The association between endogenous testosterone level and behavioral flexibility in young men - Evidence from stimulus-outcome reversal learning

Testosterone, oxytocin and co-operation: A hypothesis for the origin and function of music

Since the time of Darwin, theories have been proposed on the origin and functions of music; however, the subject remains enigmatic. The literature shows that music is closely related to important human behaviours and abilities, namely, cognition, emotion, reward and sociality (co-operation, entrainment, empathy and altruism). Notably, studies have deduced that these behaviours are closely related to testosterone (T) and oxytocin (OXT). The association of music with important human behaviours and neurochemicals is closely related to the understanding of reproductive and social behaviours being unclear. In this paper, we describe the endocrinological functions of human social and musical behaviour and demonstrate its relationship to T and OXT. We then hypothesised that the emergence of music is associated with behavioural adaptations and emerged as humans socialised to ensure survival. Moreover, the proximal factor in the emergence of music is behavioural control (social tolerance) through the regulation of T and OXT, and the ultimate factor is group survival through co-operation. The "survival value" of music has rarely been approached from the perspective of musical behavioural endocrinology. This paper provides a new perspective on the origin and functions of music.

Effect of estradiol on cognition in men undergoing androgen deprivation therapy: A randomized placebo-controlled trial

OBJECTIVE

Roles for estradiol in modulating cognition in men remain uncertain. We assessed the isolated effects of estradiol on cognition in men in the absence of testosterone.

DESIGN

Randomized trial of transdermal estradiol 0.9 mg daily, or matched placebo, for 6 months, hypothesizing that estradiol would improve verbal learning, verbal memory, and spatial problem solving over time.

PATIENTS

Men receiving androgen deprivation therapy (ADT) for prostate cancer.

MEASUREMENTS

Cognition was assessed by a tablet-based cognitive battery (Cogstate) at baseline, Month 1, Month 3, and Month 6. Anxiety and depression symptoms were assessed using the Hospital Anxiety and Depression Scale.

RESULTS

Seventy-eight participants were randomized. Baseline mean scores were 21.0 (standard deviation [SD] 4.1) for the International Shopping List test (ISL), assessing verbal learning and memory (higher scores better), and 60.4 (SD 19.5) for the Groton Maze Learning test (GML), assessing spatial problem solving (lower scores better). There was no significant difference in performance over time for the estradiol group versus the placebo group for the ISL, mean adjusted difference (MAD) 0.7 (95% confidence interval [CI] -1.2 to 2.5), p = .36, or the GML, MAD -3.2 (95% CI -12.0 to 5.6), p = 0.53. There was no significant difference between groups over time in performance in any other cognitive domain, or on depression or anxiety scores.

CONCLUSIONS

We found no major effects of estradiol on cognition in men with castrate testosterone concentrations. Although the cognitive effects of ADT are debated, this study suggests that any such effects are unlikely to be prevented by the administration of estradiol.

Androgen synthesis inhibition increases behavioural flexibility and mPFC tyrosine hydroxylase in gonadectomized male rats

Behavioural flexibility is essential to adapt to a changing environment and depends on the medial prefrontal cortex (mPFC). Testosterone administration decreases behavioural flexibility. It is well known that testosterone is produced in the gonads, but testosterone is also produced in the brain, including the mPFC and other nodes of the mesocorticolimbic system. It is unclear how testosterone produced in the brain versus the gonads influences behavioural flexibility. Here, in adult male rats, we assessed the effects of the androgen synthesis inhibitor abiraterone acetate (ABI) and long-term gonadectomy (GDX) on behavioural flexibility in two paradigms. In Experiment 1, ABI but not GDX reduced the number of errors to criterion and perseverative errors in a strategy set-shifting task. In Experiment 2, with a separate cohort of rats, ABI but not GDX reduced perseverative errors in a reversal learning task. In Experiment 1, we also examined tyrosine hydroxylase immunoreactivity (TH-ir), and ABI but not GDX increased TH-ir in the mPFC. Our findings suggest that neurally-produced androgens modulate behavioural flexibility via modification of dopamine signalling in the mesocorticolimbic system. These results indicate that neurosteroids regulate executive functions and that ABI treatment for prostate cancer might affect cognition.

Exogenous Testosterone Increases Decoy Effect in Healthy Males

There is increasing interest in the role played by testosterone in economic decision-making and social cognition. However, despite the growing body of findings in this field of research, no empirical study to date has tested whether testosterone modulates decision-making when an asymmetrically dominated decoy option is introduced in a choice set. Within a choice set that comprises two options, an asymmetrically dominated decoy option is a third option that, when introduced in the choice set, is much worse than one of the existing options, but comparable to the other existing option. Introduction of a decoy option leads to a preference toward the dominating option (i.e., decoy effect). Healthy male participants (n = 63) received a single-dose of 150 mg testosterone gel in a double-blind, placebo-controlled, between-subjects design. At 180 min post-administration, participants took part in a decision-making task to elicit decoy effect. Results showed that participants in the testosterone group made less consistent choices and more target choices (i.e., decoy effect) than participants in the placebo group. These findings are interpreted in light of the dual-process theory and are in line with existing evidence suggesting that testosterone promotes more intuitive and automatic judgments in human decision-making.