Variations of plasma leptin and adiponectin levels in autistic patients

Understanding the link between different types of maternal diabetes and the onset of autism spectrum disorders

Autism spectrum disorders (ASD) encompass a collection of neurodevelopmental disorders that exhibit impaired social interactions and repetitive stereotypic behaviors. Although the exact cause of these disorders remains unknown, it is widely accepted that both genetic and environmental factors contribute to their onset and progression. Recent studies have highlighted the potential negative impact of maternal diabetes on embryonic neurodevelopment, suggesting that intrauterine hyperglycemia could pose an additional risk to early brain development and contribute to the development of ASD. This paper presents a comprehensive analysis of the current research on the relationship between various forms of maternal diabetes, such as type 1 diabetes mellitus, type 2 diabetes mellitus, and gestational diabetes mellitus, and the likelihood of ASD in offspring. The study elucidates the potential mechanisms through which maternal hyperglycemia affects fetal development, involving metabolic hormones, immune dysregulation, heightened oxidative stress, and epigenetic alterations. The findings of this review offer valuable insights for potential preventive measures and evidence-based interventions targeting ASD.

Altered leptin level in autism spectrum disorder and meta-analysis of adipokines

BACKGROUND

Increasing evidence suggests that leptin is involved in the pathology of autism spectrum disorder (ASD). In this study, our objective was to investigate the levels of leptin in the blood of children with ASD and to examine the overall profile of adipokine markers in ASD through meta-analysis.

METHODS

Leptin concentrations were measured using an enzyme-linked immunosorbent assay (ELISA) kit, while adipokine profiling, including leptin, was performed via meta-analysis. Original reports that included measurements of peripheral adipokines in ASD patients and healthy controls (HCs) were collected from databases such as Web of Science, PubMed, and Cochrane Library. These studies were collected from September 2022 to September 2023 and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Standardized mean differences were calculated using a random effects model for the meta-analysis. Additionally, we performed meta-regression and explored heterogeneity among studies.

RESULTS

Our findings revealed a significant increase in leptin levels in children with ASD compared to HCs (p = 0.0319). This result was consistent with the findings obtained from the meta-analysis (p < 0.001). Furthermore, progranulin concentrations were significantly reduced in children with ASD. However, for the other five adipokines analyzed, there were no significant differences observed between the children with ASD and HCs children. Heterogeneity was found among the studies, and the meta-regression analysis indicated that publication year and latitude might influence the results of the meta-analysis.

CONCLUSIONS

These findings provide compelling evidence that leptin levels are increased in children with ASD compared to healthy controls, suggesting a potential mechanism involving adipokines, particularly leptin, in the pathogenesis of ASD. These results contribute to a better understanding of the pathology of ASD and provide new insights for future investigations.

Sleep problems and circadian rhythm functioning in autistic children, autism with co-occurring attention deficit hyperactivity disorder, and typically developing children: A comparative study

LAY ABSTRACT

Sleep problems are common in autism spectrum disorder (ASD) and different factors can contribute to its occurrence in this population. Misalignment of the biological clock (our circadian system) has been described as one possible explanation. While there is a body of research on sleep problems, relatively less is known about circadian functioning and the specific population of autistic children with co-occurring attention deficit hyperactivity disorder (ADHD). Using an ambulatory circadian monitoring (ACM) system, which resembles a common watch, we gathered sleep parameters and the different rhythms obtained from measuring motor activity, light exposure and distal temperature in 87 autistic children and adolescents, 27 of whom were diagnosed with co-occurring ADHD, and 30 neurotypical children and adolescents as a comparison group. Autistic children and, especially, those with co-occurring ADHD showed greater motor activity during sleep which would be worth studying in future projects which could better define this restless sleep. Of note, we observed an atypical pattern of wrist temperature, with higher values in neurotypical children, followed by autistic children and, ultimately, those with co-occurring ADHD. Temperature is one of the most valuable factors evaluated here as it is closely connected to sleep-wakefulness and the hormone melatonin. Its special pattern during day and nighttime would support the hypothesis of an atypical secretion of melatonin in autistic individuals which would also link with the higher presence of sleep problems in this neurodevelopmental condition.

Adiponectin blood levels and autism spectrum disorders: a systematic review

OBJECTIVE

To review the relationship between adiponectin levels and autism spectrum disorders (ASDs) in children.

BACKGROUND

ASDs are associated with pervasive social interaction and communication abnormalities. Researchers have studied various pathophysiological mechanisms underlying ASDs to identify predictors for an early diagnosis to optimize treatment outcomes. Immune dysfunction, perhaps mediated by a decrease in anti-inflammatory adipokine, adiponectin, along with changes in other adipokines, may play a central role in increasing the risk for ASDs. However, other factors, such as low maternal vitamin D levels, atherosclerosis, diabetes, obesity, cardio-metabolic diseases, preterm delivery, and oxytocin gene polymorphism may also contribute to increased risk for ASDs.

METHODS

Searches on the database; PubMed, Google Scholar, and Cochrane using keywords; adiponectin, adipokines, ASD, autism, autistic disorder, included English-language studies published till September 2022. Data were extracted on mean differences between adiponectin levels in children with and without ASDs.

RESULTS

The search yielded six studies providing data on adiponectin levels in young patients with ASDs. As can be seen from Table 1, four of the six studies were positive for an inverse correlation between ASD and adiponectin levels. In addition, two of the four positive and one negative studies found low adiponectin levels associated with and the severity of autistic symptoms. However, results from one reviewed study were insignificant.

