Measurement of testosterone in human sexuality research: methodological considerations

Interpersonal relationships, PNI, and health: Seeds in the 1980s, fruiting trees today

In this contribution to the Special Issue, I highlight how Janice Kiecolt-Glaser's research in the 1980s planted the seeds for two areas of social relationships and health research: loneliness and intimate/marital relationships. I review the foundational "seed" studies from the mid-to late-1980s, the research "saplings" that sprouted and grew during the subsequent twenty years, and the "mature trees" that have gone on to fruit and grow their respective areas of inquiry over the past twenty years. In addition to highlighting the mature trees that have borne rich empirical fruit, my other goal for this contribution is to draw attention to ideas and concepts from Kiecolt-Glaser's work and writing that merit further conceptual and empirical examination in the next generation of research on social relationships, psychoneuroendocrinology, psychoneuroimmunology, and health.

Influence of controlled environmental conditions in potential salivary ocular pain biomarkers for enhancing the assessment of ocular pain

PURPOSE

We endeavored to identify objective salivary biomarkers for pain, a subjective sensation with a biological basis, using molecules already described related to pain. The study aimed to analyze inter-individual differences and intersession variability in salivary potential ocular pain biomarkers on healthy subjects, in samples obtained under the influence of controlled environmental conditions.

METHODS

Thirty-four healthy subjects, 20 male, 14 female, median age 35.44 years (range 30-40) were exposed for 30 minutes under standard environmental conditions (T: 22°C, 50% relative humidity) in the Controlled Environmental Research Laboratory (CE-Lab, Vision R&D, Valladolid Spain) in two separate visits (V1, V2) at least 24 hours apart. Saliva was collected after the exposure in each of the visits, and cortisol, α-amylase (sAA), secretory IgA (sIgA), testosterone, and soluble fraction of TNFα receptor II (sTNFαRII) were analyzed by ELISA. Repeatability of inter-subject inter-session measurements was assayed by intraclass correlation coefficient (ICC).

RESULTS

There were no significant inter-session differences in testosterone (p = 0.2497), sTNFαRII (p = 0.6451) and sIgA (p = 0.9689) salivary levels. The reproducibility for salivary cortisol, sAA, testosterone, sTNFαRII and sIgA were 0.98 ng/ml, 20.58 U/ml, 21.07 μg/ml, 24.68 pg/ml and 0.19 pg/ml, respectively. Salivary cortisol, sAA, testosterone, sTNFαRII and sIgA yielded the following ICCs: 0.506, 0.569, 0.824, 0.870 and 0.4295, respectively; all these ICCs (except that for cortisol and sIgA) were found to be improved compared to those found previously by our group in a previous study in salivary samples obtained from healthy subjects under non-controlled environmental conditions; Cortisol´s ICC didn´t improve and was in both cases at the limit of acceptability.

CONCLUSION

Environmental factors such as temperature and relative humidity affect the reproducibility of measurement of some salivary molecules which have been proposed as potential pain biomarkers. The exposure of subjects to standard controlled environmental conditions before salivary sample obtention would improve the reproducibility of these molecule measures' as potential biomarkers of chronic ocular pain.

Morphologic alterations of the fear circuitry: the role of sex hormones and oral contraceptives

Background

Endogenous sex hormones and oral contraceptives (OCs) have been shown to influence key regions implicated in fear processing. While OC use has been found to impact brain morphology, methodological challenges remain to be addressed, such as avoiding selection bias between OC users and non-users, as well as examining potential lasting effects of OC intake.

Objective

We investigated the current and lasting effects of OC use, as well as the interplay between the current hormonal milieu and history of hormonal contraception use on structural correlates of the fear circuitry. We also examined the role of endogenous and exogenous sex hormones within this network.

Methods

We recruited healthy adults aged 23-35 who identified as women currently using (n = 62) or having used (n = 37) solely combined OCs, women who never used any hormonal contraceptives (n = 40), or men (n = 41). Salivary endogenous sex hormones and current users' salivary ethinyl estradiol (EE) were assessed using liquid chromatography - tandem mass spectrometry. Using structural magnetic resonance imaging, we extracted surface-based gray matter volumes (GMVs) and cortical thickness (CT) for regions of interest of the fear circuitry. Exploratory whole-brain analyses were conducted with surface-based and voxel-based morphometry methods.

Results

Compared to men, all three groups of women exhibited a larger GMV of the dorsal anterior cingulate cortex, while only current users showed a thinner ventromedial prefrontal cortex. Irrespective of the menstrual cycle phase, never users exhibited a thicker right anterior insular cortex than past users. While associations with endogenous sex hormones remain unclear, we showed that EE dosage in current users had a greater influence on brain anatomy compared to salivary EE levels and progestin androgenicity, with lower doses being associated with smaller cortical GMVs.

Discussion

Our results highlight a sex difference for the dorsal anterior cingulate cortex GMV (a fear-promoting region), as well as a reduced CT of the ventromedial prefrontal cortex (a fear-inhibiting region) specific to current OC use. Precisely, this finding was driven by lower EE doses. These findings may represent structural vulnerabilities to anxiety and stress-related disorders. We showed little evidence of durable anatomical effects, suggesting that OC intake can (reversibly) affect fear-related brain morphology.

Considering hormones as sex- and gender-related factors in biomedical research: Challenging false dichotomies and embracing complexity

The inclusion of sex and gender considerations in biomedicine has been increasing in light of calls from research and funding agencies, governmental bodies, and advocacy groups to direct research attention to these issues. Although the inclusion of both female and male participants is often an important element, overreliance on a female-male binary tends to oversimplify the interactions between sex- and gender-related factors and health, and runs a risk of being influenced by cultural stereotypes about sex and gender. When biomedical researchers are examining how hormones associated with gender and sex may influence pathways of interest, it is of crucial importance to approach this work with a critical lens on the rhetoric used, and in ways that acknowledge the complexity of hormone physiology. Here, we document the ways in which discourses around sex, gender and hormones shape our scientific thinking and practice in biomedical research, and review how the existing scientific knowledge about hormones reflects a complex and dynamic reality that is often not reflected outside of specialist niches of hormone biology. Where biomedical scientists take up sex- and gender-associated hormones as a way of addressing sex and gender considerations, it is valuable for us to bring a critical lens to the rhetoric and discourses used, to employ a sex contextualist approach in designing experimentation, and be rigorous and reflexive about the approaches used in analysis and interpretation of data. These strategies will allow us to design experimentation that goes beyond binaries, and grapples more directly with the material intricacies of sex, gender, and hormones.

