Reciprocal gaze, the mutual exchange of eye contact, plays a key role in human communication and bonding, yet it is often experienced as challenging for individuals with autism. In recent years, administration of the neuropeptide oxytocin is increasingly considered a novel approach for supporting social experiences in children with autism, but insights regarding its effects on mutual gaze or pupil dynamics remain limited—particularly regarding how chronic, repeated dosing impacts these processes.This double-blind, randomized, placebo-controlled trial examined the effects of four weeks of chronic intranasal oxytocin administration on gaze behavior and pupil dynamics during live dyadic interactions in school-aged children with autism (aged 8-12 years, 15 oxytocin, 20 placebo).While the overall duration of fixations toward the face remained unchanged, oxytocin altered the distribution of gaze, resulting in a more balanced pattern of looking toward and away from the face of a live interaction partner, an effect observed only in the oxytocin group and not in the placebo group. In addition, the four-week oxytocin administration period induced a relative increase in pupil dilation, an index of sympathetic arousal and attentional engagement, with this heightened autonomic responsivity showing a moderate association with children’s self-reported feelings of secure attachment.Together, these findings indicate that repeated oxytocin administration may modulate gaze parameters in live social interactions in children with autism. While cautiously encouraging, future work will be needed to further delineate whether these changes meaningfully reflect ameliorated experience and comfort in social settings.

Atypical oxytocinergic functioning and altered microbiome compositions have both been implicated in autism, with growing evidence of interactions between these systems. However, how exogenous oxytocin influences the oral microbiome remains largely unexplored. This exploratory study examined for the first time how oral microbiome alterations link to oxytocinergic signalling in school-aged autistic (n = 80) and non-autistic children (n = 40). Additionally, we investigated the effect of four-weeks of intranasal oxytocin administration in autistic children on oral microbiome compositions immediately post-treatment (T1) and at four-weeks follow-up (T2). At baseline, lower endogenous salivary oxytocin levels were linked to greater microbial evenness and diversity, with twelve genera showing significant associations with oxytocin levels. In autistic children, four weeks of oxytocin administration was associated with significant increases in the abundances of Centipeda immediately post-treatment (T0-T1), alongside decreases in Moraxella (T0-T1), and subsequent reductions in Rothia observed at the four-week follow-up (T1-T2). Particularly, the genus Moraxella emerged as relevant, as lower baseline abundance was associated with higher endogenous oxytocin levels, and a stronger oxytocin-induced downregulation of its abundance correlated with greater increases in endogenous oxytocin levels, accompanied by hypomethylation of the oxytocin receptor gene. All results persisted after adjusting for nutrition and dental care. This exploratory study provides initial evidence for a role of the oxytocinergic system in shaping the oral microbiome in autistic children. These results may facilitate the integration of oral microbiome profiling into autism diagnostic criteria and stimulate future studies on the use of oxytocin as a therapeutic option targeting oral microbiome alterations.

Background Preterm birth is a life-changing event, followed by hospitalization in the Neonatal Intensive Care Unit. During this critical period of biological immaturity, preterm infants encounter atypical sensory stimulation and (painful and stressful) medical interventions. Such early environmental factors can alter the development of the hypothalamic-pituitary-adrenal (HPA) axis and the oxytocinergic system, potentially leading to long-term effects on neurodevelopment. The research on these physiological markers in preterm individuals remains inconclusive, partly due to variability in study designs, sample collection, and participant selection. Studies later in life, during childhood or adulthood, are particularly scarce. Methods Oxytocin and cortisol levels, and DNA methylation of the oxytocin receptor gene (OXTR) and the glucocorticoid receptor gene (NR3C1) were assessed in 39 preterm and 38 full-term school-aged children. Salivary samples were collected at two timepoints: one sample after awakening, and two samples at the end of the study visit. Results Preterm children had lower morning oxytocin levels but similar afternoon oxytocin levels compared to full-term children. Both groups showed elevated cortisol levels in the morning compared to the afternoon. Preterm children exhibited a steeper decline in cortisol, with lower afternoon cortisol levels compared to full-term children. DNA methylation of NR3C1 was lower in preterm children, whereas no group differences were observed for OXTR. Conclusion These findings suggest differences in salivary measures of the HPA axis and oxytocinergic system in preterm school-aged children compared to full-term children, highlighting the importance of further research into the long-term impact of preterm birth and early life stressors.