CONCLUSION

Most studies reviewed yielded lower adiponectin levels in children with ASDs as well as the severity of autistic symptoms.

The early life growth of head circumference, weight, and height in infants with autism spectrum disorders: a systematic review

BACKGROUNDS

The Autism spectrum disorder (ASD) prevalence has increased significantly over the past two decades. This review summarizes the current knowledge of the association between the early life growth of head circumference (HC), weight, and height with ASD in infants.

METHODS

PubMed, Scopus, Science Direct, and Google Scholar databases were searched up to November 2021 using relevant keywords. All original articles are written in English evaluating the early life growth of HC, weight, and height in infants with ASD were eligible for the present review.

RESULTS

Totally, 23 articles involving 4959 infants were included in this review. Of 13 studies that evaluated HC of infants at birth, 10 studies (83.33%) showed that the HC at the birth of autistic children was similar to that of the average found in the control group. Among 21 studies that evaluated the HC and weight status in infants, 19 studies (90.47%) showed that autistic children had larger HC and weight than the control group or abnormal acceleration of head growth during infancy. Height growth of infants was investigated in 13 studies, of which 10 cases (76.92%) reported that infants with ASD were significantly longer than control groups. Most of he included studies had a good quality.

CONCLUSIONS

The findings suggest that in infants with ASD, without the contribution of birth growth factors and sex of the child, the growth of HC, weight, and height probably was faster than in infants with normal development, in early life. Therefore, these measurements might be useful as initial predictive biomarkers for the risk of developing ASD.

Response to Melatonin Treatment in Children With Autism spectrum Disorder and Relationship to Sleep Parameters and Melatonin Levels

Melatonin is one of the most used pharmacologic treatments for sleep problems in autism spectrum disorder, though its relationship with circadian and sleep parameters is still not well stablished. A naturalistic study was conducted in children with autism spectrum disorder, previously drug-naïve, before and after treatment with immediate-release melatonin. Circadian rhythms and sleep parameters were studied using an ambulatory circadian-monitoring device, and saliva samples were collected enabling determination of dim light melatonin onset. Twenty-six children with autism spectrum disorder (age 10.50  ±  2.91) were included. Immediate-release melatonin modified circadian rhythm as indicated by wrist skin temperature, showing an increase at night. A positive correlation was found between time of peak melatonin and sleep efficiency improvement values. Sleep-onset latency and efficiency improved with immediate-release melatonin. Immediate-release melatonin could be an effective treatment to improve sleep onset and restore a typical pattern of wrist temperature, which appears to be lost in autism spectrum disorder.

Prepregnancy BMI, gestational weight gain, and susceptibility to autism-related traits: the EARLI and HOME studies

OBJECTIVE

Excessive gestational weight gain (GWG) has been associated with autism spectrum disorder (ASD). This study sought to examine whether familial susceptibility for autism, intensity of ASD-related behaviors, or prepregnancy BMI influences the association of GWG with ASD-related behaviors.

METHODS

Using data from the Early Autism Risk Longitudinal Investigation (EARLI) study (n = 136), a familial enriched cohort of mothers who had a previous child with ASD, and the Health Outcomes and Measures of the Environment (HOME) study (n = 253), a general population cohort, gestational age and prepregnancy BMI category-specific GWG z scores were calculated. Caregivers completed the Social Responsiveness Scale (SRS) to assess the presence and severity of ASD-related traits in children aged 3 to 8 years. Using quantile regression, the association between GWG z scores and ASD-related behaviors in children was estimated.

RESULTS

In HOME, among mothers who had overweight or obesity prepregnancy BMI values, GWG z scores and SRS scores were positively associated in children with more ASD-related traits (higher SRS scores), but not in children with fewer ASD-related traits. Similar patterns were observed in EARLI among mothers with prepregnancy obesity.

CONCLUSIONS

GWG may be associated with autism-related behaviors among children who have a greater predisposition to these behaviors and who have mothers with prepregnancy overweight or obesity.

Adipocytokine correlates of childhood and adolescent mental health: A systematic review

The objective of this systematic review was to determine the current state of the literature regarding how adipocytokines associate with mental health symptoms/disorders in youth. Findings summarized in this review suggested that in neurodevelopmental disorders, higher levels of leptin, ghrelin, resistin, and visfatin as well as lower levels of adiponectin, retinol-binding protein 4, and progranulin predicted increased risk for or were conflated with autism spectrum disorder. Adipocytokine correlates of attention-deficit hyperactivity disorder and related symptoms included higher apelin, higher leptin-to-adiponectin ratio, and lower adiponectin. Evidence from studies examining anxiety symptoms evinced mixed results regarding leptin, and one study suggested higher levels of ghrelin. Depressive symptoms correlated with higher leptin and ghrelin. Research examining posttraumatic stress symptoms found higher levels of ghrelin. In research examining broadband symptoms, conflicting results emerged for associations between internalizing symptoms (i.e., symptoms of emotional stress) and leptin in youth. Low levels of adiponectin and high levels of leptin predicted externalizing symptoms. Total symptom difficulties were associated with a higher leptin-to-adiponectin ratio. Our findings suggest that adipocytokines may be an important set of biomarkers to consider as underlying mechanisms contributing to developmental psychopathology.

