Why are autism spectrum conditions more prevalent in males?

The Dynamicity of the Oxytocin Receptor in the Brain May Trigger Sensory Deficits in Autism Spectrum Disorder

Sensory processing abnormalities have been noted since the first clinical description of autism in 1940. However, it was not until the release of the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in 2013 that sensory challenges were considered as symptoms of autism spectrum disorder (ASD). Multisensory processing is of paramount importance in building a perceptual and cognitive representation of reality. For this reason, deficits in multisensory integration may be a characteristic of ASD. The neurohormone oxytocin (Oxt) is involved in the etiology of ASD, and there are several ongoing clinical trials regarding Oxt administration in ASD patients. Recent studies indicate that Oxt triggers muscle contraction modulating thermogenesis, while abnormal thermoregulation results in sensory deficits, as in ASD. Activation of the Oxt system through exposure to cold stress regulates the expression of oxytocin receptor (Oxtr) in the brain and circulating Oxt, and if this mechanism is pathologically disrupted, it can lead to sensory processing abnormalities since Oxt acts as a master gene that regulates thermogenesis. This review will describe the sensory deficits characteristic of ASD together with the recent theories regarding how the modulation of Oxt/Oxtr in the brain influences sensory processing in ASD.

IUPHAR review: Targeted therapies of signaling pathways based on the gut microbiome in autism spectrum disorders: Mechanistic and therapeutic applications

Autism spectrum disorders (ASD) are complex neurodevelopmental disorders characterized by impairments in social interaction, communication and repetitive activities. Gut microbiota significantly influences behavior and neurodevelopment by regulating the gut-brain axis. This review explores gut microbiota-influenced treatments for ASD, focusing on their therapeutic applications and mechanistic insights. In addition, this review discusses the interactions between gut microbiota and the immune, metabolic and neuroendocrine systems, focusing on crucial microbial metabolites including short-chain fatty acids (SCFAs) and several neurotransmitters. Furthermore, the review explores various therapy methods including fecal microbiota transplantation, dietary modifications, probiotics and prebiotics and evaluates their safety and efficacy in reducing ASD symptoms. The discussion shows the potential of customized microbiome-based therapeutics and the integration of multi-omics methods to understand the underlying mechanisms. Moreover, the review explores the intricate relationship between gut microbiota and ASD, aiming to develop innovative therapies that utilize the gut microbiome to improve the clinical outcomes of ASD patients. Microbial metabolites such as neurotransmitter precursors, tryptophan metabolites and SCFAs affect brain development and behavior. Symptoms of ASD are linked to changes in these metabolites. Dysbiosis in the gut microbiome may impact neuroinflammatory processes linked to autism, negatively affecting immune signaling pathways. Research indicates that probiotics and prebiotics can improve gut microbiota and alleviate symptoms in ASD patients. Fecal microbiota transplantation may also improve behavioral symptoms and restore gut microbiota balance. The review emphasizes the need for further research on gut microbiota modification as a potential therapeutic approach for ASD, highlighting its potential in clinical settings.

Lipopolysaccharide induces neuroinflammation in a valproic acid male model of autism

BACKGROUND

Autism spectrum disorders (ASD) are characterized by social skill deficits and behavior impairments. Exposure to valproic acid (VPA) has been linked to ASD in humans and ASD-like behaviors in rodents. Clinical evidence suggests that immunological damage can worsen ASD symptoms in humans.

OBJECTIVE

This study aimed to investigate the potential of lipopolysaccharide (LPS) to induce neuroinflammation in a VPA-induced autism male model.

MATERIALS

and methods: Pregnant Sprague Dawley rats were injected with 500 mg/kg of VPA on gestational day 12.5 to create an ASD rat model in their offspring. Male offspring from VPA-injected group received 10 mg/kg of LPS on postnatal day 20. Immunohistochemistry, western blotting, and immunofluorescence were used to assess the expression of NF-κB signaling pathway-related proteins and microglia in the prefrontal cortex and hippocampus. Gene Ontology and pathway enrichment analyses were conducted to predict the function of key synaptic proteins, which were further validated through real-time polymerase chain reaction analysis.

RESULTS

The results showed that VPA exposure led to increased locomotor activity, social impairment, and repetitive behaviors in male rats. NF-κB signaling pathway-related proteins were upregulated, and microglial numbers were elevated in the VPA-induced group. Furthermore, synaptic dysfunction was observed in the brains of offspring exposed to VPA. Importantly, LPS administration exacerbated autism-related behaviors in VPA-exposed male rats by promoting NF-κB signaling pathway activation, increasing microglial numbers, and downregulating key synaptic proteins.

CONCLUSIONS

This study not only contributed to understanding the importance of the NF-κB signaling pathway, microglia, and synaptic proteins in the progression of ASD, but also identified that LPS induces neuroinflammation in a valproic acid-induced male model of autism.

Gender and family-role portrayals of autism in British newspapers: An intersectional corpus-based study

A recent large-scale study on the portrayal of autism in British newspapers revealed a deficit-based coverage, which concentrated on children and boys in particular, typically represented from the mothers' perspective. This follow-up study refines these representations, considering how they differ by gender and family role. We analysed 2998 text samples, which discussed autism in the context of four combinations of gender and family roles, namely, BOY, GIRL, FATHER and MOTHER. These samples included sources with different publication dates, reporting style and political orientation. Autism representations remained negative regardless of gender and family role. Over time, stories about autistic girls started to emerge, identifying them as a distinct group explicitly compared to autistic boys. Newspapers, especially broadsheets, associated girls with diagnostic difficulties, camouflaging and sometimes gender dysphoria - discussed particularly for those assigned female at birth. The child's autism was more often attributed to maternal than paternal behaviours or lifestyle. Autistic mothers were mentioned more often than fathers and were portrayed negatively. We conclude that newspapers portray female autism as less significant than male autism and, in addition, place mothers under more ethical scrutiny than fathers. These disparities reflect both historical biases in autism research and gender and family-role stereotypes.

Androgyny and atypical sensory sensitivity associated with savant ability: a comparison between Klinefelter syndrome and sexual minorities assigned male at birth

Introduction

The extreme male brain (EMB) theory, a major causal hypothesis of autism (ASD: autism spectrum disorder), attributes excess androgens during early development as one of the causes. While studies have generally followed the EMB theory in females at birth, the co-occurrence of ASD in males at birth has been observed in conditions that are assumed to be associated with reduced androgen action during early development, including Klinefelter syndrome (KS) and sexual minorities. ASD is also associated with atypical sensory sensitivity, synesthesia, and savant syndrome.

Methods

In the present study, we examined adult KS individuals (n = 22), sexual minorities assigned male at birth (n = 66), and control males matched for age and educational background to those with KS [Exploratory analysis (control 1st): n = 36; Reanalysis (control 2nd): n = 583]. Participants completed a self-report questionnaire assessing sensory hypersensitivity/hyposensitivity, savant tendency (developed for the present study), synesthesia, and sexual aspects, including gender identity and sexual orientation.

Results

The results of the exploratory analysis suggested that individuals with KS exhibited a higher tendency toward sensory hypersensitivity/hyposensitivity than the tendency exhibited by the controls. In the Reanalysis, sexual minorities were more likely to be synesthetes, and in both analyses sexual minorities exhibited a higher savant tendency and sensory hypersensitivity/hyposensitivity than the controls. Moreover, the gender dysphoric state was associated with phenotypes observed in individuals with ASD, such as synesthesia, savant tendency, and sensory hypersensitivity/hyposensitivity.

Discussion

These results suggest a common physiological background among gender dysphoria, synesthesia, savant tendency, and atypical sensory sensitivity. Thus, androgynous features (reduced effects of sex steroids during early development) in males at birth may be partially related to the phenotype commonly observed in individuals with ASD. Based on the present results, we propose that the reduction of sex steroids during early development may lead to atypical neurodevelopment and be involved in the atypicality of external and internal sensory perception, and thus in the atypicality of self-concept integration, through the disruption of oxytocin and the gamma-aminobutyric acid system modulating the neural excitation/inhibition balance.

A Retrospective Study Distinguishing between Hyperacusis and Misophonia in children with Auditory Processing Disorder (APD)

OBJECTIVES

Decreased sound tolerance (DST) is common in children with auditory processing disorder (APD). This study aimed to differentiate between hyperacusis and misophonia in children with APD.

