Background: Abnormal thyroid function is prevalent among women and has been linked to increased risk of chronic disease. Posttraumatic stress disorder (PTSD) has been linked to thyroid dysfunction in some studies; however, the results have been inconsistent. Thus, we evaluated trauma exposure and PTSD symptoms in relation to incident thyroid dysfunction in a large longitudinal cohort of civilian women.
Methods: We used data from 45 992 women from the ongoing Nurses' Health Study II, a longitudinal US cohort study that began in 1989. In 2008, history of trauma and PTSD were assessed with the Short Screening Scale for Diagnostic and Statistical Manual of Mental Disorders, fourth edition, PTSD, and incident thyroid dysfunction was determined by participants' self-report in biennial questionnaires of physician-diagnosed hypothyroidism and Graves' hyperthyroidism. The study period was from 1989 to 2013. Proportional hazard models were used to estimate multivariable-adjusted hazard ratios and 95% confidence intervals (CIs) for incident hypothyroidism and Graves' hyperthyroidism.
Results: In multivariable-adjusted models, we found significant associations for PTSD only with hypothyroidism [p-trend <0.001; trauma with no PTSD symptoms, 1.08 (95% CI 1.02-1.15); 1-3 PTSD symptoms, 1.12 (95% CI 1.04-1.21); 4-5 PTSD symptoms, 1.23 (95% CI 1.13-1.34); and 6-7 PTSD symptoms, 1.26 (95% CI 1.14-1.40)]. PTSD was not associated with risk of Graves' hyperthyroidism (p-trend = 0.34). Associations were similar in sensitivity analyses restricted to outcomes with onset after 2008, when PTSD was assessed.
Conclusions: PTSD was associated with higher risk of hypothyroidism in a dose-dependent fashion. Highlighted awareness for thyroid dysfunction may be especially important in women with PTSD.
Keywords: Epidemiology; hypothyroidism; post-traumatic stress disorder; thyroid; trauma.