The systematic review, published in the journal JAMA Psychiatry, looked at 24 studies which covered more than 50,000 people with schizophrenia across 15 countries over four decades.
Professor Seena Fazel of Oxford’s Department of Psychiatry said: 'The perception that schizophrenia is associated with violent behaviour attracts considerable media attention and occasionally misleading headlines. This systematic review clarifies that there is now robust evidence from 24 individual studies of a modest increased risk of perpetration of violence in people with schizophrenia, but it provides the necessary context – that over a period of around four decades, this amounts to no more than 1 in 4 men and 1 in 10 women with schizophrenia for serious violent outcomes.
'This provides clinicians with an important target for prevention of violent acts by patients who may be at elevated risk, as well as helping to reduce stigma in people with schizophrenia and related disorders.'
The researchers also found that other factors such as the misuse of drugs and alcohol contributed to a doubling of violence perpetration risk in women and men with schizophrenia, which the researchers highlight as a target for prevention of such behaviour, as well as demonstrating the importance of provision of healthcare services to tackle substance misuse.
Dr Daniel Whiting of Oxford’s Department of Psychiatry said: 'The contribution of mental health disorders to violent crime is often overstated, which can bias public perception, but failing to acknowledge associations can also lead to clinical needs not being met in psychiatric services.
'This new study highlights the important contribution of newer, larger studies in the last decade to clarifying our understanding of how mental health is linked with behaviour.
'The clear message is that violence perpetration is an important outcome to prevent in people with schizophrenia. Prevention can act on many levels – from early identification and treatment to improving access to treatment, to improving how risks are assessed. The study also highlights the difficulty with the current fragmentation of services in many countries, including the UK, where there are separate services for mental health and addictions.'
The review reported evidence for the protective effects of appropriately prescribed antipsychotic medication and suggested more research and funding to investigate other preventative approaches.
The full paper, 'Association of Schizophrenia Spectrum Disorders and Violence Perpetration in Adults and Adolescents from 15 Countries. A Systematic Review and Meta-Analysis', can be read in JAMA Psychiatry.