Autistic children often experience behavioral difficulties alongside nutritional and gastro-intestinal (GI) problems, including gut dysbiosis. Recent research has highlighted important interactions between the oxytocinergic system and gut microbiome compositions, however, insights into how exogenous administration of oxytocin may influence GI health remain largely unexplored.Here, we first examined whether nutrition, GI symptoms and microbiome compositions vary in autistic versus non-autistic children, and how alterations link to clinical-behavioral difficulties and oxytocinergic signaling. Next, we examined the effect of a four-week intranasal oxytocin administration regimen on GI health/dysbiosis in autistic children enrolled in a randomized placebo-controlled trial.Compared to non-autistic children, autistic children consumed more soft drinks, and fewer vegetables and experienced abdominal pain more frequently over the past three months. Notably, epigenetic variations in the oxytocin receptor gene (OXTR) were associated with stool consistency, indicating that children with looser stools exhibited lower OXTR methylation levels, indicative of increased receptor expression. Additionally, a higher abundance of Romboutsia was associated with OXTR hypo-methylation and more anxiety-like behavior. In autistic children, the four-week oxytocin regimen had no effect on bacterial diversity but did modify stool consistency, leading to less dense stools with an overall more normal stool consistency, and an increased abundance of the potentially anti-inflammatory genus Fusicatenibacter.To conclude, this study provides novel insights into the role of the oxytocinergic system in GI symptoms and gut microbiome compositions in autistic children, and preliminary evidence suggesting a modulatory effect of exogenously administered oxytocin on these parameters.

Improved survival of very preterm (<32 weeks of gestation) infants has highlighted neurodevelopmental and socio-emotional challenges. As altered gaze behavior and autonomic functioning may contribute to these difficulties, we investigated this in thirty-nine very preterm and thirty-eight full-term 8-to-12-year-old children. We assessed gaze behavior during a semi-structured conversation. Autonomic functioning was evaluated through heart rate variability and skin conductance responses at rest and during an eye contact paradigm. Preterms exhibited shorter but more frequent gazes toward their conversation partner than full-terms. Moreover, both at rest and during the eye contact paradigm, they demonstrated higher heart rate variability. No group differences in skin conductance responses were observed at rest, but during the eye contact paradigm, preterms displayed more pronounced skin conductance responses regardless of condition. Very preterm children exhibited reduced sustained social attention and heightened autonomic activity. Nevertheless, reported subjective experiences were similar among both groups, suggesting that heightened arousal reflects general physiological reactivity rather than perceived stress. This underscores the importance of potential interventions targeting attentional control to improve socio-emotional outcomes in very preterm children.

BACKGROUND:Preterm (PT) birth is associated with important social vulnerabilities that can have long-term implications and may result in psychopathology (e.g., autism spectrum disorder). A recurring preterm behavioral phenotype has been described, although these difficulties may often be subtle and subclinical. As face processing is crucial for social interactions, and several studies have reported impaired face-processing performance in PT populations, we hypothesized that face-processing difficulties may contribute to or be a part of these social difficulties. Here, we investigated neural sensitivity to crucial sociocommunicative facial cues in school-age PT children. METHODS:Thirty-nine 8- to 12-year-old PT children born between 24 and 32 weeks of gestation and 38 term-born matched control children performed a series of innovative facial identity and expression discrimination frequency-tagging electroencephalography paradigms. More specifically, we evaluated the neural sensitivity to implicitly and automatically discriminate a different facial identity among a stream of identical faces, as well as an expressive face (fearful and happy, in separate sequences) among a stream of neutral faces. RESULTS:We found intact implicit facial identity and expression processing in both groups. Unexpectedly, PT participants showed a significantly greater neural sensitivity toward these subtle sociocommunicative facial cues. Correlations with neonatal measures such as gestational age and birth weight showed that this greater neural sensitivity was uniformly present among the PT group. CONCLUSIONS:The evidence suggests that impaired neural sensitivity to facial cues may not be the primary cause of the behavioral face-processing and social difficulties often encountered in PT children.

