Perinatal testosterone exposure and autistic-like traits in the general population: a longitudinal pregnancy-cohort study

Maternal Steroid Hormone Levels in Early Pregnancy and Autism in the Offspring: A Population-Based, Nested Case-Control Study

BACKGROUND

A role for prenatal steroid hormones in the etiology of autism has been proposed, but evidence is conflicting.

METHODS

Here, we examined serum levels of maternal estradiol, testosterone, 17-hydroxyprogesterone (OHP), and cortisol from the first trimester of gestation (mean = 10.1 weeks) in relation to the odds of diagnosed autism with and without co-occurring intellectual disability (ID) in the offspring (n = 118 autism with ID, n = 249 autism without ID, n = 477 control). Levels of maternal hormones were measured using highly sensitive liquid chromatography tandem mass spectrometry, standardized according to gestational timing of sample collection, and analyzed with restricted cubic spline logistic regression models adjusting for child's sex and maternal health, demographic, and socioeconomic factors.

RESULTS

We observed significant nonlinear associations between maternal estradiol, 17-OHP, and cortisol with autism, which varied with the presence of co-occurring ID. Compared to mean levels, lower levels of estradiol were associated with higher odds of autism with ID (odds ratio for concentrations 1 SD below the mean = 1.66; 95% CI, 1.24-2.11), while higher cortisol levels were associated with lower odds (odds ratio for 1 SD above the mean = 0.55; 95% CI, 0.36-0.88). In contrast, higher 17-OHP was associated with increased odds of autism without ID (odds ratio for 1 SD above the mean = 1.49; 95% CI, 1.11-1.99). We observed no evidence for interaction with sex of the child.

CONCLUSIONS

These findings support the notion that the maternal steroid hormonal environment in early pregnancy may contribute to autism, but also emphasize the complex relationship between early-life steroid exposure and autism.

The role of androgens and estrogens in social interactions and social cognition

Gonadal hormones are becoming increasingly recognized for their effects on cognition. Estrogens, in particular, have received attention for their effects on learning and memory that rely upon the functioning of various brain regions. However, the impacts of androgens on cognition are relatively under investigated. Testosterone, as well as estrogens, have been shown to play a role in the modulation of different aspects of social cognition. This review explores the impact of testosterone and other androgens on various facets of social cognition including social recognition, social learning, social approach/avoidance, and aggression. We highlight the relevance of considering not only the actions of the most commonly studied steroids (i.e., testosterone, 17β-estradiol, and dihydrotestosterone), but also that of their metabolites and precursors, which interact with a plethora of different receptors and signalling molecules, ultimately modulating behaviour. We point out that it is also essential to investigate the effects of androgens, their precursors and metabolites in females, as prior studies have mostly focused on males. Overall, a comprehensive analysis of the impact of steroids such as androgens on behaviour is fundamental for a full understanding of the neural mechanisms underlying social cognition, including that of humans.

Prenatal Androgen Exposure and Traits of Autism Spectrum Disorder in the Offspring: Odense Child Cohort

Fetal androgen exposure may be associated with autism spectrum disorder (ASD). We studied 1777 mother-child pairs in the prospective Odense Child Cohort. Prenatal androgen exposure was assessed by maternal 3rd trimester testosterone concentrations, maternal polycystic ovary syndrome (PCOS), and 3 months offspring anogenital distance. ASD traits were assessed at age 3 years with the ASD-symptom scale of the Child Behavior Checklist for ages 1½-5 years. Maternal testosterone was positively associated with traits of ASD in boys (p < 0.05). Maternal PCOS was associated with increased offspring ASD traits (p = 0.046), but became non-significant after excluding parental psychiatric diagnosis. Offspring anogenital distance was not linked to ASD traits. Higher prevalence of ASD in boys could be linked to higher susceptibility to fetal androgen exposure.

Sex Differences in Neurodevelopmental Disorders: A Key Role for the Immune System

Sex differences are prominent defining features of neurodevelopmental disorders. Understanding the sex biases in these disorders can shed light on mechanisms leading to relative risk and resilience for the disorders, as well as more broadly advance our understanding of how sex differences may relate to brain development. The prevalence of neurodevelopmental disorders is increasing, and the two most common neurodevelopmental disorders, Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) exhibit male-biases in prevalence rates and sex differences in symptomology. While the causes of neurodevelopmental disorders and their sex differences remain to be fully understood, increasing evidence suggests that the immune system plays a critical role in shaping development. In this chapter we discuss sex differences in prevalence and symptomology of ASD and ADHD, review sexual differentiation and immune regulation of neurodevelopment, and discuss findings from human and rodent studies of immune dysregulation and perinatal immune perturbation as they relate to potential mechanisms underlying neurodevelopmental disorders. This chapter will give an overview of how understanding sex differences in neuroimmune function in the context of neurodevelopmental disorders could lend insight into their etiologies and better treatment strategies.

Maternal androgens and autism spectrum disorder in the MARBLES prospective cohort study

Background

Maternal hormonal risk factors for autism spectrum disorder (ASD) in offspring could intersect genetic and environmental risk factors.

Objectives

This analysis explored ASD risk in association with maternal testosterone, androstenedione, and dehydroepiandrosterone (DHEA) measured in first, second, and third trimesters of pregnancy.

Methods

MARBLES is a prospective pregnancy cohort study based at the MIND Institute in Northern California that enrolls mothers who have at least one child previously diagnosed with ASD and are expecting, or planning to have another child. At 36 months the younger sibling is clinically classified as having ASD, or as non-typically developing (Non-TD), or typically developing (TD). Maternal androgens during pregnancy were measured in serum samples from 196 mothers. Multivariable logistic regression models estimated risk of ASD and Non-TD in offspring compared to TD, in relation to the log-transformed maternal androgen concentrations, at each trimester.

Results

Non-significant associations were observed, and borderline significant associations were only observed in some stratified unadjusted models. Second trimester maternal testosterone was non-significantly associated with ASD in female offspring, although not after adjustment, aRR 1.54 (95% CI 0.71, 3.33), and second trimester maternal DHEA was non-significantly associated with non-TD in male offspring, again not after adjustment, aRR 0.50 (95% CI 0.21, 1.21). Secondary analysis suggested that third trimester androgen concentrations in mothers with male offspring had significant or near significant associations with their child's Social Responsiveness Scale score.

Conclusion

No significant associations were found between maternal androgen concentrations and risk of ASD or Non-TD in the child.

A longitudinal examination of perinatal testosterone, estradiol and vitamin D as predictors of handedness outcomes in childhood and adolescence

The developmental origins of handedness remain elusive, though very early emergence suggests individual differences manifesting in utero could play an important role. Prenatal testosterone and Vitamin D exposure are considered, yet findings and interpretations remain equivocal. We examined n = 767 offspring from a population-based pregnancy cohort (The Raine Study) for whom early biological data and childhood/adolescent handedness data were available. We tested whether 18-week maternal circulatory Vitamin D (25[OH]D), and testosterone and estradiol from umbilical cord blood sampled at birth predicted variance in direction of hand preference (right/left), along with right- and left-hand speed, and the strength and direction of relative hand skill as measured by a finger-tapping task completed at 10 (Y10) and/or 16 (Y16) years. Although higher concentrations of Vitamin D predicted more leftward and less lateralized (regardless of direction) relative hand skill profiles, taken as a whole, statistically significant findings typically did not replicate across time-point (Y10/Y16) or sex (male/female) and were rarely detected across different (bivariate/multivariate) levels of analysis. Considering the number of statistical tests and generally inconsistent findings, our results suggest that perinatal testosterone and estradiol contribute minimally, if at all, to subsequent variance in handedness. Vitamin D, however, may be of interest in future studies.

Salivary testosterone in male and female youth with and without autism spectrum disorder: considerations of development, sex, and diagnosis

BACKGROUND

Puberty is characterized by significant physical, hormonal, and psychological changes, which may be especially challenging for individuals with autism spectrum disorder (ASD). Although the etiology of ASD remains uncertain, studies suggest imbalances in hormones, such as testosterone, may modulate the autism phenotype. While differences in fetal and postnatal testosterone have been reported, there is limited literature regarding testosterone variations during adolescence in ASD. We investigated morning salivary testosterone levels in youth with ASD and typical development (TD) to explore hypothesized differences, expecting elevated hormonal levels in ASD compared to TD.

