Schizophrenia: symptoms, causes and treatment

Key points

• Schizophrenia is a lasting pattern of psychotic symptoms, loss of drive and difficulty thinking clearly [4][9].
• It is not a split personality, and around 1 in 100 people experience it [4].
• Most people with schizophrenia are not violent: psychosis accounted for no more than 10% of violence in populations studied [6].
• Negative and cognitive symptoms shape daily life more than hallucinations, and medicines do less for them [9].
• NICE recommends antipsychotic medication alongside therapy, not in place of it [1].
• Not a fixed decline: around 1 in 5 met clinical recovery criteria after a first episode [8].

What schizophrenia is

Schizophrenia is a mental health diagnosis given for a lasting pattern of psychotic symptoms, meaning hallucinations, fixed beliefs others do not share and muddled thinking, together with a loss of drive, expression and mental sharpness [4][9]. Around 1 in 100 people experience it, usually starting in early adulthood [4].

If you need help now. Samaritans: call 116 123, free, 24/7. Shout: text SHOUT to 85258. NHS 111, then choose the mental health option. Call 999 if anyone is in immediate danger.

Pooling the 2007, 2014 and 2023/4 Adult Psychiatric Morbidity Surveys gives a past-year psychotic disorder prevalence of 0.5% of adults in England, a group wider than schizophrenia alone. The 2023/4 survey alone estimated 0.4% [5].

Schizophrenia does not mean a split or multiple personality [4]. That is a different and much rarer diagnosis, dissociative identity disorder.

Symptoms

Symptoms fall into three groups. Public attention goes to the first; the other two do more to shape an ordinary day [9].

Positive symptoms, meaning experiences that are added:

• hearing voices, or seeing or feeling things other people do not [4]
• fixed beliefs others do not share, often about being watched or controlled [4]
• muddled thinking and speech that is hard to follow [4]

Negative symptoms, meaning things that fall away:

• loss of motivation and withdrawal from other people [4]
• loss of interest in activities that used to matter [4]
• reduced self-care and changes to sleep [4]

Cognitive symptoms:

• difficulty with memory, learning and concentration [4]
• difficulty making decisions [4]

Around 40% of people have negative symptoms and around 80% some cognitive difficulty [9]. Both track how a person works, studies and relates to others more closely than positive symptoms do, and primary negative symptoms respond poorly to available antipsychotics [9].

The pattern is commonly confused with bipolar disorder, schizoaffective disorder, post-traumatic stress disorder and drug-induced psychosis [3].

Types

Schizophrenia has no subtypes in current NHS practice. Care is organised by stage and by which symptoms dominate [1].

• First episode psychosis. NICE says early intervention in psychosis services should be accessible to everyone with a first presentation [1].
• Predominant negative symptoms. Reduced drive, expression and social contact, rather than hallucinations, are the main difficulty [9].
• Treatment-resistant schizophrenia. Illness that has not responded adequately to at least two different antipsychotics used one after the other [1].

Causes and risk factors

There is no single cause. Schizophrenia tends to run in families, but no single gene is thought to be responsible [2].

• Family history. If one identical twin has schizophrenia, the other has around a 1 in 2 chance, against 1 in 8 for non-identical twins and 1 in 100 generally [2].
• Pregnancy and birth. Complications are more common, including low birthweight, premature labour and lack of oxygen [2].
• Brain differences. Differences in brain structure and in messengers such as dopamine describe groups, not individuals [2].
• Stress. Bereavement, job loss, relationship breakdown and abuse can trigger onset in someone already at risk [2].

The NHS notes that teenagers and young adults who use cannabis regularly are more likely to develop schizophrenia later, with stronger cannabis carrying higher risk [2]. A meta-analysis of 10 studies covering 66,816 people found the heaviest users had an odds ratio of 3.90 for a psychotic outcome (95% CI 2.84 to 5.34), rising with the amount used [7].

Its authors were careful: a causal link cannot be established with certainty [7]. Most people who use cannabis do not develop schizophrenia, and studies cannot fully separate use from the early symptoms that sometimes come first [7].

How it is diagnosed

A GP is usually the first step and refers on to the community mental health team, where a psychiatrist or specialist nurse assesses in more detail [3].

There is no single test [3]. Most professionals work from a diagnostic checklist, checking the symptoms are present and not caused by something else: recreational drug use, bipolar disorder, schizoaffective disorder, post-traumatic stress disorder, depression or anxiety [3].

No reliable national figure exists for waiting times, which vary by area. A diagnosis names a pattern and opens access to the treatments researched for it, rather than predicting how one person will do [1].

Treatment

For first episode psychosis NICE says to offer oral antipsychotic medication with psychological interventions, so the two run together [1].

• Antipsychotic medication. Offered orally, with the choice made with the person [1]. Doses are for the prescriber. NICE says not to start regular combined antipsychotic medication except briefly, such as when changing medicines [1].
• CBT for psychosis. One to one, over at least 16 planned sessions, following a manual [1].
• Family intervention. Between three months and a year, at least 10 sessions, including the person where practical [1].
• Clozapine. Offered where the illness has not responded adequately despite adequate doses of at least two different antipsychotics, tried in turn [1].

In Scotland in 2017 to 2019, men with schizophrenia lost 11.8 years of life expectancy and women 11.1 years, wider than the 9.4 and 8.2 years recorded in 2000 to 2002 [10]. Most excess deaths are from natural causes: smoking, obesity, inactivity, substance misuse, medication harms, poverty and difficulty getting physical symptoms taken seriously [10].

