Better fear conditioning is associated with reduced symptom severity in autism spectrum disorders

Cognitive behavioral phenotyping of DSCAM heterozygosity as a model for autism spectrum disorder

It is estimated that 1 in 36 children are affected by autism spectrum disorder (ASD) in the United States, which is nearly a twofold increase from a decade ago. Recent genetic studies have identified de novo loss-of-function (dnLoF) mutations in the Down Syndrome Cell Adhesion Molecule (DSCAM) as a strong risk factor for ASD. Previous research has shown that DSCAM ablation confers social interaction deficits and perseverative behaviors in mouse models. However, it remains unknown to what extent DSCAM underexpression captures the full range of behaviors, specifically cognitive phenotypes, presented in ASD. Here, we conducted a comprehensive cognitive behavioral phenotyping which revealed that loss of one copy of DSCAM , as in the DSCAM 2J +/- mice, displayed hyperactivity, increased anxiety, and motor coordination impairments. Additionally, hippocampal-dependent learning and memory was affected, including working memory, long-term memory, and contextual fear learning. Interestingly, implicit learning processes remained intact. Therefore, DSCAM LoF produces autistic-like behaviors that are similar to human cases of ASD. These findings further support a role for DSCAM dnLoF mutations in ASD and suggest DSCAM 2J +/- as a suitable model for ASD research.

Summary Statement

Autism spectrum disorder represents a growing patient population. Loss of one copy of the DSCAM gene provides a promising mouse model that reproduces autistic-like behaviors for research and therapeutic testing.

Increased NMDARs in neurons and glutamine synthetase in astrocytes underlying autistic-like behaviors of Gabrb1-/- mice

Mutations of the GABA-A receptor subunit β1 (GABRB1) gene are found in autism patients. However, it remains unclear how mutations in Gabrb1 may lead to autism. We generated Gabrb1-/- mouse model, which showed autistic-like behaviors. We carried out RNA-seq on the hippocampus and found glutamatergic pathway may be involved. We further carried out single-cell RNA sequencing on the whole brain followed by qRT-PCR, immunofluorescence, electrophysiology, and metabolite detection on specific cell types. We identified the up-regulated Glul/Slc38a3 in astrocytes, Grin1/Grin2b in neurons, glutamate, and the ratio of Glu/GABA in the hippocampus. Consistent with these results, increased NMDAR-currents and reduced GABAAR-currents in the CA1 neurons were detected in Gabrb1-/- mice. NMDAR antagonist memantine or Glul inhibitor methionine sulfoximine could rescue the abnormal behaviors in Gabrb1-/- mice. Our data reveal that upregulation of the glutamatergic synapse pathway, including NMDARs at neuronal synapses and glutamine exported by astrocytes, may lead to autistic-like behaviors.

Understanding the heterogeneity of anxiety in autistic youth: A person-centered approach

The present study aimed to examine anxiety profiles among children and adolescents on the autism spectrum. It further aimed to characterize the association between the identified anxiety profiles and key clinical and developmental variables. The Spence Children's Anxiety Scale-Parent Version (SCAS-P) data from a large international pooled sample of 870 caregivers of autistic children and adolescents (M_age  = 11.6 years, SD_age  = 2.77; 107 females) was used. Latent profile analysis identified a three-anxiety profile solution exhibiting high entropy (0.80) and high latent profile probabilities, with good classification accuracy. Identified profiles fell along the severity spectrum and were named as the mild (n = 498), moderate (n = 272) and severe (n = 100) anxiety profiles. There were no statistically significant differences between the three anxiety profiles in terms of sex distribution. Participants in the mild profile were significantly younger than those in the severe profile, had significantly fewer social communication difficulties than youth in the moderate anxiety profile group and had significantly fewer restricted and repetitive behaviors and lower cognitive functioning scores compared to participants in moderate and severe anxiety profiles. This is the first study to move beyond identifying associations and group-level differences to exploring and identifying characteristics of anxiety-based subgroups at an individual level that differ on key clinical and developmental variables. The subgroups identified in this study are a preliminary, yet important, first step towards informing future assessment and individualized interventions aiming to support young people on the autism spectrum to reduce and manage anxiety. LAY SUMMARY: This study tried to understand if there are subgroups of autistic young people who may have similar anxiety profiles. We found that we could meaningfully group young people into three groups based on how severe the anxiety symptoms their caregivers reported were: a group with low levels of anxiety, those with moderate anxiety, and those with more severe anxiety. We also found that the young people in the mild group were younger, had fewer autism traits and lower levels of intellectual functioning than young people in the other two groups.

