Adults with disabilities are more likely to be victims of violence than adults who are not disabled, according to a new study published online in The Lancet.
Mentally ill adults are at four times higher risk for violence, and adults with intellectual impairments are also particularly vulnerable.
A team of researchers from the United Kingdom's Liverpool John Moores University and the World Health Organization analyzed 26 studies on violence against disabled adults, with more than 21,000 participants from around the world.
"About 3 percent of individuals with non-specific impairments [eg, physical, mental, or emotional, or health problems that restrict activities] will have experienced violence within the past 12 months, rising to almost a quarter of people with mental illnesses," said lead author Mark Bellis of Liverpool John Moores University in a press release.
The violence, he explained, was either physical, sexual or by an intimate partner.
Experts not involved in the research say the study calls attention to the plight of many disabled adults who become targets for a variety of reasons.
Jack Levin, professor of sociology and criminology at Northeastern University in Boston, said the disabled often suffer in silence.
"It happens all too often, but we have ignored a very serious issue," he said.
He cited the case of 30-year-old Jennifer Daugherty as an example of what a surprisingly high number of mentally ill and intellectually challenged adults suffer.
Daugherty, described by her stepfather as having the mental abilities of a 12 to 14-year-old was allegedly tortured and murdered by a group of six people in western Pennsylvania in 2010. Prosecutors say a 17-year-old girl served as the group's ringleader and saw Daugherty as a romantic rival.
The group was accused of abducting Daugherty, beating her, forcing her to consume human waste and bleach, then forcing her write a suicide note before stabbing her multiple times.
Levin said that while people view what happened to Daugherty as particularly heinous, most people don't see it for the hate crime that it is. Hate crimes, he explained, are more likely to be viewed as crimes against a certain race or against people of certain sexual orientations.
The U.S. Department of Justice found that disabled adults were victims of twice as many violent crimes as adults who are not disabled, and about 15 percent of these victims believe they were targeted as a result of their impairments.
"There are a number of reasons why adults with disabilities are more vulnerable to violence," said Dick Sobsey, professor emeritus at the University of Alberta in Edmonton, Canada.
"Many of them are more vulnerable or may have limited communication abilities, either by impairment or by situations they are in," he said.
Levin added that they may not be able to fight back or to report the incidents to the authorities.
The disabled, especially those who have cognitive impairments, are often viewed as non-human.
"They have a deficit or a defect, so they can be more easily treated like animals or subhumans," said Levin, also the author of "The Violence of Hate."
Many people with disabilities are also often dependent on others, making them vulnerable to people who may feel the desire to exert power over them, Sobsey added.
Perpetrators may also be exacting revenge on people with disabilities, Levin said. Since the passage of the Americans with Disabilities Act (ADA) in 1990, which prohibits discrimination based on disabilities, people may feel that the disabled get special privileges.