The evolved behaviors that humans engage in to avoid contact with infectious diseases could help explain the pervasive stigma against mentally ill people, according to a new study.
“In response to the recurrent threat of infectious disease, a variety of species appear to have evolved behavioral adaptations to counter pathogen threat,” the study’s authors, Erik M. Lund and Ian A. Boggero, explained. “Among humans, it is believed that infectious disease was perhaps the single greatest contributor to morbidity and mortality ancestrally. In response, there exists a behavioral immune system – a psychological system designed to promote the avoidance of potential pathogen carriers.”
Animals, including humans, tend to overperceive disease cues and frequently commit false-positive errors, the researchers said — it is better to accidentally avoid someone who isn’t diseased than accidentally approach someone who is. This heightened sensitivity to disease threats “has been used to explain prejudice towards immigrants and foreigners, the physically disabled, the elderly, and the obese,” Lund and Boggero wrote.
But no research has examined the relationship between mental illness and the behavioral immune system.
“Given the physiological and behavioral similarities between normal immune responses and mental disorders, it is plausible that an oversensitive behavioral immune system would misperceive mental illness cues as physical illness,” the researchers explained.
In their study, which was published 23 July in Evolutionary Psychology, Lund and Boggero found that people were more likely to associate mental illness with sickness than with aggressive behavior or danger. The association between mental illness and disease was strengthened among those who had recently been sick and those who had been warned about a recent epidemic disease threat.
The two-part study included 251 participants, and used the Single-Target Implicit Association Test to examine associations between mental illness and other concepts.
“The present findings suggest that the stigma against the mentally ill is due, in part, to people associating mental illness with disease cues,” Lund and Boggero said. “Such knowledge could help those with mental disorders change their self-stigma and remove an important barrier from seeking treatment. Future research should investigate the mechanisms that would be most successful for changing self-stigma in those with mental illness.”
The researchers concluded: “In the broader context, mental illness stigma and prejudice negatively affects thousands of people each year, leading to reluctance to seek treatment, ostracism, job discrimination, and other negative outcomes. In order to prevent stigma or aid those already suffering from it, it is immensely important to understand its origins from every angle.”