Hormone physiology and sleep dynamics among BaYaka foragers of the Congo Basin: Gendered associations between nighttime activity, testosterone, and cortisol

Sleep quality is an important contributor to health disparities and affects the physiological function of the immune and endocrine systems, shaping how resources are allocated to life history demands. Past work in industrial and post-industrial societies has shown that lower total sleep time (TST) or more disrupted nighttime sleep are linked to flatter diurnal slopes for cortisol and lower testosterone production. There has been little focus on these physiological links in other socio-ecological settings where routine sleep conditions and nighttime activity demands differ. We collected salivary hormone (testosterone, cortisol) and actigraphy-based sleep data from Congolese BaYaka foragers (N = 39), who have relatively short and fragmented nighttime sleep, on average, in part due to their typical social sleep conditions and nighttime activity. The hormone and sleep data collections were separated by an average of 11.23 days (testosterone) and 2.84 days (cortisol). We found gendered links between nighttime activity and adults' hormone profiles. Contrary to past findings in Euro-American contexts, BaYaka men who were more active at night, on average, had higher evening testosterone than those with lower nighttime activity, with a relatively flat slope relating nighttime activity and evening testosterone in women. Women had steeper diurnal cortisol curves with less disrupted sleep. Men had steeper cortisol diurnal curves if they were more active at night. BaYaka men often hunt and socialize when active at night, which may help explain these patterns. Overall, our findings indicate that the nature of nighttime activities, including their possible social and subsistence contexts, are potentially important modifiers of sleep quality-physiology links, meriting further research across contexts.

Hormonal responses to brief social interactions: The role of psychosocial stress and relationship status

This study investigated the effects of psychosocial stress on hormonal responses to a social interaction with an opposite-sex individual to test the hypothesis that stress may interfere with or suppress adaptive neuroendocrine responses to courtship opportunities. Heterosexual men and women were randomly assigned prior to arrival to either a control or psychosocial stress condition (Trier Social Stress Test) and subsequently went through a social interaction test with an opposite-sex individual. Expected increases of testosterone for control participants who interacted with opposite-sex individuals were not observed, and changes in testosterone were not observed for those in the psychosocial stress condition either. However, exploratory analyses in control participants showed main and interaction effects of relationship status were significant for both cortisol and testosterone. Specifically, single individuals showed higher levels of cortisol compared to those in a relationship, and single individuals showed significantly higher concentrations of cortisol after a social interaction when compared to individuals who were in a relationship. For testosterone, only individuals in a relationship decreased in testosterone following the social interaction. This study suggests that relationship status and psychosocial stress may be important variables moderating the relationship between an ecological cue of a potential courtship opportunity and subsequent adaptive physiological responses.

Minimally invasive biomarkers in human and non-human primate evolutionary biology: Tools for understanding variation and adaptation

BACKGROUND

The use of minimally invasive biomarkers (MIBs - physiological biomarkers obtained from minimally invasive sample types) has expanded rapidly in science and medicine over the past several decades. The MIB approach is a methodological strength in the field of human and non-human primate evolutionary biology (HEB). Among humans and our closest relatives, MIBs provide unique opportunities to document phenotypic variation and to operationalize evolutionary hypotheses.

AIMS

This paper overviews the use of MIBs in HEB. Our objectives are to (1) highlight key research topics which successfully implement MIBs, (2) identify promising yet under-investigated areas of MIB application, and (3) discuss current challenges in MIB research, with suggestions for advancing the field.

DISCUSSION AND CONCLUSIONS

A range of MIBs are used to investigate focal topics in HEB, including energetics and life history variation/evolution, developmental plasticity, and social status and dominance relationships. Nonetheless, we identify gaps in existing MIB research on traits such as physical growth and gut function that are central to the field. Several challenges remain for HEB research using MIBs, including the need for additional biomarkers and methods of assessment, robust validations, and approaches that are standardized across labs and research groups. Importantly, researchers must provide better support for adaptation and fitness effects in hypothesis testing (e.g., by obtaining complementary measures of energy expenditure, demonstrating redundancy of function, and performing lifetime/longitudinal analyses). We point to continued progress in the use of MIBs in HEB to better understand the past, present, and future of humans and our closest primate relatives.

An Empirical Investigation of the Roles of Biological, Relational, Cognitive, and Emotional Factors in Explaining Sex Differences in Dyadic Sexual Desire

One challenge many marital couples face is that they experience discrepant levels of sexual desire for one another. Such discrepancies are particularly likely to arise in mixed-sex relationships because, at least in long-term relationships, men tend to have higher levels of sexual desire for their partner than do women. But what underlies this sex difference? We used a dyadic study of 100 mixed-sex community-based newlywed spouses to investigate the role of biological, relational, cognitive, and emotional factors in explaining sex differences in dyadic sexual desire for a long-term partner. Consistent with predictions, wives on average reported lower daily sexual desire for their spouse than did husbands. Moreover, individual differences in men's and women's levels of circulating testosterone explained this sex difference whereas relational (marital satisfaction, commitment), cognitive (sex-role identification, stress, self-esteem), and emotional (mood, depressive symptoms) factors did not. These findings advance our knowledge of factors that influence dyadic sexual desire and may have practical implications for treating relationship distress in mixed-sex marriages.