METHODS

Youth with ASD (n = 140) and TD (n = 104), ages 10 to 13 years, were enrolled as part of a longitudinal study on pubertal development. Pubertal stage was determined by gold standard physical examination, and salivary testosterone was collected in the morning immediately upon waking and 30 min after waking and averaged across 3 days. Diagnostic (ASD/TD) and sex (male/female) differences, as well as interactions with age and puberty, were examined using robust linear mixed effect models.

RESULTS

Youth with ASD showed significantly elevated testosterone concentrations compared to same-age TD peers. After the inclusion of natural cubic splines to account for nonlinearity in age, a significant age-by-sex interaction emerged with distinct developmental slopes for males and females. At younger ages, females had higher testosterone, until about 11.5 years of age, when levels began to plateau, while male testosterone concentrations continued to rapidly increase and surpass females. As expected, more advanced pubertal development was associated with elevated testosterone. In contrast, no significant effect of parent-reported social communication symptoms was observed.

LIMITATIONS

Limitations include an unequal sex distribution, non-representative sample (e.g., cognition and race/ethnicity), and inability to examine afternoon/evening testosterone due to detection limits.

CONCLUSIONS

Testosterone may play a unique role in the presentation of ASD, especially during periods of dynamic hormonal changes including puberty. Inherent developmental (age, puberty) and sex-based (male, female) factors play a more prominent role in changes in testosterone levels during adolescence. Even so, future research is warranted to determine the differential expression and impact of exposure to excess testosterone during the pubertal transition for youth with ASD.

Elevated prenatal maternal sex hormones, but not placental aromatase, are associated with child neurodevelopment

Fetal exposure to testosterone may contribute to vulnerability for autism spectrum disorder (ASD). It is hypothesized that placental aromatase prevents fetal exposure to maternal testosterone, however, this pathway and the implications for child neurodevelopment have not been fully explored. We examined the relationships between prenatal maternal testosterone and estradiol at 19.2 ± 1.3 weeks, cord blood testosterone and estradiol at birth, placental aromatase mRNA expression, and neurodevelopment using the Social Communication Questionnaire (SCQ), the Behavioral Assessment System for Children, 3rd Edition (BASC-3), and the Empathizing Quotient for Children (EQ-C) at 4.5-6.5 years of age in a sample of 270 Nulliparous-Mothers-to-be (nuMoM2b) study participants. Maternal testosterone levels were positively associated with SCQ scores, but the association was not significant after adjusting for maternal age at delivery, nor was there a significant interaction with sex. Maternal estradiol levels were negatively associated with BASC-3 Clinical Probability scores among males (n = 139). We report a significant interaction effect of cord blood testosterone and fetal sex on both total SCQ scores and t-scores on the Developmental Social Disorders subscale. Placental aromatase was not associated with any neurodevelopmental or hormone measure, but under conditions of low placental aromatase expression, high maternal testosterone was positively associated with SCQ scores in males (n = 46). No other associations between hormone levels and neurodevelopment were significant. Our findings provide a foundation for further investigation of the mechanisms through which maternal sex hormones and placental steroidogenesis may affect fetal hormone production and neurobehavior.

An investigation of a novel broad autism phenotype: increased facial masculinity among parents of children on the autism spectrum

The broad autism phenotype commonly refers to sub-clinical levels of autistic-like behaviour and cognition presented in biological relatives of autistic people. In a recent study, we reported findings suggesting that the broad autism phenotype may also be expressed in facial morphology, specifically increased facial masculinity. Increased facial masculinity has been reported among autistic children, as well as their non-autistic siblings. The present study builds on our previous findings by investigating the presence of increased facial masculinity among non-autistic parents of autistic children. Using a previously established method, a 'facial masculinity score' and several facial distances were calculated for each three-dimensional facial image of 192 parents of autistic children (58 males, 134 females) and 163 age-matched parents of non-autistic children (50 males, 113 females). While controlling for facial area and age, significantly higher masculinity scores and larger (more masculine) facial distances were observed in parents of autistic children relative to the comparison group, with effect sizes ranging from small to medium (0.16 ≤ d ≤ .41), regardless of sex. These findings add to an accumulating evidence base that the broad autism phenotype is expressed in physical characteristics and suggest that both maternal and paternal pathways are implicated in masculinized facial morphology.

No effects of siblings and twin testosterone transfer on autistic traits

Background

Having twin and non-twin siblings might influence autistic traits both prenatally and postnatally. The twin testosterone transfer hypothesis suggests that girls with a twin brother are exposed to higher levels of prenatal testosterone than girls with a twin sister, and that increased testosterone exposure masculinizes neural development and increases autistic traits. Postnatally, siblings may provide example behaviour, which could reduce autistic traits.

Methods

We studied pre- and postnatal influences of twin and non-twin siblings on mother and teacher-reported autistic traits in 7714 dizygotic twins. We examined the effect of sex of the proband child and of the siblings. We fitted regression models (for boys and girls separately) with sex of co-twin and having older and/or younger siblings of each sex as predictors.

Results

Girls' mother-reported autistic traits were slightly lower for those with a twin brother than those with a twin sister (β = -.08, p = .001, Cohen's d = -.13). This difference was not replicated in teacher-reported autistic traits (β = .01, p = .734). Boys' (mother and teacher-reported) autistic traits were not related to the sex of their co-twin (ps > 0.50). Teacher-reported autistic traits were slightly higher if girls had an older brother (β = .07, p = .013, Cohen's d = .12). Other than this small effect, we found no effect of non-twin siblings on autistic traits in either girls or boys (ps > .18).

Conclusions

We did not find increased autistic traits in girls with a twin brother compared to girls with a twin sister. This finding contributes to a body of literature that rejects the twin testosterone transfer hypothesis. In addition, we found little evidence for pre- and postnatal sibling influences. Our findings align with high heritability and absence of shared-environmental influences in ASD.

Is there an association between prenatal testosterone and autistic traits in adolescents?

Prenatal testosterone (pT) is a crucial component in physiological masculinization in humans. In line with the Prenatal Sex Steroid Theory of autism, some studies have found a positive correlation between pT and autistic traits in childhood. However, effects in adolescence have not been explored. Hormonal and environmental changes occurring during puberty may alter the strength or the nature of prenatal effects on autistic traits. The current study examines if pT relates to autistic traits in a non-clinical sample of adolescents and young adults (N = 97, 170 observations; age 13-21 years old). It also explores pT interactions with pubertal stage and timing. PT concentrations were measured from amniotic fluid extracted in the 2nd trimester of gestation via amniocentesis conducted for clinical purposes. Autistic traits were measured by self- and parent-reports on the Autism Spectrum Quotient (AQ) which provides a total score and 5 sub-scores (social skills, communication, imagination, attention switching and attention to detail). Self-reported pubertal stage was regressed on age to provide a measure of relative timing. We found no statistical evidence for a direct association between pT and autistic traits in this adolescent sample (males, females or full sample). Exploratory analyses suggested that pT correlated positively with autistic traits in adolescents with earlier puberty-onset, but statistical robustness of this finding was limited. Further exploratory post-hoc tests suggested the pT-by-pubertal timing interaction was stronger in males relative to females, in self-reported compared to parent-reported AQ and specifically for social traits. These findings require replication in larger samples. Findings have implications for understanding the effects of pT on human behavior, specifically existence of effects in adolescence.

