Testosterone increases amygdala reactivity in middle-aged women to a young adulthood level

Efficacy and safety of zuranolone in major depressive disorder: a meta-analysis of factor effect and dose-response analyses

Background

Zuranolone is recognised as a promising antidepressant agent. Our study aimed to investigate the efficacy and safety of zuranolone in treating major depressive disorder (MDD).

Methods

A systematic review was conducted by searching major databases from inception to August 20, 2023 (INPLASY: 202360087). A meta-analysis was performed by using a random-effects model to calculate effect sizes, expressed as standardised mean differences (SMDs) and odds ratios (ORs) with 95% confidence intervals (CIs). The primary outcome was improvement in depressive symptoms, while secondary outcomes included response and remission rates of depression, improvement in anxiety symptoms, incidence of dropouts, and any side effects. We conducted subgroup analyses for general MDD and postpartum-onset MDD and a dose-response meta-analysis to estimate the relationship between zuranolone dose and outcomes.

Findings

The study included seven randomised control trials involving 1789 patients. Zuranolone reduced depressive symptoms (SMD = -0.37, 95% CIs = -0.51 to -0.23), increased response rate (OR = 2.06, 95% CIs = 1.48-2.85) and remission rate (OR = 2.04, 95% CIs = 1.38-3.02), and reduced anxiety symptoms (SMD = -0.26, 95% CIs = -0.39 to -0.14). Furthermore, zuranolone-treated patients experienced more side effects than those in the control group (OR = 1.40, 95% CIs = 1.10-1.78), although dropout rate did not significantly differ between the two groups (OR = 1.13, 95% CIs = 0.85-1.49). According to the dose-response meta-analysis, zuranolone could effectively improve depression and anxiety at increasing doses up to a maximum daily dose of 30 mg; however, side effects increased with doses exceeding 30 mg. Based on subgroup analyses, zuranolone showed greater efficacy in treatment of postpartum-onset MDD than general MDD, but the difference did not reach statistical significance.

Interpretation

Our findings suggested that zuranolone is effective in alleviating depression and anxiety. Nevertheless, there is a potential risk of adverse effects. Given its therapeutic efficacy and risk of side effects, a daily dose of 30 mg appears to be the optimal choice.

Funding

Chang Gung Medical Foundation.

Fronto-amygdala resting state functional connectivity is associated with anxiety symptoms among adolescent girls more advanced in pubertal maturation

Early adolescence, with the onset of puberty, is an important period when sex differences in anxiety emerge, with girls reporting significantly higher anxiety symptoms than boys. This study examined the role of puberty on fronto-amygdala functional connectivity and risk of anxiety symptoms in 70 girls (age 11-13) who completed a resting state fMRI scan, self-report measures of anxiety symptoms and pubertal status, and provided basal testosterone levels (64 girls). Resting state fMRI data were preprocessed using fMRIPrep and connectivity indices were extracted from ventromedial prefrontal cortex (vmPFC) and amygdala regions-of-interest. We tested moderated mediation models and hypothesized that vmPFC-amygdala would mediate the relation between three indices of puberty (testosterone and adrenarcheal/gonadarcheal development) and anxiety, with puberty moderating the relation between connectivity and anxiety. Results showed a significant moderation effect of testosterone and adrenarcheal development in the right amygdala and a rostral/dorsal area of the vmPFC and of gonadarcheal development in the left amygdala and a medial area of the vmPFC on anxiety symptoms. Simple slope analyses showed that vmPFC-amygdala connectivity was negatively associated with anxiety only in girls more advanced in puberty suggesting that sensitivity to the effects of puberty on fronto-amygdala function could contribute to risk for anxiety disorders among adolescent girls.

Associations of Bioavailable Serum Testosterone With Cognitive Function in Older Men: Results From the National Health and Nutrition Examination Survey

BACKGROUND

Age-associated cognitive decline may be influenced by testosterone status. However, studies evaluating the impact of bioavailable testosterone, the active, free testosterone, on cognitive function are scarce. Our study determined the relationship between calculated bioavailable testosterone and cognitive performance in older men.

METHODS

We used data from the U.S. National Health and Nutrition Examination Survey (NHANES) between 2013 and 2014. This study consisted of 208 men aged ≥60 years. Bioavailable serum testosterone was calculated based on the total serum testosterone, sex hormone-binding globulin, and albumin levels, whereas cognitive performance was assessed through the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word List Learning Test (WLLT), Word List Recall Test (WLRT), and Intrusion Word Count Test (WLLT-IC and WLRT-IC), the Animal Fluency Test (AFT), and the Digit Symbol Substitution Test (DSST). Multiple linear regression analyses were performed upon adjustment for age, ethnicity, socioeconomic status, education level, medical history, body mass index, energy, alcohol intake, physical activity levels, and sleep duration.

RESULTS

A significant positive association between bioavailable testosterone and DSST (β: 0.049, p = .002) score was detected, with no signs of a plateau effect. No significant associations with CERAD WLLT (p = .132), WLRT (p = .643), WLLT-IC (p = .979), and WLRT-IC (p = .387), and AFT (p = .057) were observed.

CONCLUSION

Calculated bioavailable testosterone presented a significant positive association with processing speed, sustained attention, and working memory in older men above 60 years of age. Further research is warranted to elucidate the impact of the inevitable age-related decline in testosterone on cognitive function in older men.

Regulation of sex differences in risk-based decision making by gonadal hormones: Insights from rodent models

Men and women differ in their ability to evaluate options that vary in their rewards and the risks that are associated with these outcomes. Most studies have shown that women are more risk averse than men and that gonadal hormones significantly contribute to this sex difference. Gonadal hormones can influence risk-based decision making (i.e., risk taking) by modulating the neurobiological substrates underlying this cognitive process. Indeed, estradiol, progesterone and testosterone modulate activity in the prefrontal cortex, amygdala and nucleus accumbens associated with reward and risk-related information. The use of animal models of decision making has advanced our understanding of the intersection between the behavioral, neural and hormonal mechanisms underlying sex differences in risk taking. This review will outline the current state of this literature, identify the current gaps in knowledge and suggest the neurobiological mechanisms by which hormones regulate risky decision making. Collectively, this knowledge can be used to understand the potential consequences of significant hormonal changes, whether endogenously or exogenously induced, on risk-based decision making as well as the neuroendocrinological basis of neuropsychiatric diseases that are characterized by impaired risk taking, such as substance use disorder and schizophrenia.

