Having a stress-related psychiatric condition may increase the risk for autoimmune disease, a new study concludes.

Stress is known to cause physiological changes, including changes in immune function, but evidence that links it to specific diseases is limited.

This study, in JAMA, used a Swedish database of 106,464 patients who had a severe stress condition, such as post-traumatic stress disorder, acute stress reaction or adjustment disorder.

After controlling for other risk factors, they found that compared with those who had not had severe stress, those with any stress-related disorder were 36 percent more likely to have an autoimmune disease, and 29 percent more likely than their unstressed siblings. People with a PTSD diagnosis were at especially high risk — they were 46 percent more likely to develop an autoimmune illness.

“Stress really affects long-term health,” said the lead author, Dr. Huan Song, a postdoctoral fellow at the University of Iceland. “It affects not only psychiatric health, but leaves people vulnerable to other diseases. There are many treatments now available for stress-related disorders, and it’s important for people to get treatment early.”