A systematic review and meta-analysis of the association between maternal polycystic ovary syndrome and neuropsychiatric disorders in children

There is emerging evidence demonstrating an association between maternal polycystic ovary syndrome (PCOS) and autism spectrum disorder (ASD) in children, however, the cumulative effect of maternal PCOS on the development of ASD or other neuropsychiatry disorders (NPD) in children and separately for males and females has not been examined. We sought to systematically evaluate the influence of maternal PCOS on a wide range of NPD including ASD, attention deficit hyperactivity disorder (ADHD), chronic tic disorder (CDT), other behavior disorders, anxiety, depression, bipolar disorder, schizophrenia in children as well as in women of reproductive age only. We queried electronic databases including PubMed, EMBASE, and Google Scholar, until March 2021. We used DerSimonian and Laird (D-L) random effects method to compute pooled effect size in terms of odds ratio (OR). Nineteen studies (1667851 mothers, 2260622 children) were included in this study. Mothers with PCOS had an increased odds of children diagnosed with ASD (OR = 1.40, p < 0.001), ADHD (OR = 1.42, p < 0.001), CTD (OR = 1.44, p = 0.001), anxiety (OR = 1.33, p < 0.001), as well as other behavioral symptoms (OR = 1.45, p < 0.001) in the adjusted analysis. The association between maternal PCOS and ASD (OR: 1.43 vs. 1.66), ADHD (OR: 1.39 vs. 1.54), and CTD (OR: 1.42 vs. 1.51) was found to be significantly consistent between males and females, respectively. Our data do not suggest increased fetal testosterone exposure is associated with increased autistic traits in children. However, PCOS was significantly associated with increased odds of a wide range of NPD in women themselves. Maternal PCOS is a risk factor for various NPD with a similar extent in their children regardless of their underlying comorbidities. Managing PCOS is essential for women's health as well as for their children's health. More research is needed to determine the mechanisms and links between maternal PCOS and NPD in children.

Brief Report: Facial Asymmetry and Autistic-Like Traits in the General Population

Atypical facial morphology, particularly increased facial asymmetry, has been identified in some individuals with Autism Spectrum Conditions (ASC). Many cognitive, behavioural and biological features associated with ASC also occur on a continuum in the general population. The aim of the present study was to examine subthreshold levels of autistic traits and facial morphology in non-autistic individuals. Facial asymmetry was measured using three-dimensional facial photogrammetry, and the Autism-spectrum Quotient was used to measure autistic-like traits in a community-ascertained sample of young adults (n = 289). After accounting for covariates, there were no significant associations observed between autistic-like traits and facial asymmetry, suggesting that any potential facial morphology differences linked to ASC may be limited to the clinical condition.

No relationship between prenatal or early postnatal androgen exposure and autistic traits: evidence using anogenital distance and penile length measurements at birth and 3 months of age

BACKGROUND

Autism is more prevalent in males than in females. Hypotheses related to the extreme male brain theory of autism suggest that heightened androgen exposure during early development contributes to autistic traits. Whilst prior research focused mostly on the prenatal period, the current study tests the influences of androgen exposure during both the prenatal and the early postnatal periods on autistic traits during childhood.

METHODS

Anthropometric measures that are putative biomarkers of early androgen exposure were employed. Anogenital distance (AGD) was measured at birth and 3 months of age in boys and girls. Penile length at birth and 3 months of age was also measured in boys. When the children were 9-13 years old, a parent-reported questionnaire (the 10-item children's version of the Autism Spectrum Quotient; AQ-10 Child) was used to assess autistic traits in 97 boys and 110 girls.

RESULTS

There were no significant associations between any of the AGD or penile length measures and scores on the AQ-10 Child in boys, girls or the entire sample.

CONCLUSIONS

The current study provides the first test of whether early measurements of AGD and/or penile length predict subsequent autistic traits. The current findings do not support a relationship between prenatal or early postnatal androgen exposure and autistic traits. The current study augments prior research showing no consistent relationship between early androgen exposure and autistic traits.

Medical symptoms and conditions in autistic women

The sex bias in autism diagnosis suggests the involvement of sex-specific endocrine mechanisms during prenatal development, but these hormones affect health throughout life. Therefore, the current study examined the association of autism and autistic traits with conditions and symptoms related to the sex-steroid system in adult women. In total, 1230 women (361 autistic), aged 15–77 years, reported on autistic traits and medical history. Medical diagnoses and symptoms were grouped by unsupervised factor analysis, and associations with autism diagnosis and autistic traits were explored. Higher rates of reproductive system diagnoses (odds ratio = 1.035, p = 0.024), prediabetes symptoms (odds ratio = 1.319, p = 0.001), irregular puberty onset (odds ratio = 1.458, p = 0.009), and menstrual length (odds ratio = 1.368, p = 0.034) and lower rates of metabolic and vascular conditions (odds ratio = 0.654, p = 0.013) were associated with diagnosis. Reproductive system diagnoses (β = 0.114, p = 0.000), prediabetes symptoms (β = 0.188, p = 0.000), menstrual length (β = 0.071, p = 0.014), irregular puberty onset (β = 0.149, p = 0.000), excessive menstruation symptoms (β = 0.097, p = 0.003), and hyperandrogenism symptoms (β = 0.062, p = 0.040) were also associated with autistic traits. Many of the conditions and symptoms found to be associated with autism or autistic traits are also related to conditions of steroid hormones and, specifically, the sex-steroid system. The study suggests an important role for steroids in autistic women, beyond prenatal development. Clinical implications are discussed.

Genetic and morphological estimates of androgen exposure predict social deficits in multiple neurodevelopmental disorder cohorts

BACKGROUND

Neurodevelopmental disorders (NDDs) such as autism spectrum disorder (ASD) display a strong male bias. Androgen exposure is profoundly increased in typical male development, but it also varies within the sexes, and previous work has sought to connect morphological proxies of androgen exposure, including digit ratio and facial morphology, to neurodevelopmental outcomes. The results of these studies have been mixed, and the relationships between androgen exposure and behavior remain unclear.

METHODS

Here, we measured both digit ratio masculinity (DRM) and facial landmark masculinity (FLM) in the same neurodevelopmental cohort (N = 763) and compared these proxies of androgen exposure to clinical and parent-reported features as well as polygenic risk scores.

RESULTS

We found that FLM was significantly associated with NDD diagnosis (ASD, ADHD, ID; all [Formula: see text]), while DRM was not. When testing for association with parent-reported problems, we found that both FLM and DRM were positively associated with concerns about social behavior ([Formula: see text], [Formula: see text]; [Formula: see text], [Formula: see text], respectively). Furthermore, we found evidence via polygenic risk scores (PRS) that DRM indexes masculinity via testosterone levels ([Formula: see text], [Formula: see text]), while FLM indexes masculinity through a negative relationship with sex hormone binding globulin (SHBG) levels ([Formula: see text], [Formula: see text]). Finally, using the SPARK cohort (N = 9419) we replicated the observed relationship between polygenic estimates of testosterone, SHBG, and social functioning ([Formula: see text], [Formula: see text], and [Formula: see text], [Formula: see text] for testosterone and SHBG, respectively). Remarkably, when considered over the extremes of each variable, these quantitative sex effects on social functioning were comparable to the effect of binary sex itself (binary male: [Formula: see text]; testosterone: [Formula: see text] from 0.1%-ile to 99.9%-ile; SHBG: [Formula: see text] from 0.1%-ile to 99.9%-ile).

LIMITATIONS

In the devGenes and SPARK cohorts, our analyses rely on indirect, rather than direct measurement of androgens and related molecules.

CONCLUSIONS

These findings and their replication in the large SPARK cohort lend support to the hypothesis that increasing net androgen exposure diminishes capacity for social functioning in both males and females.

Associations Between Hormonal Biomarkers and Preterm Infant Health and Development During the First 2 Years After Birth

BACKGROUND

Testosterone levels have been used to examine infant boys' vulnerability to health and developmental problems, following the general theories of gender differences and the theory of extreme male brain of autism.

OBJECTIVES

As testosterone is a representative androgen hormone and is higher in preterm than full-term infants, we used this steroid to determine if hypothalamic pituitary hormones, testosterone, and cortisol, were related to physical growth, health, and development of very-low-birthweight (VLBW, BW < 1,500 g) infants.

METHOD

For this comparative longitudinal study, 40 VLBW infants were recruited from a neonatal intensive care unit of a tertiary medical center. Data were collected from medical record reviews, questionnaires, and assessments of infant development at 6, 12, and 24 months. We collected saliva at the three time points and measured hormones using enzyme-immunoassays.