Exploring the role of endocrine factors in sensitive parenting in men

Parental sensitivity has been studied extensively in parenting research. Recently, there has been increasing attention to endocrine factors that may be related to parental sensitivity, such as oxytocin, vasopressin, testosterone, and cortisol. Although hormones do not act in isolation, few studies integrated multiple hormones and examined their combined associations with parental sensitivity. The current study aimed to explore the hormonal correlates of paternal sensitivity by examining in 79 first-time fathers of young infants (2-4 months old) (1) the separate and combined associations of basal oxytocin, vasopressin, testosterone, and cortisol levels with sensitivity, and (2) the associations between paternal sensitivity and oxytocin, vasopressin, testosterone, and cortisol reactivity following father-infant interactions. We additionally explored whether interactions between the various basal hormone levels could predict paternal sensitivity. Saliva for the quantification of fathers' hormone levels was sampled before and after an interaction with their infant to determine basal levels and reactivity. Results revealed no significant associations between sensitivity and basal hormone levels or reactivity. However, results indicated that cortisol and testosterone interacted in their effects on paternal sensitive parenting. Namely, fathers with low basal cortisol levels showed more sensitivity with increasing T levels, but fathers with high cortisol levels were less sensitive with increasing T levels. However, it should be noted that the latter slope was not significantly different from zero. These findings suggest that variations in parental sensitivity might be better explained by interactions between hormones than by single hormone levels.

Salivary Testosterone and Sexual Function and Behavior in Men and Women: Findings from the Third British National Survey of Sexual Attitudes and Lifestyles (Natsal-3)

Using data from the third British National Survey of Sexual Attitudes and Lifestyles (Natsal-3) we examined associations between salivary testosterone (Sal-T) and sexual function and behavior. Single morning saliva samples were self-collected from a subsample of participants aged 18-74 years and analyzed using mass spectrometry. 1,599 men and 2,123 women were included in the analysis (40.6% of those invited to provide a sample). We adjusted for confounders in a stepwise manner: in model 1 we adjusted for age only; model 2 for age, season and relationship status, and model 3 we added BMI and self-reported health. In the fully adjusted models, among men, Sal-T was positively associated with both partnered sex (vaginal sex and concurrent partners) and masturbation. Among women, Sal-T was positively associated with masturbation, the only association with partnered sex was with ever experience of same-sex sex. We found no clear association between Sal-T and sexual function. Our study contributes toward addressing the sparsity of data outside the laboratory on the differences between men and women in the relationship between T and sexual function and behavior. To our knowledge, this is the first population study, among men and women, using a mass spectrometry Sal-T assay to do so.

The Heteronormativity Theory of Low Sexual Desire in Women Partnered with Men

Low sexual desire in women partnered with men is typically presumed to be a problem-one that exists in women and encourages a research agenda on causation and treatment targeting women. In this paper, we present a distinct way forward for research on low sexual desire in women partnered with men that attends to a more structural explanation: heteronormativity. A heteronormative worldview assumes that relationships and structures are heterosexual, gender (usually conflated with sex) is binary and complementary, and gender roles fit within narrow bounds including nurturant labor for women. We propose the heteronormativity theory of low sexual desire in women partnered with men, arguing that heteronormative gender inequities are contributing factors. We outline four hypotheses and their predictions related to: inequitable divisions of household labor, blurring of partner and mother roles, objectification of women, and gender norms surrounding sexual initiation. We discuss some mechanisms-social, physiological, and otherwise-for the heteronormativity theory, especially related to stress, objectification, and nurturance. We close by noting some limitations of our paper and the ways that the heteronormativity theory of low sexual desire in women partnered with men provides a rigorous, generative, and empirical way forward.

Fathering behavior, attachment, and engagement in childcare predict testosterone and cortisol

The present study examined testosterone (T) and cortisol (Cort) in fathers engaged with caregiving. We collected saliva samples in the mornings and evenings of two consecutive days in 150 fathers of 1- to 5-year-old children. Fathers completed questionnaires on socioeconomic status, family structure and life, sleep characteristics and body mass index (BMI), and reported on their engagement in childcare. Fathers used smartphone-based experience sampling throughout 1 week to sample ongoing activities with their children, including times of supervision, joint play, rough-and-tumble play, and cuddling episodes. External observers rated father-child attachment during a home visit. We began by testing for widely characterized covariates of T and excluded seasonal variations and known predictors associated with lowered T, such as older fathers and those with multiple and young children, lower BMI, shorter sleep duration, and sexual activity before sampling. Most interestingly, however, fathers' engagement in childcare and attachment to the child appeared more pronounced the greater the diurnal decline in T. Cuddling predicted a similar negative association, whereas joint play and rough-and-tumble play (RTP) showed enhancing effects on declining T. Interestingly, all fathering behaviors (except RTP) were positively related to lower Cort. In contrast, supervision was ineffective on both Cort and T.

Field methods and strategies for assessing female reproductive functioning

A detailed understanding of female reproductive functioning is important to many disciplines including anthropology, evolutionary theory, demography, psychology, and biomedicine. In this article, I describe strategies and methods that have been used successfully in community-based studies of human reproduction, many in remote locales, to produce high quality biomarker data. These techniques are applicable to a wide range of research questions and populations, and to persons from adolescence through senescence. I give particular attention to the inherent challenges imposed by the cyclical and somewhat unpredictable nature of the hypothalamic-pituitary-ovarian axis including the necessity and difficulty of ascertaining the timing and occurrence of ovulation, the limits of different sampling regimes for capturing fluctuations in reproductive hormones, and the critical importance of recognizing and, when possible, reducing selection bias. I discuss the relative advantages and disadvantages of collecting saliva, urine, and dried blood spots, and describe some of the subtleties involved in collecting contamination-free samples. Once samples are collected, they must be stored in a manner that minimizes degradation; I describe techniques to keep samples cold even without access to electricity or dry ice. I also discuss various issues that should be considered during initial discussions with a laboratory and when samples are assayed by the laboratory. I include examples of techniques that have worked well in actual field studies, and examples of flawed analytical approaches that should be avoided. With these and other tools, even under technology-sparse conditions, researchers can investigate variability in human physiology across the breadth of human habitats.

