4.5 Schizophrenia

SCHIZOPHRENIA

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What is schizophrenia?

A neurobiological thought disorder with a lifetime risk of approximately 1%, typically beginning in adolescence or early adulthood.

PATHOPHYSIOLOGY

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What is the main neurotransmitter hypothesis for schizophrenia?

Excess dopamine activity or increased dopamine receptor signalling in mesocorticolimbic pathways.

What evidence supports dopamine involvement in schizophrenia?

High L-dopa treatment in Parkinson’s patients can trigger schizophrenic symptoms.

BRAIN CHANGES

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What structural/functional brain changes are associated with schizophrenia?

Enlarged cerebral ventricles, reduced temporal lobe activity/size, reduced cerebral blood flow, and reduced frontal function.

CAUSES

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What are the likely causes of schizophrenia?

A combination of genetic and environmental factors within a neurodevelopmental model.

What genetic evidence supports schizophrenia risk?

Increased family risk, twin concordance (higher in monozygotic twins), and susceptibility genes such as Neuregulin 1.

What environmental factors may contribute?

Birth complications, viral infection, urban living, immigration, cannabis use in susceptible individuals, and childhood stress/trauma.

SIGNS AND SYMPTOMS

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What are the positive and negative symptoms of schizophrenia?

Positive: delusions, hallucinations, thought disorder, lack of insight; Negative: emotional flattening, social withdrawal, self-neglect, low motivation, reduced activity/speech.

DIAGNOSIS AND TREATMENT

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How is schizophrenia diagnosed and treated?

Diagnosis is clinical after excluding other causes; treatment includes antipsychotics (e.g. haloperidol, chlorpromazine, clozapine) plus social support, with some possible benefit from art therapy.