DESIGN

A retrospective study evaluating outcomes of structured history and co-morbidity following Research Domain Criteria (RDoC) frame-work. Misophonia was considered as oversensitivity to eating/chewing sounds and hyperacusis as oversensitivity to other sounds.

STUDY SAMPLE

Two hundred and seventy-nine children (160 males; 119 females), 6-16 year-olds with NVIQ ≥80, diagnosed with APD between January 2021 and December 2022.

RESULTS

One hundred and forty-three out of 279 children with APD had DST, of which 107 had hyperacusis (without misophonia) and 36 had misophonia. Misophonia co-existed with hyperacusis in 35 children (97 %), and in one child misophonia occurred without hyperacusis. Misophonia was prevalent in older children, in females, and those with tinnitus. Fear and being upset were predominant emotional responses in hyperacusis (without misophonia) while disgust and verbal abuse were prevalent in misophonia (with or without hyperacusis). Compared to children without DST, the hyperacusis (without misophonia) and misophonia (with or without hyperacusis) groups had significant higher prevalence of ADHD, anxiety, and language impairment. Educational difficulties were similar in APD irrespective of the presence or absence of DST. Despite higher tinnitus prevalence in misophonia (with or without hyperacusis) along with similar co-morbidities and educational difficulties in both hyperacusis (without misophonia) and misophonia (with or without hyperacusis), the misophonia (with or without hyperacusis) group surprisingly had less support at school which was reflected in fewer Education, Health and Care Plan (EHCP).

CONCLUSIONS

In APD misophonia mostly co-exists with hyperacusis, with differences in emotional responses, tinnitus prevalence, and gender distribution when compared to hyperacusis (without misophonia). Increase in awareness about misophonia is needed, as children with misophonia may have unidentified needs. Larger scale prospective study is required to clarify if misophonia evolves from hyperacusis, and to explore the factors underlying 'misophonia with hyperacusis' and 'misophonia without hyperacusis'. For clarity, DST studies need to specify if hyperacusis or misophonia co-existed when referring to hyperacusis or misophonia.

Brain functional connectivity, but not neuroanatomy, captures the interrelationship between sex and gender in preadolescents

Understanding sex differences in the adolescent brain is crucial, as these differences are linked to neurological and psychiatric conditions that vary between males and females. Predicting sex from adolescent brain data may offer valuable insights into how these variations shape neurodevelopment. Recently, attention has shifted toward exploring socially-identified gender, distinct from sex assigned at birth, recognizing its additional explanatory power. This study evaluates whether resting-state functional connectivity (rsFC) or cortical thickness more effectively predicts sex and sex/gender alignment (the congruence between sex and gender) and investigates their interrelationship in preadolescents. Using data from the Adolescent Brain Cognitive Development (ABCD) Study, we employed machine learning to predict both sex (assigned at birth) and sex/gender alignment from rsFC and cortical thickness. rsFC predicted sex with significantly higher accuracy (86%) than cortical thickness (75%) and combining both did not improve the rsFC model's accuracy. Brain regions most effective in predicting sex belonged to association (default mode, dorsal attention, and parietal memory) and visual (visual and medial visual) networks. The rsFC sex classifier trained on sex/gender aligned youth was significantly more effective in classifying unseen youth with sex/gender alignment than in classifying unseen youth with sex/gender unalignment. In females, the degree to which their brains' rsFC matched a sex profile (female or male), was positively associated with the degree of sex/gender alignment. Lastly, neither rsFC nor cortical thickness predicted sex/gender alignment. These findings highlight rsFC's predictive power in capturing the relationship between sex and gender and the complexity of the interplay between sex, gender, and the brain's functional connectivity and neuroanatomy.

Sex Differences in Human Brain Structure at Birth

BACKGROUND

Sex differences in human brain anatomy have been well-documented, though remain significantly underexplored during early development. The neonatal period is a critical stage for brain development and can provide key insights into the role that prenatal and early postnatal factors play in shaping sex differences in the brain.

METHODS

Here, we assessed on-average sex differences in global and regional brain volumes in 514 newborns aged 0-28 days (236 birth-assigned females and 278 birth-assigned males) using data from the developing Human Connectome Project. We also assessed sex-by-age interactions to investigate sex differences in early postnatal brain development.

RESULTS

On average, males had significantly larger intracranial and total brain volumes, even after controlling for birth weight. After controlling for total brain volume, females showed significantly greater total cortical gray matter volumes, whilst males showed greater total white matter volumes. After controlling for total brain volume in regional comparisons, females had significantly increased white matter volumes in the corpus callosum and increased gray matter volumes in the bilateral parahippocampal gyri (posterior parts), left anterior cingulate gyrus, bilateral parietal lobes, and left caudate nucleus. Males had significantly increased gray matter volumes in the right medial and inferior temporal gyrus (posterior part) and right subthalamic nucleus. Effect sizes ranged from small for regional comparisons to large for global comparisons. Significant sex-by-age interactions were noted in the left anterior cingulate gyrus and left superior temporal gyrus (posterior parts).

CONCLUSIONS

Our findings demonstrate that sex differences in brain structure are already present at birth and remain comparatively stable during early postnatal development, highlighting an important role of prenatal factors in shaping sex differences in the brain.

Placenta-specific CYP11A1 overexpression lead to autism-like symptom in offspring with altered steroid hormone biosynthesis in the placenta-brain axis and rescued by vitamin D intervention

Alterations in steroid hormone regulation have been implicated in the etiology and progression of autism spectrum disorders (ASD), with the enzyme cytochrome P450 family 11 subfamily A member 1 (CYP11A1)-a key catalyst in cholesterol side-chain cleavage, prominently expressed in the adrenal glands, ovaries, testes, and placenta-standing at the forefront of these investigations. The potential link between aberrations in placental Cyp11a1 expression and the resultant neurodevelopmental disorders, along with the mechanisms underpinning such associations, remains inadequately delineated. In this study, we employed a placental trophoblast-specific Cyp11a1 Hipp11 (H11) knock-in murine model to dissect the phenotypic manifestations within the placenta and progeny, thereby elucidating the underlying mechanistic pathways. Behavioral analyses revealed a diminution in social interaction capabilities alongside an augmented anxiety phenotype, as evidenced by open field and elevated plus maze assessments; both phenotypes were ameliorated after vitamin D3 supplementation. Electrophysiological assays underscored the augmented inhibition of paired-pulse facilitation, indicating impaired neuroplasticity in Cyp11a1 H11-modified mice. An elevation in progesterone concentrations was noted, alongside a significant upregulation of Th1-related cytokines (IL-6 and TNFα) across the plasma, placental, and frontal cortex-a pathological state mitigable through vitamin D3 intervention. Western blotting revealed a vitamin D-mediated rectification of vitamin D receptor and PGC-1α expression dysregulations. Immunofluorescence assays revealed microglial activation in the knock-in model, which was reversible upon vitamin D3 treatment. In conclusion, Cyp11a1 overexpression in the placenta recapitulated an autism-like phenotype in murine models, and vitamin D3 administration effectively ameliorated the resultant neurobehavioral and neuroinflammatory derangements. This study substantiates the application of Cyp11a1 as a biomarker in prenatal diagnostics and posits that prenatal vitamin D3 supplementation is a viable prophylactic measure against perturbations in steroid hormone metabolism associated with ASD pathogenesis.

Does Screen Time Do More Damage in Boys Than Girls?

Background Technological progress, particularly accelerated by the recent pandemic, has led to the digitalization of many aspects of daily life. Consequently, children are increasingly exposed to screen time, raising concerns about its potential impact on early development. Methods Four separate questionnaires were developed for different age groups (12-18 months, 19-30 months, 31-48 months, and 49-72 months). Data were collected over a two-month period from three major pediatric facilities, and social media platforms were also utilized to reach participants. The total sample size consisted of 5,137 children. Results Exposure to active screen time was found to increase the risk of expressive language delay, with a significant correlation identified between early screen time exposure and expressive language delay. In the 12-18 months age group, the OR was 1.52 (p = 0.008, χ²(1) = 7.08, p = 0.008), while in the 19-30 months age group, the OR was 1.79 (p = 0.0002; χ²(1) = 14.30, p < 0.001). Conclusions This study provides significant insights into the complex relationship between screen time exposure and expressive language development in young children. Our findings reveal that early screen time exposure is associated with a higher risk of expressive language delay. The data suggest that children aged 12-30 months are especially vulnerable. However, we cannot definitively state that the amount of average daily screen time is significantly changing the outcome. Conversely, we also found that a lack of screen time exposure may be associated with an increased risk of language delay in children aged 31-48 months, highlighting the nuanced role of screen time in child development. Parental supervision is a critical factor; however, our study indicates that higher levels of supervision do not consistently mitigate the risks associated with screen time across all age groups. Further research is warranted to explore the underlying factors contributing to the observed differences in susceptibility to expressive language delay among genders and to examine the long-term impacts of early screen exposure. By understanding these dynamics, we can better support children's developmental needs in an increasingly screen-saturated environment.