PURPOSE:Whilst the survival rate of preterm (PT) children has increased significantly, the number of neurodevelopmental problems and behavioural difficulties throughout the lifespan has also risen, especially in those born very or extremely PT. These vulnerabilities can lead to certain psychopathologies, though there is also evidence for a specific subclinical and more subtle behavioural pattern in PTs. Our aim is to pinpoint important vulnerabilities of PT children and to further investigate this "preterm behavioural phenotype". METHODS:We investigated a group of thirty-nine school-aged very and extremely PT children without major neurological impairments or a formal autism diagnosis, and we compared them to a cohort of thirty-eight age- and sex-matched full-term (FT) controls. Autism-related difficulties in social functioning and repetitive behaviours, as well as behavioural problems, anxiety, and attachment, were assessed through self-reports from the child and/or informant reports from the parent(s) and clinicians, with informant sources varying across assessments. RESULTS:Compared to FT peers, PT children displayed significantly increased anxiety, attention problems and autism-related social difficulties. No significant group differences were evident in terms of autism-related restricted/repetitive behaviours or self-reports of peer and parental attachment. CONCLUSION:Even in a PT population without major neurological impairments or a clinical diagnosis of autism, important clinical-behavioural differences were evident in line with a preterm behavioural phenotype. Thus, delineating this subclinical PT pattern can be of relevance to recognize and validate meaningful difficulties experienced by these children that fail to reach the clinical threshold but could still benefit from certain interventions.

Background Shifts in peak frequencies of oscillatory neural rhythms are put forward as a principal mechanism by which cross‐frequency coupling/decoupling is implemented in the brain. During active neural processing, functional integration is facilitated through transitory formations of “harmonic” cross‐frequency couplings, whereas “nonharmonic” decoupling among neural oscillatory rhythms is postulated to characterize the resting, default state of the brain, minimizing the occurrence of spurious, noisy, background couplings. Methods Within this exploratory, randomized, placebo‐controlled trial, we assessed whether the transient occurrence of nonharmonic and harmonic relationships between peak‐frequencies in the alpha (8–14 Hz) and theta (4–8 Hz) bands is impacted by intranasal administration of oxytocin, a neuromodulator implicated in improving homeostasis and reducing stress/anxiety. To do so, resting‐state electroencephalography was acquired before and after 4 weeks of oxytocin administration (12 IU twice‐daily) in children with autism spectrum disorder (8–12 years, n = 33 oxytocin; n = 34 placebo). At the baseline, neural assessments of children with autism were compared with those of a matched cohort of children without autism ( n = 40). Results Compared to nonautistic peers, autistic children displayed a lower incidence of nonharmonic alpha‐theta cross‐frequency decoupling, indicating a higher incidence of spurious “noisy” coupling in their resting brain ( p = .001). Dimensionally, increased neural coupling was associated with more social difficulties ( p = .002) and lower activity of the parasympathetic “rest & digest” branch of the autonomic nervous system ( p = .018), indexed with high‐frequency heart‐rate‐variability. Notably, after oxytocin administration, the transient formation of nonharmonic cross‐frequency configurations was increased in the cohort of autistic children ( p < .001), indicating a beneficial effect of oxytocin on reducing spurious cross‐frequency‐interactions. Furthermore, parallel epigenetics changes of the oxytocin receptor gene indicated that the neural effects were likely mediated by changes in endogenous oxytocinergic signaling ( p = .006). Conclusions Chronic oxytocin induced important homeostatic changes in the resting‐state intrinsic neural frequency architecture, reflective of reduced noisy oscillatory couplings and improved signal‐to‐noise properties.

