Is Oxytocin Application for Autism Spectrum Disorder Evidence-Based?

Modulation of the thermosensory system by oxytocin

Oxytocin (OT) is a neurohormone involved early in neurodevelopment and is implicated in multiple functions, including sensory modulation. Evidence of such modulation has been observed for different sensory modalities in both healthy and pathological conditions. This review summarizes the pleiotropic modulation that OT can exercise on an often overlooked sensory system: thermosensation. This system allows us to sense temperature variations and compensate for the variation to maintain a stable core body temperature. Oxytocin modulates autonomic and behavioral mechanisms underlying thermoregulation at both central and peripheral levels. Hyposensitivity or hypersensitivity for different sensory modalities, including thermosensitivity, is a common feature in autism spectrum disorder (ASD), recapitulated in several ASD mouse models. These sensory dysregulations occur early in post-natal development and are correlated with dysregulation of the oxytocinergic system. In this study, we discussed the potential link between thermosensory atypia and the dysregulation of the oxytocinergic system in ASD.

Impact of caesarean delivery on children's autism-like behaviours: the mediation of exclusive breastfeeding

Background

The rate of autism spectrum disorder (ASD) has been rising worldwide, and therefore it is important to identify potential causes of ASD to facilitate early prevention. This study examined the role of breastfeeding and the association between caesarean delivery (CD) and children’s autism spectrum disorder.

Methods

The data were from the Ma’anshan birth cohort (MABC) in China, that was set up between May 2013 and September 2014. Women within 14 gestational weeks were recruited. The delivery mode was extracted from medical notes and infant feeding was obtained from questionnaire surveys. Autism-like behaviour was assessed using the Checklist for Autism in Toddlers (CHAT-23) when children were 18 months old, and 3 years of age. At 5 years of age, autism-like behaviour was assessed using the Clancy Autism Behavior Scale behavior. Structural equation models tested the mediation effects of breastfeeding between CD and children’s autism spectrum disorder.

Results

In all, 1520 (48.89%) women gave birth via CD, and 406 (13.86%) children were identified with autism-like behaviours at 18 months. Compared with women giving birth via vaginal delivery, those giving birth via CD were more likely to experience a higher proportion of delayed initiation of breastfeeding (p < 0.01), and delayed onset of lactogenesis (p < 0.01). CD was associated with a lower proportion of exclusive breastfeeding at 4 months after delivery (p = 0.02). Autism-like behaviour was less likely amongst infants with exclusively breastfeeding at 4 months than amongst those not exclusively breastfeeding at 4 months (p < 0.01). SEM indicated that women who gave birth by CD were more likely to stop exclusive breastfeeding in the first 4 months (standard estimations = − 0.04, p = 0.02), and those children who were not exclusively breastfed at 4 months were more likely to have autism-like behaviours (standard estimations = − 0.05, p < 0.01). The associations persisted at 3 years, but not at 5 years.

Conclusions

Exclusive breastfeeding at 4 months of age mediated the association between caesarean delivery and children’s autism-like behaviours.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13006-022-00493-6.

Risk factors in autism spectrum disorder: A Tunisian case-control study

Background

Autism spectrum disorder (ASD) is a neurodevelopmental condition that causes disability in social interaction, communication, and restrictive and repetitive behaviors. Common environmental factors like prenatal, perinatal, and/or postnatal factors play a key role in ASD etiologies. Moreover, specific metabolic disorders can be associated with ASD.

Subjects and methods

We performed a retrospective case-control study in child psychiatry clinics, involving 51 children with ASD and 40 typical development controls (TDC).

Results

We found a correlation between children being breastfed for less than 6 months, having fathers more than 40 years old at childbirth in ASD compared to TDC group. Our study also associated low blood cholesterol and low erythrocyte magnesium levels with increased risk for ASD.

Conclusion

Findings support the implication of total cholesterol (TC) and erythrocyte magnesium level in defining autism outcome.