RESULTS

General and generalized mixed models showed that a 1pg/ml increment of testosterone was related to a -0.42% decrease in body weight, a -0.18% decrease in length, and a -0.10% decrease in head circumference. Cortisol levels were not associated with any outcome variable. The interactions between testosterone and time on physical growth and socioemotional development also occurred.

DISCUSSION

Elevated testosterone levels can be a biological risk factor for poor infant growth and development. Theories about the effects of elevated prenatal testosterone could be useful in predicting health and developmental outcomes among VLBW infants. Research beyond the first 2 years will be needed as infants show more socioemotional and behavioral problems as they grow older.

The Prenatal Hormone Milieu in Autism Spectrum Disorder

Though the etiology of autism spectrum disorder (ASD) remains largely unknown, recent findings suggest that hormone dysregulation within the prenatal environment, in conjunction with genetic factors, may alter fetal neurodevelopment. Early emphasis has been placed on the potential role of in utero exposure to androgens, particularly testosterone, to theorize ASD as the manifestation of an "extreme male brain." The relationship between autism risk and obstetric conditions associated with inflammation and steroid dysregulation merits a much broader understanding of the in utero steroid environment and its potential influence on fetal neuroendocrine development. The exploration of hormone dysregulation in the prenatal environment and ASD development builds upon prior research publishing associations with obstetric conditions and ASD risk. The insight gained may be applied to the development of chronic adult metabolic diseases that share prenatal risk factors with ASD. Future research directions will also be discussed.

Meconium androgens are correlated with ASD-related phenotypic traits in early childhood in a familial enriched risk cohort

BACKGROUND

Prenatal exposure to increased androgens has been suggested as a risk factor for autism spectrum disorder (ASD). This hypothesis has been examined by measurement of steroids in amniotic fluid, cord blood, saliva, and blood with mixed results.

METHODS

To provide an orthogonal measure of fetal exposure, this study used meconium, the first stool of a newborn, to measure prenatal androgen exposure from infants in the Early Autism Risk Longitudinal Investigation (EARLI). EARLI is a familial-enriched risk cohort that enrolled pregnant mothers who already had a child with an ASD diagnosis. In the younger child, we investigated the association between meconium unconjugated (u) and total (t) concentrations of major androgens testosterone (T), dehydroepiandrosterone (DHEA), and androstenedione (A4), and ASD-related traits at 12 and 36 months of age. Traits were measured at 12 months with Autism Observation Scale for Infants (AOSI) and at 36 months with total score on the Social Responsiveness Scale (SRS). One hundred and seventy children had meconium and AOSI, 140 had meconium and SRS, and 137 had meconium and both AOSI and SRS.

RESULTS

Separate robust linear regressions between each of the log-transformed androgens and log-transformed SRS scores revealed three-way interaction between sex of the child, sex of the proband, and testosterone concentration. In the adjusted analyses, t-T, u-A4, and u-DHEA (P ≤ 0.01) were positively associated with AOSI scores, while u-T (P = 0.004) and u-DHEA (P = 0.007) were positively associated with SRS total score among females with female probands (n = 10). Additionally, higher concentrations of u-T (P = 0.01) and t-T (P = 0.01) predicted higher SRS total score in males with male probands (n = 63). Limitations Since we explored three-way interactions, this resulted in a limited sample size for some analyses. This study was from an enriched-risk cohort which may limit generalizability, and this study used ASD-assessment scales as outcomes instead of diagnostic categories. Additionally, the novel use of meconium in this study limits the ability to compare the results in this cohort to others due to the paucity of research on meconium.

CONCLUSIONS

This study supports the utility of meconium for studies of endogenous fetal metabolism and suggests the sex of older siblings with autism should be considered as a biological variable in relevant studies.

Human gender development

Human gender-related behavior/psychology is shaped by a developmental system that involves numerous influences interacting over time. Understanding of the full range of elements in the system and how they interact is currently incomplete. The available evidence suggests, however, that early exposure to testosterone, postnatal socialization, e.g., by parents and peers, and self-socialization related to cognitive understanding of gender are important elements. This article focuses on prenatal and early neonatal influences of testosterone on gender-related psychological/behavioral outcomes, and contextualizes these hormonal influences within an understanding of socialization influences. There is consistent evidence that early testosterone exposure influences childhood gender role behavior, including sex-typical toy play, as well as gender identity and sexual orientation. Evidence for similar hormonal influences on spatial ability and on traits related to autism, or autistic spectrum disorder, is inconsistent. Evidence from girls exposed to elevated testosterone prenatally suggests that they experience alterations in processes of external socialization, as well as self-socialization, and that these, along with early testosterone exposure, shape gender-related outcomes.

Autistic traits, systemising, empathising, and theory of mind in transgender and non-binary adults

BACKGROUND

Prior research examining autistic traits in gender minority adults has reported mixed findings. Most prior studies did not include non-binary individuals. Little is known about the mechanisms shaping autistic traits in gender minority adults. This study examined autistic traits, as well as constructs related to the extreme male brain theory of autism and the mindblindness theory, in transgender and non-binary adults.

METHODS

An online survey was conducted to assess autism-related traits in 323 gender minority adults, including 74 transgender men (individuals assigned female at birth and identify as a man), 95 transgender women (individuals assigned male at birth and identify as a woman), 104 non-binary AFAB (individuals assigned female at birth and identify as non-binary), and 50 non-binary AMAB (individuals assigned male at birth and identify as non-binary). Autistic traits, systemising, empathising, and Theory of Mind (ToM) were measured using the Autism Spectrum Quotient (AQ), the short forms of the Systemising Quotient (SQ-Short) and the Empathy Quotient (EQ-Short), the 10-item version of the Empathy Quotient (EQ-10) and the Reading the Mind in the Eyes Test (Eyes Test). Participants' scores on these measures were compared with previously published scores based on large-scale general population samples including thousands of participants.

RESULTS

On average, compared with control females in the general population samples, both transgender men and non-binary AFAB scored significantly higher on the AQ and the SQ-Short but scored significantly lower on the EQ-Short, the EQ-10, and the Eyes Test. No clear or consistent group differences emerged when transgender women and non-binary AMAB were compared with control males.

LIMITATIONS

The present study does not have a large sample of gender minority adults. It has been argued that the measures employed may not provide a precise assessment of the psychological constructs of interest. The present study has a "non-clinical" sample. However, not all gender minorities have access to or require clinical services, and so a "non-clinical" sample may be more representative of the gender minority community as a whole than samples recruited through clinics.

CONCLUSIONS

The current findings suggest a "masculinised" autism-related profile and reduced ToM in transgender men and in non-binary AFAB. These findings might be interpreted to support the extreme male brain theory of autism and the mindblindness theory. Further research is needed to corroborate these findings.

Endocrine Insights into the Pathophysiology of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a class of neurodevelopmental disorders that affects males more frequently than females. Numerous genetic and environmental risk factors have been suggested to contribute to the development of ASD. However, no one factor can adequately explain either the frequency of the disorder or the male bias in its prevalence. Gonadal, thyroid, and glucocorticoid hormones all contribute to normal development of the brain, hence perturbations in either their patterns of secretion or their actions may constitute risk factors for ASD. Environmental factors may contribute to ASD etiology by influencing the development of neuroendocrine and neuroimmune systems during early life. Emerging evidence suggests that the placenta may be particularly important as a mediator of the actions of environmental and endocrine risk factors on the developing brain, with the male being particularly sensitive to these effects. Understanding how various risk factors integrate to influence neural development may facilitate a clearer understanding of the etiology of ASD.