Peripubertal Alterations of Leptin Levels in Patients with Autism Spectrum Disorder and Elevated or Normal Body Weight

Leptin, which plays a key role in energy homeostasis, is known as a neurotrophic factor possibly linking nutrition and neurodevelopment. Available data on the association between leptin and autism spectrum disorder (ASD) are confusing. The aim of this study was to explore whether plasma levels of leptin in pre- and post-pubertal children with ASD and/or overweightness/obesity differ from those of BMI- and age-matched healthy controls. Leptin levels were determined in 287 pre-pubertal children (mean age 8.09 years), classified as follows: ASD with overweightness/obesity (ASD+/Ob+); ASD without overweightness/obesity (ASD+/Ob-); non-ASD with overweightness/obesity (ASD-/Ob+); non-ASD without overweightness/obesity (ASD-/Ob-). The assessment was repeated in 258 of the children post-pubertally (mean age 14.26 years). There were no significant differences in leptin levels either before or after puberty between ASD+/Ob+ and ASD-/Ob+ or between ASD+/Ob- and ASD-/Ob-, although there was a strong trend toward significance for higher pre-pubertal leptin levels in ASD+/Ob- than in ASD-/Ob-. Post-pubertal leptin levels were significantly lower than pre-pubertal levels in ASD+/Ob+, ASD-/Ob+, and ASD+/Ob- and higher in ASD-/Ob-. Leptin levels, elevated pre-pubertally in the children with overweightness/obesity as well as in children with ASD and normal BMI, decrease with age, in contrast to the increasing leptin levels in healthy controls.

Leptin antagonism improves Rett syndrome phenotype in symptomatic male Mecp2-null mice

Rett syndrome (RTT) is a severe neurodevelopmental disorder that arise from de novo mutations in the X-linked gene MECP2 (methyl-CpG-binding protein 2). Circulating levels of the adipocyte hormone leptin are elevated in RTT patients and rodent models of the disease. Leptin targets a large number of brain structures and regulates a wide range of developmental and physiological functions which are altered in RTT. We hypothesized that elevated leptin levels might contribute to RTT pathogenesis. Accordingly, we show that pharmacological antagonism of leptin or genetic reduction of leptin production prevents the degradation of health status, weight loss and the progression of breathing and locomotor deficits. At the neuronal level, the anti-leptin strategies rescue the hippocampal excitatory/inhibitory imbalance and synaptic plasticity impairment. Targeting leptin might therefore represent a new approach for RTT treatment.

Vitamin D Status in Children with Autism Spectrum Disorders: Determinants and Effects of the Response to Probiotic Supplementation

A relationship between the presence of clinical symptoms and gastrointestinal (GI) disturbances associated with nutritional deficiencies, including vitamin D (25(OH)D) deficiency, has been observed in autism spectrum disorder (ASD). The aim was to evaluate 25(OH)D levels according to the annual rhythm cycle, gender, the severity of autism, nutritional or clinical status, inflammatory and metabolic biomarkers, GI symptoms, and the clinical response to probiotic/placebo supplementation in preschooler children with ASD. Eighty-one ASD preschoolers (67 males) were assessed with standardized tools for ASD severity (ADOS score) and GI symptoms (by GI-Index at six-items and at nine-items, the latter defined as the Total GI-Index). The 25(OH)D levels were compared among different ASD subgroups according to metabolic and inflammatory biomarkers (leptin, insulin, resistin, PAI-1, MCP-1, TNF-alfa, and IL-6), gender, and the presence or absence of: (i) GI symptoms, (ii) the response to probiotic supplementation (the improvement of GI symptomatology), (iii) the response to probiotic supplementation (improvement of ASD severity). Only 25% of the ASD children presented an adequate 25(OH)D status (≥30 ng/mL according to the Endocrine Society guidelines). All the 25(OH)D levels falling in the severe deficiency range (<10 ng/mL) were observed in the male subgroup. A significant inverse correlation between 25(OH)D and leptin was observed (R = −0.24, p = 0.037). An inverse correlation was found between 25(OH)D levels and the GI Index 6-Items and Total GI-Index (R = −0.25, p = 0.026; −0.27, = 0.009) and a direct relationship with the probiotic response (R = 0.4, p = 0.05). The monitoring of 25(OH)D levels and the co-administration of 25(OH)D and probiotic supplementation could be considered in ASD from early ages.

Sleep Problems and Circadian Functioning in Children and Adolescents With Autism Spectrum Disorder

BACKGROUND

Sleep problems are a prevalent comorbidity in autism spectrum disorder (ASD) with a multifactorial basis in which circadian misalignment has been described.

METHODS

A cross-sectional study was conducted including 52 children and adolescents with ASD (9.85 ± 3.07) and 27 children and adolescent controls with normal intellectual functioning (8.81 ± 2.14). They were matched for age, sex, and body mass index, and all were drug-naïve. An ambulatory circadian monitoring device was used to record temperature and motor, body position, sleep, and light intensity.

RESULTS

Individuals with ASD presented longer sleep-onset latency, lower sleep efficiency, and decreased total sleep time and tended to be more sedentary and have less exposure to light. They also showed lower amplitude, low interdaily stability, and a different pattern of wrist temperature across the day, with a midpoint of sleep that did not concur with sleep midpoint indicated by the rest of circadian parameters.

CONCLUSIONS

The sleep problems observed in this sample resemble those reported previously, with the exception of nocturnal awakenings which did not show differences. The ambulatory circadian monitoring device enabled measurement of circadian parameters such as temperature which, until now, were scarcely described in children with ASD and could be used to better understand sleep and circadian system in ASD.