Positive Affect Moderates the Relationship Between Salivary Testosterone and a Health Behavior Composite in University Females

Background

Testosterone is released in both men and women and plays an important role in social functioning and motivation. Greater testosterone in women has been associated with negative physical health outcomes, while lower testosterone has been associated with psychological disorders. The following cross-sectional study examined the contribution of salivary testosterone, positive and negative affect, and demographic variables in predicting a composite health behavior score (cigarette use, hours of sleep, fruit/vegetable intake, following an exercise routine).

Method

The sample (mean age 21.17, SD = 6.13) consisted of 87 female university students asked to complete a demographic and lifestyle behavior questionnaire, the Positive and Negative Affect Schedule, and provide a saliva sample. Participants self-identified as Latina (37.9%), European American (32.2%), Asian American (5.7%), African American (4.6%), or Mixed/other (19.5%). Hierarchical regression analyses were used to examine whether positive and negative affect served as a moderator between salivary testosterone and a health behavior composite.

Results

Results indicated that positive affect moderated the relationship between salivary testosterone and the composite health behavior score (t = − 2.42, p = .018, Adj. R² = .21, F (5, 81) = 5.07, p < .001) such that the healthiest behaviors were observed in participants with high positive affect and low salivary testosterone. Findings remained after adjusting for oral contraceptive use, income level, relationship status, and ethnicity.

Conclusions

These results provide a preliminary foundation for future research examining the interplay of neuroendocrine function, psychological factors (i.e., positive affect), and behavior. Further empirical studies can focus on expanding this research in larger, representative samples.

Testosterone and Fathers’ Parenting Unraveled: Links with the Quantity and Quality of Father-Child Interactions

Objective

Individual differences in quality of father involvement in caregiving might in part be explained by fathers’ testosterone (T) levels. We examined the links between fathers’ (n = 32) salivary T levels, amount of time spent with their child (12–30 months of age), type of father-child interaction, and fathers’ sensitivity.

Methods

During two home visits, video observations of father-child interactions were conducted to measure fathers’ sensitivity during a challenging and harmonious interaction. Fathers’ saliva was collected several times throughout the day on a working day and on the home visit days, including right before and after each father-child interaction.

Results

Fathers’ T secretion throughout the day was lower on home visit days (i.e., days with a higher amount of time spent with their child) than on a working day. For both challenging and harmonious father-child interactions, mean T levels did not differ before and after father-child interactions. However, individual changes in fathers’ T levels during the father-child interactions did predict fathers’ sensitivity. Specifically, the more T increased during the challenging interaction, or decreased during the harmonious interaction, the more sensitive the father was during that interaction as well as during a subsequent interaction.

Conclusions

Parenting quality is most optimal when fathers’ T system reacts in the expected direction given the context of the father-child interaction, i.e., a T decrease during a harmonious interaction and a T increase during a challenging interaction. Our study underscores the importance of examining the interplay between biology, behavior, and caregiving context in fathers’ parenting.

Adult attachment and testosterone reactivity: Fathers' avoidance predicts changes in testosterone during the strange situation procedure

We assessed parents' testosterone reactivity to the Strange Situation Procedure (SSP), a moderately stressful parent-infant interaction task that pulls for parental nurturance and caregiving behavior. Parents (146 mothers, 154 fathers) interacted with their 1-year-old infants, and saliva samples were obtained pre- and post-task to assess changes in testosterone. We examined whether testosterone reactivity differed between mothers and fathers, the extent to which parents' characteristic approaches to closeness (i.e., adult attachment orientation) contributed to testosterone changes, and whether any influences of adult attachment orientation were independent of more general personality characteristics (i.e., the Big Five personality dimensions). Results revealed that mothers and fathers showed comparable declines in testosterone during the SSP, and that these declines were attenuated among fathers with a more avoidant attachment orientation (i.e., those less comfortable with closeness). Associations between fathers' avoidance and testosterone reactivity were statistically independent of broader personality traits. Our findings provide some of the first evidence for short-term changes in both mothers' and fathers' testosterone in contexts that pull for nurturance. Moreover, these findings demonstrate that individual differences in adult attachment may play an important role in understanding such changes. We discuss possible explanations for gender differences in associations between adult attachment and parents' testosterone reactivity, and the extent to which testosterone reactivity might be sensitive to changes in context for mothers versus fathers.

Expanding Statistical Frontiers in Sexual Science: Taxometric, Invariance, and Equivalence Testing

Sexual scientists must choose from among myriad methodological and analytical approaches when investigating their research questions. How can scholars learn whether sexualities are discrete or continuous? How is sexuality constructed? And to what extent are sexuality-related groups similar to or different from one another? Though commonplace, quantitative attempts at addressing these research questions require users to possess an increasingly deep repertoire of statistical knowledge and programming skills. Recently developed open-source software offers powerful yet accessible capacity to researchers wishing to perform strong quantitative tests. Taking advantage of these new statistical opportunities will require sexual scientists to become familiar with new analyses, including taxometric analysis, tests of measurement variability and differential item functioning, and equivalence testing. In the current article, I discuss each of these analyses, providing conceptual and historical overviews. I also address common misunderstandings for each analysis that may discourage researchers from implementing them. Finally, I describe current best practices when using each analysis, providing reproducible coding examples and interpretations along the way, in an attempt to reduce barriers to the uptake of these analyses. By aspiring to explore these new statistical frontiers in sexual science, sexuality researchers will be better positioned to test their substantive theories of interest.

Androgen receptor gene polymorphism and sexual function in midlife women

PURPOSE

To assess the impact of serum androgen levels and androgen receptor CAG polymorphism on sexual function in 45 healthy midlife women living in a heterosexual relationship.

METHODS

Cross-sectional study [Cantonal Ethics Committee Bern (Ref.-Nr.

KEK-BE

087/13)].

MAIN OUTCOME MEASURES

Association between androgen serum levels, androgen receptor CAG polymorphism and sexual function was assessed by the FSFI-d questionnaire.