A broad autism phenotype expressed in facial morphology

Autism spectrum disorder is a heritable neurodevelopmental condition diagnosed based on social and communication differences. There is strong evidence that cognitive and behavioural changes associated with clinical autism aggregate with biological relatives but in milder form, commonly referred to as the 'broad autism phenotype'. The present study builds on our previous findings of increased facial masculinity in autistic children (Sci. Rep., 7:9348, 2017) by examining whether facial masculinity represents as a broad autism phenotype in 55 non-autistic siblings (25 girls) of autistic children. Using 3D facial photogrammetry and age-matched control groups of children without a family history of ASD, we found that facial features of male siblings were more masculine than those of male controls (n = 69; p < 0.001, d = 0.81 [0.36, 1.26]). Facial features of female siblings were also more masculine than the features of female controls (n = 60; p = 0.005, d = 0.63 [0.16, 1.10]). Overall, we demonstrated for males and females that facial masculinity in non-autistic siblings is increased compared to same-sex comparison groups. These data provide the first evidence for a broad autism phenotype expressed in a physical characteristic, which has wider implications for our understanding of the interplay between physical and cognitive development in humans.

Foetal oestrogens and autism

Elevated latent prenatal steroidogenic activity has been found in the amniotic fluid of autistic boys, based on measuring prenatal androgens and other steroid hormones. To date, it is unclear if other prenatal steroids also contribute to autism likelihood. Prenatal oestrogens need to be investigated, as they play a key role in synaptogenesis and corticogenesis during prenatal development, in both males and females. Here we test whether levels of prenatal oestriol, oestradiol, oestrone and oestrone sulphate in amniotic fluid are associated with autism, in the same Danish Historic Birth Cohort, in which prenatal androgens were measured, using univariate logistic regression (n = 98 cases, n = 177 controls). We also make a like-to-like comparison between the prenatal oestrogens and androgens. Oestradiol, oestrone, oestriol and progesterone each related to autism in univariate analyses after correction with false discovery rate. A comparison of standardised odds ratios showed that oestradiol, oestrone and progesterone had the largest effects on autism likelihood. These results for the first time show that prenatal oestrogens contribute to autism likelihood, extending the finding of elevated prenatal steroidogenic activity in autism. This likely affects sexual differentiation, brain development and function.

Sex/gender differences in neurology and psychiatry: Autism

Autism is a heterogenous set of early-onset neurodevelopmental conditions that are more prevalent in males than in females. Due to the high phenotypic, neurobiological, developmental, and etiological heterogeneity in the autism spectrum, recent research programs are increasingly exploring whether sex- and gender-related factors could be helpful markers to clarify the heterogeneity in autism and work toward a personalized approach to intervention and support. In this chapter, we summarize recent clinical and neuroscientific research addressing sex/gender influences in autism and explore how sex/gender-based investigations shed light on similar or different underlying neurodevelopmental mechanisms of autism by sex/gender. We review evidence that may help to explain some of the underlying sex-related biological mechanisms associated with autism, including genetics and the effects of sex steroid hormones in the prenatal environment. We conclude that current research points toward coexisting quantitative and, perhaps more evidently, qualitative sex/gender-modulation effects in autism across multiple neurobiological aspects. However, converging findings of specific neurobiological presentations and sex/gender-informed mechanisms cutting across the many subgroups within the autism spectrum are still lacking. Future research should use big data approaches and new stratification methods to decompose sex/gender-related heterogeneity in autism and work toward personalized, sex/gender-informed intervention and support for autistic people.

Sex-specific variation in facial masculinity/femininity associated with autistic traits in the general population

Reports linking prenatal testosterone exposure to autistic traits and to a masculinized face structure have motivated research investigating whether autism is associated with facial masculinization. This association has been reported with greater consistency for females than for males, in studies comparing groups with high and low levels of autistic traits. In the present study, we conducted two experiments to examine facial masculinity/femininity in 151 neurotypical adults selected for either low, mid-range, or high levels of autistic traits. In the first experiment, their three-dimensional facial photographs were subjectively rated by 41 raters for masculinity/femininity and were objectively analysed. In the second experiment, we generated 6-face composite images, which were rated by another 36 raters. Across both experiments, findings were consistent for ratings of photographs and composite images. For females, a linear relationship was observed where femininity ratings decreased as a function of higher levels of autistic traits. For males, we found a U-shaped function where males with mid-range levels of traits were rated lowest on masculinity. Objective facial analyses revealed that higher levels of autistic traits were associated with less feminine facial structures in females and less masculine structures in males. These results suggest sex-specific relationships between autistic traits and facial masculinity/femininity.

Maternal polycystic ovarian syndrome in autism spectrum disorder: a systematic review and meta-analysis

There is evidence showing a positive correlation between prenatal androgens and their effect on the development of central nervous system and the autistic spectrum disorder (ASD) phenotype in offspring of mothers with polycystic ovary syndrome (PCOS). We applied a systematic review to investigate whether women with PCOS have increased odds of having a child with ASD, while, secondarily, if these women themselves are at high risk of having the disease. Major databases from inception until 14th October 2018 were searched. The primary outcome measure was the odds of an ASD diagnosis in children of mothers with diagnosed PCOS, while the secondary outcome was the odds of ASD diagnosis in women with PCOS. Scheduled subgroup analyses were according to the time of birth and maternal age. We assessed the odds ratio (OR), using a random-effects model; heterogeneity was assessed by I² and τ² statistics. The quality of the evidence was evaluated using the Newcastle-Ottawa Scale. Ten studies were eligible for inclusion, including a total of 33,887 ASD children and 321,661 non-ASD children. Diagnosed PCOS was associated with a 1.66 times increase in the odds of ASD in the offspring [95% CI: 1.51, 1.83, p = 1.99 × 10^-25, 7 studies, I² = 0%, τ² = 0]. Women with PCOS were 1.78 times more likely to be diagnosed with ASD (95% CI: 1.10, 2.87, p = 0.0179, 5 studies, I² = 85.4%, τ² = 0.2432). Additional analyses did not change the initial result. The overall quality of the evidence was high. The pooled effects size displayed low heterogeneity (I² = 0%) for the primary outcome. While the heterogeneity in the secondary outcome appears to attenuate when only high quality studies are synthesized, still the result exhibits significant heterogeneity. Τhe available data allowed a subgroup analysis only for classification system for PCOS diagnosis and showed a significant increase of ASD diagnosis in the offspring of women with Read Code and ICD diagnosed PCOS. In conclusion, the available evidence suggests that women with PCOS have increased odds of having a child with ASD, an effect size estimate based on a large number of patients from studies of good quality. Regarding the evidence on the prevalence of ASD in PCOS women, results suggest that women with PCOS are more likely to be diagnosed with ASD.

Does testosterone impair men's cognitive empathy? Evidence from two large-scale randomized controlled trials

The capacity to infer others' mental states (known as 'mind reading' and 'cognitive empathy') is essential for social interactions across species, and its impairment characterizes psychopathological conditions such as autism spectrum disorder and schizophrenia. Previous studies reported that testosterone administration impaired cognitive empathy in healthy humans, and that a putative biomarker of prenatal testosterone exposure (finger digit ratios) moderated the effect. However, empirical support for the relationship has relied on small sample studies with mixed evidence. We investigate the reliability and generalizability of the relationship in two large-scale double-blind placebo-controlled experiments in young men (n = 243 and n = 400), using two different testosterone administration protocols. We find no evidence that cognitive empathy is impaired by testosterone administration or associated with digit ratios. With an unprecedented combined sample size, these results counter current theories and previous high-profile reports, and demonstrate that previous investigations of this topic have been statistically underpowered.

Cord blood Per- and polyfluoroalkyl substances, placental steroidogenic enzyme, and cord blood reproductive hormone

BACKGROUND

Per- and polyfluoroalkyl substances (PFASs) are widely used in China, but little is known about the association between prenatal PFASs exposure and fetal reproductive development as well as its potential mechanism.

OBJECTIVE

We investigated the effects of cord blood PFASs on fetal reproductive hormones and its potential mechanism in relation to steroidogenic enzymes.