ASPG and DAD1 are potential placental-derived biomarkers for ASD-like symptom severity levels in male/female offspring

INTRODUCTION

An early evaluating system for autism spectrum disorder (ASD) severity is crucial. Questionnaire survey is challenging for accurately assessing the severity levels for ASD in children.

METHODS

Offspring with ASD-like phenotypes were induced by treating pregnant mice with Poly (I:C) at GD12.5 and the placentae corresponding to the offspring were obtained by caesarean. The autism severity composite score (ASCS) for offspring was calculated through behavioral tests. HE staining and immunohistochemistry were used to observe the morphology of placenta. Candidate biomarkers were identified by weighted protein co-expression network analysis (WPCNA) combined with machine learning and further validated by ELISA. Sperman's was used to analyze the correlation between biomarkers and metabolome.

RESULTS

The placental weight and mean vascular area of male offspring with ASD-like phenotypes were significantly decreased compared with typical mice. According to the WPCNA, four modules were identified and significantly correlated with ASCS of offspring. Two biomarkers (ASPG and DAD1) with high correlation with ASCS in offspring were identified.

DISCUSSION

VEGF pathway may contribute to sexual dimorphism in placental morphology within mice with ASD-like phenotypes in term. The placental ASPG and DAD1 levels could reflect ASD-like symptom severity levels in male/female mice offspring.

Prenatal environmental risk factors for autism spectrum disorder and their potential mechanisms

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that is globally increasing in prevalence. The rise of ASD can be partially attributed to diagnostic expansion and advocacy efforts; however, the interplay between genetic predisposition and modern environmental exposures is likely driving a true increase in incidence. A range of evidence indicates that prenatal exposures are critical. Infection during pregnancy, gestational diabetes, and maternal obesity are established risk factors for ASD. Emerging areas of research include the effects of maternal use of selective serotonin reuptake inhibitors, antibiotics, and exposure to toxicants during pregnancy on brain development and subsequent ASD. The underlying pathways of these risk factors remain uncertain, with varying levels of evidence implicating immune dysregulation, mitochondrial dysfunction, oxidative stress, gut microbiome alterations, and hormonal disruptions. This narrative review assesses the evidence of contributing prenatal environmental factors for ASD and associated mechanisms as potential targets for novel prevention strategies.

People with higher systemizing traits have wider right hands

Introduction

Various genetic mutations have been implicated in autism spectrum disorder (ASD). Some candidate genes for ASD are known to be related to signal transduction and may be involved in hand development as well as neurodevelopment. Therefore, although subtle, anatomical variations in hand configurations may be observed in individuals with ASD. However, except for research on the finger ratio, which has been suggested to be related to prenatal sex hormone exposure, only few studies have been conducted. Given the spectrum characteristics of ASD, we explored whether hand configurations are associated with ASD-related traits in the general population.

Methods

Photographs of the dorsal surface of each hand were obtained, and the distances between the metacarpophalangeal joints and finger lengths were measured. The Autism Spectrum Quotient, Empathy Quotient, and Systemizing Quotient were used to evaluate ASD-related traits.

Results

We found a significant positive correlation between the aspect ratio of the right hand and the Systemizing Quotient score: individuals with a larger width relative to the finger length showed more systemizing traits.

Discussion

These findings suggest that gene polymorphisms or prenatal sex hormone exposure may underlie the relationship between systemizing traits and hand configurations.

Sex chromosomes and hormones independently influence healthy brain development but act similarly after cranial radiation

The course of normal development and response to pathology are strongly influenced by biological sex. For instance, female childhood cancer survivors who have undergone cranial radiation therapy (CRT) tend to display more pronounced cognitive deficits than their male counterparts. Sex effects can be the result of sex chromosome complement (XX vs. XY) and/or gonadal hormone influence. The contributions of each can be separated using the four-core genotype mouse model (FCG), where sex chromosome complement and gonadal sex are decoupled. While studies of FCG mice have evaluated brain differences in adulthood, it is still unclear how sex chromosome and sex hormone effects emerge through development in both healthy and pathological contexts. Our study utilizes longitudinal MRI with the FCG model to investigate sex effects in healthy development and after CRT in wildtype and immune-modified Ccl2-knockout mice. Our findings in normally developing mice reveal a relatively prominent chromosome effect prepubertally, compared to sex hormone effects which largely emerge later. Spatially, sex chromosome and hormone influences were independent of one another. After CRT in Ccl2-knockout mice, both male chromosomes and male hormones similarly improved brain outcomes but did so more separately than in combination. Our findings highlight the crucial role of sex chromosomes in early development and identify roles for sex chromosomes and hormones after CRT-induced inflammation, highlighting the influences of biological sex in both normal brain development and pathology.

Autistic People's Experience of Empathy and the Autistic Empathy Deficit Narrative

Background

There is a dominant discourse, both in clinical texts and throughout the academic literature, that autistic people lack empathy; however, over the past decade, both clinicians and academics have increasingly rejected deficit-based descriptions of autism in favor of more nuanced explanations of the experience of autistic individuals in a social world.

Methods

This study asked 76 autistic individuals about their own experience of empathy and the oft-cited empathy deficit. Data were thematically analyzed and revealed a wide array of empathic self-concepts among respondents.

Results

Notably, there was a high proportion of hyper-empathic experiences. Many respondents reported their empathic responses to be overwhelming, or even distressing. These different experiences of empathy contrast with societal expectations of empathy, which often result in additional labor for autistic people as they navigate the non-autistic centered world.

Conclusion

Although the academic literature is, in some areas, slowly moving away from a deficit perspective, more broadly there is still a negative impact from misconceptions around autistic people and empathy. Further work needs to be done to not only explore this misconception at a societal (rather than academic) level, but also better bridge the gap around the changing ideas of empathy and real-world understanding of autistic empathy.

Using Organoids to Model Sex Differences in the Human Brain

Sex differences are widespread during neurodevelopment and play a role in neuropsychiatric conditions such as autism, which is more prevalent in males than females. In humans, males have been shown to have larger brain volumes than females with development of the hippocampus and amygdala showing prominent sex differences. Mechanistically, sex steroids and sex chromosomes drive these differences in brain development, which seem to peak during prenatal and pubertal stages. Animal models have played a crucial role in understanding sex differences, but the study of human sex differences requires an experimental model that can recapitulate complex genetic traits. To fill this gap, human induced pluripotent stem cell-derived brain organoids are now being used to study how complex genetic traits influence prenatal brain development. For example, brain organoids from individuals with autism and individuals with X chromosome-linked Rett syndrome and fragile X syndrome have revealed prenatal differences in cell proliferation, a measure of brain volume differences, and excitatory-inhibitory imbalances. Brain organoids have also revealed increased neurogenesis of excitatory neurons due to androgens. However, despite growing interest in using brain organoids, several key challenges remain that affect its validity as a model system. In this review, we discuss how sex steroids and the sex chromosomes each contribute to sex differences in brain development. Then, we examine the role of X chromosome inactivation as a factor that drives sex differences. Finally, we discuss the combined challenges of modeling X chromosome inactivation and limitations of brain organoids that need to be taken into consideration when studying sex differences.

Atopic Dermatitis and Autism Spectrum Disorders: Common Role of Environmental and Clinical Co-Factors in the Onset and Severity of Their Clinical Course

Increasing evidence suggests an association between atopic dermatitis, the most chronic inflammatory disease of the skin, and autism spectrum disorders, which are a group of neurodevelopmental diseases. Inflammation and immune dysregulation associated with genetic and environmental factors seem to characterize the pathophysiological mechanisms of both conditions. We conducted a literature review of the PubMed database aimed at identifying the clinical features and alleged risk factors that could be used in clinical practice to predict the onset of ASD and/or AD or worsen their prognosis in the context of comorbidities.