Evaluation of Appetite-Regulating Hormones ın Young Children with Autism Spectrum Disorder

This study aimed to investigate the role of leptin, ghrelin, neuropeptide Y, and nesfatin-1 in young children with autism spectrum disorder (ASD). A total of 44 children with ASD and 44 healthy controls aged 18-60 months were included. Plasma levels of hormones were measured using commercial enzyme-linked immunosorbent assay kits. Plasma leptin and ghrelin levels were significantly higher in the ASD group than in the control group. However, no significant difference for plasma neuropeptide Y and nesfatin-1 levels was detected between the groups. No relation was found between the severity of ASD symptoms, severity of eating problems, and plasma levels of hormones. Leptin and ghrelin may play a potential role in the pathogenesis of ASD.

Serum adiponectin levels are reduced in autism spectrum disorder and association with severity of symptoms

Recent evidence highlights the role of adiponectin in the pathophysiology of autism spectrum disorder (ASD), yielding conflicting results. The aims of this study were (1) To assess the adiponectin levels of children with ASD and typical developing (TP); (2) To investigate the relationship between adiponectin levels and symptom severity of children with ASD. This is a single-center cross-sectional study from China. From December 2017 to November 2019, first-diagnosis and drug-naïve children with ASD were included. Same TP children who were matched with clinical groups by gender and age were included as the control group. The enzyme-linked immunosorbent assay (ELISA) kit was used to determine serum concentrations of adiponectin. We recorded 176 children (88 were ASD and 88 were TP children) and 77.3% (n = 136) were boys and the mean age was 4.3 years (standard deviations [S.D.]: 1.2). The mean (S.D.) levels of adiponectin were 9.01(2.19) and 11.55(2.32) μg/ml for those with ASD and TP subjects. The difference between those two groups was significant (t = 7.169, p < 0.001). There was a negative correlation between serum levels of adiponectin and Childhood Autism Rating Scale [CARS] score (r = -0.498, p < 0.001). At admission, 39 ASD (54.5%) had a minor autism (CARS<37). In these children, the mean (S.D.) adiponectin level was higher than that observed in children with moderate-to-severe clinical severity (10.09[2.32] vs.8.15[1.64] μg/ml, P < 0.001). This study shows that serum adiponectin. Levels are decreased in ASD when compared with in healthy children. The findings also indicate an inverse association between serum adiponectin levels and severity of symptoms in ASD.

Associations Among Maternal Metabolic Conditions, Cord Serum Leptin Levels, and Autistic Symptoms in Children

INTRODUCTION

Accumulating evidence has shown that maternal metabolic conditions, such as pre-pregnancy overweight, diabetes mellitus, and hypertensive disorders of pregnancy (HDP) are potential risk factors of autism spectrum disorder (ASD). However, it remains unclear how these maternal conditions lead to neurodevelopmental outcomes in the offspring, including autistic symptoms. Leptin, an adipokine that has pro-inflammatory effects and affects fetal neurodevelopment, is a candidate mediator of the association between maternal metabolic factors and an increased risk of ASD. However, whether prenatal exposure to leptin mediates the association between maternal metabolic conditions and autistic symptoms in children has not been investigated yet.

METHODS

This study investigated the associations between mothers' metabolic conditions (pre-pregnancy overweight, diabetes mellitus during or before pregnancy, and HDP), leptin concentrations in umbilical cord serum, and autistic symptoms among 762 children from an ongoing cohort study, using generalized structural equation modeling. We used the Social Responsive Scale, Second Edition (SRS-2) at 8-9 years old to calculate total T-scores. Additionally, we used the T-scores for two subdomains: Social Communication and Interaction (SCI) and Restricted Interests and Repetitive Behavior (RRB).

RESULTS

Umbilical cord leptin levels were associated with pre-pregnancy overweight [coefficient = 1.297, 95% confidence interval (CI) 1.081-1.556, p = 0.005] and diabetes mellitus (coefficient = 1.574, 95% CI 1.206-2.055, p = 0.001). Furthermore, leptin levels were significantly associated with SRS-2 total T-scores (coefficient = 1.002, 95% CI 1.000-1.004, p = 0.023), SCI scores (coefficient = 1.002, 95% CI 1.000-1.004, p = 0.020), and RRB scores (coefficient = 1.001, 95% CI 1.000-1.003, p = 0.044) in children. Associations between maternal metabolic factors and autistic symptoms were not significant.

DISCUSSION

The present study uncovered an association between cord leptin levels and autistic symptoms in children, while maternal metabolic conditions did not have an evident direct influence on the outcome. These results imply that prenatal pro-inflammatory environments affected by maternal metabolic conditions may contribute to the development of autistic symptoms in children. The findings warrant further investigation into the role of leptin in the development of autistic symptoms.

Association Between Gestational Weight Gain and Autism Spectrum Disorder in Offspring: A Meta-Analysis

OBJECTIVE

This study aimed to quantitatively examine the association between gestational weight gain (GWG) and risk of autism spectrum disorder (ASD) in offspring.

METHODS

Electronic databases were searched for studies of excessive or inadequate GWG, as compared with recommended GWG, in relation to the risk of ASD in offspring. Measures of the association from primary studies were pooled using a meta-analytic approach and expressed as weighted odds ratios (ORs) with 95% CIs.

RESULTS

Nine studies were identified, including 323,253 participants with 4,135 cases of ASD from five cohort studies and 1,462 cases and 3,265 controls from four case-control studies. Evidence from cohort studies indicates that both excessive and inadequate GWG was significantly associated with a higher risk for ASD in offspring. The pooled OR of ASD was 1.10 (95% CI: 1.02-1.18) for excessive GWG and 1.13 (95% CI: 1.04-1.24) for inadequate GWG using recommended GWG as the reference. Evidence from case-control studies suggests that excessive GWG (1.38 [95% CI: 1.19-1.62]) but not inadequate GWG (0.87 [95% CI: 0.72-1.04]) was significantly associated with a higher risk for ASD.