METHODS

Ten selected PFASs (n = 351) including PFOS, PFOA, PFBS, PFDA, PFDoA, PFHpA, PFHxS, PFNA, PFOSA, and PFUA, and two reproductive hormones estradiol (E2) (n = 351) and testosterone (T) (n = 349) were measured in 351 cord blood serum samples from a Chinese birth cohort between 2010 and 2013. Three steroidogenic enzymes including P450arom (n = 125), 3β-HSD1 (n = 123), and 17β-HSD1 (n = 116) were measured in 125 placental tissue samples. Linear regression tested the associations between cord blood PFASs and reproductive hormones in cord blood. Mediation analysis assessed the role of placental steroidogenic enzymes between cord blood PFASs and reproductive hormones.

RESULTS

The positive associations between PFOA, PFHxS and E2 levels, PFOS, PFUA, PFNA and T levels, and PFOS, PFUA and T/E2 ratio were significant. PFUA, PFNA, PFDA, PFHxS, and ∑PFASs were associated with higher P450arom levels. PFHxS was also associated with increased 3β-HSD1 and 17β-HSD1 levels. These associations were more pronounced in females than males when stratified by gender. Furthermore, 17β-HSD1 demonstrated mediating effects in the positive association between cord blood PFHxS and E2 levels in females.

CONCLUSION

Our findings suggested the potential impacts of cord blood PFASs on fetal reproductive hormones, in which steroidogenic enzymes may play important roles. These associations were more pronounced in females than males.

Symptom severity in autism spectrum disorder is related to the frequency and severity of nausea and vomiting during pregnancy: a retrospective case-control study

Background

Nausea and vomiting during pregnancy (NVP) is thought to be caused by changes in maternal hormones during pregnancy. Differences in hormone exposure during prenatal life have been implicated in the causal pathways for some cases of autism spectrum disorder (ASD). However, no study has investigated whether the presence and severity of NVP may be related to symptom severity in offspring with ASD.

Methods

A large sample of children with ASD (227 males and 60 females, aged 2 to 18 years) received a clinical assessment, during which parents completed questionnaires regarding their child’s social (Social Responsiveness Scale, SRS) and communication (Children’s Communication Checklist–2nd edition, CCC-2) symptoms. Parents also reported on a 5-point scale the frequency and severity of NVPs during the pregnancy of the child being assessed: (1) no NVP during the pregnancy, (2) occasional nausea, but no vomiting, (3) daily nausea, but no vomiting, (4) occasional vomiting, with or without nausea, and (5) daily nausea and vomiting.

Results

Impairments in social responsiveness in offspring, as indexed by SRS total score, significantly increased as a function of the frequency and severity of their mothers’ NVP, as did the level of language difficulties as indexed by the Global Communication Composite of the CCC-2.

Conclusions

The strong, positive association between increasing frequency and severity of NVP and ASD severity in offspring provides further evidence that exposure to an atypical hormonal environment during prenatal life may affect neurodevelopment and contribute to the ASD phenotype. Given that the measure of NVP symptoms in the current study was based on retrospective recall, replication of this finding is required before strong conclusions can be drawn.

Electronic supplementary material

The online version of this article (10.1186/s13229-018-0223-7) contains supplementary material, which is available to authorized users.

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.

Prenatal dioxin exposure estimated from dioxins in breast milk and sex hormone levels in umbilical cord blood in Vietnamese newborn infants

Dioxin concentrations remain elevated in the environment and humans residing near the former US Air Force base in Bien Hoa city, South Vietnam. We recruited 210 mother-infant pairs for whom breast milk dioxin levels were reported in our previous study. Cord blood samples were collected from 162 mother-infant pairs. We selected 16 cord blood samples with a volume over 20mL and fat content of ≥0.03g. Toxic equivalent levels of polychlorinated dibenzodioxins and polychlorinated dibenzofurans (TEQ-PCDD/Fs) and concentrations of 17 congeners, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), in cord blood were measured and compared with levels in breast milk (Study 1). Levels of 2,3,7,8-TCDD and TEQ-PCDD/Fs in cord blood samples were highly and significantly correlated with those in breast milk samples in the same pairs. This suggests dioxins in breast milk reflect prenatal dioxin exposure. Estradiol (E2) and testosterone (TS) were measured in cord blood serum from 162 samples. Associations between dioxins in breast milk and cord blood sex hormones were analyzed by infant sex, after adjusting for confounding factors (Study 2). Increased levels of TEQ-PCDD/Fs in breast milk were associated with decreased cord blood TS in girls. In boys, a significant reduction of cord blood TS was observed in those exposed to 2,3,7,8-TCDD at high levels (≥5.5pg/g lipid). There was no significant association between E2 and dioxins in breast milk in either sex. These results suggest increased prenatal dioxin exposure is associated with decreased cord TS, but in boys, only high level of 2,3,7,8-TCDD influence cord blood TS.

Hypermasculinised facial morphology in boys and girls with Autism Spectrum Disorder and its association with symptomatology

Elevated prenatal testosterone exposure has been associated with Autism Spectrum Disorder (ASD) and facial masculinity. By employing three-dimensional (3D) photogrammetry, the current study investigated whether prepubescent boys and girls with ASD present increased facial masculinity compared to typically-developing controls. There were two phases to this research. 3D facial images were obtained from a normative sample of 48 boys and 53 girls (3.01-12.44 years old) to determine typical facial masculinity/femininity. The sexually dimorphic features were used to create a continuous 'gender score', indexing degree of facial masculinity. Gender scores based on 3D facial images were then compared for 54 autistic and 54 control boys (3.01-12.52 years old), and also for 20 autistic and 60 control girls (4.24-11.78 years). For each sex, increased facial masculinity was observed in the ASD group relative to control group. Further analyses revealed that increased facial masculinity in the ASD group correlated with more social-communication difficulties based on the Social Affect score derived from the Autism Diagnostic Observation Scale-Generic (ADOS-G). There was no association between facial masculinity and the derived Restricted and Repetitive Behaviours score. This is the first study demonstrating facial hypermasculinisation in ASD and its relationship to social-communication difficulties in prepubescent children.

The role of cholesterol metabolism and various steroid abnormalities in autism spectrum disorders: A hypothesis paper

Based on evidence from the relevant research literature, we present a hypothesis that there may be a link between cholesterol, vitamin D, and steroid hormones which subsequently impacts on the development of at least some of the "autisms" [Coleman & Gillberg]. Our hypothesis, driven by the peer reviewed literature, posits that there may be links between cholesterol metabolism, which we will refer to as "steroid metabolism" and findings of steroid abnormalities of various kinds (cortisol, testosterone, estrogens, progesterone, vitamin D) in autism spectrum disorder (ASD). Further research investigating these potential links is warranted to further our understanding of the biological mechanisms underlying ASD. Autism Res 2017. © 2017 The Authors Autism Research published by Wiley Periodicals, Inc. on behalf of International Society for Autism Research. Autism Res 2017, 10: 1022-1044. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Differences in testosterone and its precursors by sex of the offspring in meconium

Prenatal metabolism exerts profound effects on development. The first stool of the newborn, meconium, provides a window into the prenatal metabolic environment. The objective of this study was to examine the feasibility of meconium as a novel matrix to quantify prenatal steroid levels. We quantified parameters of analytical interest regarding the use of meconium, including sample stability. We hypothesized that meconium steroid content would differ by sex, prompting analysis of meconium to test effects of prenatal steroid metabolism. Meconium from 193 newborns enrolled in the Early Autism Risk Longitudinal Investigation (EARLI) study, including 107 males, and 86 females, were analyzed by isotope dilution-liquid chromatography-high resolution mass spectrometry (ID-LC-HRMS) while blinded to identity for testosterone (T), androstenedione (AD), and dehydroepiandrosterone (DHEA). Steroid levels were compared by sex, and investigations of potential trends resulting from sample storage or processing was conducted. The unconjugated steroid content of meconium in ng/g (mean, standard deviation) was for males: T (2.67, 8.99), AD (20.01, 28.12), DHEA (13.96, 23.57) and for females: T (0.82, 1.63), AD (22.32, 24.38), DHEA (21.06, 43.49). T was higher in meconium from males (p=0.0333), and DHEA was higher in meconium from females (p=0.0202). 6 female and 3 male T values were below the limit of detection. No extreme variability in hydration or trend in steroid levels by storage time was detected. Sexually dimorphic levels of hormones may reflect gestational differentiation, and future studies should consider meconium analysis.