Astrocytes derived from ASD individuals alter behavior and destabilize neuronal activity through aberrant Ca2+ signaling

The cellular mechanisms of autism spectrum disorder (ASD) are poorly understood. Cumulative evidence suggests that abnormal synapse function underlies many features of this disease. Astrocytes regulate several key neuronal processes, including the formation of synapses and the modulation of synaptic plasticity. Astrocyte abnormalities have also been identified in the postmortem brain tissue of ASD individuals. However, it remains unclear whether astrocyte pathology plays a mechanistic role in ASD, as opposed to a compensatory response. To address this, we combined stem cell culturing with transplantation techniques to determine disease-specific properties inherent to ASD astrocytes. We demonstrate that ASD astrocytes induce repetitive behavior as well as impair memory and long-term potentiation when transplanted into the healthy mouse brain. These in vivo phenotypes were accompanied by reduced neuronal network activity and spine density caused by ASD astrocytes in hippocampal neurons in vitro. Transplanted ASD astrocytes also exhibit exaggerated Ca²⁺ fluctuations in chimeric brains. Genetic modulation of evoked Ca²⁺ responses in ASD astrocytes modulates behavior and neuronal activity deficits. Thus, this study determines that astrocytes derived from ASD iPSCs are sufficient to induce repetitive behavior as well as cognitive deficit, suggesting a previously unrecognized primary role for astrocytes in ASD.

The relationship between social and academic outcomes and anxiety for children and adolescents on the autism spectrum: A systematic review

Anxiety is the most common co-occurring condition in children on the autism spectrum but the potential impacts of anxiety on social and academic outcomes of children on the autism spectrum have not been systematically examined. In this review, 50 studies were identified that explore the relationship between anxiety and scores on social or academic measures in children on the autism spectrum. Social competence was frequently measured, and the findings of these studies were mixed. While other social constructs have received little attention, associations were found between anxiety and victimisation, and anxiety and social relationships. Only three studies focused on the impact of anxiety on scores on academic measures, highlighting the need for further research in this area. Anxiety was most frequently measured using subscales from broader behavioural instruments, which may not capture the range of anxiety symptoms of children on the autism spectrum. Future studies that include multi-informant methodologies and proportional representation of females and children with intellectual disability will further knowledge of the impact of anxiety in children on the spectrum.

Research Review: The relationship between social anxiety and social cognition in children and adolescents: a systematic review and meta-analysis

BACKGROUND

Childhood Social Anxiety Disorder (SAD) is common and impairing. The recommended treatment is a disorder specific form of cognitive behavioural therapy (CBT) that includes social skills training and, whilst they appear to be more effective than more general treatments, it is not clear whether social skills training is the critical component involved in improved outcomes, particularly given that evidence for the relationship between social anxiety and social skills deficits in children is inconsistent. This may be partly due to an overlap in their observable features, and because the nature of the association may vary in different contexts (e.g. according to child age). An alternative approach is to examine the association between social anxiety and the social cognitive capacities that underpin social skills. This paper aims to examine the association between social anxiety and social cognition in children and adolescents, and examine conceptual and methodological moderators of this relationship.

METHODS

Papers published between 1980 and 2019 were screened systematically. Fifty studies were identified from which an effect size could be calculated for the relationship between social anxiety and social cognition, including 15,411 children and adolescents.

RESULTS

An overall significant, but moderate effect (r = -.15) was identified, where increased social anxiety was associated with lower social cognitive ability. Moderation analyses revealed specific associations within studies examining social anxiety among participants with and without ASD who were older than 7 years old, and studies assessing the relationship between social anxiety and specific aspects of Theory of Mind (ToM). No significant association was identified between social anxiety and emotion recognition.