Shifts in peak frequencies of oscillatory neural rhythms are put forward as a principal mechanism by which cross-frequency coupling/decoupling is implemented in the brain. During active neural processing, functional integration is facilitated through transitory formations of “harmonic” cross-frequency couplings, whereas “nonharmonic” decoupling among neural oscillatory rhythms is postulated to characterize the resting, default state of the brain, minimizing the occurrence of spurious, noisy, background couplings. Within this exploratory, randomized, placebo-controlled trial, we assessed whether the transient occurrence of nonharmonic and harmonic relationships between peak-frequencies in the alpha (8–14 Hz) and theta (4–8 Hz) bands is impacted by intranasal administration of oxytocin, a neuromodulator implicated in improving homeostasis and reducing stress/anxiety. To do so, resting-state electroencephalography was acquired before and after 4 weeks of oxytocin administration (12 IU twice-daily) in children with autism spectrum disorder (8–12 years, n  = 33 oxytocin; n  = 34 placebo). At the baseline, neural assessments of children with autism were compared with those of a matched cohort of children without autism ( n  = 40). Compared to nonautistic peers, autistic children displayed a lower incidence of nonharmonic alpha-theta cross-frequency decoupling, indicating a higher incidence of spurious “noisy” coupling in their resting brain ( p  = .001). Dimensionally, increased neural coupling was associated with more social difficulties ( p  = .002) and lower activity of the parasympathetic “rest & digest” branch of the autonomic nervous system ( p  = .018), indexed with high-frequency heart-rate-variability. Notably, after oxytocin administration, the transient formation of nonharmonic cross-frequency configurations was increased in the cohort of autistic children ( p  < .001), indicating a beneficial effect of oxytocin on reducing spurious cross-frequency-interactions. Furthermore, parallel epigenetics changes of the oxytocin receptor gene indicated that the neural effects were likely mediated by changes in endogenous oxytocinergic signaling ( p  = .006). Chronic oxytocin induced important homeostatic changes in the resting-state intrinsic neural frequency architecture, reflective of reduced noisy oscillatory couplings and improved signal-to-noise properties.

Similar to the gut microbiome, oral microbiome compositions have been suggested to play an important role in the etiology of autism. However, empirical research on how variations in the oral microbiome relate to clinical-behavioral difficulties associated with autism remains sparse. Furthermore, it is largely unknown how potentially confounding lifestyle variables, such as oral health and nutrition, may impact these associations. To fill this gap, the current study examined diagnosis-related differences in oral microbiome composition between 80 school-aged autistic children (8-12 years; 64 boys, 16 girls) versus 40 age-matched typically developing peers (32 boys, 8 girls). In addition, associations with individual differences in social functioning (SRS-2), repetitive behavior (RBS-R) and anxiety (SCARED) were explored, as well as the impact of several lifestyle variables regarding nutrition and oral health. Results provide important indications that the bacterial genera Solobacterium, Stomatobaculum, Ruminococcaceae UCG.014, Tannerella and Campylobacter were significantly more abundant in autistic compared to non-autistic children. Furthermore, the former four bacteria that were significantly more abundant in the autistic children showed significant associations with parent-reported social difficulties, repetitive and restrictive behavior and with parent-reported anxiety-like behavior. Importantly, associations among oral microbiome and quantitative diagnostic characteristics were not significantly driven by differences in lifestyle variables. This exploratory study reveals significant differences in oral microbiome composition between autistic and non-autistic children, even while controlling for potential confounding lifestyle variables. Furthermore, the significant associations with clinical characteristics suggest that individual differences in microbiome composition might be involved in shaping the clinical phenotype of autism. However, these associations warrant further exploration of the oral microbiome's potential beyond the oral cavity and specifically with respect to neuropsychiatric conditions.

Clinical efficacy of intranasal administration of oxytocin is increasingly explored in autism spectrum disorder, but to date, the biological effects of chronic administration regimes on endogenous oxytocinergic function are largely unknown. Here exploratory biological assessments from a completed randomized, placebo-controlled trial showed that children with autism (n = 79, 16 females) receiving intranasal oxytocin for four weeks (12 IU, twice daily) displayed significantly higher salivary oxytocin levels 24 hours after the last oxytocin nasal spray administration, but no longer at a four-week follow up session. Regarding salivary oxytocin receptor gene ( OXTR) epigenetics (DNA-methylation), oxytocin-induced reductions in OXTR DNA-methylation were observed, suggesting a facilitation of oxytocin receptor expression in the oxytocin compared to the placebo group. Notably, heightened oxytocin levels post-treatment were significantly associated with reduced OXTR DNA-methylation and improved feelings of secure attachment. These findings indicate that four weeks of chronic oxytocin administration stimulated the endogenous oxytocinergic system in children with autism.

