Schizophrenia
A psychotic disorder rooted in dysregulated dopaminergic signalling that produces positive symptoms through subcortical excess and negative/cognitive symptoms through cortical deficit, diagnosed on duration and function rather than any single test.
In a nutshell
Schizophrenia arises from dysregulated dopaminergic signalling: subcortical excess produces aberrant salience and thus positive symptoms (delusions, hallucinations), while relative prefrontal deficiency produces negative and cognitive symptoms. Diagnosis requires persistence of characteristic symptoms for at least a month with functional decline, once organic and substance causes are excluded.
Classic presentation
A young adult develops persecutory delusions and third-person auditory hallucinations over weeks, alongside social withdrawal and declining self-care, with no evidence of substance use or an organic cause.
Key points
- Positive symptoms (delusions, hallucinations, disorganisation) reflect subcortical dopaminergic excess; negative symptoms (avolition, affective flattening, alogia) reflect relative prefrontal deficiency, a different mechanism that responds less well to antipsychotics.
- Diagnosis requires symptom persistence for the diagnostic duration threshold with functional decline, not a single psychotic experience.
- Always exclude substance-induced psychosis and organic causes, particularly in first-episode presentations.
- Early intervention (rapid access to specialist psychosis services) improves long-term outcomes because a shorter duration of untreated psychosis predicts a better trajectory.
- Antipsychotics plus CBT for psychosis and family intervention together reduce relapse more than medication alone.
- Clozapine is reserved for treatment resistance (failure of two adequate antipsychotic trials) and requires mandatory blood monitoring for agranulocytosis.
First-line investigation
Detailed mental state examination and collateral history to characterise and time the psychotic symptoms, alongside a urine drug screen and organic bloods to exclude substance-induced or organic causes.
First-line management
Urgent referral to early intervention in psychosis services, with an antipsychotic started alongside psychological therapy (CBT for psychosis) and family intervention where relevant.
Exam traps
- A single hallucination or delusional experience does not equal schizophrenia: the duration and functional decline criteria must be met and other causes excluded.
- Negative symptoms are frequently mistaken for depression; they reflect a distinct prefrontal deficit and respond poorly to antipsychotics alone.
- Cannabis and stimulant use are common precipitants and confounders in first-episode psychosis and must always be screened for.
- Clozapine requires regular full blood count monitoring due to the risk of agranulocytosis, a classic exam safety point.
- Antipsychotics carry significant cardiometabolic risk, so physical health monitoring is part of ongoing management, not an afterthought.
Educational content pending clinical review. Not medical advice.