The interplay between glutamatergic circuits and oxytocin neurons in the hypothalamus and its relevance to neurodevelopmental disorders

Oxytocin (OXT) neurons of the hypothalamus are at the center of several physiological functions, including milk ejection, uterus contraction, and maternal and social behavior. In lactating females, OXT neurons show a pattern of burst firing and inter-neuron synchronization during suckling that leads to pulsatile release of surges of OXT into the bloodstream to stimulate milk ejection. This pattern of firing and population synchronization may be facilitated in part by hypothalamic glutamatergic circuits, as has been observed in vitro using brain slices obtained from male rats and neonates. However, it remains unknown how hypothalamic glutamatergic circuits influence OXT cell activity outside the context of lactation. In this review, we summarize the in vivo and in vitro studies that describe the synchronized burst firing pattern of OXT neurons and the implication of hypothalamic glutamate in this pattern of firing. We also make note of the few studies that have traced glutamatergic afferents to the hypothalamic paraventricular and supraoptic nuclei. Finally, we discuss the genetic findings implicating several glutamatergic genes in neurodevelopmental disorders, including autism spectrum disorder, thus underscoring the need for future studies to investigate the impact of these mutations on hypothalamic glutamatergic circuits and the OXT system.

Current knowledge, challenges, new perspectives of the study, and treatments of Autism Spectrum Disorder

Over the past 70 years, the understanding of Autism Spectrum Disorder (ASD) improved greatly and is characterized as a heterogeneous neuropsychiatric syndrome. ASD is characterized by difficulties in social communication, restricted and repetitive behavior, interests, or activities. And it is often described as a combination of genetic predisposition and environmental factors. There are many treatments and approaches to ASD, including pharmacological therapies with antipsychotics, antidepressants, mood regulators, stimulants, and behavioral ones. However, no treatment is capable of reverting ASD. This review provides an overview of animal models of autism. We summarized genetic and environmental models and then valproic acid treatment as a useful model for ASD. As well as the main therapies and approaches used in the treatment, relating them to the neurochemical pathways altered in ASD, emphasizing the pharmacological potential of peptides and bioinspired compounds found in animal venoms as a possible future treatment for ASD.

Intranasal oxytocin in the treatment of autism spectrum disorders: A multilevel meta-analysis

Intranasal oxytocin has been shown to promote social functioning and has recently been applied as a treatment for autism spectrum disorders (ASD). The current meta-analysis aims to assess the crucial question of oxytocin's efficacy in the treatment of ASD. We performed a systematic literature search, including randomized, single- or double-blind/open-label and placebo-controlled clinical trials as well as single-arm, non-randomized and uncontrolled studies investigating exogenous oxytocin effect on ASD. A total of 28 studies (N = 726 ASD patients) met our predefined inclusion criteria. We used a multilevel meta-analytic model and found that oxytocin had beneficial effects on social functioning, but did not find strong evidence for symptoms improvement in the non-social domain. Our findings suggest that oxytocin administration can be regarded as an effective treatment for some core aspects of ASD, especially in the domain of social functioning, highlighting the promise of using oxytocin as a new-generation therapeutic to address core social impairments in ASD.

Imaging of intranasal drug delivery to the brain

Intranasal (IN) delivery is a rapidly developing area for therapies with great potential for the treatment of central nervous system (CNS) diseases. Moreover, in vivo imaging is becoming an important part of therapy assessment, both clinically in humans and translationally in animals. IN drug delivery is an alternative to systemic administration that uses the direct anatomic pathway between the olfactory/trigeminal neuroepithelium of the nasal mucosa and the brain. Several drugs have already been approved for IN application, while others are undergoing development and testing. To better understand which imaging modalities are being used to assess IN delivery of therapeutics, we performed a literature search with the key words "Intranasal delivery" and "Imaging" and summarized these findings in the current review. While this review does not attempt to be fully comprehensive, we intend for the examples provided to allow a well-rounded picture of the imaging tools available to assess IN delivery, with an emphasis on the nose-to-brain delivery route. Examples of in vivo imaging, for both humans and animals, include magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), gamma scintigraphy and computed tomography (CT). Additionally, some in vivo optical imaging modalities, including bioluminescence and fluorescence, have been used more in experimental testing in animals. In this review, we introduce each imaging modality, how it is being utilized and outline its strengths and weaknesses, specifically in the context of IN delivery of therapeutics to the brain.

Attenuated relationship between salivary oxytocin levels and attention to social information in adolescents and adults with autism spectrum disorder: a comparative study

BACKGROUND

Previous research studies have assessed the relationship between attention to social information and peripheral (e.g., plasma and salivary) oxytocin (OT) levels in typically developing (TD) children and children with autism spectrum disorder (ASD). A relationship between them was observed in TD children, but not in children with ASD. However, this relationship remains unexamined in other age groups. To clarify whether this lack of association is maintained throughout development in individuals with ASD, we aimed to assess the relationship between salivary OT levels and attention to social information in adolescents and adults with and without ASD.