Children born very preterm (VPT, < 32 weeks of gestation) have an increased risk of developing socio-emotional difficulties. Possible neural substrates for these socio-emotional difficulties are alterations in the structural connectivity of the social brain due to premature birth. The objective of the current study was to study microstructural white matter integrity in VPT versus full -term (FT) born school -aged children along twelve white matter tracts involved in socio-emotional processing. Diffusion MRI scans were obtained from a sample of 35 VPT and 38 FT 8 -to -12 -year -old children. Tractography was performed using TractSeg, a state-of-the-art neural network -based approach, which offers investigation of detailed tract profiles of fractional anisotropy (FA). Group differences in FA along the tracts were investigated using both a traditional and complementary functional data analysis approach. Exploratory correlations were performed between the Social Responsiveness Scale (SRS -2), a parent -report questionnaire assessing difficulties in social functioning, and FA along the tract. Both analyses showed significant reductions in FA for the VPT group along the middle portion of the right SLF I and an anterior portion of the left SLF II. These group differences possibly indicate altered white matter maturation due to premature birth and may contribute to altered functional connectivity in the Theory of Mind network which has been documented in earlier work with VPT samples. Apart from reduced social motivation in the VPT group, there were no significant group differences in reported social functioning, as assessed by SRS -2. We found that in the VPT group higher FA values in segments of the left SLF I and right SLF II were associated with better social functioning. Surprisingly, the opposite was found for segments in the right IFO, where higher FA values were associated with worse reported social functioning. Since no significant correlations were found for the FT group, this relationship may be specific for VPT children. The current study overcomes methodological limitations of previous studies by more accurately segmenting white matter tracts using constrained spherical deconvolution based tractography, by applying complementary tractometry analysis approaches to estimate changes in FA more accurately, and by investigating the FA profile along the three components of the SLF.

Difficulties with (non-verbal) social communication, including facial expression processing, constitute a hallmark of autism. Intranasal administration of oxytocin has been considered a potential therapeutic option for improving social difficulties in autism, either by enhancing the salience of social cues or by reducing the social stress and anxiety experienced in social encounters. We recorded fMRI brain activity while presenting neutral, fearful and scrambled faces, to compare the neural face processing signature of autistic children (n = 58) with that of matched non-autistic controls (n = 38). Next, in the autistic children group, we implemented this fMRI face processing task in a double-blind, placebo-controlled, multiple-dose oxytocin clinical trial, to evaluate the impact of four-week repeated oxytocin administration (24 IU daily dose) on brain activity in face processing regions. No significant diagnostic-group differences were identified between autistic versus non-autistic children with regard to neural face processing. Furthermore, no significant treatment effects were found in the oxytocin clinical trial. However, exploratory analyses (uncorrected for multiple comparisons) demonstrated decreases in brain activity in the left superior temporal sulcus (STS) and inferior frontal region in the oxytocin compared to the placebo group, and change-from-baseline analyses in the oxytocin group revealed significantly reduced neural activity in the core face-processing network (STS, inferior occipital, and posterior fusiform), as well as in amygdala and inferior frontal region. These findings suggest an attenuating effect of multiple-dose oxytocin administration on neural face processing, potentially supporting the anxiolytic account of oxytocin.

