53 Endogenous testosterone levels are predictive of symptom reduction with exposure therapy in social anxiety disorder showed that stronger reductions in symptom severity were related to lower baseline testosterone levels (see Figure 3.2B for an illustration of this effect). The fact that the baseline testosterone levels predicted symptom severity reduction, but in the direction opposite from what we predicted may suggest that it is the relative dynamics of the HPG-axis system rather than the absolute testosterone levels in the system that are important for exposure therapy success. In order to test this further, we additionally checked whether effects for reactive testosterone would disappear without controlling for the initial testosterone levels (thus subtracting testosterone sample 1 from sample 3, without controlling for the initial levels at sample 1) and found that this was the case (Estimate = -2.79(2.12), F(1,66) = 1.73, p = 0.19). This finding suggests that it is the relative and not the absolute reactivity of the HPA-axis system that positively relates to treatment outcome. Discussion In this proof-of-concept study, we demonstrated that reactivity of the HPG-axis constitutes a promising biomarker of response to exposure therapy in social anxiety disorder. Specifically, we showed that those patients who displayed relatively high pre-exposure testosterone reactivity (e.g., rises in testosterone in anticipation of a challenging situation) showed better outcomes following a standardized session of exposure therapy. The finding that low pre-treatment baseline testosterone levels were also associated with better outcome was unexpected and may suggest that the relative reactivity of the HPG-axis contributed to the success of the exposure session, rather than the absolute testosterone levels in the system. This interpretation was further supported by the finding that outcomes were specific for relative reactivity (baseline controlled) and not the absolute reactivity (absolute increase) of the HPG-axis to the treatment-preparation session. Together, these findings support the social challenge hypothesis (Wingfield et al., 1990), which posits that rises in testosterone in preparation to a challenging encounter lead to approach behavior and corresponding reductions in anxiety (Archer, 2006; Bos, Panksepp, et al., 2012). We hope that this early work stimulates further research in this area that has the potential to facilitate the goal of improving exposure therapy outcomes for SAD. One important follow-up to the current study is the testing of the putative pathway for the observed relation. We did not index approach behavior in the current study. Establishing increased approach behavior during exposure therapy as a behavioral consequence of pre-treatment testosterone reactivity and understanding the nature of the relations be3
RkJQdWJsaXNoZXIy MTk4NDMw