RESULTS

In our cohort of healthy, midlife, well-educated, middle-class, mostly postmenopausal women living in a heterosexual satisfying partnership, sexual function was perceived to remain stable or to decline during menopausal transition with sexual desire scoring lowest (FSFI-d 3.3 ± 0.9). Androgen serum levels did not correlate with sexual function. Mean CAG repeat number was 21.6 ± 1.9. There was a highly inverse though non-significant correlation between female sexual function and AR CAG repeat polymorphism with specifically higher numbers of CAG repeats being significantly positively correlated to more frequent or more severe pain during or after sexual intercourse.

CONCLUSION

The AR polymorphism is a non-negligible factor in female sexual function. Future studies on female sexual (dys)function should incorporate its assessment.

Interactions Among Sexual Activity, Menstrual Cycle Phase, and Immune Function in Healthy Women

Past research has found menstrual-cycle-related changes in functional immune response; we examined if sexual activity also changed markers of immune defense. We followed 32 naturally cycling women (15 sexually active with a partner ≥ 1 time/week, 17 sexually abstinent for the last four months) over one menstrual cycle. Participants provided serum and saliva samples at menses and ovulation, and additional saliva samples at midfollicular and midluteal phases. At each phase, participants also self-reported symptoms associated with colds, flu, pain, menstrual discomfort, and premenstrual syndrome. We tested saliva and serum for ability to kill Escherichia coli or Candida albicans, and serum for complement protein activity. For serum-mediated pathogen killing, among sexually active women only, there was a significant midcycle decrease in killing of E. coli. For saliva-mediated pathogen killing, among abstinent women only, there was a significant midcycle decrease in killing of E. coli, and midcycle increase in killing of C. albicans. Sexually active women had significantly lower complement activity than abstinent women overall. Finally, both groups reported lower physical symptoms at midcycle and higher symptoms at menses. There may be important differences in immune function between healthy women who are sexually active versus abstinent. Further replication is warranted.

Average Associations Between Sexual Desire, Testosterone, and Stress in Women and Men Over Time

Sexual desire and testosterone are widely assumed to be directly and positively linked to each other despite the lack of supporting empirical evidence. The literature that does exist is mixed, which may result from a conflation of solitary and dyadic desire, and the exclusion of contextual variables, like stress, known to be relevant. Here, we use the Steroid/Peptide Theory of Social Bonds as a framework for examining how testosterone, solitary and partnered desire, and stress are linked over time. To do so, we collected saliva samples (for testosterone and cortisol) and measured desire as well as other variables via questionnaires over nine monthly sessions in 78 women and 79 men. Linear mixed models showed that testosterone negatively predicted partnered desire in women but not men. Stress moderated associations between testosterone and solitary desire in both women and men, but differently: At lower levels of stress, higher average testosterone corresponded to higher average solitary desire for men, but lower solitary desire on average for women. Similarly, for partnered desire, higher perceived stress predicted lower desire for women, but higher desire for men. We conclude by discussing the ways that these results both counter presumptions about testosterone and desire but fit with the existing literature and theory, and highlight the empirical importance of stress and gender norms.

No relationship between autistic traits and salivary testosterone concentrations in men from the general population

It is suggested that testosterone may play a part in the higher prevalence of Autism Spectrum Disorder (ASD) in males compared to females. Previous studies have reported elevated postnatal testosterone levels in children and women with ASD but not in men. We compared levels of salivary testosterone across 67 undergraduate males (M_age 19.5 yrs, SD 1.92) selected for low, mid-range and high levels of autistic traits assessed using the Autism-spectrum Quotient. Analyses revealed no significant differences in testosterone concentrations across the three groups. The current data add to the increasing evidence for the lack of relationship between autistic traits and postnatal levels of testosterone in men.

An Investigation of the Effects of Testosterone and Behavioral Expressions of Pain on Sex/Gender Differences in Pain Perception

Research indicates that women are more susceptible to pain than men, but the reason for this difference is unclear. While estrogen and progesterone have been implicated, testosterone has not received adequate consideration in the literature. Additionally, incorporating behavioral expressions, or exaggerations, of pain as an important aspect of pain perception is receiving increasing attention. The current study examined the role of testosterone in female pain expression and perception via the cold pressor test. Following all participant exclusions, 46 healthy participants (32 women) provided saliva samples for testosterone analysis using enzyme-linked immunosorbent assay before and after rating their pain during the cold pressor test. Participants used a visual analog scale to indicate how the 2℃ water was perceived, ranging from “worst pain imaginable” to “no pain.” The researcher also noted whether a participant displayed overt behavioral expressions of pain such as jumping and cursing. The results revealed that men reported lower visual analog scale scores than women, indicating less perceived pain. A subgroup of women who displayed overt behavioral responses to pain seemed to be driving this sex/gender difference. It was expected that this subgroup of females would have corresponding changes in testosterone that would further explain the observed sex/gender differences, but this was not supported. Collectively, these data add to the previous literature investigating sex/gender differences in pain perception and highlight the importance of studying overt behavioral expressions of pain. Testosterone may alter this behavior and subsequent pain perception, but the contributions of testosterone are likely subtle and were not detected in this study.

Multifaceted Sexual Desire and Hormonal Associations: Accounting for Social Location, Relationship Status, and Desire Target

Sexual desire is typically measured as a unitary erotic phenomenon and is often assumed by biological and biomedical researchers, as well as the lay public, to be directly connected to physiological parameters like testosterone (T). In the present study, we empirically examined how conceptualizing sexual desire as multifaceted might clarify associations with T and contextual variables. To do so, we used the Sexual Desire Questionnaire (DESQ), which assesses multifaceted dyadic sexual desire, to explore how contextual variables such as social location, relationship status, and desire target (e.g., partner vs. stranger) might be meaningful for reports of sexual desire and associated hormonal correlations. We focused on women (N = 198), because sexual desire and testosterone are generally unlinked in healthy men. Participants imagined a partner or stranger while answering the 65 DESQ items and provided a saliva sample for hormone assay. Analyses showed that the DESQ factored differently for the current sample than in previous research, highlighting how sexual desire can be constructed differently across different populations. We also found that, for the Intimacy, Eroticism, and Partner Focus factors, mean scores were higher when the desire target was a partner relative to a stranger for participants in a relationship, but equally high between partner versus stranger target for single participants. DESQ items resolved into meaningful hormonal desire components, such that high endorsement of Fantasy Experience was linked to higher T, and higher cortisol was linked with lower endorsement of the Intimacy factor. We argue that conceptualizing desire as multifaceted and contextualized when assessing hormonal links-or questions in general about desire-can clarify some of its complexities and lead to new research avenues.