CONCLUSIONS

Significant associations between social anxiety and social cognitive abilities appear to be accounted for by elevated social anxiety among children with ASD, and those with difficulties in specific aspects of ToM but not broader social skills, such as emotion recognition. This reinforces the importance of accurately identifying and treating social anxiety within ASD populations. In addition, treatments for social anxiety among neurotypical populations may benefit from targeting particular aspects of ToM rather than emotion recognition and other broad social skills.

Is autonomic function during resting-state atypical in Autism: A systematic review of evidence

BACKGROUND

Theories of differences in resting-state arousal in autistic individuals are influential. Differences in arousal during resting-state would impact engagement and adaptation to the environment, having a cascading effect on development of attentional and social skills.

OBJECTIVES

We systematically evaluated the evidence for differences in measures of autonomic arousal (heart rate, pupillometry or electrodermal activity) during resting-state in autistic individuals; to understand whether certain contextual or methodological factors impact reports of such differences.

DATA SOURCES

We searched PsycInfo, MEDLINE and EMBASE databases for papers published until 16th May 2019. Of 1207 titles initially identified, 60 met inclusion criteria.

RESULTS AND CONCLUSIONS

Of the 51 studies that investigated group differences between neurotypical and autistic participants, 60.8 % found evidence of group differences. While findings of hyperarousal were more common, particularly using indices of parasympathetic function, findings of hypo-arousal and autonomic dysregulation were also consistently present. Importantly, experimental context played a role in revealing such differences. The evidence is discussed with regard to important methodological factors and implications for future research are described.

Where does fear originate in the brain? A coordinate-based meta-analysis of explicit and implicit fear processing

Processing of fear is of crucial importance for human survival and it can generally occur at explicit and implicit conditions. It is worth noting that explicit and implicit fear processing produces different behavioral and neurophysiological outcomes. The present study capitalizes on the Activation Likelihood Estimation (ALE) method of meta-analysis to identify: (a) the "core" network of fear processing in healthy individuals; (b) common and specific neural activations associated with explicit and implicit processing of fear. Following PRISMA guidelines, a total of 92 fMRI and PET studies were included in the meta-analysis. The overall analysis show that the core fear network comprises the amygdala, pulvinar, and fronto-occipital regions. Both implicit and explicit fear processing activated amygdala, declive, fusiform gyrus, and middle frontal gyrus, suggesting that these two types of fear processing share a common neural substrate. Explicit fear processing elicited more activations at the pulvinar and parahippocampal gyrus, suggesting visual attention/orientation and contextual association play important roles during explicit fear processing. In contrast, implicit fear processing elicited more activations at the cerebellum-amygdala-cortical pathway, indicating an 'alarm' system underlying implicit fear processing. These findings have shed light on the neural mechanism underlying fear processing at different levels of awareness.

How are attention, learning, and social cognition related on the non-clinical autistic spectrum?

Autism spectrum disorder (ASD) - and autistic traits more generally - are associated with a heterogeneous pattern of differences in cognitive function. These include differences in associative learning, attention, and processing of social information. All three cognitive functions have importance in clinical, educational, and research contexts. The present study investigates the relationships between these functions in the context of autistic traits in the neurotypical population. In an online study, we asked a group of over 400 people to complete the Autism Spectrum Quotient questionnaire. We also asked participants to complete one of two standard attentional learning paradigms - either a Kamin blocking or an attentional highlighting task. To investigate the relation of attention and learning to social information processing, we incorporated social cues in one of each kind of paradigm. We found Kamin blocking increased with increasing number of autistic traits, in particular the sub-trait attention switching, but only for non-social cues. We found that highlighting decreased with increasing number of traits, in particular the sub-trait communication, but only for social cues. We interpret these findings as evidence of a crucial role for attention in other characteristics of the broader autistic phenotype, and discuss the relevance of these results for cognitive explanations of autistic traits and symptoms.

Enhanced social learning of threat in adults with autism

Background

Recent theories have linked autism to challenges in prediction learning and social cognition. It is unknown, however, how autism affects learning about threats from others “demonstrators” through observation, which contains predictive learning based on social information. The aims of this study are therefore to investigate social fear learning in individual with autism spectrum disorder (ASD) and to examine whether typically developing social cognition is necessary for successful observational learning.