CONCLUSIONS

The accumulated evidence has supported that gaining weight outside the recommended GWG is associated with a higher risk for ASD in offspring.

A potential role of fatty acid binding protein 4 in the pathophysiology of autism spectrum disorder

Autism spectrum disorder is a neurodevelopmental disorder characterized by difficulties in social communication and interaction, as well as repetitive and characteristic patterns of behaviour. Although the pathogenesis of autism spectrum disorder is unknown, being overweight or obesity during infancy and low weight at birth are known as risks, suggesting a metabolic aspect. In this study, we investigated adipose tissue development as a pathophysiological factor of autism spectrum disorder by examining the serum levels of adipokines and other metabolic markers in autism spectrum disorder children (n = 123) and typically developing children (n = 92) at 4–12 years of age. Among multiple measures exhibiting age-dependent trajectories, the leptin levels displayed different trajectory patterns between autism spectrum disorder and typically developing children, supporting an adipose tissue-dependent mechanism of autism spectrum disorder. Of particular interest, the levels of fatty acid binding protein 4 (FABP4) were significantly lower in autism spectrum disorder children than in typically developing subjects, at preschool age (4–6 years old: n = 21 for autism spectrum disorder and n = 26 for typically developing). The receiver operating characteristic curve analysis discriminated autism spectrum disorder children from typically developing children with a sensitivity of 94.4% and a specificity of 75.0%. We re-sequenced the exons of the FABP4 gene in a Japanese cohort comprising 659 autism spectrum disorder and 1000 control samples, and identified two rare functional variants in the autism spectrum disorder group. The Trp98Stop, one of the two variants, was transmitted to the proband from his mother with a history of depression. The disruption of the Fabp4 gene in mice evoked autism spectrum disorder-like behavioural phenotypes and increased spine density on apical dendrites of pyramidal neurons, which has been observed in the postmortem brains of autism spectrum disorder subjects. The Fabp4 knockout mice had an altered fatty acid composition in the cortex. Collectively, these results suggest that an ‘adipo-brain axis’ may underlie the pathophysiology of autism spectrum disorder, with FABP4 as a potential molecule for use as a biomarker.

Inflammatory Biomarkers are Correlated with Some Forms of Regressive Autism Spectrum Disorder

Background: Several studies have tried to investigate the role of inflammatory biomarkers in Autism Spectrum Disorder (ASD), and their correlations with clinical phenotypes. Despite the growing research in this topic, existing data are mostly contradictory. Methods: Eighty-five ASD preschoolers were assessed for developmental level, adaptive functioning, gastrointestinal (GI), socio-communicative and psychopathological symptoms. Plasma levels of leptin, resistin, plasminogen activator inhibitor-1 (PAI-1), macrophage chemoattractant protein-1 (CCL2), tumor necrosis factor-alfa (TNF-α), and interleukin-6 (IL-6) were correlated with clinical scores and were compared among different ASD subgroups according to the presence or absence of: (i) GI symptoms, (ii) regressive onset of autism. Results: Proinflammatory cytokines (TNF-α, IL-6 and CCL2) were lower than those reported in previous studies in children with systemic inflammatory conditions. GI symptoms were not correlated with levels of inflammatory biomarkers except for resistin that was lower in ASD-GI children (p = 0.032). Resistin and PAI-1 levels were significantly higher in the group with “regression plus a developmental delay” onset (Reg+DD group) compared to groups without regression or with regression without a developmental delay (p < 0.01 for all). Conclusions: Our results did not highlight the presence of any systemic inflammatory state in ASD subjects neither disentangling children with/without GI symptoms. The Reg + DD group significantly differed from others in some plasmatic values, but these differences failed to discriminate the subgroups as possible distinct ASD endo-phenotypes.

The zebrafish subcortical social brain as a model for studying social behavior disorders

Social behaviors are essential for the survival and reproduction of social species. Many, if not most, neuropsychiatric disorders in humans are either associated with underlying social deficits or are accompanied by social dysfunctions. Traditionally, rodent models have been used to model these behavioral impairments. However, rodent assays are often difficult to scale up and adapt to high-throughput formats, which severely limits their use for systems-level science. In recent years, an increasing number of studies have used zebrafish (Danio rerio) as a model system to study social behavior. These studies have demonstrated clear potential in overcoming some of the limitations of rodent models. In this Review, we explore the evolutionary conservation of a subcortical social brain between teleosts and mammals as the biological basis for using zebrafish to model human social behavior disorders, while summarizing relevant experimental tools and assays. We then discuss the recent advances gleaned from zebrafish social behavior assays, the applications of these assays to studying related disorders, and the opportunities and challenges that lie ahead.

Risk Factors for Unhealthy Weight Gain and Obesity among Children with Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a developmental disorder characterized by social and communication deficits and repetitive behaviors. Children with ASD are also at a higher risk for developing overweight or obesity than children with typical development (TD). Childhood obesity has been associated with adverse health outcomes, including insulin resistance, diabetes, heart disease, and certain cancers. Importantly some key factors that play a mediating role in these higher rates of obesity include lifestyle factors and biological influences, as well as secondary comorbidities and medications. This review summarizes current knowledge about behavioral and lifestyle factors that could contribute to unhealthy weight gain in children with ASD, as well as the current state of knowledge of emerging risk factors such as the possible influence of sleep problems, the gut microbiome, endocrine influences and maternal metabolic disorders. We also discuss some of the clinical implications of these risk factors and areas for future research.