DNA Methylation in Autism Spectrum Disorders: Biomarker or Pharmacological Target?

Autism spectrum disorder (ASD) is a group of heterogeneous neurodevelopmental disabilities with persistent impairments in cognition, communication, and social behavior. Although environmental factors play a role in ASD etiopathogenesis, a growing body of evidence indicates that ASD is highly inherited. In the last two decades, the dramatic rise in the prevalence of ASD has interested researchers to explore the etiologic role of epigenetic marking and incredibly abnormal DNA methylation. This review aimed to explain the current understanding of the association between changes in DNA methylation signatures and ASD in patients or animal models. We reviewed studies reporting alterations in DNA methylation at specific genes as well as epigenome-wide association studies (EWASs). Finally, we hypothesized that specific changes in DNA methylation patterns could be considered a potential biomarker for ASD diagnosis and prognosis and even a target for pharmacological intervention.

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.

Weak central coherence in adults with ASD: Evidence from eye-tracking and thematic content analysis of social scenes

Central Coherence Weakness has been defined as a tendency for local rather than global processing that may underlie core deficits in Autism Spectrum Disorder (ASD). In social contexts it may be expressed in difficulties to integrate social cues arising from the recognition of emotions in faces or from the environment in order to understand people's interactions. A sample of 28 adults diagnosed with ASD Level 1 and 25 controls was submitted to a cartoon-like task with the instruction to describe social scenes and to Navon letter stimuli. Both quantitative measures and qualitative (thematic content analysis) procedures were used to assess performance. Heatmap and fixation preferences according to the stimuli quadrants were used to investigate eye-tracking patterns. A tendency to local processing, independently of the stimuli type, in the ASD participants was observed. Data from visual tracking by quadrants and from verbal reports suggest loss of social cues important for understanding context. Their reaction time and response duration were increased in relation to controls. The findings corroborate the idea that weak central coherence may be part of the cognitive phenotype in ASD.

Gender diversity in autistic and neurotypical youth over adolescence and puberty: A longitudinal study

Recent research in autism spectrum disorder (ASD) has suggested a higher prevalence of gender diversity in individuals diagnosed with ASD. Adolescence is a critical period for the consolidation of gender identity, yet the extent to which the experience of gender diversity is stable over adolescence and puberty in autistic youth is poorly understood. The aim of the study was to examine the consistency of gender diversity using the gender diversity screening questionnaire for self- and parent-report of youth (GDSQ-S, GDSQ-P) over a four-year longitudinal study of pubertal development in youth with ASD (N = 140, 36 assigned-female-at birth (AFAB)) and typical development (TD, N = 104, 58 assigned-male-at-birth [AMAB]) and their parents. The extent to which diagnosis (ASD vs. TD), assigned sex (AFAB vs. AMAB) and developmental level (age, puberty) predict GDSQ trajectory over time was explored. There was a significant diagnosis by sex-assigned-at-birth by age interaction for GDSQ-S Gender Diversity, p = 0.002, showing higher scores in autistic AFAB youth over adolescence, and TD AFAB showing initially lower, then increasing levels over adolescence. For GDSQ-P, Gender Incongruence was significantly different between the groups, p = 0.032, showing higher incongruence for autistic AFAB around age 10, decreasing between age 12-14 before increasing again, while TD AFAB evidence the inverse trend. AMAB trends were stable. The significant diagnostic, developmental and sex-based differences indicate AFAB youth experience greater gender diversity that evolves over development. Findings suggest gender identity formation is nuanced and may be influenced by pubertal progression, hormonal patterns, and psychosocial factors. Results underscore the need for enhanced understanding of the unique, dynamic profiles of females-assigned-at-birth.

Sex-related patterns of functional brain networks in children and adolescents with autism spectrum disorder

Although numerous studies have emphasized the male predominance in autism spectrum disorder (ASD), how sex differences are related to the topological organization of functional networks remains unclear. This study utilized imaging data from 86 ASD (43 females, aged 7-18 years) and 86 typically developing controls (TCs) (43 females, aged 7-18 years) obtained from Autism Brain Imaging Data Exchange databases, constructed individual whole-brain functional networks, used a graph theory analysis to compute topological metrics, and assessed sex-related differences in topological metrics using a 2 × 2 factorial design. At the global level, females with ASD exhibited significantly higher cluster coefficient and local efficiency than female TCs, while no significant difference was observed between males with ASD and male TCs. Meanwhile, the neurotypical sex differences in cluster coefficient and local efficiency observed in TCs were not present in ASD. At the nodal level, ASD exhibited abnormal nodal centrality in the left middle temporal gyrus.

Towards understanding sex differences in autism spectrum disorders

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterized by social deficits, repetitive behaviours and lack of empathy. Its significant genetic heritability and potential comorbidities often lead to diagnostic and therapeutic challenges. This review addresses the biological basis of ASD, focusing on the sex differences in gene expression and hormonal influences. ASD is more commonly diagnosed in males at a ratio of 4:1, indicating a potential oversight in female-specific ASD research and a risk of underdiagnosis in females. We consider how ASD manifests differently across sexes by exploring differential gene expression in female and male brains and consider how variations in steroid hormones influence ASD characteristics. Synaptic function, including excitation/inhibition ratio imbalance, is influenced by gene mutations and this is explored as a key factor in the cognitive and behavioural manifestations of ASD. We also discuss the role of micro RNAs (miRNAs) and highlight a novel mutation in miRNA-873, which affects a suite of key synaptic genes, neurexin, neuroligin, SHANK and post-synaptic density proteins, implicated in the pathology of ASD. Our review suggests that genetic predisposition, sex differences in brain gene expression, and hormonal factors significantly contribute to the presentation, identification and severity of ASD, necessitating sex-specific considerations in diagnosis and treatments. These findings advocate for personalized interventions to improve the outcomes for individuals with ASD.

Broad Autism Phenotype and Gait in Parents of Children With and Without Autism Spectrum Disorder

Background

Autism spectrum disorder (ASD) is a highly heritable neurodevelopmental disorder. Research has shown that parents and relatives of children with ASD often exhibit subthreshold ASD-like characteristics known as broad autism phenotype (BAP) as well as impairments in motor behaviours.

Purpose

The current study aimed to examine the BAP traits and motor behaviours, that is, gait in 44 parents of children with ASD and in 48 parents of typically developing children (TD).

Methods

The BAP traits were measured using the broad autism phenotype questionnaire (BAPQ), and a low-cost computer vision-based framework was utilised to quantify the gait in children with ASD and their parents and TD children and their parents.

Results

The parents of children with ASD consistently displayed significantly higher scores on rigid personality and pragmatic language, however, there were no significant differences between the two group of parents on aloof personality of BAP traits. On gait parameters, the parents of children with ASD had a reduced gait speed in comparison to parents of TD children. There were no meaningful similarities in gait parameters of children with ASD and their parents.

Conclusions

These findings support the presence of ASD-like traits in the parents of children with ASD and gait speed as a putative motor endophenotype of ASD.

Practice is the best of all instructors-Effects of enactment encoding and episodic future thinking on prospective memory performance in high-functioning adults with autism spectrum disorder

Prospective memory (PM) is the ability to remember to carry out intended actions in the future. The present study investigated the effects of episodic future thinking (EFT) and enactment encoding (EE) on PM performance in autistic adults (ASD). A total of 72 autistic individuals and 70 controls matched for age, gender, and cognitive abilities completed a computerized version of the Dresden breakfast Task, which required participants to prepare breakfast following a set of rules and time restrictions. A two (group: ASD vs. controls) by three (encoding condition: EFT vs. EE vs. standard) between-subjects design was applied. Participants were either instructed to engage in EFT or EE to prepare to the different tasks prior to performing the Dresden breakfast or received standard instructions. Analyses of variance were conducted. Autism-spectrum-disorders (ASD) participants did not differ from control participants in their PM performance, regardless of which strategy they used. Compared to the standard condition, EE but not EFT improved time-based PM performance in all participants. This is the first study to find spared time-based PM performance in autistic individuals. The results confirm earlier results of beneficial effects of EE on PM performance. Findings are discussed with regards to the methodology used, sample composition as well as autistic characteristics.