Methods

Adults with ASD (n = 23) and neurotypical controls (n = 25) completed a social fear learning (SFL) procedure in which participants watched a “demonstrator” receiving electrical shocks in conjunction with a previously neutral conditioned stimulus (CS+), but never with a safe control stimulus (CS−). Skin conductance was used to measure autonomic responses of learned threat responses to the CS+ versus CS−. Visual attention was measured during learning using eye tracking. To establish a non-social learning baseline, each participant also underwent a test of Pavlovian conditioning.

Results

During learning, individuals with ASD attended less to the demonstrator’s face, and when later tested, displayed stronger observational, but not Pavlovian, autonomic indices of learning (skin conductance) compared to controls. In controls, both higher levels of attention to the demonstrator’s face and trait empathy predicted diminished expressions of learning during test.

Limitations

The relatively small sample size of this study and the typical IQ range of the ASD group limit the generalizability of our findings to individuals with ASD in the average intellectual ability range.

Conclusions

The enhanced social threat learning in individuals with ASD may be linked to difficulties using visual attention and mental state attributions to downregulate their emotion.

Investigating the Subcortical Route to the Amygdala Across Species and in Disordered Fear Responses

Over the past few decades, evidence has come to light that there is a rapid subcortical shortcut that transmits visual information to the amygdala, effectively bypassing the visual cortex. This pathway purportedly runs from the superior colliculus to the amygdala via the pulvinar, and thus presents a methodological challenge to study noninvasively in the human brain. Here, we present our recent work where we reliably reconstructed the white matter structure and directional flow of neural signal along this pathway in over 600 healthy young adults. Critically, we found structure-function relationships for the pulvinar-amygdala connection, where people with greater fibre density had stronger functional neural coupling and were also better at recognising fearful facial expressions. These results tie together recent anatomical evidence from other visual primates with very recent optogenetic research on rodents demonstrating a functional role of this pathway in producing fear responses. Here, we discuss how this pathway might operate alongside other thalamo-cortical circuits (such as pulvinar to middle temporal area) and how its structure and function may change according to the sensory input it receives. This newly established circuit might play a potentially important role in autism and/or anxiety disorders.

Strengthening risk prediction using statistical learning in children with autism spectrum disorder

Purpose

The purpose of this paper is to investigate the prediction ability in children with ASD in the risk-involving situations and compute the impact of statistical learning (SL) in strengthening their risk knowledge. The learning index and stability with time are also calculated by comparing their performance over three consecutive weekly sessions (session 1, session 2 and session 3).

Design/methodology/approach

Participants were presented with a series of images, showing simple and complex risk-involving situations, using the psychophysical experimental paradigm. The stimuli in the experiment were provided with different levels of difficulty in order to keep the legacy of the prediction and SL-based experiment intact.

Findings

The first phase of experimental work showed that children with ASD accurately discriminated the risk, although performed poorly as compared to neurotypical. The attenuated response in differentiating risk levels indicates that children with ASD have a poor and underdeveloped sense of risk. The second phase investigated their capability to extract the information from repetitive patterns and calculated SL stability value in time. The learning curve shows that SL is intact and stable with time (average session r=0.74) in children with ASD.

Research limitations/implications

The present work concludes that impaired action prediction could possibly be one of the factors underlying underdeveloped sense of risk in children with ASD. Their SL capability shows that risk knowledge can be strengthened in them. In future, the studies should investigate the impact of age and individual differences, by using knowledge from repetitive trials, on the learning rate and trajectories.

Practical implications

SL, being an integral part of different therapies, rehabilitation schemes and intervention systems, has the potential to enhance the cognitive and functional abilities of children with ASD.

Originality/value

Past studies have provided evidence regarding the work on the prediction ability in individuals with ASD. However, it is unclear whether the risk-involving/dangerous situations play any certain role to enhance the prediction ability in children with ASD. Also, there are limited studies predicting risk knowledge in them. Based on this, the current work has investigated the risk prediction in children with ASD.