That is why NICE sets out monitoring of weight, blood glucose, blood lipids and blood pressure through the first year and then annually [1].

Living with schizophrenia

Treat the annual physical health check as part of your care. Your secondary care team is responsible for it for the first 12 months, or until your condition has stabilised, whichever is longer, and your GP yearly after that [1].

If you want to work or study, ask about supported employment, which NICE says should be offered to anyone wishing to find or return to work [1]. You decide how much to tell an employer or university, and need not give a diagnosis to ask for adjustments.

If you are a relative or carer, you are entitled to help in your own right. NICE says a carer-focused education and support programme should be offered as early as possible to all carers, that services should assess carers’ needs yearly, and that carers be included in decisions if the person agrees [1]. Rethink suggests asking the person you care for what their symptoms are, so you both know what to watch for [4].

When to speak to a professional

See a GP if you or someone close to you has been hearing or seeing things others do not, holding beliefs others find impossible, or losing drive and withdrawing over weeks [4]. Say if it is the first time, and ask about early intervention in psychosis services [1].

Contact the care team sooner if symptoms return after a stable period, or if physical health checks have been missed for over a year [1].

Get urgent help the same day if you are thinking about ending your life or cannot keep yourself safe. Samaritans: 116 123. Shout: text SHOUT to 85258. NHS 111, then the mental health option. Call 999 in an emergency.

Common questions

Is schizophrenia a split personality?

No [4]. The confusion comes from the word itself, from Greek roots meaning split mind. Split or multiple personality is a different and much rarer diagnosis, dissociative identity disorder.

Are people with schizophrenia dangerous?

Most are not. Violence risk is raised, but mainly among those who also misuse alcohol or drugs: pooled odds were 8.9 with substance misuse and 2.1 without [6]. Psychosis accounted for no more than 10% of violence in populations studied [6]. People with schizophrenia are far more likely to be harmed by others than to harm anyone [4].

Can you recover from schizophrenia?

Some do, and the picture is not one of steady decline. Across 26 samples and 3,877 people with first-episode schizophrenia, 20.8% (95% CI 17.3 to 24.8) met criteria for clinical recovery over an average of 9.5 years, needing sustained gains in both symptoms and social or working life [8]. Rates varied widely between studies [8].

Does cannabis cause schizophrenia?

Cannabis raises risk, and causation has not been settled. Heavy use carries roughly four times the odds of a psychotic outcome compared with no use, and risk rises with the amount used [7]. Regular use in the teenage years and stronger cannabis both appear riskier [2]. Most people who use cannabis never develop schizophrenia [7].

Clinical review pending

References

1. National Institute for Health and Care Excellence. Psychosis and schizophrenia in adults: prevention and management. NICE clinical guideline CG178, 2014. https://www.ncbi.nlm.nih.gov/books/NBK555203/
2. NHS. Causes: Schizophrenia. nhs.uk. https://www.nhs.uk/mental-health/conditions/schizophrenia/causes/
3. NHS. Diagnosis: Schizophrenia. nhs.uk. https://www.nhs.uk/mental-health/conditions/schizophrenia/diagnosis/
4. Rethink Mental Illness. Schizophrenia. rethink.org. https://www.rethink.org/advice-and-information/about-mental-illness/mental-health-conditions/schizophrenia/
5. NHS England Digital. Adult Psychiatric Morbidity Survey: Survey of Mental Health and Wellbeing, England, 2023/4. Chapter 12: Psychotic disorder, published 27 November 2025. https://digital.nhs.uk/data-and-information/publications/statistical/adult-psychiatric-morbidity-survey/survey-of-mental-health-and-wellbeing-england-2023-24/psychotic-disorder
6. Fazel S, Gulati G, Linsell L, Geddes JR, Grann M. Schizophrenia and violence: systematic review and meta-analysis. PLOS Medicine, 2009, volume 6, issue 8, e1000120. https://journals.plos.org/plosmedicine/article?id=10.1371%2Fjournal.pmed.1000120
7. Marconi A, Di Forti M, Lewis CM, Murray RM, Vassos E. Meta-analysis of the association between the level of cannabis use and risk of psychosis. Schizophrenia Bulletin, 2016, volume 42, issue 5, pages 1262 to 1269. https://academic.oup.com/schizophreniabulletin/article/42/5/1262/2413827
8. Hansen HG, Speyer H, Starzer M, et al. Clinical recovery among individuals with a first-episode schizophrenia: an updated systematic review and meta-analysis. Schizophrenia Bulletin, 2023, volume 49, issue 2, pages 297 to 308. https://academic.oup.com/schizophreniabulletin/article/49/2/297/6677549
9. Correll CU, Schooler NR. Negative symptoms in schizophrenia: a review and clinical guide for recognition, assessment, and treatment. Neuropsychiatric Disease and Treatment, 2020, volume 16, pages 519 to 534. https://www.dovepress.com/negative-symptoms-in-schizophrenia-a-review-and-clinical-guide-for-rec-peer-reviewed-fulltext-article-NDT
10. Fleetwood KJ, Alotaibi R, Scheuer SH, Smith DJ, Wild SH, Jackson CA. Time trends in life expectancy of people with severe mental illness in Scotland, 2000 to 2019: population-based study. BJPsych Open, 2025, volume 11, issue 3, article e103. https://www.cambridge.org/core/journals/bjpsych-open/article/time-trends-in-life-expectancy-of-people-with-severe-mental-illness-in-scotland-20002019-populationbased-study/FE8E255948BC84042E937E8AD74CA5AE