Maternal obesity: sex-specific in utero changes in fetal brain autophagy and mTOR

OBJECTIVE

Maternal obesity affects 39.7% of reproductive-age women in the United States. Emerging research has suggested that in utero exposure to maternal obesity is associated with adverse neurodevelopmental outcomes, but knowledge of underlying mechanisms in human samples is lacking.

METHODS

A matched case-control study was performed in women with singleton fetuses who were undergoing elective pregnancy termination at gestational ages 15 to 21 weeks. Maternal adiponectin levels from plasma were measured using ELISA kits. RNA was extracted from fetal brain tissue using RNeasy Mini Kit (QIAGEN). mRNA expression from ADIPOR1, ADIPOR2, MTOR, ATG5, ATG7, BECN1, and MAP1LC3B was quantified through the ΔΔCt method and using GAPDH as a housekeeping gene.

RESULTS

We have identified transcription patterns associated with inhibition of autophagy in male fetal brain tissue exposed to maternal obesity (↑MTOR, ↓ATG5, ↓ATG7, and ↓MAP1LC3B), with female fetuses demonstrating either no change in transcription or nonsignificant changes associated with increased autophagy. There was significant downregulation of the autophagy-associated gene BECN1 in both male and female individuals who were exposed to obesity in utero.

CONCLUSIONS

We present novel evidence suggesting that in utero exposure to maternal obesity in humans may significantly affect neurodevelopment, especially in male fetuses, through alterations in normal autophagy molecular mechanisms and with adiponectin as a potential mediator.

The Role of Sertoli Cell Hormones in Male Preponderance Observed in Autism Spectrum Disorder

Introduction

There is a significant, but poorly understood, male preponderance in prevalence of autism spectrum disorder (ASD). The aim of this study was to examine the relationship between male preponderance in ASD and Inhibin B (InhB) and Anti-Müllerian hormone (AMH) levels and the 2D/4D finger ratio associated with fetal androgen exposure.

Methods

42 patients with ASD and 42 neurotypical controls between the ages of 5 and 10 were included. ASD diagnosis and severity were determined using K-SADS PL (Kiddie-SADS - Present and Life Time) Version 2016 and the Childhood Autism Rating Scale (CARS). Serum InhB and AMH were measured. The 2D/4D finger length ratio was also calculated for hand anthropometric measurements.

Results

Serum InhB levels were higher in children diagnosed with ASD compared to the neurotypical controls (p=0.003). Serum AMH levels were similar in both groups. Positive correlation was determined between AMH and CARS scores (r=0.315, p=0.05). 2D/4D finger ratios in the ASD group were significantly lower than in the control group (p<0.001).

Conclusion

The study findings suggest that InhB, AMH, and fetal testosterone may be associated with male preponderance in ASD. More research is now required for a better understanding of this subject.

Prenatal Androgen Exposure Induces Anxiety-Like Behavior in Ewes

INTRODUCTION

In humans, prenatal androgen excess can lead to a broad spectrum of pathologies in adulthood, including polycystic ovary syndrome (PCOS). Women with PCOS present a variety of reproductive and metabolic disturbances and they also face increased risk to develop neuropsychiatric disorders such as depression and anxiety. Despite the high prevalence, the cause of depressive and anxiety symptoms is not fully elucidated. The use of androgenized ewe models can provide valuable insights into the pathogenesis of PCOS, as they closely mimic the reproductive, neuroendocrine, and metabolic characteristics observed in women with this condition.

METHOD

We studied the impact of prenatal exposure to testosterone propionate on cognitive and behavioral performances of Ile-de-France ewes, using a plethora of behavioral tests for anxiety and cognitive performances.

RESULTS

Our findings indicate that prenatal androgenized ewes exhibit markedly elevated levels of anxiety-like behavior compared to control animals, while showing no discernible differences in cognitive performance.

CONCLUSION

These discoveries offer novel perspectives on how maternal androgen excess contributes to anxiogenic effects in PCOS preclinical models, underscoring the ewe's significance as a model for conducting mechanistic studies to unravel the physiological and molecular aspects of anxiety.

Infant microbes and metabolites point to childhood neurodevelopmental disorders

This study has followed a birth cohort for over 20 years to find factors associated with neurodevelopmental disorder (ND) diagnosis. Detailed, early-life longitudinal questionnaires captured infection and antibiotic events, stress, prenatal factors, family history, and more. Biomarkers including cord serum metabolome and lipidome, human leukocyte antigen (HLA) genotype, infant microbiota, and stool metabolome were assessed. Among the 16,440 Swedish children followed across time, 1,197 developed an ND. Significant associations emerged for future ND diagnosis in general and for specific ND subtypes, spanning intellectual disability, speech disorder, attention-deficit/hyperactivity disorder, and autism. This investigation revealed microbiome connections to future diagnosis as well as early emerging mood and gastrointestinal problems. The findings suggest links to immunodysregulation and metabolism, compounded by stress, early-life infection, and antibiotics. The convergence of infant biomarkers and risk factors in this prospective, longitudinal study on a large-scale population establishes a foundation for early-life prediction and intervention in neurodevelopment.

Prevalence of autism spectrum disorder among children in Southeast Asia from 2002 to 2022: An updated systematic review and meta-analysis

Background and Aims

Autism spectrum disorder (ASD) is a neurodevelopmental condition that impacts the brain, characterized by challenges in social communication and interaction, often accompanied by repetitive behaviors or focused interests. This study sheds light on the prevalence of ASD within the Southeast Asian region.

Methods

The study protocol was registered in PROSPERO (Registration No: CRD42023413915). Appropriate search terms and Boolean operators were employed to explore electronic databases for relevant articles. Data thus extracted were prepared in Excel and analyzed in Comprehensive Meta-Analysis Software. The effect measure utilized in the study was represented by the proportion, and the choice between a fixed or random-effect model depended on the observed heterogeneity. Visual feedback was provided through the use of forest plots and funnel plots.

Results

A total of 14 studies were included in the qualitative and quantitative synthesis after screening the imported studies. The prevalence of ASD was six per 1000 population (proportion: 0.006; CI: 0.002-0.017; I 2: 99.263%). Among the ASD cases, 64.4% (proportion: 0.644; CI: 0.590-0.693; I 2: 9.937%) were males and 35.6% (proportion: 0.356; CI: 0.307-0.410; I 2: 9.937%) were females.

Conclusion

The prevalence of ASD in Southeast Asia was estimated to be six cases per 1000 individuals, with a higher prevalence among males. This study contributes to our understanding of ASD prevalence in the region, although it is essential to note certain limitations in estimating prevalence.

Excess neonatal testosterone causes male-specific social and fear memory deficits in wild-type mice

Neurodevelopmental disorders (ND) disproportionately affect males compared to females, and Autism Spectrum Disorder (ASD) in particular exhibits a 4:1 male bias. The biological mechanisms of this female protection or male susceptibility have not been identified. There is some evidence to suggest that fetal/neonatal gonadal hormones, which play pivotal roles in many aspects of development, may contribute. Here, we investigate the role of testosterone administration during a critical period of development, and its effects on social approach and fear learning in C57BL/6J wildtype mice. Male, but not female mice treated with testosterone on the day of birth (PN0) exhibited deficits in both social behavior and contextual fear conditioning, whereas mice treated with the same dose of testosterone on postnatal day 18 (PN18) did not display such impairments. Testosterone administration did not induce anxiogenic effects or lead to changes in body weight compared to the vehicle-treated group. These impairmeants are relevant to ND and may help identify novel treatment targets.

A matter of precision? Scene imagery in individuals with high-functioning autism spectrum disorder

The ability to create mental representations of scenes is essential for remembering, predicting, and imagining. In individuals with autism spectrum disorders (ASD) this ability may be impaired. Considering that autistic characteristics such as weak central coherence or reduced communication abilities may disadvantage autistic participants in traditional imagery tasks, this study attempted to use a novel task design to measure the ability of scene imagery. Thirty high-functioning adults with ASD and 27 non-autistic matched control adults were asked to describe imagined fictitious scenes using two types of scene imagery tasks. In a free imagery task, participants were asked to imagine a scene based on a given keyword. In a guided imagery task, participants had to imagine a scene based on a detailed description of the scene. Additionally, narrative abilities were assessed using the Narrative Scoring Scheme. Statistical analyses revealed no group effects in the free and guided imagery of fictional scenes. Participants with ASD performed worse than control participants in the narrative task. Narrative abilities correlated positively with performance in both imagery tasks in the ASD group only. Hence, individuals with ASD seem to show as good imagery abilities as non-autistic individuals. The results are discussed in the light of the differences between imagery and imagination and possible gender differences.