Cord and Early Childhood Plasma Adiponectin Levels and Autism Risk: A Prospective Birth Cohort Study

Emerging research suggests that adiponectin, a cytokine produced by adipose tissue, may be implicated in ASD. In this prospective birth cohort study (n = 847), we assessed the association between cord, early childhood plasma adiponectin and the risk of developing ASD. ASD was defined based on ICD codes of physician diagnosis. Cord adiponectin levels were inversely associated with ASD risk (aOR 0.50; 95% CI 0.33, 0.77), independent of preterm birth, early childhood adiponectin and other known ASD risk factors. Early childhood adiponectin, assessed prior to ASD diagnosis, was associated with lower risk of ASD, which attenuated after adjusting for cord adiponectin, indicating the relative importance of cord adiponectin in ASD risk. Further research is warranted to confirm our findings and elucidate biological mechanisms.

Oxidative Stress, Maternal Diabetes, and Autism Spectrum Disorders

Autism spectrum disorders (ASD) are a group of early-onset neurodevelopmental conditions characterized by alterations in brain connectivity with cascading effects on neuropsychological functions. To date, in the framework of an increasing interest about environmental conditions which could interact with genetic factors in ASD pathogenesis, many authors have stressed that changes in the intrauterine environment at different stages of pregnancy, such as those linked to maternal metabolic pathologies, may lead to long-term conditions in the newborn. In particular, a growing number of epidemiological studies have highlighted the role of obesity and maternal diabetes as a risk factor for developing both somatic and psychiatric disorders in humans, including ASD. While literature still fails in identifying specific etiopathological mechanisms, a growing body of evidence is available about the presence of a relationship between maternal immune dysregulation, inflammation, oxidative stress, and the development of ASD in the offspring. In this framework, results from high-fat diet animal models about the role played by oxidative stress in shaping offspring neurodevelopment may help in clarifying the pathways through which maternal metabolic conditions are linked with ASD. The aim of this review is to provide an overview of literature about the effects of early life insults linked to oxidative stress which may be involved in ASD etiopathogenesis and how this relationship can be explained in biological terms.

Fetal and Infancy Growth Pattern, Cord and Early Childhood Plasma Leptin, and Development of Autism Spectrum Disorder in the Boston Birth Cohort

Leptin is a proinflammatory cytokine that plays an important role in energy homeostasis. Emerging evidence suggests that leptin levels are altered in children with autism spectrum disorder (ASD); however, this has not been studied prospectively. Rapid growth during infancy and early childhood has been implicated in ASD, but the evidence is inconsistent. As leptin is involved in growth and is a potential risk factor for ASD, we explored the associations between (a) cord, early childhood leptin and ASD; and (b) birth weight for gestational age, early childhood weight gain, and ASD. We also assessed the mediating role of leptin in the relationship between weight gain during infancy and ASD. This study was conducted in a sample of 822 subjects from the Boston Birth Cohort. ASD was defined from diagnostic codes in electronic medical records. Extremely rapid weight gain during infancy was associated with a greater ASD risk and this persisted after adjusting for potential confounders (aOR: 3.11; 95% CI: 1.37, 7.07). Similarly, children that had higher plasma leptin levels, prior to ASD diagnosis, had an increased ASD risk in both unadjusted and adjusted models (aOR: 7.87; 95% CI: 2.06, 30.04). Further, early childhood leptin indirectly mediated the relationship between rapid weight gain and ASD. No associations were found between birth weight for gestational age, cord leptin and risk of ASD. Our findings provide a basis to further explore whether the combination of early life growth pattern and a biomarker such as leptin can predict ASD earlier. Autism Res 2018, 11: 1416-1431. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Is early life growth and a biomarker leptin related to ASD risk? To answer this question, we followed 822 children from birth and found that those who gained weight very quickly in infancy, had higher leptin levels in early childhood, had a greater chance of later ASD diagnosis. More research is needed to see if infant's weight gain pattern along with a biomarker (such as leptin) can be used to identify children with ASD sooner.

Pioglitazone abolishes autistic-like behaviors via the IL-6 pathway

Autism is characterized by social deficits, communication abnormalities, and repetitive behaviors. The risk factors appear to include genetic and environmental conditions, such as prenatal infections and maternal dietary factors. Previous investigations by our group have demonstrated that prenatal exposure to lipopolysaccharide (LPS), which mimics infections by gram-negative bacteria, induces autistic-like behaviors. No effective treatment yet exists for autism. Therefore, we used our rat model to test a possible treatment for autism. We selected pioglitazone to block or ease the impairments induced by LPS because although this drug was designed as an anti-diabetic drug (it has an insulin effect), it also exerts anti-inflammatory effects. Juvenile offspring were treated daily with pioglitazone, and the main behaviors related to autism, namely, socialization (play behavior) and communication (50-kHz ultrasonic vocalizations), were studied. Biomarkers linked to autism and/or pioglitazone were also studied to attempt to understand the mechanisms involved, namely, IL-6, TNF-alpha, MCP-1, insulin, and leptin. Prenatal LPS exposure induced social deficits and communicational abnormalities in juvenile rat offspring as well as elevated plasma IL-6 levels. Daily postnatal pioglitazone treatment blocked the impairments found in terms of the time spent on social interaction, the number of vocalizations (i.e., autistic-like behaviors) and the elevated plasma IL-6 levels. Thus, pioglitazone appears to be a relevant candidate for the treatment of autism. The present findings may contribute to a better understanding and treatment of autism and associated diseases.