Biological Sex, Gender, and Public Policy

Policy debates have focused on who can participate in or access single-sex activities or services. This article describes how science of the biology of sex is relevant to three major policy areas: parenting (including leaves), sports, and public spaces. We focus on what scientists know about sex and gender (and gender/sex, where gender and sex are intertwined), and the role of various biological factors, including hormones such as testosterone and estradiol as well as genetics, gonads, genitals, and more. The policies under debate often use “biological sex,” but this fails to account for scientific understandings of sex and gender, misrepresents sex as single-faceted and binary, and overlooks scientific consensus about the importance of gender and identity.

How Did Erectile Dysfunction Become "Natural"? A Review of the Critical Social Scientific Literature on Medical Treatment for Male Sexual Dysfunction

This article reviews the multidisciplinary social science literature assessing the social consequences of medical treatment for male sexual dysfunction. This literature applies medicalization theory and social constructionist approaches to gender to assert that Euro-American cultural ideals of masculinity and sexuality, as well as ageism and ableism, determine which sexual changes and experiences get defined as "dysfunction" and shape the marketing and use of medical treatments for those changes. These medical responses assuage the suffering of men who become unable to meet cultural ideals for sexuality but in the process make reductive norms for male sexuality seem biologically natural. In addition, the critical social science research suggests that an economic logic underlies the process of redefining diversity and change in men's sexual function as medical pathology. However, comparative qualitative data on men's and their sexual partners' experiences of sexuality and aging across world regions suggest that people do not universally accept the narrow ideals of male sexuality embedded in medical discourse regarding men's sexual dysfunction. The diversity in people's sexual desires across the life course and their responses to sexual function change highlight the cultural nature of medical definitions of sexual dysfunction.

A review of human male field studies of hormones and behavioral reproductive effort

The purpose of this paper is to review field studies of human male hormones and reproductive behavior. We first discuss life history theory and related conceptual considerations. As illustrations, distinctive features of human male life histories such as coalitional aggression, long-term partnering and paternal care are noted, along with their relevance to overall reproductive effort and developmental plasticity. We address broad questions about what constitutes a human male field study of hormones and behavior, including the kinds of hormone and behavioral measures employed in existing studies. Turning to several sections of empirical review, we present and discuss evidence for links between prenatal and juvenile androgens and sexual attraction and aggression. This includes the proposal that adrenal androgens-DHEA and androstenedione-may play functional roles during juvenility as part of a life-stage specific system. We next review studies of adult male testosterone responses to competition, with these studies emphasizing men's involvement in individual and team sports. These studies show that men's testosterone responses differ with respect to variables such as playing home/away, winning/losing, and motivation. Field studies of human male hormones and sexual behavior also focus on testosterone, showing some evidence of patterned changes in men's testosterone to sexual activity. Moreover, life stage-specific changes in male androgens may structure age-related differences in sexual behavior, including decreases in sexual behavior with senescence. We overview the considerable body of research on male testosterone, partnerships and paternal care, noting the variation in social context and refinements in research design. A few field studies provide insight into relationships between partnering and paternal behavior and prolactin, oxytocin, and vasopressin. In the third section of the review, we discuss patterns, limitations and directions for future research. This includes discussion of conceptual and methodological issues future research might consider as well as opportunities for contributions in under-researched male life stages (juvenility, senescence) and hormones (e.g., vasopressin).

Preliminary Study of Testosterone and Empathy in Determining Recidivism and Antisocial Behavior

Recidivism, repeated criminal behavior after conviction and correction of prior offenses, is a costly problem across the nation. However, the contribution of empathy in determining the risk of recidivism has received limited attention, although lack of empathy has been related to antisocial personality disorder in various studies. Studies linked testosterone to aggression, antisocial behavior, and criminality, and evidence support hormonal connections between empathy and aggression. Adult male prison inmates convicted of violent or nonviolent offenses were included in a cross-sectional study of empathy, antisocial behavior, salivary testosterone, and recidivism. Subjects underwent criminal history, Empathy Quotient, Levenson Self-Report Psychopathy Scale, Beck Depression Inventory, Spielberger State-Trait Anxiety Inventory, and salivary testosterone assays. Bivariate analyses indicated multiple correlations between variables. Multivariate modeling analyses found a significant relationship between self-reported conviction number and psychopathy scale score (p = 0.013). These preliminary results suggest avenues of investigation of factors contributing to recidivism risk.

Testosterone and immune-reproductive tradeoffs in healthy women

Although testosterone (T) has been characterized as universally immunosuppressive across species and sexes, recent ecoimmunology research suggests that T's immunomodulatory effects (enhancing/suppressing) depend on the organism's reproductive context. Very little is known about the immune effects of T in healthy females, and even less about how reproductive effort modulates the immune effects of T in humans. We investigated how the interaction between endogenous T and sexual activity predicted menstrual cycle-related changes in several measures of immunity: inflammation (indexed by interleukin-6, IL-6), adaptive immunity (indexed by immunoglobulin A, IgA), and functional immunity (indexed by bactericidal assay). Thirty-two healthy women (sexually abstinent, N=17; sexually active with one male partner, N=15) provided saliva samples at four points in the menstrual cycle: menses, follicular, ovulation, and luteal phases. Among sexually abstinent women, T was positively associated with IL-6 across the cycle; for sexually active women, however, T was positively associated with IL-6 in the luteal phase only, and negatively associated with IL-6 at ovulation. High T predicted higher IgA among women who reported infrequent intercourse, but lower IgA among women who reported very frequent intercourse. Finally, across groups, T was positively associated with greater bacterial killing at menses, but negatively associated in the luteal phase. Overall, rather than being universally immunosuppressive, T appeared to signal immunomodulation relevant to reproduction (e.g., lowering inflammation at ovulation, potentially preventing immune interference with conception). Our findings support the hypothesis that the immunomodulatory effects of endogenous T in healthy females depend on sexual and reproductive context.