Sex differences in fetal brain functional network topology

The fetal period is a critical stage in brain development, and understanding the characteristics of the fetal brain is crucial. Although some studies have explored aspects of fetal brain functional networks, few have specifically focused on sex differences in brain network characteristics. We adopted the graph theory method to calculate brain network functional connectivity and topology properties (including global and nodal properties), and further compared the differences in these parameters between male and female fetuses. We found that male fetuses showed an increased clustering coefficient and local efficiency than female fetuses, but no significant group differences concerning other graph parameters and the functional connectivity matrix. Our study suggests the existence of sex-related distinctions in the topological properties of the brain network at the fetal stage of development and demonstrates an increase in brain network separation in male fetuses compared with female fetuses.

Sex-biased single-cell genetic landscape in mice with autism spectrum disorder

Autistic spectrum disorder (ASD) is a male-biased, heterogeneous neurodevelopmental disorder that affects approximately 1%-2% of the population. Prenatal exposure to valproic acid (VPA) is a recognized risk factor for ASD, but the cellular and molecular basis of VPA-induced ASD at the single-cell resolution is unclear. Here, we aim to compare the cellular and molecular differences in the hippocampus between male and female prenatal mice with ASD at the single-cell transcriptomic level. The transcriptomes of more than 45,000 cells are assigned to 12 major cell types, including neurons, glial cells, vascular cells, and immune cells. Cell type-specific genes with altered expression after prenatal VPA exposure are analyzed, and the largest number of differentially expressed genes (DEGs) are found in neurons, choroid plexus epithelial cells, and microglia. In microglia, several pathways related to inflammation are found in both males and females, including the tumor necrosis factor (TNF), nuclear factor kappa B (NF-κB), toll-like receptor (TLR), and mitogen-activated protein kinase (MAPK) signaling pathways, which are important for the induction of autistic-like behavior. Additionally, we note that several X-linked genes, including Bex1, Bex3, and Gria3, were among the male-specific DEGs of neurons. This pioneering study describes the landscape of the transcriptome in the hippocampus of autistic mice. The elucidation of sexual differences could provide innovative strategies for the prevention and treatment of ASD.

Deep learning models reveal replicable, generalizable, and behaviorally relevant sex differences in human functional brain organization

Sex plays a crucial role in human brain development, aging, and the manifestation of psychiatric and neurological disorders. However, our understanding of sex differences in human functional brain organization and their behavioral consequences has been hindered by inconsistent findings and a lack of replication. Here, we address these challenges using a spatiotemporal deep neural network (stDNN) model to uncover latent functional brain dynamics that distinguish male and female brains. Our stDNN model accurately differentiated male and female brains, demonstrating consistently high cross-validation accuracy (>90%), replicability, and generalizability across multisession data from the same individuals and three independent cohorts (N ~ 1,500 young adults aged 20 to 35). Explainable AI (XAI) analysis revealed that brain features associated with the default mode network, striatum, and limbic network consistently exhibited significant sex differences (effect sizes > 1.5) across sessions and independent cohorts. Furthermore, XAI-derived brain features accurately predicted sex-specific cognitive profiles, a finding that was also independently replicated. Our results demonstrate that sex differences in functional brain dynamics are not only highly replicable and generalizable but also behaviorally relevant, challenging the notion of a continuum in male-female brain organization. Our findings underscore the crucial role of sex as a biological determinant in human brain organization, have significant implications for developing personalized sex-specific biomarkers in psychiatric and neurological disorders, and provide innovative AI-based computational tools for future research.

Exploring sex differences: insights into gene expression, neuroanatomy, neurochemistry, cognition, and pathology

Increased knowledge about sex differences is important for development of individualized treatments against many diseases as well as understanding behavioral and pathological differences. This review summarizes sex chromosome effects on gene expression, epigenetics, and hormones in relation to the brain. We explore neuroanatomy, neurochemistry, cognition, and brain pathology aiming to explain the current state of the art. While some domains exhibit strong differences, others reveal subtle differences whose overall significance warrants clarification. We hope that the current review increases awareness and serves as a basis for the planning of future studies that consider both sexes equally regarding similarities and differences.

Sex differences in brain-behavior relationships in the first two years of life

Background

Evidence for sex differences in cognition in childhood is established, but less is known about the underlying neural mechanisms for these differences. Recent findings suggest the existence of brain-behavior relationship heterogeneities during infancy; however, it remains unclear whether sex underlies these heterogeneities during this critical period when sex-related behavioral differences arise.

Methods

A sample of 316 infants was included with resting-state functional magnetic resonance imaging scans at neonate (3 weeks), 1, and 2 years of age. We used multiple linear regression to test interactions between sex and resting-state functional connectivity on behavioral scores of working memory, inhibitory self-control, intelligence, and anxiety collected at 4 years of age.

Results

We found six age-specific, intra-hemispheric connections showing significant and robust sex differences in functional connectivity-behavior relationships. All connections are either with the prefrontal cortex or the temporal pole, which has direct anatomical pathways to the prefrontal cortex. Sex differences in functional connectivity only emerge when associated with behavior, and not in functional connectivity alone. Furthermore, at neonate and 2 years of age, these age-specific connections displayed greater connectivity in males and lower connectivity in females in association with better behavioral scores.

Conclusions

Taken together, we critically capture robust and conserved brain mechanisms that are distinct to sex and are defined by their relationship to behavioral outcomes. Our results establish brain-behavior mechanisms as an important feature in the search for sex differences during development.

Sex, hormones and cerebrovascular function: from development to disorder

Proper cerebrovascular development and neurogliovascular unit assembly are essential for brain growth and function throughout life, ensuring the continuous supply of nutrients and oxygen. This involves crucial events during pre- and postnatal stages through key pathways, including vascular endothelial growth factor (VEGF) and Wnt signaling. These pathways are pivotal for brain vascular growth, expansion, and blood-brain barrier (BBB) maturation. Interestingly, during fetal and neonatal life, cerebrovascular formation coincides with the early peak activity of the hypothalamic-pituitary-gonadal axis, supporting the idea of sex hormonal influence on cerebrovascular development and barriergenesis.Sex hormonal dysregulation in early development has been implicated in neurodevelopmental disorders with highly sexually dimorphic features, such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). Both disorders show higher prevalence in men, with varying symptoms between sexes, with boys exhibiting more externalizing behaviors, such as aggressivity or hyperactivity, and girls displaying higher internalizing behaviors, including anxiety, depression, or attention disorders. Indeed, ASD and ADHD are linked to high prenatal testosterone exposure and reduced aromatase expression, potentially explaining sex differences in prevalence and symptomatology. In line with this, high estrogen levels seem to attenuate ADHD symptoms. At the cerebrovascular level, sex- and region-specific variations of cerebral blood flow perfusion have been reported in both conditions, indicating an impact of gonadal hormones on the brain vascular system, disrupting its ability to respond to neuronal demands.This review aims to provide an overview of the existing knowledge concerning the impact of sex hormones on cerebrovascular formation and maturation, as well as the onset of neurodevelopmental disorders. Here, we explore the concept of gonadal hormone interactions with brain vascular and BBB development to function, with a particular focus on the modulation of VEGF and Wnt signaling. We outline how these pathways may be involved in the underpinnings of ASD and ADHD. Outstanding questions and potential avenues for future research are highlighted, as uncovering sex-specific physiological and pathological aspects of brain vascular development might lead to innovative therapeutic approaches in the context of ASD, ADHD and beyond.

Genomic insights and advanced machine learning: characterizing autism spectrum disorder biomarkers and genetic interactions

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition characterized by altered brain connectivity and function. In this study, we employed advanced bioinformatics and explainable AI to analyze gene expression associated with ASD, using data from five GEO datasets. Among 351 neurotypical controls and 358 individuals with autism, we identified 3,339 Differentially Expressed Genes (DEGs) with an adjusted p-value (≤ 0.05). A subsequent meta-analysis pinpointed 342 DEGs (adjusted p-value ≤ 0.001), including 19 upregulated and 10 down-regulated genes across all datasets. Shared genes, pathogenic single nucleotide polymorphisms (SNPs), chromosomal positions, and their impact on biological pathways were examined. We identified potential biomarkers (HOXB3, NR2F2, MAPK8IP3, PIGT, SEMA4D, and SSH1) through text mining, meriting further investigation. Additionally, ‎we shed light on the roles of RPS4Y1 and KDM5D genes in neurogenesis and neurodevelopment. Our analysis detected 1,286 SNPs linked to ASD-related conditions, of which 14 high-risk SNPs were located on chromosomes 10 and X. We highlighted potential missense SNPs associated with FGFR inhibitors, suggesting that it may serve as a promising biomarker for responsiveness to targeted therapies. Our explainable AI model identified the MID2 gene as a potential ASD biomarker. This research unveils vital genes and potential biomarkers, providing a foundation for novel gene discovery in complex diseases.

