Women with post-traumatic stress disorder are at increased risk to developing rheumatoid arthritis, whether or not they smoke, according to a study recently published in the journal Arthritis Care & Research.
Post-traumatic stress disorder (PTSD) is a condition that may develop after someone is exposed to one or more traumatic events. PTSD is characterized by intrusive memories of the event, increased arousal, avoidance of experiences associated with the traumatic event, and loss of interest in activities and relationships.
The role of PTSD in the risk for autoimmune diseases has garnered particular interest because several studies implicate stress in the pathogenesis of autoimmune diseases.
To examine the association between symptoms of PTSD and risk of rheumatoid arthritis and to characterize the role of smoking, researchers in the study titled “In Post-Traumatic Stress Disorder and Risk for Incident Rheumatoid Arthritis” studied 49,693 women enrolled in the Nurses’ Health Study II, an ongoing cohort study of 116,430 female nurses ages 25 to 42 years at enrollment in 1989.
The participants were asked to complete questionnaires about lifestyle, health practices, and health conditions at baseline and every two years thereafter. Study participants completed the Brief Trauma Questionnaire and a PTSD screener to identify whether and when trauma and PTSD symptoms may have occurred. Importantly, study subjects did not have rheumatoid arthritis or systemic lupus erythematosus at baseline.
The incidence of smoking was higher among participants who had PTSD symptoms, with a prevalence of 8 percent among women with four or more PTSD symptoms compared to 5.6 percent among women with fewer than four symptoms.
Women with four or more PTSD symptoms were also more likely to report more than 10 pack-years of smoking (22.1 percent) compared to women with fewer PTSD symptoms (16.1 percent).
The results further revealed that compared to no history of trauma/PTSD symptoms, the hazards ratio (HR) for more than four PTSD symptoms and incident rheumatoid arthritis was 1.76 in models adjusted for age, race, and socioeconomic status.
Importantly, the risk to develop rheumatoid arthritis increased with more symptoms of PTSD. When smoking was added to this model, the HR for rheumatoid arthritis remained elevated (HR 1.60). Results from a subgroup analysis, excluding women who smoked before PTSD onset, were basically unchanged (HR 1.68).
These results indicate that women with high PTSD symptomatology have an elevated risk for rheumatoid arthritis, independent of smoking; however, the mechanisms behind this association remain unclear.
“Further studies are necessary to examine the role of other behaviors and clinical characteristics, such as alcohol consumption and obesity, as potential confounders and/or mediators of the association between PTSD and risk for rheumatoid arthritis,” the authors concluded in their study. “In addition, assessments of serum and salivary cortisol levels, to characterize basal HPA axis activity and the stress response, are needed to investigate biologic pathways linking PTSD with an increased risk for RA,” the authors wrote.