METHODS

We recruited male adolescents and adults with ASD (n = 17) and TD participants (n = 24). Using the all-in-one eye-tracking system Gazefinder, we measured the percentage fixation time allocated to social information. We also measured the salivary OT levels and Autism Spectrum Quotient (AQ) of participants. Subsequently, we confirmed group differences and conducted a correlation analysis to investigate the relationships between these three measures.

RESULTS

Salivary OT levels did not show any significant difference between the ASD and TD groups and were negatively correlated with the AQ in the whole-group analysis, but not in within-group analysis. Individuals with ASD had significantly lower percentage fixation times than did TD individuals for eye regions in human faces with/without mouth motion, for upright biological motion, and for people regions in the people and geometry movies. The percentage of fixation for geometric shapes in the people and geometry movies was significantly higher in the ASD than in the TD group. In the TD group, salivary OT levels were positively correlated with percentage fixation times for upright biological motion and people and negatively correlated with inverted biological motion and geometry. However, no significant correlations were found in the ASD group.

CONCLUSIONS

Our exploratory results suggest that salivary OT levels in adolescents and adults with ASD are less indicative of attention to social stimuli than they are in TD adolescents and adults. It is suggested that their association is slightly weaker in adolescents and adults with ASD and that this attenuated relationship appears to be maintained throughout development.

Chronic oxytocin administration as a tool for investigation and treatment: A cross-disciplinary systematic review

Oxytocin (OT) subserves various physiological, behavioral, and cognitive processes. This paired with the ability to administer OT with minimal and inconsistent side effects has spurred research to explore its therapeutic potential. Findings from single-dose studies indicate that OT administration may be beneficial, at least under certain circumstances. The state of the field, however, is less clear regarding effects from chronic OT administration, which more closely resembles long-term treatment. To address this gap, this review synthesizes existing findings on the use of chronic OT administration in animal and human work. In addition to detailing the effects of chronic OT administration across different functional domains, this review highlights factors that have contributed to mixed findings. Based on this review, a basic framework of interrelated regulatory functions sensitive to chronic OT administration is offered. The paper also identifies future research directions across different contexts, populations, and outcomes, specifically calling for more systematic and standardized research on chronic OT administration in humans to supplement and expand what is currently known from preclinical work.

Prevention or Amelioration of Autism-Like Symptoms in Animal Models: Will it Bring Us Closer to Treating Human ASD?

Since the first animal model of valproic acid (VPA) induced autistic-like behavior, many genetic and non-genetic experimental animal models for Autism Spectrum Disorder (ASD) have been described. The more common non-genetic animal models induce ASD in rats and mice by infection/inflammation or the prenatal or early postnatal administration of VPA. Through the establishment of these models, attempts have been made to ameliorate or even prevent ASD-like symptoms. Some of the genetic models have been successfully treated by genetic manipulations or the manipulation of neurotransmission. Different antioxidants have been used (i.e., astaxanthin, green tea, piperine) to reduce brain oxidative stress in VPA-induced ASD models. Agents affecting brain neurotransmitters (donepezil, agmatine, agomelatine, memantine, oxytocin) also successfully reduced ASD-like symptoms. However, complete prevention of the development of symptoms was achieved only rarely. In our recent study, we treated mouse offspring exposed on postnatal day four to VPA with S-adenosine methionine (SAM) for three days, and prevented ASD-like behavior, brain oxidative stress, and the changes in gene expression induced by VPA. In this review, we describe, in addition to our data, the existing literature on the prevention/amelioration of ASD-like symptoms. We also discuss the possible mechanisms underlying some of these phenomena. Finally, we describe some of the clinical trials in children with ASD that were carried out as a result of data from animal studies, especially those with polyunsaturated fatty acids (PUFAs).

From bedside to bench and back: Translating ASD models

Autism spectrum disorders (ASD) represent a heterogeneous group of disorders defined by deficits in social interaction/communication and restricted interests, behaviors, or activities. Models of ASD, developed based on clinical data and observations, are used in basic science, the "bench," to better understand the pathophysiology of ASD and provide therapeutic options for patients in the clinic, the "bedside." Translational medicine creates a bridge between the bench and bedside that allows for clinical and basic science discoveries to challenge one another to improve the opportunities to bring novel therapies to patients. From the clinical side, biomarker work is expanding our understanding of possible mechanisms of ASD through measures of behavior, genetics, imaging modalities, and serum markers. These biomarkers could help to subclassify patients with ASD in order to better target treatments to a more homogeneous groups of patients most likely to respond to a candidate therapy. In turn, basic science has been responding to developments in clinical evaluation by improving bench models to mechanistically and phenotypically recapitulate the ASD phenotypes observed in clinic. While genetic models are identifying novel therapeutics targets at the bench, the clinical efforts are making progress by defining better outcome measures that are most representative of meaningful patient responses. In this review, we discuss some of these challenges in translational research in ASD and strategies for the bench and bedside to bridge the gap to achieve better benefits to patients.