Association between Fetal Adipokines and Child Behavioral Problems at Preschool Age: The Hokkaido Study on Environment and Children's Health

Studies have suggested associations between maternal obesity and mental health problems of their children. However, the underlying mechanism is largely unknown. A possible mechanism can be via inflammatory states and the other possible mechanism is metabolic hormone-induced programming. Cross-talk between adipokines, including inflammatory cytokines and metabolic hormones secreted from adipose tissue and the central nervous system needs to be further investigated to elucidate the mechanism. Thus, the aim of this study was to investigate the association between fetal adipokine levels and child behavioral problems at preschool age. Cord blood adiponectin, leptin, tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) levels were measured and child behavioral problems were assessed using the Strengths and Difficulties Questionnaire at preschool age. Logistic regression models adjusted by related maternal factors were performed to examine the association between cord blood adipokines and child behavioral problems. Three hundred and sixty-one children were included in the final analysis. A significant association between decreased hyperactivity/inattention and increased leptin was found (OR = 0.22, 95% CI: 0.06–0.89). Cord blood adiponectin, TNF-α and IL-6 levels were not associated with child behavioral problems. Our findings suggested that cord blood adipokines, particularly, leptin level, may be a predictor of hyperactivity/inattention problems at preschool age.

Impact of epilepsy and antiepileptic medications on the metabolic profile in adults with autism spectrum disorder and intellectual disabilities

Epilepsy is common in individuals with autism spectrum disorder (ASD) and intellectual disabilities (ID). Antiepileptic medications, such as valproic acid (VPA), were associated with changes in BMI, metabolic syndrome, dyslipidemia, and hyperinsulinemia. This study aimed to investigate how epilepsy and antiepileptic treatments affect BMI, fasting blood glucose (FBG), and total cholesterol of individuals with ASD or ID. Data on epilepsy diagnoses, treatment with VPA, carbamazepine or other antiepileptics, BMI, FBG, and total cholesterol levels were obtained from the medical charts of 80 adults with ASD and 77 adults with ID and analyzed using appropriate statistical tools. Participants with epilepsy had lower BMI and FBG than participants without epilepsy (BMI: 23.18 ± 5.43 vs. 25.61 ± 5.74 kg/m2, respectively, F = 6.64, d.f. = 1.140; P = 0.011, FBG: 72.53 ± 11.26 vs. 79.98 ± 14.64 mg/dl, respectively, F = 10.46, d.f. = 1.135 P = 0.002). Those treated with VPA had lower total cholesterol levels compared with those untreated (156.56 ± 26.13 vs. 172.42 ± 33.82 mg/dl, respectively, F = 7.44, d.f. = 1.150; P = 0.007), but did not differ in BMI and FBG. Individuals with ASD or ID, and epilepsy were leaner and had lower FBG than those without epilepsy. In addition, total cholesterol levels were lower in VPA-treated participants than in untreated ones, but BMI and FBG levels were similar.

Maternal high-fat diet programming of the neuroendocrine system and behavior

This article is part of a Special Issue "SBN 2014". Maternal obesity, metabolic state, and diet during gestation have profound effects on offspring development. The prevalence of neurodevelopmental and mental health disorders has risen rapidly in the last several decades in parallel with the rise in obesity rates. Evidence from epidemiological studies indicates that maternal obesity and metabolic complications increase the risk of offspring developing behavioral disorders such as attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASD), and schizophrenia. Animal models show that a maternal diet high in fat similarly disrupts behavioral programming of offspring, with animals showing social impairments, increased anxiety and depressive behaviors, reduced cognitive development, and hyperactivity. Maternal obesity, metabolic conditions, and high fat diet consumption increase maternal leptin, insulin, glucose, triglycerides, and inflammatory cytokines. This leads to increased risk of placental dysfunction, and altered fetal neuroendocrine development. Changes in brain development that likely contribute to the increased risk of behavioral and mental health disorders include increased inflammation in the brain, as well as alterations in the serotonergic system, dopaminergic system and hypothalamic-pituitary-adrenal (HPA) axis.

Changes in adipokine levels in autism spectrum disorders

BACKGROUND AND OBJECTIVE

The etiopathogenesis of autism spectrum disorders (ASD) is largely unknown, but it seems to involve dysfunction in several biological systems. Among many possible biological pathways, the immune system has emerged as potentially involved. Recent studies have shown association between cytokines (molecules that mediate immune cell interaction) and ASD. Adipokines are cytokines secreted mainly by adipose tissue and may have systemic effects. The main objective of this study was to compare the plasma levels of three adipokines between patients with ASD and healthy controls. Another aim was to correlate the levels of these adipokines and the severity of autistic symptoms as measured by the Social Responsiveness Scale (SRS).

METHODS

We collected plasma from 30 patients and 19 controls and measured the levels of adiponectin, leptin and resistin using a commercially available kit. We also used the SRS as a tool to assess the severity of autistic symptoms.

RESULTS

We found decreased levels of resistin, increased levels of leptin and unaltered levels of adiponectin in plasma from ASD subjects in comparison with controls. There was also a negative correlation between the levels of adiponectin and the severity of symptoms as assessed by the SRS.

CONCLUSION

There are significant changes in the plasma levels of adipokines from patients with ASDs. They suggest the occurrence of systemic changes in ASD and may be hallmarks of the disease.