Incorporating Sex As a Biological Variable in Neuropsychiatric Research: Where Are We Now and Where Should We Be?

Understanding the multiplicity of ways in which sex can alter the brain is essential to crafting policies and treatments that are beneficial for all human beings. This is particularly true for the field of neuropsychopharmacology, as many neuropsychiatric disorders exhibit gender bias in the frequency, severity, or response to treatment. The goal of this circumspective is to provide two views on the current state of the art of the relations between sex and the brain, relations that are studied almost exclusively by comparing females and males on specific end points, from gene expression to behavior. We start by suggesting a framework for defining what is being measured and what it means. We suggest that 'sex differences' can be classified on four dimensions: (1) persistent vs transient across the lifespan; (2) context independent vs dependent; (3) dimorphic vs continuous; and (4) a direct vs an indirect consequence of sex. To accurately classify a sex difference along these dimensions, one may need to compare females and males under varied conditions. We next discuss current data on the mechanisms of sexual differentiation of the brain and on sex differences in the brain to conclude that the brain of each male and female is a mosaic of relative masculinization, feminization, and sameness, which theoretically could produce an infinite variety of individuals. We also raise the possibility that sex differences in the brain are canalized, which may act to both enhance and restrain variation between males and females. We end by discussing ways to consider sex when studying neuropsychiatric disorders.

Partnered sexual activity moderates menstrual cycle-related changes in inflammation markers in healthy women: an exploratory observational study

OBJECTIVE

To examine differences in inflammation markers in sexually active versus abstinent women and observe changes in inflammation markers across the menstrual cycle. Cycle-related immune fluctuations may have evolved to reduce interference with conception. If so, reproductively active (i.e., sexually active) women should show the most variability in cytokine expression.

DESIGN

Participants provided serum samples at menses and ovulation (from which cytokines were assayed) and saliva samples at menses and during follicular, ovulation, and luteal phases (from which C-reactive protein [CRP] was assayed). Participants self-reported intercourse frequency during the study.

SETTING

Academic research laboratory.

PATIENT(S)

Thirty-two healthy, naturally cycling premenopausal women (sexually active, n = 15; abstinent, n = 17).

INTERVENTION(S)

Observational study.

MAIN OUTCOME MEASURE(S)

Levels of proinflammatory cytokines (interleukin-6 [IL-6], interferon γ [IFN-γ], tumor necrosis factor-α [TNF-α]), an anti-inflammatory cytokine (interleukin-4 [IL-4]), and a marker of total inflammation (CRP).

RESULT(S)

Sexually active women had higher levels of all of the immune markers measured, including both pro- and anti-inflammatory cytokines, than abstinent women. Relative to sexually active women, abstinent women had less change across the menstrual cycle in levels of CRP. Among sexually active women, higher intercourse frequency predicted greater midcycle decreases in CRP, IL-6, and IFN-γ and midcycle increases in IL-4.

CONCLUSION(S)

Sexual activity may stimulate a complex interaction between pro- and anti-inflammatory cytokines that subsequently drives midcycle declines in inflammation.

Salivary Testosterone Levels and Health Status in Men and Women in the British General Population: Findings from the Third National Survey of Sexual Attitudes and Lifestyles (Natsal-3)

CONTEXT

Salivary T (Sal-T) measurement by liquid chromatography-tandem mass spectroscopy resents the opportunity to examine health correlates of Sal-T in a large-scale population survey.

OBJECTIVE

This study sought to examine associations between Sal-T and health-related factors in men and women age 18-74 years.

DESIGN AND SETTING

Morning saliva samples were obtained from participants in a cross-sectional probability-sample survey of the general British population (Natsal-3). Self-reported health and lifestyle questions were administered as part of a wider sexual health interview.

PARTICIPANTS

Study participants included 1599 men and 2123 women.

METHODS

Sal-T was measured using liquid chromatography-tandem mass spectroscopy. Linear regression was used to examine associations between health factors and mean Sal-T.

RESULTS

In men, mean Sal-T was associated with a range of health factors after age adjustment, and showed a strong independent negative association with body mass index (BMI) in multivariable analysis. Men reporting cardiovascular disease or currently taking medication for depression had lower age-adjusted Sal-T, although there was no association with cardiovascular disease after adjustment for BMI. The decline in Sal-T with increasing age remained after adjustment for health-related factors. In women, Sal-T declined with increasing age; however, there were no age-independent associations with health-related factors or specific heath conditions with the exception of higher Sal-T in smokers.

CONCLUSIONS

Sal-T levels were associated, independently of age, with a range of self-reported health markers, particularly BMI, in men but not women. The findings support the view that there is an age-related decline in Sal-T in men and women, which cannot be explained by an increase in ill health. Our results demonstrate the potential of Sal-T as a convenient measure of tissue androgen exposure for population research.

Identification with Stimuli Moderates Women's Affective and Testosterone Responses to Self-Chosen Erotica

Sexual thoughts are sufficient to increase testosterone (T) in women, yet erotic films are not. A key confound in past studies is autonomy in stimulus selection: women choose the content of their sexual thoughts but films have been selected by researchers. We hypothesized that self-chosen erotic films, compared to researcher-chosen erotic films, would (1) increase women's self-reported arousal, enjoyment, and identification with stimuli, and decrease negative affect; and (2) increase T. Participants (N = 116 women) were randomly assigned to a neutral documentary condition or one of three erotic film conditions: high choice (self-chosen erotica from participants' own sources), moderate choice (self-chosen erotica from films preselected by sexuality researchers), or no choice (researcher-chosen erotica). Participants provided saliva samples for T before and after viewing the film in the privacy of their homes. Compared to researcher-chosen erotica, self-chosen erotica increased self-reported arousal and enjoyment, but also unexpectedly disgust, guilt, and embarrassment. Self-chosen erotica only marginally increased identification with stimuli compared to researcher-chosen erotica. Overall, film condition did not affect T, but individual differences in identification moderated T responses: among women reporting lower levels of identification, the moderate choice condition decreased T compared to the no choice condition, but this difference was not observed among women with higher identification. These results highlight the importance of cognitive/emotional factors like identification for sexually modulated T. However, self-chosen erotica results in more ambivalent rather than unequivocally positive cognitive/emotional responses, perhaps because stigma associated with viewing erotica for women becomes more salient when choosing stimuli.