A Systematic Review of the Role of Oxytocin, Cortisol, and Testosterone in Facial Emotional Processing

A topic of interest is the way decoding and interpreting facial emotional expressions can lead to mutual understanding. Facial emotional expression is a basic source of information that guarantees the functioning of other higher cognitive processes (e.g., empathy, cooperativity, prosociality, or decision-making, among others). In this regard, hormones such as oxytocin, cortisol, and/or testosterone have been found to be important in modifying facial emotion processing. In fact, brain structures that participate in facial emotion processing have been shown to be rich in receptors for these hormones. Nonetheless, much of this research has been based on correlational designs. In recent years, a growing number of researchers have tried to carry out controlled laboratory manipulation of these hormones by administering synthetic forms of these hormones. The main objective of this study was to carry out a systematic review of studies that assess whether manipulation of these three hormones effectively promotes significant alterations in facial emotional processing. To carry out this review, PRISMA quality criteria for reviews were followed, using the following digital databases: PsycINFO, PubMed, Dialnet, Psicodoc, Web of Knowledge, and the Cochrane Library, and focusing on manuscripts with a robust research design (e.g., randomized, single- or double-blind, and/or placebo-controlled) to increase the value of this systematic review. An initial identification of 6340 abstracts and retrieval of 910 full texts led to the final inclusion of 101 papers that met all the inclusion criteria. Only about 18% of the manuscripts included reported a direct effect of hormone manipulation. In fact, emotional accuracy seemed to be enhanced after oxytocin increases, but it diminished when cortisol and/or testosterone increased. Nonetheless, when emotional valence and participants' gender were included, hormonal manipulation reached significance (in around 53% of the articles). In fact, these studies offered a heterogeneous pattern in the way these hormones altered speed processing, attention, and memory. This study reinforces the idea that these hormones are important, but not the main modulators of facial emotion processing. As our comprehension of hormonal effects on emotional processing improves, the potential to design good treatments to improve this ability will be greater.

Attractin Participates in Schizophrenia by Affecting Testosterone Levels

Attractin (ATRN) is a widely expressed glycoprotein that is involved in energy homeostasis, neurodevelopment, and immune response. It is encoded by a gene spanning 180 kb on chromosome 20p13, a region previously implicated in schizophrenia by linkage studies. To address a possible role of ATRN in disorders of the central nervous system, we created an atrn knockout zebrafish line and performed behavioral tests. Adult atrn^–/– zebrafish exhibited more pronounced attack behavior relative to wild-type control zebrafish in a tracking analysis. Biochemical analysis revealed elevated testosterone levels in atrn^–/– zebrafish. At the gene expression level, we noted an upregulation of cyp51 and hsd17b7, key proteins in testosterone synthesis in the brains of both adult and larvae of atrn^–/– zebrafish. In order to further elucidate the relationship between testosterone and behavioral syndromes, we then compared testosterone levels of 9,008 psychiatric patients and 247 healthy controls from the same catchment area. Of all subjects examined, male subjects with schizophrenia exhibited lower testosterone levels compared with controls. In contrast, female subjects with a diagnosis of schizophrenia or bipolar disorder featured higher testosterone levels than did same sex controls. Purposeful sampling of extreme groups showed reduced ATRN expression in a subset of these subjects. Finally, we identified 14 subjects with ATRN mutations. All of whom displayed abnormal testosterone levels. In summary, the interplay of ATRN and testosterone may help to explain sexual dimorphisms in selected behavioral phenotypes.

Development of a single-dose intranasal testosterone administration paradigm for use in men and women

For over two decades, researchers in the field of human social neuroendocrinology have been using single-dose pharmacological challenge protocols to determine the causal effects of testosterone on psychological, behavioural, and neural processes. Most of these single-dose administration studies have so far used (1) single-sex samples and (2) varying modes of testosterone administration (intramuscular, transdermal, sublingual, and intranasal) that produced vastly different dose-response curves. Moreover, whereas studies with male participants increased men's testosterone concentrations within the high normal physiological range, studies with women typically increased testosterone concentrations to supraphysiological levels. The purpose of this study was to develop a single-dose administration protocol using intranasal testosterone that would produce a proportionally similar rise in testosterone for both sexes. We found that an 11 mg intranasal testosterone dose in men and a 0.3 mg dose in women raised testosterone concentrations to the high normal physiological range for each sex, producing similar dose-response dynamics in both sexes. This paradigm will allow researchers to design studies with mixed-sex samples that test physiologically plausible sex differences/similarities in the causal effects of testosterone. It will also provide a replicable protocol to examine the possible adaptive functions of acute increases in testosterone in both sexes.

Testosterone treatment, internalizing symptoms, and body image dissatisfaction in transgender boys

OBJECTIVE

Many transgender adolescents experience clinically elevated anxiety and depression. Testosterone (T), used as a gender affirming treatment, may reduce symptoms of anxiety and depression. We assessed the effect of gender affirming T treatment on internalizing symptoms, body image dissatisfaction, and activation patterns within the amygdala-prefrontal cortex circuit in transgender adolescent boys.

METHOD

Symptoms of generalized anxiety, social anxiety, depression, suicidality and body image dissatisfaction were measured by self-report and brain activation was measured during a face processing task with functional MRI in a group of 19 adolescent transgender boys receiving T treatment and 23 not receiving gonadal hormone treatment (UT).

RESULTS

Severity of anxiety and depression was significantly lower in the T treated group relative to the UT group, along with a trend of lower suicidality. The T group also reported less distress with body features and exhibited stronger connectivity within the amygdala-prefrontal cortex circuit compared to the UT group. Finally, group differences on depression and suicidality were directly associated with body image dissatisfaction, and anxiety symptoms were moderated by amygdala-prefrontal cortex connectivity differences between groups.

CONCLUSION

T treatment is associated with lower levels of internalizing symptoms among transgender adolescent boys. T is also associated with greater body satisfaction and greater connectivity in a neural circuit associated with anxiety and depression. Satisfaction with body image was found to overlap with the association between T and both depression and suicidality, and amygdala-prefrontal co-activation moderated the role of T on anxiety.

Effects of testosterone administration on fMRI responses to executive function, aggressive behavior, and emotion processing tasks during severe exercise- and diet-induced energy deficit

BACKGROUND

Clinical administration of testosterone is widely used due to a variety of claimed physical and cognitive benefits. Testosterone administration is associated with enhanced brain and cognitive function, as well as mood, in energy-balanced males, although such relationships are controversial. However, the effects of testosterone administration on the brains of energy-deficient males, whose testosterone concentrations are likely to be well below normal, have not been investigated.

