (Ingrezza) or deutetrabenazine (Austedo). Clonazepam may provide partial relief.

Neuroleptic malignant syndrome (NMS) — psychiatric emergency: Hyperthermia (fever >38°C), muscle rigidity, altered mental status, autonomic instability (diaphoresis, tachycardia, BP lability). Elevated CK (often >1000, can be >100,000). Onset: hours to 30 days after antipsychotic initiation or dose change. Management: STOP antipsychotic immediately, supportive care (cooling, IV hydration), bromocriptine (dopamine agonist), dantrolene (muscle relaxant for hyperthermia/rigidity), ICU admission for severe cases.