The oxytocin system of mice and men-Similarities and discrepancies of oxytocinergic modulation in rodents and primates

Nonapeptides and their respective receptors have been conserved throughout evolution and display astonishing similarities among the animal kingdom. They can be found in worms, birds, fish, amphibians, reptiles and mammals, including rodents, non-human primates and humans. In particular, the neuropeptide oxytocin (OT) has attracted the attention of scientists due to its profound effects on social behavior. However, although both the neuropeptide and its receptor are identical in rodents and primates, the effects of OT vary greatly in the two species. Here, we provide a brief overview about OT's role in the evolution of mammals and provide reasons for the manifold effects of OT within the brain with a particular focus on the discrepancy of OT's effects in rodents and primates. In addition, we suggest new approaches towards improvement of translatability of scientific studies and highlight the most recent advances in animal models for autism spectrum disorder, a disease, in which the normal function of the OT system seems to be impaired.

The effects of adjunctive intranasal oxytocin in patients with schizophrenia

OBJECTIVES

Both human and animal studies have suggested that oxytocin may have therapeutic potential in the treatment of schizophrenia. We evaluated the effects of intranasal oxytocin on cognition and its predictive factors in Japanese patients with schizophrenia.

METHODS

Subjects were 16 chronic schizophrenia patients who underwent intranasal oxytocin treatment for 3 months and were assessed for changes in severity of clinical symptoms and cognitions. Fifteen of the 16 subjects underwent 3-Tesla magnetic resonance imaging.

RESULTS

Oxytocin significantly reduced scores on the positive and negative syndrome scale, especially on the negative symptoms. As for cognition, there was an improvement of the verbal fluency. Furthermore, the change of the negative score in positive and negative syndrome scale showed a negative correlation with the gray matter volumes of the right insula and left cingulate cortex.

CONCLUSIONS

Our results indicate that daily administration of intranasal oxytocin may be effective for ameliorating clinical symptoms and cognitive functions in chronic schizophrenia patients, and this improvement may be related to the gray matter volume of the right insula and left cingulate cortex.

Study protocol of the ASD-Net, the German research consortium for the study of Autism Spectrum Disorder across the lifespan: from a better etiological understanding, through valid diagnosis, to more effective health care

BACKGROUND

Autism Spectrum Disorder (ASD) is a severe, lifelong neurodevelopmental disorder with early onset that places a heavy burden on affected individuals and their families. Due to the need for highly specialized health, educational and vocational services, ASD is a cost-intensive disorder, and strain on health care systems increases with increasing age of the affected individual.

METHODS

The ASD-Net will study Germany's largest cohort of patients with ASD over the lifespan. By combining methodological expertise from all levels of clinical research, the ASD-Net will follow a translational approach necessary to identify neurobiological pathways of different phenotypes and their appropriate identification and treatment. The work of the ASD-Net will be organized into three clusters concentrating on diagnostics, therapy and health economics. In the diagnostic cluster, data from a large, well-characterized sample (N = 2568) will be analyzed to improve the efficiency of diagnostic procedures. Pattern classification methods (machine learning) will be used to identify algorithms for screening purposes. In a second step, the developed algorithm will be tested in an independent sample. In the therapy cluster, we will unravel how an ASD-specific social skills training with concomitant oxytocin administration can modulate behavior through neurobiological pathways. For the first time, we will characterize long-term effects of a social skills training combined with oxytocin treatment on behavioral and neurobiological phenotypes. Also acute effects of oxytocin will be investigated to delineate general and specific effects of additional oxytocin treatment in order to develop biologically plausible models for symptoms and successful therapeutic interventions in ASD. Finally, in the health economics cluster, we will assess service utilization and ASD-related costs in order to identify potential needs and cost savings specifically tailored to Germany. The ASD-Net has been established as part of the German Research Network for Mental Disorders, funded by the BMBF (German Federal Ministry of Education and Research).