METHODS

This study collected functional magnetic resonance imaging (fMRI) data from 50 non-obese young men before (PRE) and shortly after (POST) 28 days of severe exercise-and-diet-induced energy deficit during which testosterone (200 mg testosterone enanthate per week in sesame oil, TEST) or placebo (sesame seed oil only, PLA) were administered. Scans were also collected after a post-energy-deficit weight regain period (REC). Participants completed five fMRI tasks that assessed aspects of: 1) executive function (Attention Network Task or ANT; Multi-Source Interference Task or MSIT; AXE Continuous Processing Task or AXCPT); 2) aggressive behavior (Provoked Aggression Task or AGG); and 3) latent emotion processing (Emotional Face Processing or EMO).

RESULTS

Changes over time in task-related fMRI activation in a priori defined task-critical brain regions during performance of 2 out of 5 tasks were significantly different between TEST and PLA, with TEST showing greater levels of activation during ANT in the right anterior cingulate gyrus at POST and during MSIT in several brain regions at REC. Changes over time in objective task performance were not statistically significant; testosterone-treated volunteers had greater self-reported anger during AGG at POST.

CONCLUSIONS

Testosterone administration can alter some aspects of brain function during severe energy deficit and increase levels of anger.

Single dose testosterone administration modulates the temporal dynamics of distractor processing

Some evidence suggests that testosterone can increase attentional orientation toward biologically relevant stimuli and increase sustained attention during goal-oriented behaviors. While rare irregular distractors often capture attention involuntarily and distract us away from the task at hand, we hypothesized that testosterone might (1) facilitate attentional orientation to novel distractors that are of potential behavioral relevance and (2) inhibit information processing of distractors that are irrelevant to the task. To test this hypothesis, we investigated the effects of testosterone on distractor processing in a novelty oddball task, during which infrequent target and distractor sounds were interspersed within a series of frequent non-target sounds. Using a double-blind, placebo-controlled within-participant design, we administered a single dose of either testosterone or placebo to 34 healthy male volunteers and compared their electroencephalographic responses to distractors. Increased amplitude of the early (260-310 ms) P3 component-which has been associated with phasic arousal and alertness triggered by novel stimuli-was observed in the testosterone session than in the placebo session. This early-P3 response mediated the effect of testosterone administration on target hit rate during the task. In addition, less α-oscillation suppression-which has been associated with the inhibition of task-irrelevant information processing-was observed in response to distractors later (538-757 ms) in the testosterone session than in the placebo session. These results suggest that testosterone facilitated phasic arousal to novel distractors during the early-latency stage, which might have influenced behavioral performance during the task. Furthermore, testosterone inhibited task-irrelevant information processing during the late-latency stage, which allowed better reorientation of attention back to the primary task. Our findings highlight the role of testosterone in distractor processing, and provide a theoretical basis for treating attention-related behavioral disorders with hormone therapies.

Sex hormones and human brain function

Sex hormones have organizational and activational effects on the human brain and can interact with the neurotransmitter systems. These biologic mechanisms may have a far-reaching impact, with both behavioral consequences and structural as well as functional brain modulation. The impact of cycling hormone levels throughout the menstrual cycle on cognitive and emotion processing has especially received some attention recently. Therefore, the aim of this chapter is to give an overview of findings regarding the effects of estradiol and progesterone, but also testosterone, on functional brain domains comprising cognition, emotion, and reward processing.

Testosterone reactivity to competition and competitive endurance in men and women

Transient shifts in testosterone occur during competition and are thought to positively influence dominance behavior aimed at enhancing social status. However, individual differences in testosterone reactivity to status contests have not been well-studied in relation to real-time expressions of competitive behavior among men and women. This research tests the association between changes in endogenous testosterone levels during competition and performance in terms of competitive endurance. Participant sex, social presence, and relative status outcomes (e.g., winning vs. losing) are tested as moderators of this relationship. In two studies, men and women (total N = 398) competed in the competitive will task (timed weight-holding) either individually or in the presence of an opponent (Study 1) or as a team with and without the presence of a competitor team (Study 2). Results showed a positive relationship between testosterone reactivity and performance for men, particularly those who won or ranked highest among their group - with increasing testosterone predicting better performance and decreasing testosterone predicting worse performance. For women, the effect only emerged among individuals who competed in dyads and lost. In Study 2, an exploratory mediation analysis revealed that individual differences in trait dominance predicted both testosterone reactivity to competition and task performance, with testosterone reactivity (moderated by sex and status outcome) partially explaining the direct relationship between dominance-related traits and behavior. Our goal was to examine testosterone reactivity in relation to real-time competitive effort and highlight the potential role of this relationship in explaining how individual differences in trait dominance produce competitive behavior.

Testosterone administration in human social neuroendocrinology: Past, present, and future

Over the past 20 years, social neuroendocrinology researchers have developed pharmacological challenge paradigms to assess the extent to which testosterone plays a causal role in human psychological and behavioural processes. The current paper provides a brief summary of this research and offers recommendations for future research examining the neuroendocrine mechanisms underlying human behaviour.

Nervous and Endocrine System Dysfunction in Posttraumatic Stress Disorder: An Overview and Consideration of Sex as a Biological Variable

Decades of research into the biological mechanisms of posttraumatic stress disorder (PTSD) suggests that chronic activation of the stress response leads to long-lasting changes in the structure and function of the nervous and endocrine systems. While the prevalence of PTSD is twice as high in females as males, little is known about how sex differences in neuroendocrine systems may contribute to PTSD. In response to the paucity of research on sex-related mechanisms, the National Institutes of Health created a policy that asks researchers to consider sex as a biological variable. This review provides an overview of the current understanding of nervous and endocrine dysfunction in PTSD (e.g., neural circuitry, autonomic arousal, hormonal response), highlighting areas where the influence of sex has been characterized and where further research is needed. We also provide recommendations for using the sex-as-a-biological-variable policy to address specific gaps in PTSD neuroscience research.

Effects of Oral Contraceptive Androgenicity on Visuospatial and Social-Emotional Cognition: A Prospective Observational Trial

Oral contraceptives (OCs) containing estrogen and progesterone analogues are widely used amongst reproductive-aged women, but their neurocognitive impact is poorly understood. Preliminary studies suggest that OCs improve verbal memory and that OCs with greater androgenic activity may improve visuospatial ability. We sought to explore the cognitive impact of OCs by assessing performance of OC users at different stages of the OC cycle, and comparing this performance between users of different OC formulations according to known androgenic activity. We conducted a prospective, observational trial of OC users, evaluating cognitive performance with CogState software on two occasions: days 7-10 of active hormonal pill phase, and days 3-5 of the inactive pill phase (coinciding with the withdrawal bleed resembling menstruation). Thirty-five OC users (18 taking androgenic formulations, 17 taking anti-androgenic) were assessed. Analysis by androgenic activity showed superior performance by users of androgenic OCs, as compared to anti-androgenic OCs, in visuospatial ability and facial affect discrimination tasks. A growing understanding of cognitive effects of OC progestin androgenicity may have implications in choice of OC formulation for individuals and in future OC development.