VIII. Captured in terminology: Sex, sex categories, and sex differences

Swayed by the clear distinction between male and female genitalia, the question of how far these categories extend into human biology has attracted humans for centuries. This question is sometimes being framed as whether the effects of sex are restricted to the genital organs or penetrate the entire organism. Here I argue that the two questions are not equivalent and that whereas the answer to the question, how far sex penetrates the body, is – deep down to the level of every cell, the answer to the question, how far the categories, “male” and “female”, do, is – probably nowhere beyond the genitals. That the two questions are often used interchangeably reflects the prevailing conceptualization of sex as a dichotomous system or process that exerts profound effects on other systems (e.g., the brain), leading to sexual dimorphism (i.e., two forms, male versus female) also of these systems. Here I discuss the question of whether the effects of sex result in dimorphic systems, focusing on the case of sex effects on the brain. I show that although there are sex/gender differences in brain and behavior, humans and human brains are comprised of highly variable ‘mosaics’ of features, some more prevalent in females, others more prevalent in males.

The Sexual Acceptability of Contraception: Reviewing the Literature and Building a New Concept

How contraceptives affect women's sexual well-being is critically understudied. Fortunately, a growing literature focuses on sexual aspects of contraception, especially hormonal contraception's associations with libido. However, a more holistic approach to contraceptive sexual acceptability is needed to capture the full range of women's sexual experiences. We conducted a narrative literature review of this topic, working with an original sample of 3,001 citations published from 2005 to 2015. In Part 1, we draw from a subset of this literature (264 citations) to build a new conceptual model of sexual acceptability. Aspects include macro factors (gender, social inequality, culture, and structure), relationship factors (dyadic influences and partner preferences), and individual factors (sexual functioning, sexual preferences, such as dis/inhibition, spontaneity, pleasure, the sexual aspects of side effects, such as bleeding, mood changes, sexual identity and sexual minority status, and pregnancy intentions). In Part 2, we review the empirical literature on the sexual acceptability of individual methods (103 citations), applying the model as much as possible. Results suggest contraceptives can affect women's sexuality in a wide variety of positive and negative ways that extend beyond sexual functioning alone. More attention to sexual acceptability could promote both women's sexual well-being and more widespread, user-friendly contraceptive practices.

Effects of gendered behavior on testosterone in women and men

Testosterone is typically understood to contribute to maleness and masculinity, although it also responds to behaviors such as competition. Competition is crucial to evolution and may increase testosterone but also is selectively discouraged for women and encouraged for men via gender norms. We conducted an experiment to test how gender norms might modulate testosterone as mediated by two possible gender→testosterone pathways. Using a novel experimental design, participants (trained actors) performed a specific type of competition (wielding power) in stereotypically masculine vs. feminine ways. We hypothesized in H1 (stereotyped behavior) that wielding power increases testosterone regardless of how it is performed, vs. H2 (stereotyped performance), that wielding power performed in masculine but not feminine ways increases testosterone. We found that wielding power increased testosterone in women compared with a control, regardless of whether it was performed in gender-stereotyped masculine or feminine ways. Results supported H1 over H2: stereotyped behavior but not performance modulated testosterone. These results also supported theory that competition modulates testosterone over masculinity. Our findings thus support a gender→testosterone pathway mediated by competitive behavior. Accordingly, cultural pushes for men to wield power and women to avoid doing so may partially explain, in addition to heritable factors, why testosterone levels tend to be higher in men than in women: A lifetime of gender socialization could contribute to "sex differences" in testosterone. Our experiment opens up new questions of gender→testosterone pathways, highlighting the potential of examining nature/nurture interactions and effects of socialization on human biology.

Interaction of menstrual cycle phase and sexual activity predicts mucosal and systemic humoral immunity in healthy women

Several studies have documented shifts in humoral immune parameters (e.g., immunoglobulins) across the menstrual cycle in healthy women. It is thought that these shifts may reflect dynamic balancing between reproduction and pathogen defense, as certain aspects of humoral immunity may disrupt conception and may be temporarily downregulated at ovulation. If so, one could expect maximal cycle-related shifts of humoral immunity in individuals invested in reproduction - that is, women who are currently sexually active - and less pronounced shifts in women who are not reproductively active (i.e., abstinent). We investigated the interaction of sexual activity, menstrual cycle phase, and humoral immunity in a sample of 32 healthy premenopausal women (15 sexually active, 17 abstinent). Participants provided saliva samples during their menses, follicular phase, ovulation (as indicated by urine test for LH surge), and luteal phase, from which IgA was assayed. Participants also provided blood samples at menses and ovulation, from which IgG was assayed. Sexually active participants provided records of their frequency of sexual activity as well as condom use. At ovulation, sexually active women had higher IgG than abstinent women (d=0.77), with women reporting regular condom use showing larger effects (d=0.63) than women reporting no condom use (d=0.11). Frequency of sexual activity predicted changes in IgA (Cohen's f(2)=0.25), with women reporting high frequency of sexual activity showing a decrease in IgA at ovulation, while women reporting low frequency or no sexual activity showing an increase in IgA at ovulation. Taken together, these findings support the hypothesis that shifts in humoral immunity across the menstrual cycle are associated with reproductive effort, and could contribute to the mechanisms by which women's physiology navigates tradeoffs between reproduction and immunity.