Dissecting the autism-associated 16p11.2 locus identifies multiple drivers in neuroanatomical phenotypes and unveils a male-specific role for the major vault protein

BACKGROUND

Using mouse genetic studies and systematic assessments of brain neuroanatomical phenotypes, we set out to identify which of the 30 genes causes brain defects at the autism-associated 16p11.2 locus.

RESULTS

We show that multiple genes mapping to this region interact to regulate brain anatomy, with female mice exhibiting far fewer brain neuroanatomical phenotypes. In male mice, among the 13 genes associated with neuroanatomical defects (Mvp, Ppp4c, Zg16, Taok2, Slx1b, Maz, Fam57b, Bola2, Tbx6, Qprt, Spn, Hirip3, and Doc2a), Mvp is the top driver implicated in phenotypes pertaining to brain, cortex, hippocampus, ventricles, and corpus callosum sizes. The major vault protein (MVP), the main component of the vault organelle, is a conserved protein found in eukaryotic cells, yet its function is not understood. Here, we find MVP expression highly specific to the limbic system and show that Mvp regulates neuronal morphology, postnatally and specifically in males. We also recapitulate a previously reported genetic interaction and show that Mvp+/-;Mapk3+/- mice exhibit behavioral deficits, notably decreased anxiety-like traits detected in the elevated plus maze and open field paradigms.

CONCLUSIONS

Our study highlights multiple gene drivers in neuroanatomical phenotypes, interacting with each other through complex relationships. It also provides the first evidence for the involvement of the major vault protein in the regulation of brain size and neuroanatomy, specifically in male mice.

Similar overall expression, but different profiles, of autistic traits, sensory processing, and mental health between young adult males and females

Recent trends suggest that autism is more common in females than traditionally held. Additionally, some argue that females express autistic traits differently than males. Dimensional views of autism could shed light on these issues, especially with regards to understudied behavioral areas, such as sensory processing. We examined autistic traits, sensory processing, anxiety, and related behaviors in a large sample of neurotypical young adult males and females (n = 1,122; 556 female; ages 19-26). Participants completed an online survey containing questionnaires related to the above. Between groups statistical analyses, as well as within groups correlations and mediation analyses containing these constructs were then computed. We also carried out a cluster analysis to establish groups with behavioral similarities and estimate within-cluster male/female ratios. Results showed modest differences in the overall expression of autistic traits and sensory processing, if any, between males and females. Conversely, more detailed examination of survey subtests and mediation analyses revealed differing profiles between these groups. Cluster analysis uncovered a group comprised of both males (69.8%) and females (30.2%) who exhibited elevated degrees of autism-related behaviors, suggesting a higher proportion of females than would be predicted by traditional ratios. Taken together, these findings suggest that males and females may not differ as much as previously thought in their general levels of autistic traits or sensory processing, but may present with distinct profiles of such behaviors. These novel results add to our understanding of autistic traits in females and have the potential to positively influence diagnostic and support practices.

Describing the male registered nursing workforce toward increasing male representation in professional nursing

BACKGROUND

Men are significantly underrepresented in nursing and increasing their numbers should be a priority.

PURPOSE

To describe the male nursing workforce in terms of size, demographics, education, and work settings.

METHODS

Using data from the 2018 National Sample Survey of Registered Nurses, we performed a secondary descriptive analysis.

FINDINGS

We find that 9.6% of registered nurses are men. Men are more likely than women to hold an associate degree and clinical doctorates, be nurse anesthetists and supervisors, and work in emergency settings but less likely than females to participate in teaching.

DISCUSSION

To increase male representation in nursing we must simultaneously rearticulate what it means for a job to be "female" while also showing that nursing incorporates many skills and interests traditionally coded as "male." We can also show men that nursing offers appealing employment that can lead to a deeply fulfilling personal and professional life.

Prenatal Metal Exposure Alters the Placental Proteome in a Sex-Dependent Manner in Extremely Low Gestational Age Newborns: Links to Gestational Age

Prenatal exposure to toxic metals is associated with altered placental function and adverse infant and child health outcomes. Adverse outcomes include those that are observed at the time of birth, such as low birthweight, as well as those that arise later in life, such as neurological impairment. It is often the case that these adverse outcomes show sex-specific responses in relation to toxicant exposures. While the precise molecular mechanisms linking in utero toxic metal exposures with later-in-life health are unknown, placental inflammation is posited to play a critical role. Here, we sought to understand whether in utero metal exposure is associated with alterations in the expression of the placental proteome by identifying metal associated proteins (MAPs). Within the Extremely Low Gestational Age Newborns (ELGAN) cohort (n = 230), placental and umbilical cord tissue samples were collected at birth. Arsenic (As), cadmium (Cd), lead (Pb), selenium (Se), and manganese (Mn) concentrations were measured in umbilical cord tissue samples via ICP-MS/MS. Protein expression was examined in placental samples using an LC-MS/MS-based, global, untargeted proteomics analysis measuring more than 3400 proteins. MAPs were then evaluated for associations with pregnancy and neonatal outcomes, including placental weight and gestational age. We hypothesized that metal levels would be positively associated with the altered expression of inflammation/immune-associated pathways and that sex-specific patterns of metal-associated placental protein expression would be observed. Sex-specific analyses identified 89 unique MAPs expressed in female placentas and 41 unique MAPs expressed in male placentas. Notably, many of the female-associated MAPs are known to be involved in immune-related processes, while the male-associated MAPs are associated with intracellular transport and cell localization. Further, several MAPs were significantly associated with gestational age in males and females and placental weight in males. These data highlight the linkage between prenatal metal exposure and an altered placental proteome, with implications for altering the trajectory of fetal development.

Comprehensive analysis of sex differences in the function and ultrastructure of hippocampal presynaptic terminals

Sex differences in the brain, encompassing variations in specific brain structures, size, cognitive function, and synaptic connections, have been identified across numerous species. While previous research has explored sex differences in postsynaptic structures, synaptic plasticity, and hippocampus-dependent functions, the hippocampal presynaptic terminals remain largely uninvestigated. The hippocampus is a critical structure responsible for multiple brain functions. This study examined presynaptic differences in cultured hippocampal neurons derived from male and female mice using a combination of biochemical assays, functional analyses measuring exocytosis and endocytosis of synaptic vesicle proteins, ultrastructural analyses via electron microscopy, and presynaptic Ca2+-specific optical probes. Our findings revealed that female neurons exhibited a higher number of synaptic vesicles at presynaptic terminals compared to male neurons. However, no significant differences were observed in presynaptic protein expression, presynaptic terminal ultrastructure, synaptic vesicle exocytosis and endocytosis, or presynaptic Ca2+ alterations between male and female neurons.

Fetal sex differences in placental LCPUFA ether and plasmalogen phosphatidylethanolamine and phosphatidylcholine contents in pregnancies complicated by obesity

BACKGROUND

We have previously reported that maternal obesity reduces placental transport capacity for lysophosphatidylcholine-docosahexaenoic acid (LPC-DHA), a preferred form for transfer of DHA (omega 3) to the fetal brain, but only in male fetuses. Phosphatidylethanolamine (PE) and phosphatidylcholine (PC), have either sn-1 ester, ether or vinyl ether (plasmalogen) linkages to primarily unsaturated and monounsaturated fatty acids and DHA or arachidonic acid (ARA, omega 6) in the sn-2 position. Whether ether and plasmalogen PC and PE metabolism in placenta impacts transfer to the fetus is unexplored. We hypothesized that ether and plasmalogen PC and PE containing DHA and ARA are reduced in maternal-fetal unit in pregnancies complicated by obesity and these differences are dependent on fetal sex.

