A Bayesian Modelling Approach to Examine the Role of Testosterone Administration on the Endowment Effect and Risk-Taking

We investigated the effects of testosterone administration on aspects of decision-making within the Prospect Theory framework. Using bayesian modeling, we assessed risk-taking under framing and Endowment Effect (effect of possession). We administered 100mg testosterone to forty men in a double-blind placebo-controlled fully-randomized cross-over experiment where they participated in two tasks. One was a risktaking task with binary choices under positive and negative framing with different probabilities. In a second task, participants had to bid for for two categories of items, hedonic and utilitarian. We observed a significant increase in serum testosterone concentrations after transdermal application. Compared to placebo, testosterone administration increased risk-taking under the positive framing and decreased under the negative framing. The sensitivity to gain was positive in each framing. Our model showed that decision-making is jointly influenced by testosterone and the trade-off between gains and losses. Moreover, while the endowment effect was more pronounced for hedonic than for utilitarian items, the effect was independent of testosterone. The findings provide novel information for the complex modulatory role of testosterone on risk-taking. The proposed models of effects of individual differences in testosterone on risk-taking could be used as predictive models.

Does Testosterone Administration Increase Competitiveness, Confidence and Financial Risk-taking in Men?

The sex steroid hormone testosterone regulates male-typical behaviors such as aggression and displays of dominance in non-human animals. According to the Challenge Hypothesis, these effects arise from context-sensitive testosterone increases that facilitate inter-male competitions over resources, status, and mates. A growing literature documents similar effects of testosterone on economic behaviors related to competition and risk-taking in humans, though findings to date have been mixed. Here, we report two randomized double-blind placebo-controlled testosterone administration experiments, whose combined sample (N = 334) is substantially larger than any previous investigation of the topic (N1 = 91, N2 = 243). The studies were designed independently by research groups in Europe and the US, and both investigated testosterone’s effects on men’s willingness to compete, confidence, and risk-taking—dimensions of economic behavior that are theoretically linked to the Challenge Hypothesis, show robust sex differences, and predict important real-life outcomes such as career choice. We find no evidence for effects of testosterone on any of the behavioral tasks studied across the two experiments, with effect point estimates that are small and inconsistent. The studies had 90% statistical power to detect effects that are larger than d = 0.68 and d = 0.42 respectively, and equivalence tests confidently reject effects that are greater than these magnitudes. Our findings cast doubt on the proposition that testosterone is a meaningful causal driver of the stereotypically “masculine” dimensions of economic behavior studied, and suggest that even if true effects existed, detecting them experimentally would be challenging.

The enhancing effects of testosterone in exposure treatment for social anxiety disorder: a randomized proof-of-concept trial

Individuals with a social anxiety disorder (SAD) show hypofunctioning of the hypothalamus–pituitary-gonadal (HPG) axis, which is linked to social fear and avoidance behavior. As testosterone administration has been shown to facilitate social-approach behavior in this population, it may enhance the effectiveness of exposure treatment. In this proof-of-concept study, we performed a randomized clinical assay in which 55 women diagnosed with SAD received two exposure therapy sessions. Session 1 was supplemented with either testosterone (0.50 mg) or placebo. Next, transfer effects of testosterone augmentation on within-session subjective fear responses and SAD symptom severity were assessed during a second, unenhanced exposure session (session 2) and at a 1-month follow-up, respectively. The participants having received testosterone showed a more reactive fear pattern, with higher peaks and steeper reductions in fear levels in session 2. Post-hoc exploration of moderating effects of endogenous testosterone levels, revealed that this pattern was specific for women with high basal testosterone, both in the augmented and in the transfer session. In contrast, the participants with low endogenous testosterone showed reduced peak fear levels throughout session 1, again with transfer to the unenhanced session. Testosterone did not significantly affect self-reported anxiety. The effects of testosterone supplementation on fear levels show transfer to non-enhanced exposure, with effects being modulated by endogenous testosterone. These first preliminary results indicate that testosterone may act on important fear mechanisms during exposure, providing the empirical groundwork for further exploration of multi-session testosterone-enhanced exposure treatment for SAD.

457 The Impact of PAP Therapy on Hematocrit in OSA and Polycythemia: A Pilot Study

Introduction Untreated polycythemia leads to complications including thrombosis. Obstructive sleep apnea (OSA) is commonly associated with secondary erythrocytosis, which testosterone therapy can perpetuate. Effects of positive airway pressure (PAP) on elevated hematocrit (HCT) is unknown. We hypothesize PAP adherence can reduce HCT in men with OSA and polycythemia. Methods Retrospective chart review of male outpatients with newly diagnosed OSA and HCT≥45% at or 3 months before polysomnography (PSG) was conducted. Intervention group consisted of patients initiating PAP for OSA. HCT within 6 months of PAP initiation and PSG were recorded for intervention and control groups, respectively. Primary endpoint was time-to-HCT reduction of HCT<50% plus 3% decrease. Cox proportional-hazards analysis was used to assess time-to-HCT response. Demographics, smoking history, testosterone administration, STOP-Bang score, AHI, and PAP compliance data were obtained. Patients excluded if PAP not indicated, or if PSG, PAP compliance, or repeat HCT were unavailable. Results 41 men with OSA had HCT≥45%, of which 16 had HCT≥50%. Median age was 60 years and median BMI was 32 kg/m2. 28 started PAP. 21 met definition for PAP compliance within 6 months. Median AHI of intervention and control groups were 23 and 19 events/hr, respectively. Mean baseline HCT of both groups were 49 and 50, respectively. No significant difference in age, BMI, smoking history, testosterone therapy, and baseline HCT between both groups noted. 39% of intervention group exhibited HCT response at 1 or more longitudinal assessments, versus 38% of control. Intervention group had higher mean STOP-Bang than control (mean 5.9 vs. 4.6, p=0.01) and trended towards higher mean baseline AHI (27.4 vs. 19.0, p= 0.06). Time-to-event analysis controlling for STOP-Bang and AHI demonstrated PAP was not associated with time-to-HCT response (HR = 1.3, 95% CI = 0.4–4.4). In moderate-severe OSA patients, 40% of intervention group had HCT response compared to 14% of control, though difference was not significant (HR = 2.5, 95% CI = 0.3–20.0). Conclusion Moderate-severe OSA patients trended towards reduction in HCT with PAP, although not statistically significant. Testosterone administration did not affect HCT response to PAP in this cohort. Larger studies are required to determine HCT response to PAP in these patients. Support (if any):