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What is Schizophrenia?

A serious mental disorder involving psychosis — hallucinations and delusions — together with disorganised thinking and reduced motivation and expression. It usually begins in late adolescence or early adulthood, and outcomes are far more varied and often better than its reputation suggests.

From the PsychologyOrbit knowledge base, last updated 2 November 2026.

Knowledge base Updated 2 November 2026 1 views

Schizophrenia

A serious mental disorder involving psychosis — hallucinations and delusions — together with disorganised thinking and reduced motivation and expression. It usually begins in late adolescence or early adulthood, and outcomes are far more varied and often better than its reputation suggests.

Definition

Symptoms are usually grouped as:

  • Positive symptoms: hallucinations (most often hearing voices), delusions, and disorganised speech or behaviour.
  • Negative symptoms: reduced motivation, pleasure, speech and emotional expression.
  • Cognitive symptoms: problems with attention, working memory and processing speed, often present before the first episode and closely linked to day-to-day functioning.

Diagnosis requires symptoms to persist and to affect functioning, and other causes — substances, medical conditions, mood disorders — must be ruled out. Lifetime prevalence is roughly 0.3 to 0.7 percent.

History

Emil Kraepelin described 'dementia praecox' in the 1890s as a deteriorating illness of early life. Eugen Bleuler coined 'schizophrenia' in 1908, meaning a splitting of mental functions — not a split personality, which is a persistent and harmful misunderstanding.

The introduction of chlorpromazine in the 1950s transformed treatment and led to the dopamine hypothesis.

Theory

Schizophrenia is understood as a neurodevelopmental disorder with many contributing causes.

  • Genetic: heritability is high, and risk comes from many common variants of small effect plus rare variants of larger effect.
  • Environmental: obstetric complications, childhood adversity, migration, urban upbringing and heavy cannabis use, especially high-potency cannabis, all raise risk.
  • Dopamine: the current version of the dopamine hypothesis locates the final common pathway in increased dopamine synthesis and release in the striatum, which may make ordinary experiences feel strangely significant.

Research

Antipsychotic medication reduces positive symptoms and lowers relapse rates, but has less effect on negative and cognitive symptoms and carries metabolic and movement side-effects.

Recovery is more common than the old picture allowed, but defining it strictly, a meta-analysis found that about one person in seven met criteria for recovery over time. Early intervention services improve short-term outcomes.

People with schizophrenia die on average 15 to 20 years earlier than the general population, mostly from physical illness.

Applications

Treatment combines medication with psychosocial interventions: family intervention, cognitive behavioural therapy for psychosis, supported employment such as Individual Placement and Support, and physical health care.

Early intervention in psychosis services aim to shorten the time between first symptoms and treatment.

Criticism

  • Heterogeneity. Two people with the diagnosis may share no symptoms, which leads some researchers to prefer a psychosis spectrum.
  • Stigma and misunderstanding, including the split-personality myth and exaggerated links with violence; people with schizophrenia are more often victims than perpetrators of violence.
  • Diagnostic disparities. Some ethnic minority groups are diagnosed at markedly higher rates in some countries, reflecting both real social risk factors and bias.
  • Overreliance on medication at the expense of psychosocial support in many services.

References

  • McCutcheon, R. A., Reis Marques, T., & Howes, O. D. (2020). Schizophrenia — An overview. JAMA Psychiatry, 77(2), 201-210.
  • Howes, O. D., & Kapur, S. (2009). The dopamine hypothesis of schizophrenia: Version III — the final common pathway. Schizophrenia Bulletin, 35(3), 549-562.
  • Jääskeläinen, E., et al. (2013). A systematic review and meta-analysis of recovery in schizophrenia. Schizophrenia Bulletin, 39(6), 1296-1306.
  • Hjorthøj, C., Stürup, A. E., McGrath, J. J., & Nordentoft, M. (2017). Years of potential life lost and life expectancy in schizophrenia: A systematic review and meta-analysis. The Lancet Psychiatry, 4(4), 295-301.
Written for PsychologyOrbit and reviewed before publishing. It is a summary for professionals and students, not clinical guidance, and it is not a substitute for the primary sources listed above.