METHODS

In maternal, umbilical cord plasma and placentas from obese women (11 female/5 male infants) and normal weight women (9 female/7 male infants), all PC and PE species containing DHA and ARA were analyzed by LC-MS/MS. Placental protein expression of enzymes involved in phospholipid synthesis, were determined by immunoblotting. All variables were compared between control vs obese groups and separated by fetal sex, in each sample using the Benjamini-Hochberg false discovery rate adjustment to account for multiple testing.

RESULTS

Levels of ester PC containing DHA and ARA were profoundly reduced by 60-92% in male placentas of obese mothers, while levels of ether and plasmalogen PE containing DHA and ARA were decreased by 51-84% in female placentas. PLA2G4C abundance was lower in male placentas and LPCAT4 abundance was lower solely in females in obesity. In umbilical cord, levels of ester, ether and plasmalogen PC and PE with DHA were reduced by 43-61% in male, but not female, fetuses of obese mothers.

CONCLUSIONS

We found a fetal sex effect in placental PE and PC ester, ether and plasmalogen PE and PC containing DHA in response to maternal obesity which appears to reflect an ability of female placentas to adapt to maintain optimal fetal DHA transfer in maternal obesity.

Sex Differences in Brain Disorders

A remarkable feature of the brain is its sexual dimorphism. Sexual dimorphism in brain structure and function is associated with clinical implications documented previously in healthy individuals but also in those who suffer from various brain disorders. Sex-based differences concerning some features such as the risk, prevalence, age of onset, and symptomatology have been confirmed in a range of neurological and neuropsychiatric diseases. The mechanisms responsible for the establishment of sex-based differences between men and women are not fully understood. The present paper provides up-to-date data on sex-related dissimilarities observed in brain disorders and highlights the most relevant features that differ between males and females. The topic is very important as the recognition of disparities between the sexes might allow for the identification of therapeutic targets and pharmacological approaches for intractable neurological and neuropsychiatric disorders.

Vasopressin as Possible Treatment Option in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is rather common, presenting with prevalent early problems in social communication and accompanied by repetitive behavior. As vasopressin was implicated not only in salt-water homeostasis and stress-axis regulation, but also in social behavior, its role in the development of ASD might be suggested. In this review, we summarized a wide range of problems associated with ASD to which vasopressin might contribute, from social skills to communication, motor function problems, autonomous nervous system alterations as well as sleep disturbances, and altered sensory information processing. Beside functional connections between vasopressin and ASD, we draw attention to the anatomical background, highlighting several brain areas, including the paraventricular nucleus of the hypothalamus, medial preoptic area, lateral septum, bed nucleus of stria terminalis, amygdala, hippocampus, olfactory bulb and even the cerebellum, either producing vasopressin or containing vasopressinergic receptors (presumably V1a). Sex differences in the vasopressinergic system might underline the male prevalence of ASD. Moreover, vasopressin might contribute to the effectiveness of available off-label therapies as well as serve as a possible target for intervention. In this sense, vasopressin, but paradoxically also V1a receptor antagonist, were found to be effective in some clinical trials. We concluded that although vasopressin might be an effective candidate for ASD treatment, we might assume that only a subgroup (e.g., with stress-axis disturbances), a certain sex (most probably males) and a certain brain area (targeting by means of virus vectors) would benefit from this therapy.

Sex differences of the triple network model in children with autism: A resting-state fMRI investigation of effective connectivity

Autism spectrum disorder (ASD) has a pronounced male predominance, but the underlying neurobiological basis of this sex bias remains unclear. Gender incoherence (GI) theory suggests that ASD is more neurally androgynous than same-sex controls. Given its central role, altered structures and functions, and sex-dependent network differences in ASD, the triple network model, including the central executive network (CEN), default mode network (DMN), and salience network (SN), has emerged as a candidate for characterizing this sex difference. Here, we measured the sex-related effective connectivity (EC) differences within and between these three networks in 72 children with ASD (36 females, 8-14 years) and 72 typically developing controls (TCs) (36 females, 8-14 years) from 5 sites of the Autism Brain Imaging Data Exchange repositories using a 2 × 2 analysis of covariance factorial design. We also assessed brain-behavior relationships and the effects of age on EC. We found significant diagnosis-by-sex interactions on EC: females with ASD had significantly higher EC than their male counterparts within the DMN and between the SN and CEN. The interaction pattern supported the GI theory by showing that the higher EC observed in females with ASD reflected a shift towards the higher level of EC displayed in male TCs (neural masculinization), and the lower EC seen in males with ASD reflected a shift towards the lower level of EC displayed in female TCs (neural feminization). We also found significant brain-behavior correlations and significant effects of age on EC.

Brain structure underlying the empathizing-systemizing difference in children with autism spectrum disorder

BACKGROUND

Behavioral research has shown that children with autism spectrum disorder (ASD) have a higher empathizing-systemizing difference (D score) than normal children. However, there is no research about the neuroanatomical mechanisms of the empathizing-systemizing difference in children with ASD.

METHODS

Participants comprised 41 children with ASD and 39 typically developing (TD) children aged 6‒12 years. Empathizing-systemizing difference was estimated using the D score from the Chinese version of Children's Empathy Quotient and Systemizing Quotient. We quantified brain morphometry, including global and regional brain volumes and surface-based cortical measures (cortical thickness, surface area, and gyrification) via structural magnetic resonance imaging.

RESULTS

We found that the D score was significantly negatively associated with amygdala gray matter volume [β =  -0.16; 95% confidence interval (CI): -0.30,  -0.02; P value = 0.030] in children with ASD. There was a significantly negative association between D score and gyrification in the left lateral occipital cortex (LOC) in children with ASD (B =  -0.10; SE = 0.03; cluster-wise P value = 0.006) and a significantly positive association between D score and gyrification in the right fusiform in TD children (B = 0.10; SE = 0.03; cluster-wise P value = 0.022). Moderation analyses demonstrated significant interactions between D score and diagnosed group in amygdala gray matter volume (β = 0.19; 95% CI 0.04, 0.35; P value = 0.013) and left LOC gyrification (β = 0.11; 95% CI 0.05, 0.17; P value = 0.001) but not in right fusiform gyrification (β = 0.08; 95% CI -0.02, 0.17; P value = 0.105).

CONCLUSIONS

Neuroanatomical variation in amygdala volume and gyrification of LOC could be potential biomarkers for the empathizing-systemizing difference in children with ASD but not in TD children. Large-scale neuroimaging studies are necessary to test the replicability of our findings.

Sex differences in placenta-derived markers and later autistic traits in children

Autism is more prevalent in males and males on average score higher on measures of autistic traits. Placental function is affected significantly by the sex of the fetus. It is unclear if sex differences in placental function are associated with sex differences in the occurrence of autistic traits postnatally. To assess this, concentrations of angiogenesis-related markers, placental growth factor (PlGF) and soluble fms-like tyrosine kinase (sFlt-1) were assessed in maternal plasma of expectant women in the late 1^st (mean= 13.5 [SD = 2.0] weeks gestation) and 2^nd trimesters (mean=20.6 [SD = 1.2] weeks gestation), as part of the Generation R Study, Rotterdam, the Netherlands. Subsequent assessment of autistic traits in the offspring at age 6 was performed with the 18-item version of the Social Responsiveness Scale (SRS). Associations of placental protein concentrations with autistic traits were tested in sex-stratified and cohort-wide regression models. Cases with pregnancy complications or a later autism diagnosis (n = 64) were also assessed for differences in placenta-derived markers. sFlt-1 levels were significantly lower in males in both trimesters but showed no association with autistic traits. PlGF was significantly lower in male pregnancies in the 1^st trimester, and significantly higher in the 2^nd trimester, compared to female pregnancies. Higher PlGF levels in the 2^nd trimester and the rate of PlGF increase were both associated with the occurrence of higher autistic traits (PlGF-2^nd: n = 3469,b = 0.24 [SE = 0.11], p = 0.03) in both unadjusted and adjusted linear regression models that controlled for age, sex, placental weight and maternal characteristics. Mediation analyses showed that higher autistic traits in males compared to females were partly explained by higher PlGF or a faster rate of PlGF increase in the second trimester (PlGF-2^nd: n = 3469, ACME: b = 0.005, [SE = 0.002], p = 0.004). In conclusion, higher PlGF levels in the 2^nd trimester and a higher rate of PlGF increase are associated with both being male, and with a higher number of autistic traits in the general population.