Testosterone effects on functional amygdala lateralization: A study in adolescent transgender boys and cisgender boys and girls

The influence of testosterone on the development of human brain lateralization has been subject of debate for a long time, partly because studies investigating this are necessarily mostly correlational. In the present study we used a quasi-experimental approach by assessing functional brain lateralization in trans boys (female sex assigned at birth, diagnosed with Gender Dysphoria, n = 21) before and after testosterone treatment, and compared these results to the functional lateralization of age-matched control groups of cisgender boys (n = 20) and girls (n = 21) around 16 years of age. The lateralization index of the amygdala was determined with functional magnetic resonance imaging (fMRI) during an emotional face matching task with angry and fearful faces, as the literature indicates that boys show more activation in the right amygdala than girls during the perception of emotional faces. As expected, the lateralization index in trans boys shifted towards the right amygdala after testosterone treatment, and the cumulative dose of testosterone treatment correlated significantly with amygdala lateralization after treatment. However, we did not find any significant group differences in lateralization and endogenous testosterone concentrations predicted rightward amygdala lateralization only in the cis boys, but not in cis girls or trans boys. These inconsistencies may be due to sex differences in sensitivity to testosterone or its metabolites, which would be a worthwhile course for future studies.

Anxiety in transition: Neuroendocrine mechanisms supporting the development of anxiety pathology in adolescence and young adulthood

Adolescence marks a key developmental window during which emotion dysregulation increases, along with risk for the onset of anxiety and other affect-related pathologies. Although emotion dysregulation and related pathologies normatively decline during the transition into adulthood, this does not occur for a sizable minority of individuals. Finally, sex differences in anxiety emerge during adolescence, with females developing a 2-fold increase in risk relative to males. Unfortunately, a neurobiological model of the mechanisms that cause these changes during adolescence has yet to be proposed. In the present work, we first provide brief reviews of relevant literature. Next, we outline a dual-mechanism model focused on (i) the influence of pubertal testosterone on key emotion-regulation circuitry (i.e., orbitofrontal cortex-amygdala coupling) and (ii) myelination of the fiber bundles connecting such circuitry (i.e., uncinate fasciculus). The proposed model offers a set of specific, testable hypotheses that will hopefully spur much needed cross-disciplinary research.

Increased neural reactivity to emotional pictures in men with high hair testosterone concentrations

Testosterone has been linked to alterations in the activity of emotion neurocircuitry including amygdala, orbitofrontal cortex (OFC) and insula and diminished functional amygdala/prefrontal coupling. Such associations have only ever been studied using acute measures of testosterone, thus little is known about respective relationships with long-term testosterone secretion. Here, we examine associations between hair testosterone concentration (HTC), an index of long-term cumulative testosterone levels and neural reactivity during an emotional passive viewing task using functional magnetic resonance imaging (fMRI). Forty-six men viewed negative, positive and neutral pictures in the MRI. HTCs were assessed from 2 cm hair segments. The emotional paradigm elicited neural activation in the amygdala, insula and OFC. HTCs were associated with increased reactivity to negative pictures in the insula and increased reactivity to positive pictures in the OFC. We show an association of long-term testosterone levels with increased emotional reactivity in the brain. These results suggest a heightened emotional vigilance in individuals with high trait testosterone levels.

Prospective associations of androgens and sex hormone-binding globulin with 12-month, lifetime and incident anxiety and depressive disorders in men and women from the general population

BACKGROUND

Findings on associations of androgens and sex hormone-binding globulin (SHBG) with anxiety and depressive disorders in the general population remain inconclusive.

METHODS

We used data of n = 993 men and n = 980 women from the Study of Health in Pomerania (SHIP, a prospective-longitudinal general population study from northeastern Germany). Immunoassay-measured serum concentrations of total testosterone, androstenedione and SHBG were assessed when participants were aged 20-80. 12-month, lifetime and incident DSM-IV anxiety and depressive disorders were assessed with the DIA-X/M-CIDI at 10-year follow-up, when participants were aged 29-89. Logistic regressions were adjusted for age, smoking, alcohol consumption, physical activity, waist circumference, hypertension and oral contraceptive use (women only) at baseline and follow-up interval.

RESULTS

In men and women, androgens and SHBG were not associated significantly with incident anxiety and depressive disorders. In men, higher total testosterone predicted any 12-month (OR = 1.46) and lifetime (OR = 1.34) anxiety disorder, lifetime social phobia (OR = 2.15), and 12-month (OR = 1.48) and lifetime (OR = 1.39) specific phobia, but neither 12-month nor lifetime depression. Moreover, androstenedione in men interacted with age in predicting lifetime anxiety disorders (OR = 0.98): Higher androstenedione more strongly predicted lifetime anxiety in younger vs. older men. These findings, however, did not survive correction for multiple testing. In women, androgens and SHBG were not associated significantly with 12-month and lifetime anxiety and depressive disorders.

LIMITATIONS

The follow-up period was relatively long and other factors might have affected the examined associations.

CONCLUSIONS

Higher serum total testosterone in men and androstenedione in younger men may relate to an increased risk of anxiety disorders.

Human social neuroendocrinology: Review of the rapid effects of testosterone

Contribution to Special Issue on Fast effects of steroids. It is well documented that testosterone concentrations change rapidly within reproductively relevant contexts (e.g., competition, mate-seeking). It has been argued that such rapid changes in testosterone may serve to adaptively fine-tune ongoing and/or future social behaviour according to one's social environment. In this paper, we review human correlational and experimental evidence suggesting that testosterone fluctuates rapidly in response to competition and mate-seeking cues, and that such acute changes may serve to modulate ongoing and/or future social behaviours (e.g., risk-taking, competitiveness, mate-seeking, and aggression). Some methodological details, which limit interpretation of some of this human work, are also discussed. We conclude with a new integrative model of testosterone secretion and behaviour, the Fitness Model of Testosterone Dynamics. Although we focus primarily on human aggression in this review, we also highlight research on risk-taking, competitiveness, and mate-seeking behaviour.

