Patients with mental illness may be at greater risk for becoming victims of homicide than people without mental illness, according to a new study in the United Kingdom.
Researchers found that, among all 1,496 homicide victims in England and Wales during a three-year study period, 6 percent (90) had been under the care of mental-health services in the year before their death, and about one-third (29) of the victims who had mental illness were killed by other patients with mental illness.
"The findings of our study are an important reminder that, although the overall risk of patients committing homicide is greater than the risk of being a victim of homicide, mentally ill people are often vulnerable to the violence of others," study author Cathryn Rodway, a research associate at the University of Manchester in the United Kingdom, told Live Science in an email. (Within the same three-year period, 213 mental-illness patients in England and Wales were convicted of homicide — a number that constituted 12 percent of all homicide convictions during this time, the researchers wrote.)
Historically, the public has been more concerned about the violence coming from mental-health patients than the potential vulnerability of those patients to violent acts by others, the researchers said.
In the study, the researchers examined data on the victims and perpetrators of all homicides in England and Wales between January 2003 and December 2005.
The investigators also found that 23 of the 29 mental-health patients who were killed by another mental-health patient knew their killer, either as partners (35 percent), family members (15 percent) or acquaintances (38 percent). [Understanding the 10 Most Destructive Human Behaviors]
In 21 of the cases, both the victims and the perpetrators were patients at the same mental-health facility, according to the study, published (Wednesday) June 18 in the journal The Lancet Psychiatry.
There are a few reasons why mental-health patients may have an increased likelihood of being a homicide victim, the researchers said.
"The increased risk may be related to the patient's social environment, their use of alcohol or drugs, or the people with whom they come into contact, including other patients with a history of violence," Rodway said, adding that these factors should be taken into consideration in clinical care plans for mental-health patients.
In fact, the study results showed that 66 percent of the patients who were victims, as well as 93 percent of the patients who were perpetrators, misused drugs and alcohol, whereas 24 percent of the victims and an equal percentage of the perpetrators had a history of violence, including convictions for homicide, attempted murder, bodily harm and assault.
"Research suggests that risk factors among patient victims — such as substance use, low socioeconomic status, type of psychopathology and engagement in behaviors that increase risk [of being a homicide victim] — could be targeted," Alyssa Rheingold, a researcher at the Medical University of South Carolina, who was not involved in the study, wrote in a commentary accompanying the study in the journal.
However, further studies should explore "these individual characteristics, their interactions and their contribution to the risk of homicide," Rheingold wrote.
Follow Agata Blaszczak-Boxe on Twitter. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.
