Stress disorders tied to risk for life-threatening infections

People who have stress disorders like PTSD may be more vulnerable to potentially life-threatening infections, especially if they are diagnosed at younger ages or dealing with other psychiatric issues, a recent study suggests.

Researchers examined data on 144,919 people diagnosed with post-traumatic stress disorder (PTSD), adjustment disorders common after a major life change like a death or move, and other stress-related conditions. They also looked at data for 184,612 siblings of these subjects who didn’t have a stress disorder, along with more than 1.4 million unrelated individuals without these disorders.

After an average follow-up of eight years, the annual incidence of life-threatening infections – including infections of the nervous system or heart - was 2.9 in every 1,000 people with stress disorders, compared with 1.7 in every 1,000 siblings and 1.3 in every 1,000 unrelated individuals.

“Severe or prolonged emotional stress causes alterations in multiple bodily functions through dysregulation in the release of stress hormones,” said Dr. Huan Song, lead author of the study and a researcher at the Karolinska Institute in Stockholm.

“The hypothesis behind our research is that a severe reaction to trauma or other life stressors, through these pathways, leads to impaired immune function and thereby susceptibility to infection,” Song said by email.

Previous research has linked stress to an increased risk of acute and respiratory infections, the study authors note in The BMJ. The current analysis, however, focused only on life-threatening infections, including endocarditis caused by infections of the lining of the heart chambers and heart valves, meningitis and other nervous system infections, and infections that lead to sepsis.

During the study, a total of 2,197 people with a history of stress disorders developed life-threatening infections, as did 2,646 of their siblings.

People with stress disorders were 47% more likely to develop infections than those without any history of stress-disorders.

When people with stress disorders took certain antidepressant medications over the first year after their diagnosis, they were 19% less likely to develop life-threatening infections later on, the study also found.

The study wasn’t a controlled experiment designed to prove whether or how stress disorders might increase risk of infections, or to what extent any treatment for stress might alter the infection risk.

One limitation of the analysis is that it relied on outpatient clinic records to identify people with stress disorders, and it’s possible this might have omitted patients with milder cases, the study authors note.

Researchers also lacked data on certain lifestyle habits that can also impact infection risk, like smoking, drinking and illegal drug use.

Even so, the findings add to a large body of evidence linking PTSD and other stress-related mental health problems to an increased risk of poor physical health, Jonathan Bisson of Cardiff University School of Medicine in the UK writes in an editorial accompanying the study.

“The main message to patients suffering from severe emotional reactions after trauma or other life stressors is it is important to seek treatment or timely medical care,” Song said.