Sex Hormones and Processing of Facial Expressions of Emotion: A Systematic Literature Review

Background: We systematically reviewed the literature to determine the influence of sex hormones on facial emotion processing (FEP) in healthy women at different phases of life. Methods: Searches were performed in PubMed, Web of Science, PsycINFO, LILACS, and SciELO. Twenty-seven articles were included in the review and allocated into five different categories according to their objectives and sample characteristics (menstrual cycle, oral contraceptives, pregnancy/postpartum, testosterone, and progesterone). Results: Despite the limited number of studies in some categories and the existence of inconsistencies in the results of interest, the findings of the review suggest that FEP may be enhanced during the follicular phase. Studies with women taking oral contraceptives showed reduced recognition accuracy and decreased responsiveness of different brain structures during FEP tasks. Studies with pregnant women and women in the postpartum showed that hormonal changes are associated with alterations in FEP and in brain functioning that could indicate the existence of a hypervigilant state in new and future mothers. Exogenous administration of testosterone enhanced the recognition of threatening facial expressions and the activation of brain structures involved in the processing of emotional stimuli. Conclusions: We conclude that sex hormones affect FEP in women, which may have an impact in adaptive processes of the species and in the onset of mood symptoms associated with the premenstrual syndrome.

Single dose testosterone administration modulates emotional reactivity and counterfactual choice in healthy males

Testosterone has been implicated in the regulation of emotional responses and risky decision-making. However, the causal effect of testosterone upon emotional decision-making, especially in non-social settings, is still unclear. The present study investigated the role of testosterone in counterfactual thinking: regret is an intense negative emotion that arises from comparison of an obtained outcome from a decision against a better, non-obtained (i.e. counterfactual) alternative. Healthy male participants (n = 64) received a single-dose of 150 mg testosterone Androgel in a double-blind, placebo-controlled, between-participants design. At 180 min post-administration, participants performed the counterfactual thinking task. We applied a computational model derived from behavioral economic principles to uncover latent decision-making mechanisms that may be invisible in simple choice analyses. Our data showed that testosterone increased the ability to use anticipated regret to guide choice behavior, while reducing choice based on expected value. On affective ratings, testosterone increased sensitivity to both obtained and counterfactual outcomes. These findings provide evidence that testosterone causally modulates emotional decision-making, and highlight the role of testosterone in affective sensitivity.

Developmental relations between amygdala volume and anxiety traits: Effects of informant, sex, and age

Although substantial human and animal evidence suggests a role for the amygdala in anxiety, literature linking amygdala volume to anxiety symptomatology is inconclusive, with studies finding positive, negative, and null results. Clarifying this brain–behavior relation in middle to late childhood is especially important, as this is a time both of amygdala structural maturation and the emergence of many anxiety disorders. The goal of the current study was to clarify inconsistent findings in previous literature by identifying factors moderating the relation between amygdala volume and anxiety traits in a large sample of typically developing children aged 6–13 years (N = 72). In particular, we investigated the moderating effects of informant (parent vs. child), age, and sex. We found that children's reports (i.e., self-reports) were related to amygdala volume; children who reported higher anxiety levels had smaller amygdalae. This negative relation between amygdala volume and anxiety weakened with age. There was also an independent effect of sex, such that relations were stronger in males than in females. These results indicate the importance of considering sample and informant characteristics when charting the neurobiological mechanisms underlying developmental anxiety.

Sex differences in neural responses to subliminal sad and happy faces in healthy individuals: Implications for depression

Twice as many women as men suffer from mood and anxiety disorders, yet the biological underpinnings of this phenomenon have been understudied and remain unclear. We and others have shown that the hemodynamic response to subliminally presented sad or happy faces during functional MRI (fMRI) is a robust biomarker for the attentional bias toward negative information classically observed in major depression. Here we used fMRI to compare the performance of healthy females (n = 28) and healthy males (n = 28) on a backward masking task using a fast event-related design with gradient-recalled, echoplanar imaging with sensitivity encoding. The image data were compared across groups using a region-of-interest analysis with small-volume correction to control for multiple testing (P_corrected  < 0.05, cluster size ≥ 20 voxels). Notably, compared with males, females showed greater BOLD activity in the subgenual anterior cingulate cortex (sgACC) and the right hippocampus when viewing masked sad vs. masked happy faces. Furthermore, females displayed reduced BOLD activity in the right pregenual ACC and left amygdala when viewing masked happy vs. masked neutral faces. Given that we have previously reported similar findings for depressed participants compared with healthy controls (regardless of gender), our results raise the possibility that on average healthy females show subtle emotional processing biases that conceivably reflect a subgroup of women predisposed to depression. Nevertheless, we note that the differences between males and females were small and derived from region-of-interest rather than voxelwise analyses. © 2016 Wiley Periodicals, Inc.

Functional significance of men's testosterone reactivity to social stimuli

Rapid testosterone fluctuations in response to social stimuli are observed across a wide range of species, and the highly conserved nature of these fluctuations suggests an adaptive function. This paper reviews the current literature on testosterone reactivity, primarily in human males, and illustrates how life-history theory provides an adequate theoretical framework to interpret findings. The review is structured around supporting evidence suggesting that situations implicated in mating effort either directly (e.g., interactions with a mate) or indirectly (e.g., intrasexual competition) are generally associated with a brief elevation of testosterone, while situations implicated in parenting effort (e.g., nurturant interactions with offspring) are generally associated with a decline in testosterone. Further, we discuss how these fluctuations in testosterone have been linked to future behaviors, and how situational, motivational, and physiological variables moderate the interplay between social stimuli, testosterone reactivity, and behavior. Supporting the notion that testosterone can play a causal role in modulating behavior in response to social stimuli, we also summarize recent single administration studies examining the effects of testosterone on physiology, neurobiology, and behavior. A conceptual model provides links between supported findings, and hypothesized pathways requiring future testing.

Conduct problems in youth and the RDoC approach: A developmental, evolutionary-based view

Problems related to aggression in young people are traditionally subsumed under the header of conduct problems, which include conduct disorder and oppositional defiant disorder. Such problems in children and adolescents are an important societal and mental health problem. In this paper we present an evolutionarily informed developmental psychopathology view of conduct problems inspired by the NIMH Research Domain Criteria (RDoC) initiative. We assume that while there are many pathways to conduct problems, chronic or temporary impairments in the domain of social cognition or mentalizing are a common denominator. Specifically, we conceptualize conduct problems as reflecting temporary or chronic difficulties with mentalizing, that is, the capacity to understand the self and others in terms of intentional mental states, leading to a failure to inhibit interpersonal violence through a process of perspective-taking and empathy. These difficulties, in turn, stem from impairments in making use of a normally evolutionarily protected social learning system that functions to facilitate intergenerational knowledge transmission and protect social collaborative processes from impulsive and aggressive action. Temperamental, biological, and social risk factors in different combinations may all contribute to this outcome. This adaptation then interacts with impairments in other domains of functioning, such as in negative and positive valence systems and cognitive systems. This view highlights the importance of a complex interplay among biological, psychological, and environmental factors in understanding the origins of conduct problems. We outline the implications of these views for future research and intervention.

