Women with severe mental illness are up to five times more likely to be victims of sexual assault than the general population, new research shows.

Around 40% of women with severe mental illness become victims of rape or attempted rape, and are two to three times more likely to suffer domestic violence. Of these women, 53% had attempted suicide as a result.

In the general population, 7% of women had been victims of rape or attempted rape, of whom 3% had attempted suicide.

Research led by University College London and King's College London, found that 12% of men with severe mental illness had been seriously sexually assaulted, compared with 0.5% of the general male population.

"The number of rape victims among women with severe mental illness is staggering," says lead author Dr Hind Khalifeh of UCL's Division of Psychiatry.

Sexual assault could lead to suicide

The findings are based on interviews with 303 randomly-recruited psychiatric outpatients who had been in contact with community services for a year or more, 60% of whom had been diagnosed with schizophrenia.

Their responses were compared to those from the 2011 to 2012 Crime Survey for England and Wales. A wide range factors, including age, ethnicity and marital status, were also taken into account.

Dr Khalifeh added that clinicians assessing people after a suicide attempt should consider asking them if they have been sexually assaulted.

"Currently this is not done and so patients may miss opportunities to receive specialist support," he said.

Men and women with mental illness were also found to be more likely to be victims of domestic violence than the general population, with 69% of women and 49% of men with severe mental illness reporting suffering adulthood domestic violence.

Violence and mental illness connection

Although the study shows a strong association between mental illness and sexual and domestic violence, in some cases of violence may have contributed to or caused the onset of mental illness, rather than taking place after a diagnosis had been made.

However, any violence participants experienced in the 12 months preceding the study would have been after they were diagnosed with a mental illness, since all participants had been under the care of mental health services for at least a year.

The results were adjusted for drug and alcohol use over the year, but this did not significantly affect the study's results.

Senior author Louise Howard, of King's, said that patients with severe mental illness are at substantially increased risk of becoming a victim of domestic and sexual violence.

"Despite the public's concern about violence being perpetrated by patients with severe mental illness, the reality for patients is that they are at increased risk of being victims of some of the most damaging types of violence."

The study, funded by the Medical Research Council and the Big Lottery, was published in Psychological Medicine.