DISCUSSION

The highly integrated structure of the ASD-Net guarantees sustained collaboration of clinicians and researchers to alleviate individual distress, harm, and social disability of patients with ASD and reduce costs to the German health care system.

TRIAL REGISTRATION

Both clinical trials of the ASD-Net are registered in the German Clinical Trials Register: DRKS00008952 (registered on August 4, 2015) and DRKS00010053 (registered on April 8, 2016).

The potential role of oxytocin and perinatal factors in the pathogenesis of autism spectrum disorders - review of the literature

Autism Spectrum Disorders (ASD) are characterized by: social and communication impairments, and by restricted repetitive behaviors. The aim of the present paper is to review abnormalities of oxytocin (OXT) and related congenital malformations in ASD. A literature search was conducted in the PubMed database up to 2016 for articles related to the pathomechanism of ASD, abnormalities of OXT and the OXT polymorphism in ASD. The pathomechanism of ASD has yet to be. The development of ASD is suggested to be related to abnormalities of the oxytocin-arginin-vasopressin system. Previous results suggest that OXT and arginine vasopressin (AVP) may play a role in the etiopathogenesis of ASD.

Oxytocin and Animal Models for Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a group of complex neurodevelopmental conditions characterized by deficits in social communication and by repetitive and stereotypic patterns of behaviors, with no pharmacological treatments available to treat these core symptoms. Oxytocin is a neuropeptide that powerfully regulates mammalian social behavior and has been shown to exert pro-social effects when administered intranasally to healthy human subjects. In the last decade, there has been a significant interest in using oxytocin to treat social behavior deficits in ASD. However, little attention has been paid to whether the oxytocin system is perturbed in subgroups of individuals with ASD and whether these individuals are likely to benefit more from an oxytocin treatment. This oversight may in part be due to the enormous heterogeneity of ASD and the lack of methods to carefully probe the OXT system in human subjects. Animal models for ASD are valuable tools to clarify the implication of the oxytocin system in ASD and can help determine whether perturbation in this system should be considered in future clinical studies as stratifying biomarkers to inform targeted treatments in subgroups of individuals with ASD. In this chapter, we review the literature on genetic- and environmental-based animal models for ASD, in which perturbations in the oxytocin system and/or the effect of oxytocin administration on the ASD-associated phenotype have been investigated.

Clinical trial of modulatory effects of oxytocin treatment on higher-order social cognition in autism spectrum disorder: a randomized, placebo-controlled, double-blind and crossover trial

BACKGROUND

Autism spectrum disorders are neurodevelopmental conditions with severe impairments in social communication and interaction. Pioneering research suggests that oxytocin can improve motivation, cognition and attention to social cues in patients with autism spectrum disorder. The aim of this clinical trial is to characterize basic mechanisms of action of acute oxytocin treatment on neural levels and to relate these to changes in different levels of socio-affective and -cognitive functioning.

METHODS

This clinical study is a randomized, double-blind, cross-over, placebo-controlled, multicenter functional magnetic resonance imaging study with two arms. A sample of 102 male autism spectrum disorder patients, diagnosed with Infantile Autistic Disorder (F84.0 according to ICD-10), Asperger Syndrome (F84.5 according to ICD-10), or Atypical Autism (F84.1 according to ICD-10) will be recruited and will receive oxytocin and placebo nasal spray on two different days. Autism spectrum disorder patients will be randomized to determine who receives oxytocin on the first and who on the second visit. Healthy control participants will be recruited and case-control matched to the autism spectrum disorder patients. The primary outcome will be neural network activity, measured with functional magnetic resonance imaging while participants perform socio-affective and -cognitive tasks. Behavioral markers such as theory of mind accuracy ratings and response times will be assessed as secondary outcomes in addition to physiological measures such as skin conductance. Trait measures for alexithymia, interpersonal reactivity, and social anxiety will also be evaluated. Additionally, we will analyze the effect of oxytocin receptor gene variants and how these potentially influence the primary and secondary outcome measures. Functional magnetic resonance imaging assessments will take place at two time points which will be scheduled at least two weeks apart to ensure a sufficient wash-out time after oxytocin treatment. The study has been approved by an ethical review board and the competent authority.

DISCUSSION

Revealing the mechanisms of acute oxytocin administration, especially on the socio-affective and -cognitive domains at hand, will be a further step towards novel therapeutic interventions regarding autism.

TRIAL REGISTRATION

German Clinical Trial Register DRKS00010053 . The trial was registered on the 8^th of April 2016.