Umbilical cord blood androgen levels and ASD-related phenotypes at 12 and 36 months in an enriched risk cohort study

Background

Autism spectrum disorder (ASD) affects more than 1% of children in the USA. The male-to-female prevalence ratio of roughly 4:1 in ASD is a well-recognized but poorly understood phenomenon. An explicit focus on potential etiologic pathways consistent with this sex difference, such as those involving prenatal androgen exposure, may help elucidate causes of ASD. Furthermore, the multi-threshold liability model suggests that the genetic mechanisms in females with ASD may be distinct and may modulate ASD risk in families with female ASD in the pedigree.

Methods

We examined umbilical cord blood from 137 children in the Early Autism Risk Longitudinal Investigation (EARLI) cohort. EARLI is an ASD-enriched risk cohort with all children having an older sibling already diagnosed with ASD. Fetal testosterone (T), androstenedione (A4), and dehyroepiandrosterone (DHEA) levels were measured in cord blood using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Robust linear regression models were used to determine associations between cord blood androgen levels and 12-month Autism Observation Scales for Infants (AOSI) scores and 36-month Social Responsiveness Scale (SRS) scores adjusting for potential confounders.

Results

Increasing androgens were not associated with increasing 12-month AOSI score or 36-month total SRS score in either boys or girls. However, the association between T and autistic traits among subjects with a female older affected sibling was greater at 12 months (test of interaction, P = 0.008) and deficits in reciprocal social behavior at 36 months were also greater (test of interaction, P = 0.006) than in subjects whose older affected sibling was male.

Conclusions

While increased prenatal testosterone levels were not associated with autistic traits at 12 or 36 months, our findings of a positive association in infants whose older ASD-affected siblings were female suggests an androgen-related mechanism that may be dependent on, or related to, genetic liability factors present more often in families containing female ASD cases. However, this initial finding, based on a small subgroup of our sample, should be interpreted with considerable caution.

Electronic supplementary material

The online version of this article (doi:10.1186/s13229-017-0118-z) contains supplementary material, which is available to authorized users.

Environmental factors associated with autism spectrum disorder: a scoping review for the years 2003-2013

INTRODUCTION

The number of children diagnosed with autism spectrum disorder (ASD) has been rapidly rising in the past decade. The etiology of this disorder, however, is largely unknown, although the environmental relative to the genetic contribution is substantial. We conducted a scoping review to comprehensively assess the current state of knowledge of the environmental factors present from preconception to early life associated with ASD, and to identify research gaps.

METHODS

We searched electronic databases MEDLINE, PsycINFO and ERIC for articles on potential risk factors or protective factors from the physical and social environments associated with ASD and its subclassifications published between 1 January, 2003, and 12 July, 2013. We categorized articles into broad themes: chemical, physiological, nutritional and social factors, based on environmental exposure.

RESULTS

We identified over 50 000 publications, but after ineligible studies were screened out, 315 articles remained. Most of these studies examined physiological factors, followed closely by chemical factors, and to a much lesser extent, nutritional and social factors, associated with ASD. Despite a vast literature and many heterogeneous studies, several risk factors emerged consistently: chemical factors such as traffic-related air pollutants; physiological factors including advanced parental age, preterm birth, low birth weight, hyperbilirubinemia and clustering of pregnancy complications; and maternal immigrant status. Despite extensive research on vaccines, findings overwhelmingly demonstrate no support for an association with ASD.

CONCLUSION

The lack of consistency, temporality and specificity of associations between environmental factors and ASD remains the largest barrier to establishing causal relationships. More robust research is required to resolve inconsistencies in the literature. Future research should explore underlying mechanisms of associations between the risk factors that we identified and ASD.

No relationship between prenatal androgen exposure and autistic traits: convergent evidence from studies of children with congenital adrenal hyperplasia and of amniotic testosterone concentrations in typically developing children

BACKGROUND

There is a marked male preponderance in autism spectrum conditions. The extreme male brain theory and the fetal androgen theory of autism suggest that elevated prenatal testosterone exposure is a key contributor to autistic traits. The current paper reports findings from two separate studies that test this hypothesis.

METHODS

A parent-report questionnaire, the Childhood Autism Spectrum Test (CAST), was employed to measure autistic traits in both studies. The first study examined autistic traits in young children with congenital adrenal hyperplasia (CAH), a condition causing unusually high concentrations of testosterone prenatally in girls. Eighty one children with CAH (43 girls) and 72 unaffected relatives (41 girls), aged 4-11 years, were assessed. The second study examined autistic traits in relation to amniotic testosterone in 92 typically developing children (48 girls), aged 3-5 years.

RESULTS

Findings from neither study supported the association between prenatal androgen (testosterone) exposure and autistic traits. Specifically, young girls with and without CAH did not differ significantly in CAST scores and amniotic testosterone concentrations were not significantly associated with CAST scores in boys, girls, or the whole sample.

CONCLUSIONS

These studies do not support a relationship between prenatal testosterone exposure and autistic traits. These findings augment prior research suggesting no consistent relationship between early androgen exposure and autistic traits.

Commentary: Are we expecting too much from the extreme male brain theory of autism? A reflection on Kung et al. (2016)

Kung et al. (2016) contribute further evidence demonstrating no clear link between prenatal androgen exposure and the autism phenotype. Do these findings represent a nail in the coffin for the extreme male brain (EMB) theory of autism, or are we simply asking too much of the hypothesis? This commentary highlights the inconsistent findings that have appeared to undermine the EMB theory, but presents an argument that the data may not present an adequate test of the hypothesis. A research agenda is then outlined - the investigation of simple behavioural traits rather than the full combination of ASD behaviours - which may provide greater clarity as to how prenatal androgen exposure relates to developmental psychopathology.

Pleiotropic Mechanisms Indicated for Sex Differences in Autism

Sexual dimorphism in common disease is pervasive, including a dramatic male preponderance in autism spectrum disorders (ASDs). Potential genetic explanations include a liability threshold model requiring increased polymorphism risk in females, sex-limited X-chromosome contribution, gene-environment interaction driven by differences in hormonal milieu, risk influenced by genes sex-differentially expressed in early brain development, or contribution from general mechanisms of sexual dimorphism shared with secondary sex characteristics. Utilizing a large single nucleotide polymorphism (SNP) dataset, we identify distinct sex-specific genome-wide significant loci. We investigate genetic hypotheses and find no evidence for increased genetic risk load in females, but evidence for sex heterogeneity on the X chromosome, and contribution of sex-heterogeneous SNPs for anthropometric traits to ASD risk. Thus, our results support pleiotropy between secondary sex characteristic determination and ASDs, providing a biological basis for sex differences in ASDs and implicating non brain-limited mechanisms.

No relationship between early postnatal testosterone concentrations and autistic traits in 18 to 30-month-old children

Background

Some previous research has suggested that testosterone prenatally contributes to gender differences in autistic traits, but little is known about the role of testosterone during early postnatal development (mini-puberty). Two prior studies found no sex difference in testosterone postnatally in saliva samples and detected little to no relationship between testosterone postnatally and autistic traits in toddlers. These findings may reflect late measurements of testosterone at 3 to 4 months of age, after the peak of mini-puberty at 1 to 3 months of age. The present study examined the relationship between testosterone at 1 to 3 months of age and autistic traits at 18 to 30 months of age.

Findings

Testosterone was measured in saliva samples collected from children at 1 to 3 months of age. When the children (40 boys, 47 girls) reached 18 to 30 months of age, parents completed the Quantitative Checklist for Autism in Toddlers (Q-CHAT). Boys had higher concentrations of testosterone postnatally and higher Q-CHAT scores than girls. However, testosterone did not correlate with Q-CHAT scores in boys, girls, or the entire sample.

Conclusions

The current results suggest that testosterone during the early postnatal period does not contribute to later autistic traits. Given our relatively small samples and therefore limited power, however, further research could usefully examine if testosterone in saliva samples collected during the peak of mini-puberty in larger groups predicts autistic traits or other traits that show gender differences.

