Thyroid hormones, interpersonal violence and personality traits : clinical studies in high-risk psychiatric cohorts

Abstract

Suicidal and violent behaviors as well as early life adversity are prevalent in clinical high-risk populations. Early life adversity is related to developmental dysregulation of behavioral and emotional traits. The neuroendocrine systems involved in the development of dysfunctional behavior and impulsive aggressive traits are not fully known. The overall aim of this thesis was to investigate the relationship between thyroid hormones and personality traits, as well as to exposure to interpersonal violence and violent behavior in two high-risk cohorts of patients with a history of suicide attempts.

In study I we investigated personality traits assessed by the Karolinska Scales of Personalityin relation to peripheral thyroid hormones in 100 euthyroid suicide attempters.

In studies II and III, we studied the relationship between exposure to, and expression of interpersonal violence and adult levels of thyroid and cortisol hormones in 92 clinically euthyroid women with borderline personality disorder (BPD), with at least two prior suicide attempts. The Karolinska Interpersonal Violence Scale was used to assess exposure to, and expression of interpersonal violence. Baseline thyroid function was evaluated by measuring plasma free and bound triiodothyronine (FT3 and T3), thyroxine (FT4 and T4), and thyroidstimulating hormone (TSH) with immunoassays. The FT3/FT4 ratio was used to estimate the peripheral deiodination. Plasma cortisol was also measured.

In study IV we investigated the screening validity of the Karolinska Interpersonal Violence Scale, in predicting post-traumatic stress disorder (PTSD) in 106 women with BPD, with at least two prior suicide attempts.

In study I, we found that in male suicide attempters, the T3/FT4 ratio was negatively correlated to Aggressiveness and positively correlated to Detachment. In study II, 67% of women with BPD reported Medium High or High levels of exposure to interpersonal violence as a child. The FT3/FT4 ratio showed a significant negative correlation with exposure to violence as a child. Patients with PTSD had significantly higher plasma cortisol levels. In study III, the mean expression of interpersonal violence as an adult was significantly higher in BPD patients as compared to healthy controls. Adult expression of interpersonal violence among females with BPD, showed a significant positive correlation with the T3 levels. T3 and comorbid diagnosis of alcohol abuse were independent predictors of adult expression of interpersonal violence. In study IV, the PTSD diagnosis was valid for (58%) women with BPD. The KIVS – exposure of lifetime interpersonal violence, displayed a fair accuracy of predicting diagnosis of PTSD.

Our findings indicate that peripheral thyroid hormones may be associated with early life adversity, adult aggressive traits and interpersonal violence in clinical high-risk psychiatric populations. Karolinska Interpersonal Violence Scale may be used for PTSD screening.