Altered ghrelin levels in boys with autism: a novel finding associated with hormonal dysregulation

Autism is a neurodevelopmental disorder with unclear pathogenesis. Many clinical observations and hormone studies have suggested the involvement of the neuroprotective hormone ghrelin in autism. The current study aimed to investigate the potential role of ghrelin in autism and to elucidate the associated hormonal dysregulation. This case-control study investigated acyl ghrelin (AG), des-acyl ghrelin (DG), total testosterone (TT), free testosterone (FT), leptin and growth hormone (GH) levels in 31 male children with autism and 28 healthy age and sex-matched controls. Hormone levels were measured in the blood using enzyme-linked immunosorbent assay and chemiluminescence immunoassay kits. AG, DG and GH levels were significantly lower in the autism group than in the control group (p ≤ 0.001, p ≤ 0.005 and p ≤ 0.05, respectively). However, TT, FT and leptin levels were significantly higher in the autism group than in the control group (p ≤ 0.05, p ≤ 0.001 and p ≤ 0.01, respectively). Our results for the first time demonstrate low AG and DG levels in autistic children. Considering the capacity of ghrelin to affect neuroinflammatory and apoptotic processes that are linked to autism, this study suggests a potential role for the hormone ghrelin in the pathogenesis of autism.

Current perspectives on physical activity and exercise recommendations for children and adolescents with autism spectrum disorders

Recent evidence suggests that childhood obesity is increasing in children who are developing typically as well as in children with developmental disabilities such as autism spectrum disorders (ASDs). Impairments specific to autism as well as general environmental factors could lead to an imbalance between the intake and expenditure of energy, leading to obesity. In this article, we describe the mechanisms by which autism-specific impairments contribute to obesity. The evidence on exercise interventions to improve physical fitness, address obesity, and reduce autism-specific impairments in children and adolescents with ASDs is discussed. Limited evidence is currently available for exercise interventions in individuals with ASDs. Therefore, literature on other pediatric developmental disabilities and children who are developing typically was reviewed to provide recommendations for clinicians to assess physical activity levels, to promote physical fitness, and to reduce obesity in children and adolescents with ASDs. There is a clear need for further systematic research to develop sensitive assessment tools and holistic multisystem and multifactorial obesity interventions that accommodate the social communication, motor, and behavioral impairments of individuals with ASDs.

The impact of leptin on perinatal development and psychopathology

Leptin has long been associated with metabolism as it is a critical regulator of both food intake and energy expenditure, but recently, leptin dysregulation has been proposed as a mechanism of psychopathology. This review discusses the evidence supporting a role for leptin in mental health disorders and describes potential mechanisms that may underlie this association. Leptin plays a critical role in pregnancy and in fetal growth and development. Leptin's role and profile during development is examined in available human studies, and the validity of applying studies conducted in animal models to the human population are discussed. Rodents experience a postnatal leptin surge, which does not occur in humans or larger animal models. This suggests that further research using large mammal models, which have a leptin profile across pregnancy and development similar to humans, are of high importance. Maternal obesity and hyperleptinemia correlate with increased leptin levels in the umbilical cord, placenta, and fetus. Leptin levels are thought to impact fetal brain development; likely by activating proinflammatory cytokines that are known to impact many of the neurotransmitter systems that regulate behavior. Leptin is likely involved in behavioral regulation as leptin receptors are widely distributed in the brain, and leptin influences cortisol release, the mesoaccumbens dopamine pathway, serotonin synthesis, and hippocampal synaptic plasticity. In humans, both high and low levels of leptin are reported to be associated with psychopathology. This inconsistency is likely due to differences in the metabolic state of the study populations. Leptin resistance, which occurs in the obese state, may explain how both high and low levels of leptin are associated with psychopathology, as well as the comorbidity of obesity with numerous mental illnesses. Leptin resistance is likely to influence disorders such as depression and anxiety where high leptin levels have been correlated with symptomatology. Schizophrenia is also associated with both low and high leptin levels. However, as anti-psychotics pharmacotherapy induces weight gain, which elevates leptin levels, drug-naïve populations are needed for further studies. Elevated circulating leptin is consistently found in childhood neurodevelopmental disorders including autism spectrum disorders and Rhett disorder. Further, studies on the impact of leptin and leptin resistance on psychopathology and neurodevelopmental disorders are important directions for future research. Studies examining the mechanisms by which exposure to maternal obesity and hyperleptinemia during fetal development impact brain development and behavior are critical for the health of future generations.

The need for a comprehensive molecular characterization of autism spectrum disorders

Autism spectrum disorders (ASD) are a heterogeneous group of disorders which have complex behavioural phenotypes. Although ASD is a highly heritable neuropsychiatric disorder, genetic research alone has not provided a profound understanding of the underlying causes. Recent developments using biochemical tools such as transcriptomics, proteomics and cellular models, will pave the way to gain new insights into the underlying pathological pathways. This review addresses the state-of-the-art in the search for molecular biomarkers for ASD. In particular, the most important findings in the biochemical field are highlighted and the need for establishing streamlined interaction between behavioural studies, genetics and proteomics is stressed. Eventually, these approaches will lead to suitable translational ASD models and, therefore, a better disease understanding which may facilitate novel drug discovery efforts in this challenging field.

Repositioning leptin as a therapy for Alzheimer's disease

The data from the initial clinical trials utilizing recombinant human leptin as an obesity therapy were published in 1998. Since then, numerous studies have been described which address dosage, safety and efficacy of leptin replacement for a variety of disorders with diverse patient groups, including pediatric and adult subjects. We review the current clinical trial data, demonstrate that leptin administration is safe for long term use in humans, and summarize reported cognitive benefits. The functions of leptin in neuroprotection and cognition have been largely overlooked. Accumulating data suggest a very significant application of leptin may be a therapy for Alzheimer's disease.