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by difficulties in social communication and interaction. Crucial for efficient social interaction is the ability to quickly and accurately extract information from a person's face. Frequency-tagging electroencephalography (EEG) is a novel tool to quantify face-processing sensitivity in a robust and implicit manner. In terms of intervention approaches, intranasal administration of oxytocin (OT) is increasingly considered as a potential pharmacological approach for improving socio-communicative difficulties in ASD, through enhancing social salience and/or reducing (social) stress and anxiety. In this randomized, double-blind, placebo-controlled, mechanistic pharmaco-neuroimaging clinical trial, we implemented frequency-tagging EEG to conduct an exploratory investigation into the impact of repeated OT administration (4 weeks, 12 IU, twice daily) on neural sensitivity towards happy and fearful facial expressions in children with ASD (8–12 years old; OT: n  = 29; placebo: n  = 32). Neural effects were assessed at baseline, post-nasal spray (24 hr after the last nasal spray) and at a follow-up session, 4 weeks after the OT administration period. At baseline, neural assessments of children with ASD were compared with those of an age- and gender-matched cohort of neurotypical (NT) children ( n  = 39). Children with ASD demonstrated reduced neural sensitivity towards expressive faces, as compared to NT children. Upon nasal spray administration, children with ASD displayed a significant increase in neural sensitivity at the post- and follow-up sessions, but only in the placebo group, likely reflecting an implicit learning effect. Strikingly, in the OT group, neural sensitivity remained unaffected from the baseline to the post-session, likely reflecting a dampening of an otherwise typically occurring implicit learning effect. First, we validated the robustness of the frequency-tagging EEG approach to assess reduced neural sensitivity towards expressive faces in children with ASD. Furthermore, in contrast to social salience effects observed after single-dose administrations, repeated OT administration dampened typically occurring learning effects in neural sensitivity. In line with OT's social anxiolytic account, these observations possibly reflect a predominant (social) stress regulatory effect towards emotionally evocative faces after repeated OT administration.

Background Clinical efficacy of chronic intranasal administration of oxytocin is increasingly explored in autism spectrum disorder (ASD), but to date, little is known regarding its biological effects and in particular how chronic administration regimes impact endogenous oxytocinergic function. Methods To fill this gap, this double-blind, randomized, placebo-controlled study explored chronic oxytocin administration effects on endogenous salivary oxytocin levels and oxytocin receptor gene ( OXTR ) epigenetics (DNA methylation) in 8-to-12-year-old children with ASD (n = 79, 16 females). Biological sampling was performed at baseline (pre-treatment), immediately (24 hours) after the four-week oxytocin administration period (12 IU, twice daily) and at a follow-up session, four weeks after the last nasal spray administration. Results Compared to placebo, children receiving the oxytocin nasal spray displayed significantly higher salivary oxytocin levels 24 hours after the last oxytocin nasal spray administration, but no longer at the four-week follow up session. Regarding epigenetics, oxytocin-induced reductions in OXTR methylation were observed, reflecting a facilitation of oxytocin receptor expression in the oxytocin, compared to the placebo group. Notably, heightened oxytocin levels post-treatment were significantly associated with reduced OXTR DNA methylation and improved feelings of secure attachment. Conclusion Four weeks of chronic oxytocin administration stimulated the endogenous oxytocinergic system in children with ASD, as evidenced by increased salivary oxytocin levels and reduced OXTR DNA methylation (indicating increased receptor expression).

Introduction: Intranasal administration of oxytocin presents a promising new approach to reduce disability associated with an autism spectrum disorder diagnosis. Previous investigations have emphasized the amygdala as the neural foundation for oxytocin’s acute effects. However, to fully understand oxytocin’s therapeutic potential, it is crucial to gain insight into the neuroplastic changes in amygdala circuitry induced from chronic oxytocin administrations, particularly in pediatric populations. Objective: We aimed to examine the impact of a 4-week course of intranasal oxytocin on amygdala functional connectivity in children with autism, compared to placebo. Additionally, we investigated whether oxytocin improves cardiac autonomic arousal, as indexed by high-frequency heart rate variability. Methods: Fifty-seven children with autism aged 8–12 years (45 boys, 12 girls) participated in a double-blind, randomized pharmaco-neuroimaging trial involving twice-daily administrations of intranasal oxytocin or placebo. Resting-state fMRI scans and simultaneous, in-scanner heart rate recordings were obtained before, immediately after, and 4 weeks after the nasal spray administration period. Results: Significant reductions in intrinsic amygdala-orbitofrontal connectivity were observed, particularly at the 4-week follow-up session. These reductions were correlated with improved social symptoms and lower cardiac autonomic arousal. Further, oxytocin’s neural and cardiac autonomic effects were modulated by epigenetic modifications of the oxytocin receptor gene. The effects were more pronounced in children with reduced epigenetic methylation, signifying heightened expression of the oxytocin receptor. Conclusion: These findings underscore that a 4-week oxytocin administration course decreases amygdala connectivity and improves cardiac autonomic balance. Epigenetic modulators may explain inter-individual variation in responses to oxytocin.