Exogenous Testosterone Rapidly Increases Aggressive Behavior in Dominant and Impulsive Men

BACKGROUND

Although traditional wisdom suggests that baseline levels of testosterone (T) promote aggressive behavior, decades of research have produced findings that have been largely weak and inconsistent. However, more recent experimental work suggests that exogenous administration of T rapidly potentiates amygdala and hypothalamus responses to angry facial expressions. Notably, these brain regions are rich in androgen receptors and play a key role in modulating aggressive behavior in animal models.

METHODS

The present experiment extends this work by examining whether acutely increasing T potentiates aggressive behavior in men. In a double-blind, placebo-controlled, between-subject design, healthy adult men (n = 121) were administered either T or placebo, and subsequently engaged in a well-validated decision-making game that measures aggressive behavior in response to social provocation. In light of prior correlational research, we also assessed the extent to which T's effects on aggressive behavior would depend on variability in trait dominance and/or trait self-control.

RESULTS

Exogenous T on its own did not modulate aggressive behavior. However, T's effects on aggression were strongly influenced by variation in trait dominance and trait self-control. Specifically, T caused an increase in aggressive behavior, but only among men scoring relatively high in trait dominance or low in trait self-control.

CONCLUSIONS

These findings are the first to demonstrate that T can rapidly (within 60 minutes) potentiate aggressive behavior, but only among men with dominant or impulsive personality styles.

The right way to kiss: directionality bias in head-turning during kissing

Humans have a bias for turning to the right in a number of settings. Here we document a bias in head-turning to the right in adult humans, as tested in the act of kissing. We investigated head-turning bias in both kiss initiators and kiss recipients for lip kissing, and took into consideration differences due to sex and handedness, in 48 Bangladeshi heterosexual married couples. We report a significant male bias in the initiation of kissing and a significant bias in head-turning to the right in both kiss initiators and kiss recipients, with a tendency among kiss recipients to match their partners’ head-turning direction. These interesting outcomes are explained by the influences of societal learning or cultural norms and the potential neurophysiological underpinnings which together offer novel insights about the mechanisms underlying behavioral laterality in humans.

Delta Subunit-Containing Gamma-Aminobutyric Acid A Receptor Disinhibits Lateral Amygdala and Facilitates Fear Expression in Mice

BACKGROUND

Maintaining gamma-aminobutyric acidergic (GABAergic) inhibition in the amygdala within a physiological range is critical for the appropriate expression of emotions such as fear and anxiety. The synaptic GABA type A receptor (GABA_AR) is generally known to mediate the primary component of amygdala inhibition and prevent inappropriate expression of fear. However, little is known about the contribution of the extrasynaptic GABA_AR to amygdala inhibition and fear.

METHODS

By using mice expressing green fluorescent protein in interneurons (INs) and lacking the δ subunit-containing GABA_AR (GABA_A(δ)R), which is exclusively situated in the extrasynaptic membrane, we systematically investigated the role of GABA_A(δ)R in regulating inhibition in the lateral amygdala (LA) and fear learning using the combined approaches of immunohistochemistry, electrophysiology, and behavior.

RESULTS

In sharp contrast to the established role of synaptic GABA_AR in mediating LA inhibition, we found that either pharmacological or physiological recruitment of GABA_A(δ)R resulted in the weakening of GABAergic transmission onto projection neurons in LA while leaving the glutamatergic transmission unaltered, suggesting disinhibition by GABA_A(δ)R. The disinhibition arose from IN-specific expression of GABA_A(δ)R with its activation decreasing the input resistance of local INs and suppressing their activation. Genetic deletion of GABA_A(δ)R attenuated its role in suppressing LA INs and disinhibiting LA. Importantly, the GABA_A(δ)R facilitated long-term potentiation in sensory afferents to LA and permitted the expression of learned fear.

CONCLUSIONS

Our findings suggest that GABA_A(δ)R serves as a brake rather than a mediator of GABAergic inhibition in LA. The disinhibition by GABA_A(δ)R may help to prevent excessive suppression of amygdala activity and thus ensure the expression of emotion.

Physiological and psychological effects of testosterone during severe energy deficit and recovery: A study protocol for a randomized, placebo-controlled trial for Optimizing Performance for Soldiers (OPS)

BACKGROUND

The physiological consequences of severe energy deficit include hypogonadism and the loss of fat-free mass. Prolonged energy deficit also impacts physical performance, mood, attentiveness, and decision-making capabilities. This study will determine whether maintaining a eugonadal state during severe, sustained energy deficit attenuates physiological decrements and maintains mental performance. This study will also assess the effects of normalizing testosterone levels during severe energy deficit and recovery on gut health and appetite regulation.

METHODS

Fifty physically active men will participate in a 3-phase, randomized, placebo-controlled study. After completing a 14-d, energy-adequate, diet acclimation phase (protein: 1.6g∙kg^-1∙d^-1; fat: 30% total energy intake), participants will be randomized to undergo a 28-d, 55% energy deficit phase with (DEF+TEST: 200mg testosterone enanthate per week) or without (DEF) exogenous testosterone. Diet and physical activity will be rigorously controlled. Recovery from the energy deficit (ad libitum diet, no testosterone) will be assessed until body mass has been recovered within ±2.5% of initial body mass. Body composition, stable isotope methodologies, proteomics, muscle biopsies, whole-room calorimetry, molecular biology, activity/sleep monitoring, personality and cognitive function assessments, functional MRI, and comprehensive biochemistries will be used to assess physiological and psychological responses to energy restriction and recovery feeding while volunteers are in an expected hypogonadal versus eugonadal state.

DISCUSSION

The Optimizing Performance for Soldiers (OPS) study aims to determine whether preventing hypogonadism will mitigate declines in physical and mental function that typically occur during prolonged energy deficit, and the efficacy of testosterone replacement on recovery from severe underfeeding.

TRIAL REGISTRATION

NCT02734238.