Autistic Trait, Empathy, and Attention-Deficit/Hyperactivity Symptoms in Women with Idiopathic Hirsutism

Aim:

Many psychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD), disruptive behavioral disorders, autism spectrum disorders, and some psychiatric characteristics, such as poor empathizing, are regarded to be related to elevated levels of androgens or androgen sensitivity. Thus, numerous studies have investigated the potential association between androgen-related physical diseases and these psychiatric conditions. Idiopathic hirsutism (IH) is a disease characterized by an increased sensitivity of the pilosebaceous unit to circulating androgens in women. The purpose of this study was to examine whether IH has a relationship with androgen-related psychiatric conditions.

Materials and Methods:

Totally 37 females with IH and 33 healthy female controls were included in this study. Childhood and present ADHD symptoms of the participants were assessed using the Wender Utah Rating Scale (WURS) and the Adult ADHD Self-Report Scale, respectively. The Autism-spectrum quotient and the interpersonal reactivity index were used to assess autistic traits and different aspects of empathy. Hirsutism severity was measured using the Ferriman–Gallwey scoring system.

Results:

No significant difference was found between the patients and controls on psychiatric questionnaire scores, except for a trend for subjects with IH to show higher levels of the school-associated problems than controls according to WURS. The severity of hirsutism was strongly correlated with the WURS irritability and behavioral problems/impulsivity subscores and WURS total score, and moderately correlated with the WURS attentional deficit subscore.

Conclusions:

This study provides preliminary evidence that common etiological factors may be involved in both the severity of IH, ADHD, and coexisting disruptive behavioral problems.

Perceived Gender Ratings for High and Low Scorers on the Autism-Spectrum Quotient Consistent with the Extreme Male Brain Account of Autism

The Extreme Male Brain (EMB) theory posits that autistic traits are linked to excessive exposure to testosterone in utero. While findings from a number of studies are consistent with this theory, other studies have produced contradictory results. For example, some findings suggest that rather than being linked to hypermasculinization for males, or defeminization for females, elevated levels of autistic traits are instead linked to more androgynous physical features. The current study provided further evidence relevant to the EMB and androgony positions by comparing groups of males selected for high or low scores on the Autism-spectrum Quotient (AQ) as to the rated masculinity of their faces and voices, and comparable groups of females as to the rated femininity of their faces and voices. The voices of High-AQ males were rated as more masculine than those of Low-AQ males, while the faces of High-AQ females were rated as less feminine than those of Low-AQ females. There was no effect of AQ group on femininity ratings for female voices or on masculinity ratings for male faces. The results thus provide partial support for a link between high levels of autistic-like traits and hypermasculinization for males and defeminization for females, consistent with the EMB theory.

The perinatal androgen to estrogen ratio and autistic-like traits in the general population: a longitudinal pregnancy cohort study

BACKGROUND

Prenatal androgen exposure has been hypothesized to be linked to autism spectrum disorder (ASD). While previous studies have found a link between testosterone levels in amniotic fluid and autistic-like traits, a similar relationship has not been found for testosterone in umbilical cord blood. However, it may be the net biological activity of multiple androgens and estrogens that influences postnatal effects of prenatal sex steroids. Accordingly, composite levels of androgens (A) and estrogens (E) were investigated, along with their ratio, in relation to autistic-like traits in young adulthood.

METHODS

Sex steroid data in umbilical cord blood were available from 860 individuals at delivery. Samples were analyzed for androgens (testosterone, androstenedione, and dehydroepiandrosterone) and estrogens (estrone, estradiol, estriol, and estetrol). Levels of bioavailable testosterone, estradiol, and estrone were measured and used to calculate A and E composites and the A to E ratio. Participants were approached in early adulthood to complete the autism-spectrum quotient (AQ) as a self-report measure of autistic-like traits, with 183 males (M = 20.10 years, SD = 0.65 years) and 189 females (M =19.92 years, SD = 0.68 years) providing data.

RESULTS

Males exhibited significantly higher androgen composites and A to E composite ratios than females. Males also scored significantly higher on the details/patterns subscale of the AQ. Subsequent categorical and continuous analyses, which accounted for covariates, revealed no substantial relationships between the A/E composites or the A to E ratio and the AQ total or subscale scores.

CONCLUSIONS

The current study found no link between the A/E composites or the A to E ratio in cord blood and autistic-like traits in the population as measured by the AQ. These outcomes do not exclude the possibility that these sex steroid variables may predict other neurodevelopmental traits in early development.

Sexually dimorphic facial features vary according to level of autistic-like traits in the general population

BACKGROUND

In a recent study, Bejerot et al. observed that several physical features (including faces) of individuals with an autism spectrum disorder (ASD) were more androgynous than those of their typically developed counterparts, suggesting that ASD may be understood as a 'gender defiant' disorder. These findings are difficult to reconcile with the hypermasculinisation account, which proposes that ASD may be an exaggerated form of cognitive and biological masculinity. The current study extended these data by first identifying six facial features that best distinguished males and females from the general population and then examining these features in typically developing groups selected for high and low levels of autistic-like traits.

METHODS

In study 1, three-dimensional (3D) facial images were collected from 208 young adult males and females recruited from the general population. Twenty-three facial distances were measured from these images and a gender classification and scoring algorithm was employed to identify a set of six facial features that most effectively distinguished male from female faces. In study 2, measurements of these six features were compared for groups of young adults selected for high (n = 46) or low (n = 66) levels of autistic-like traits.

RESULTS

For each sex, four of the six sexually dimorphic facial distances significantly differentiated participants with high levels of autistic-like traits from those with low trait levels. All four features were less masculinised for high-trait males compared to low-trait males. Three of four features were less feminised for high-trait females compared to low-trait females. One feature was, however, not consistent with the general pattern of findings and was more feminised among females who reported more autistic-like traits. Based on the four significantly different facial distances for each sex, discriminant function analysis correctly classified 89.7% of the males and 88.9% of the females into their respective high- and low-trait groups.

CONCLUSIONS

The current data provide support for Bejerot et al.'s androgyny account since males and females with high levels of autistic-like traits generally showed less sex-typical facial features than individuals with low levels of autistic-like traits.

The sex ratio of full and half siblings of people diagnosed with an autism spectrum disorder: a Danish Nationwide Register Study

In the extreme male brain theory of autism sex steroid hormones are hypothesized to influence brain development and to mediate sex differences in developmental psychopathology. Within this scope we examined the sex ratio (proportion of males) in siblings of individuals diagnosed with autism spectrum disorders (ASD). We did a nationwide, register based cohort study of the sex ratio in 17,380 siblings of the 10,297 patients diagnosed with ASD at age 17 years and younger and registered in the nationwide Danish Psychiatric Central Register between 1994 and 2012. Among the 17,380 siblings 8,828 were males and 8,552 females. This yields a sex ratio of 0.508, which is not different from the Danish live birth sex ratio of 0.513 during the relevant years (P = 0.18). Overall, our findings provide no support for the hypothesis that there are relatively more males among the siblings of people with ASD. Accordingly, our results do not give support to the extreme male brain theory of autism.

Etiologies underlying sex differences in Autism Spectrum Disorders

The male predominance of Autism Spectrum Disorders (ASD) is one of the best-known, and at the same time, one of the least understood characteristics of these disorders. In this paper we review genetic, epigenetic, hormonal, and environmental mechanisms underlying this male preponderance. Sex-specific effects of Y-linked genes (including SRY expression leading to testicular development), balanced and skewed X-inactivation, genes that escape X-inactivation, parent-of-origin allelic imprinting, and the hypothetical heterochromatin sink are reviewed. These mechanisms likely contribute to etiology, instead of being simply causative to ASD. Environments, both internal and external, also play important roles in ASD's etiology. Early exposure to androgenic hormones and early maternal immune activation comprise environmental factors affecting sex-specific susceptibility to ASD. The gene-environment interactions underlying ASD, suggested here, implicate early prenatal stress as being especially detrimental to boys with a vulnerable genotype.