Mental illness carries a lot of stigma -- that's well known to researchers and to people who struggle with these disorders. People tend not to want to work, be friends, or live with those suffering from mental illness.

When Lehigh University psychology professor Jessecae Marsh explored some of the beliefs that could contribute to stigma, she found a surprising reason: Many people think that mental illness is contagious.

Those who believe that were most likely to stigmatize people suffering with these disorders.
"So, in other words, if you thought that you could catch a given mental disorder, you were less likely to be willing to be around people with that mental disorder," Marsh explained.

When asked about 12 different disorders, such as bipolar disorder or anorexia, 77% of participants were willing to endorse that you could catch one of those disorders and then describe a mechanism for how that happened.

Marsh said the fact that people think mental illness might be contagious has big implications for designing anti-stigma campaigns, which often aim to liken mental illness to physical illness. But this effort to explain that mental illness is not a sign of weakness could backfire, she said.

"We know that medical disorders that people think are highly contagious like tuberculosis can be extremely stigmatized," she said. "So just by reframing mental disorders as medical disorders does not mean that people will stigmatize them less, because you still think you can catch them, and they are contagious in different ways."

People were especially likely to think disorders such as depression and anorexia were contagious, Marsh said.