Testosterone and human behavior: the role of individual and contextual variables

The study of testosterone and aggression originated in experimental studies of animals, showing a direct causal link in some species. Human studies showed an overall weak correlation between testosterone and aggression. A theoretical framework ('the challenge hypothesis') enabled testosterone-behavior interactions in humans to be framed within a theory that emphasized hormonal responses to competition influencing subsequent aggressive behavior. The short-term administrations of testosterone to young women and to young men showed influences on behavioral and neural processes associated with aggression. Other findings are that testosterone influences aggression in high dominance men, and in those with low cortisol levels; and that testosterone can affect both aggressive and prosocial behavior, within the context of an experimental game.

Endogenous testosterone is associated with lower amygdala reactivity to angry faces and reduced aggressive behavior in healthy young women

Testosterone and cortisol have been proposed to influence aggressive behavior by altering the neural processing of facial threat signals. However, this has not been investigated in direct social interactions. Here, we explored the joint impact of testosterone, cortisol, and brain reactivity to anger expressions on women’s reactive aggression in the Social Threat Aggression Paradigm (STAP). The STAP is a competitive reaction time task in which the purported opponent displays either an angry or a neutral facial expression at the beginning of each trial and delivers increasingly loud sound blasts to the participants, successfully provoking them. Strikingly, salivary testosterone at scan-time was negatively related to both aggression and basolateral amygdala (BLA) reactivity to angry faces, whereas cortisol had no effect. When the opponent looked angry, BLA-orbitofrontal coupling was reduced, and BLA reactivity was positively related to aggression. The latter relationship was fully mediated by bilateral superior temporal gyrus (STG) activation. Our results thus support previous neurobiological models of aggression, and extend them by demonstrating that fast amygdala responses to threat modulate STG activity in order to favor aggressive retaliation. Furthermore, our study agrees with recent evidence underscoring a fear-reducing and strategically prosocial effect of testosterone on human social behavior.

Subcortical gray matter changes in transgender subjects after long-term cross-sex hormone administration

Sex-steroid hormones are primarily involved in sexual differentiation and development and are thought to underlie processes related to cognition and emotion. However, divergent results have been reported concerning the effects of hormone administration on brain structure including side effects like brain atrophy and dementia. Cross-sex hormone therapy in transgender subjects offers a unique model for studying the effects of sex hormones on the living human brain. In this study, 25 Female-to-Male (FtM) and 14 Male-to-Female (MtF) subjects underwent MRI examinations at baseline and after a period of at least 4-months of continuous cross-sex hormone administration. While MtFs received estradiol and anti-androgens, FtM subjects underwent high-dose testosterone treatment. The longitudinal processing stream of the FreeSurfer software suite was used for the automated assessment and delineation of brain volumes to assess the structural changes over the treatment period of cross-sex hormone administration. Most prominent results were found for MtFs receiving estradiol and anti-androgens in the form of significant decreases in the hippocampal region. Further analysis revealed that these decreases were reflected by increases in the ventricles. Additionally, changes in progesterone levels correlated with changes in gray matter structures in MtF subjects. In line with prior studies, our results indicate hormonal influences on subcortical structures related to memory and emotional processing. Additionally, this study adds valuable knowledge that progesterone may play an important role in this process.

Testosterone causes both prosocial and antisocial status-enhancing behaviors in human males

Although popular discussion of testosterone's influence on males often centers on aggression and antisocial behavior, contemporary theorists have proposed that it instead enhances behaviors involved in obtaining and maintaining a high social status. Two central distinguishing but untested predictions of this theory are that testosterone selectively increases status-relevant aggressive behaviors, such as responses to provocation, but that it also promotes nonaggressive behaviors, such as generosity toward others, when they are appropriate for increasing status. Here, we tested these hypotheses in healthy young males by injecting testosterone enanthate or a placebo in a double-blind, between-subjects, randomized design (n = 40). Participants played a version of the Ultimatum Game that was modified so that, having accepted or rejected an offer from the proposer, participants then had the opportunity to punish or reward the proposer at a proportionate cost to themselves. We found that participants treated with testosterone were more likely to punish the proposer and that higher testosterone levels were specifically associated with increased punishment of proposers who made unfair offers, indicating that testosterone indeed potentiates aggressive responses to provocation. Furthermore, when participants administered testosterone received large offers, they were more likely to reward the proposer and also chose rewards of greater magnitude. This increased generosity in the absence of provocation indicates that testosterone can also cause prosocial behaviors that are appropriate for increasing status. These findings are inconsistent with a simple relationship between testosterone and aggression and provide causal evidence for a more complex role for testosterone in driving status-enhancing behaviors in males.

Effects of exogenous testosterone and mating context on men's preferences for female facial femininity

Correlational research suggests that men show greater attraction to feminine female faces when their testosterone (T) levels are high. Men's preferences for feminine faces also seem to vary as a function of relationship context (short versus long-term). However, the relationship between T and preferences for female facial femininity has yet to be tested experimentally. In the current paper, we report the results of two experiments examining the causal role of T in modulating preferences for facial femininity across both short and long-term mating contexts. Results of Experiment 1 (within-subject design, n=24) showed that participants significantly preferred feminized versus masculinized versions of women's faces. Further, participants showed a stronger preference for feminine faces in the short versus the long-term context after they received T, but not after they received placebo. Post-hoc analyses suggested that this effect was driven by a lower preference for feminine faces in the long-term context when on T relative to placebo, and this effect was found exclusively for men who received placebo on the first day of testing, and T on the second day of testing (i.e., Order x Drug x Mating context interaction). In Experiment 2 (between-subject design, n=93), men demonstrated a significant preference for feminized female faces in the short versus the long-term context after T, but not after placebo administration. Collectively, these findings provide the first causal evidence that T modulates men's preferences for facial femininity as a function of mating context.

A quantitative and qualitative review of the effects of testosterone on the function and structure of the human social-emotional brain

Social and affective research in humans is increasingly using functional and structural neuroimaging techniques to aid the understanding of how hormones, such as testosterone, modulate a wide range of psychological processes. We conducted a meta-analysis of functional magnetic resonance imaging (fMRI) studies of testosterone administration, and of fMRI studies that measured endogenous levels of the hormone, in relation to social and affective stimuli. Furthermore, we conducted a review of structural MRI i.e. voxel based morphometry (VBM) studies which considered brain volume in relation to testosterone levels in adults and in children. In the included testosterone administration fMRI studies, which consisted of female samples only, bilateral amygdala/parahippocampal regions as well as the right caudate were significantly activated by social-affective stimuli in the testosterone condition. In the studies considering endogenous levels of testosterone, stimuli-invoked activations relating to testosterone levels were noted in the bilateral amygdala/parahippocampal regions and the brainstem. When the endogenous testosterone studies were split by sex, the significant activation of the brain stem was seen in the female samples only. Significant stimuli-invoked deactivations relating to endogenous testosterone levels were also seen in the right and left amygdala/parahippocampal regions studies. The findings of the VBM studies were less consistent. In adults larger volumes in the limbic and temporal regions were associated with higher endogenous testosterone. In children, boys showed a positive correlation between testosterone and brain volume in many regions, including the amygdala, as well as global grey matter volume, while girls showed a neutral or negative association between testosterone levels and many brain volumes. In conclusion, amygdalar and parahippocampal regions appear to be key target regions for the acute actions of testosterone in response to social and affective stimuli, while neurodevelopmentally the volumes of a broader network of brain structures are associated with testosterone levels in a sexually dimorphic manner.

