Increase of serum triiodothyronine concentration in soldiers with combat-related chronic post-traumatic stress disorder with or without alcohol dependence

Summary Background Post-traumatic stress disorder (PTSD) is a relatively new psychiatric disorder with three clusters of symptoms: trauma re-experiencing, avoidance, and increased arousal. The condition develops after a person sees, is involved in, or hears of an extreme traumatic stressor such as war, torture, natural catastrophe, assault, rape, or serious accident. PTSD is also often comorbid with other psychiatric disorders, especially with alcohol dependence. Several hormonal alterations have been reported in veterans with combatrelated PTSD, including elevations in certain thyroid hormones, e.g., total T3; however, previous studies have not controlled for alcohol dependence, a common comorbid psychiatric disorder in this population. Objective The first aim of our study was to assess possible differences in basal serum levels of free triiodothyronine (FT3), total triiodothyronine (TT3), free thyroxine (FT4), total thyroxine (TT4), and thyroid stimulating hormone (TSH) in Croatian soldiers with combat-related chronic PTSD alone or comorbid with alcohol dependence and in healthy controls. The second purpose of the study was to determine any correlation between duration of combat activities, number of combat traumas, intensity and duration of PTSD symptoms, and serum levels of TT3, FT3, TT4, FT4, and TSH in this sample. Method We analyzed basal serum FT3, TT3, FT4, TT4, and TSH concentrations in soldiers with combat-related chronic PTSD (N=43), combat-related chronic PTSD comorbid with alcohol dependence (N=41), and in healthy controls (N=39) using a luminoimmunochemical assay. Results Soldiers with chronic combat-related PTSD with or without comorbid alcohol addiction had significantly higher values of TT3 than the control group (F=19.556, p<0.01). There was a significant correlation between TT3 levels and number of traumatic events in both the PTSD group (r=0.663, p<0.01) and those with PTSD comorbid with alcohol dependence (r=0.836, p<0.01). There was also a significant correlation between TT3 levels and symptoms of increased arousal in both PTSD (r=0.419, p<0.01) and PTSD comorbid with alcohol dependence (r=0.516, p<0.01). Conclusion Elevated concentrations of serum TT3 are associated with combat-related PTSD, regardless of its comorbidity with alcohol dependence, and also with the number of traumatic events and symptoms of increased arousal. Given that current pharmacotherapy for PTSD is inadequate, reduction of TT3 may be a new strategy for pharmacologic intervention that could contribute to more effective treatment of this disorder.