The Relationship Between PTSD and Infectious Diseases

Are we forgetting mental health in our conversations regarding infectious disease? A recent study is sending a reminder to clinicians of the relationship between mental health and infectious disease outcomes.

Post-traumatic stress disorder (PTSD) is one that might have a correlation with increased risk for infections, like urinary tract infections and skin infections. The National Institute of Health (NIH) defines PTSD as occurring following “exposure to a potentially traumatic event that is beyond a typical stressor. Events that may lead to PTSD include, but are not limited to, violent personal assaults, natural or human-caused disasters, accidents, combat, and other forms of violence.” Moreover, the NIH notes that one-half of all American adults will experience a traumatic event in their lives, but most do not develop PTSD. The NIH report reports that in the past year 3.5% of American adults had PTSD, with a higher prevalence observed in women.

A study in Denmark was undertaken to assess if there was a relationship between PTSD and the incidence of infections. This is not the first study that looked to traumatic life experiences as a risk for infections though, as a nationwide study in Sweden found that women who experienced a loss of a family member had an increased risk of sexually transmitted infection, like gonorrhea or chlamydia. Of those women, they found that those who lost a spouse had a higher risk than those who lost a child or sibling, likely due to a change of sex partners.

The investigators assessed 3784 Danish-born residents of Denmark who were diagnosed with PSTD at a psychiatric treatment facility between January 1995 and December 201. Another 1200 people were added to the cohort who had been diagnosed with PTSD, but in a non-psychiatric treatment facility. A matched comparison cohort of Danish-born residents without a PTSD diagnosis was created with a ratio of 5 to 1 as the same size was much larger (n=24,920).

The study team then assess the association between PTSD diagnosis and 28 different types of infection, ranging from urinary tract infections to central nervous system infections and infectious complications of procedures. To analyze this information, they “fit Cox proportional hazards regression models to examine associations between PTSD diagnosis and infections. To account for multiple estimations, we adjusted the hazard ratios (HRs) using semi-Bayes shrinkage. We calculated interaction contrasts to assess the presence of interaction between PTSD diagnosis and sex.”

The investigators found that not only were the majority of PTSD cohort members younger than 60 years and female, but they also had a higher proportion of diagnosis of anxiety disorders and depression. Ultimately, they found that those with PTSD diagnosis were at an increased risk for infections than those without a diagnosis. There were more diagnoses of urinary tract infections in those women with PTSD than those without, while skin infections were more prevalent in men with PTSD diagnoses than women with PTSD diagnosis. The findings related to urinary tract infections was the strongest evidence of a relationship between PTSD diagnosis and risk of infection.

This study is especially unique in that it shows there is a desperate need to better understand the roles and relationships between mental health and infections. Moreover, there were slight associations between PTSD and pneumonia, which is another avenue for analysis. This study points to a very neglected aspect of infectious disease treatment/prevention and patient outreach.