A testosterone-related structural brain phenotype predicts aggressive behavior from childhood to adulthood

Structural covariance, the examination of anatomic correlations between brain regions, has emerged recently as a valid and useful measure of developmental brain changes. Yet the exact biological processes leading to changes in covariance, and the relation between such covariance and behavior, remain largely unexplored. The steroid hormone testosterone represents a compelling mechanism through which this structural covariance may be developmentally regulated in humans. Although steroid hormone receptors can be found throughout the central nervous system, the amygdala represents a key target for testosterone-specific effects, given its high density of androgen receptors. In addition, testosterone has been found to impact cortical thickness (CTh) across the whole brain, suggesting that it may also regulate the structural relationship, or covariance, between the amygdala and CTh. Here, we examined testosterone-related covariance between amygdala volumes and whole-brain CTh, as well as its relationship to aggression levels, in a longitudinal sample of children, adolescents, and young adults 6-22 years old. We found: (1) testosterone-specific modulation of the covariance between the amygdala and medial prefrontal cortex (mPFC); (2) a significant relationship between amygdala-mPFC covariance and levels of aggression; and (3) mediation effects of amygdala-mPFC covariance on the relationship between testosterone and aggression. These effects were independent of sex, age, pubertal stage, estradiol levels and anxious-depressed symptoms. These findings are consistent with prior evidence that testosterone targets the neural circuits regulating affect and impulse regulation, and show, for the first time in humans, how androgen-dependent organizational effects may regulate a very specific, aggression-related structural brain phenotype from childhood to young adulthood.

Digit ratio (2D:4D) and psychopathic traits moderate the effect of exogenous testosterone on socio-cognitive processes in men

Recent evidence suggests that testosterone is negatively correlated with empathic processes in both men and women. Also, administration of testosterone to young women impairs socio-cognitive performance as assessed using the "Reading the Mind in the Eyes Task", especially among those exposed to elevated testosterone concentrations prenatally. However, the extent to which testosterone plays a similar causal role in socio-cognitive abilities in men is currently unknown. Here, using a crossover, double-blind, placebo-controlled, within-subject design, we investigated the extent to which a single administration of testosterone to healthy young men (N=30) would impair socio-cognitive abilities assessed using the "Reading the Mind in the Eyes Task" (RMET). Also, we investigated whether individual differences in 2D:4D ratio and psychopathic traits would moderate the effect of testosterone on task performance. Results indicated that testosterone administration on its own did not impair RMET performance. However, variability in both 2D:4D ratio and psychopathic traits moderated the effect of testosterone on task performance. Specifically, testosterone impaired RMET performance among individuals with relatively low (i.e., masculinized) 2D:4D ratio and among individuals scoring relatively low on the interpersonal/affective facet (i.e., Factor 1) of psychopathy. Our findings highlight the importance of considering theoretically- and empirically-based individual difference factors when attempting to characterize the neuroendocrine mechanisms underlying socio-cognitive processes.

Maternal testosterone exposure increases anxiety-like behavior and impacts the limbic system in the offspring

During pregnancy, women with polycystic ovary syndrome (PCOS) display high circulating androgen levels that may affect the fetus and increase the risk of mood disorders in offspring. This study investigated whether maternal androgen excess causes anxiety-like behavior in offspring mimicking anxiety disorders in PCOS. The PCOS phenotype was induced in rats following prenatal androgen (PNA) exposure. PNA offspring displayed anxiety-like behavior in the elevated plus maze, which was reversed by flutamide [androgen receptor (AR) blocker] and tamoxifen [selective estrogen receptor (ER) modulator]. Circulating sex steroids did not differ between groups at adult age. The expression of serotonergic and GABAergic genes associated with emotional regulation in the amygdala was consistent with anxiety-like behavior in female, and partly in male PNA offspring. Furthermore, AR expression in amygdala was reduced in female PNA offspring and also in females exposed to testosterone in adult age. To determine whether AR activation in amygdala affects anxiety-like behavior, female rats were given testosterone microinjections into amygdala, which resulted in anxiety-like behavior. Together, these data describe the anxiety-like behavior in PNA offspring and adult females with androgen excess, an impact that seems to occur during fetal life, and is mediated via AR in amygdala, together with changes in ERα, serotonergic, and GABAergic genes in amygdala and hippocampus. The anxiety-like behavior following testosterone microinjections into amygdala demonstrates a key role for AR activation in this brain area. These results suggest that maternal androgen excess may underpin the risk of developing anxiety disorders in daughters and sons of PCOS mothers.

Changes in spatial cognition and brain activity after a single dose of testosterone in healthy women

Studies have consistently shown that males perform better than females on several spatial tasks. Animal and human literature suggests that sex hormones have an important role in both establishing and maintaining this difference. The aim of the present study was to examine the effects of exogenous testosterone on spatial cognition and brain activity in healthy women. A cross-sectional, double-blind, randomized, placebo-controlled study was performed in 42 healthy young women who either received one dose of 0.5mg sublingual testosterone or placebo. They then learned a virtual environment and performed navigation tasks during functional magnetic resonance imaging (fMRI). Subsequently, their knowledge of the virtual environment, self-reported navigation strategy, and mental rotation abilities were measured. The testosterone group had improved representations of the directions within the environment and performed significantly better on the mental rotation task compared to the placebo group, but navigation success and navigation strategy were similar in the two groups. Nevertheless, the testosterone group had significantly increased activity within the medial temporal lobe during successful navigation compared to the placebo group, and a positive correlation between testosterone load and medial temporal lobe activity was found. Fetal testosterone levels, measured as second-to-fourth digit length ratio, interacted significantly with parahippocampal activity and tended towards giving higher mental rotation task scores. These results demonstrated that testosterone had a limited effect pertaining specifically to spatial cognition involving 3D-visualization in healthy women, while complex behaviors such as navigation, relying more on learned strategies, were not altered despite increased neuronal activity in relevant brain regions.