The Autism-Related Protein PX-RICS Mediates GABAergic Synaptic Plasticity in Hippocampal Neurons and Emotional Learning in Mice

GABAergic dysfunction underlies many neurodevelopmental and psychiatric disorders. GABAergic synapses exhibit several forms of plasticity at both pre- and postsynaptic levels. NMDA receptor (NMDAR)–dependent inhibitory long-term potentiation (iLTP) at GABAergic postsynapses requires an increase in surface GABA_ARs through promoted exocytosis; however, the regulatory mechanisms and the neuropathological significance remain unclear. Here we report that the autism-related protein PX-RICS is involved in GABA_AR transport driven during NMDAR–dependent GABAergic iLTP. Chemically induced iLTP elicited a rapid increase in surface GABA_ARs in wild-type mouse hippocampal neurons, but not in PX-RICS/RICS–deficient neurons. This increase in surface GABA_ARs required the PX-RICS/GABARAP/14–3-3 complex, as revealed by gene knockdown and rescue studies. iLTP induced CaMKII–dependent phosphorylation of PX-RICS to promote PX-RICS–14-3-3 assembly. Notably, PX-RICS/RICS–deficient mice showed impaired amygdala–dependent fear learning, which was ameliorated by potentiating GABAergic activity with clonazepam. Our results suggest that PX-RICS–mediated GABA_AR trafficking is a key target for GABAergic plasticity and its dysfunction leads to atypical emotional processing underlying autism.

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The autism-related protein PX-RICS is involved in promoted GABA_AR transport during chemically induced iLTP.

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PX-RICS/RICS-null mice show impaired amygdala–dependent fear learning, which is alleviated by enhancing GABAergic activity.

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PX-RICS is a key target for GABAergic plasticity and its dysfunction causes atypical emotional processing underlying autism.

PX-RICS facilitates constitutive transport of GABA_ARs in neurons. PX-RICS deficiency leads to autistic-like social behaviors in mice and in patients with Jacobsen syndrome. Rare single-nucleotide variations in PX-RICS are linked to non-syndromic autism, schizophrenia and alexithymia. These findings strongly suggest that PX-RICS dysfunction impairs socio-emotional processing of the brain. Here we show that PX-RICS is also involved in activity–dependent GABA_AR transport for GABAergic synaptic plasticity, and its dysfunction results in impaired emotional learning associated with the amygdale. Elucidation of the molecular link between GABAergic plasticity and socio-emotional learning could lead to a better understanding of autism pathogenesis and treatment.

Psychophysiological and Behavioral Responses to a Novel Intruder Threat Task for Children on the Autism Spectrum

We measured skin conductance response (SCR) to escalating levels of a direct social threat from a novel, ecologically-relevant experimental paradigm, the Intruder Threat Task. We simultaneously evaluated the contribution of social symptom severity and behavioral movement. Children with AS group showed less psychophysiological reactivity to social threat than controls across all three phases of the experiment. In the AS group, greater social impairment was significantly associated with reduced SCR. However, movement activity predicted SCR while diagnosis did not. Research and treatment need to account for the complex interplay of emotional reactivity and social behavior in AS. Psychophysiology studies of AS should consider the impact of possible confounds such as movement.

Autistic Traits and Symptoms of Social Anxiety are Differentially Related to Attention to Others' Eyes in Social Anxiety Disorder

Autism spectrum disorder (ASD) and social anxiety disorder (SAD) have partly overlapping symptoms. Gaze avoidance has been linked to both SAD and ASD, but little is known about differences in social attention between the two conditions. We studied eye movements in a group of treatment-seeking adolescents with SAD (N = 25), assessing SAD and ASD dimensionally. The results indicated a double dissociation between two measures of social attention and the two symptom dimensions. Controlling for social anxiety, elevated autistic traits were associated with delayed orienting to eyes presented among distractors. In contrast, elevated social anxiety levels were associated with faster orienting away from the eyes, when controlling for autistic traits. This distinction deepens our understanding of ASD and SAD.

Reinforcement Learning in Autism Spectrum Disorder

Early behavioral interventions are recognized as integral to standard care in autism spectrum disorder (ASD), and often focus on reinforcing desired behaviors (e.g., eye contact) and reducing the presence of atypical behaviors (e.g., echoing others' phrases). However, efficacy of these programs is mixed. Reinforcement learning relies on neurocircuitry that has been reported to be atypical in ASD: prefrontal-sub-cortical circuits, amygdala, brainstem, and cerebellum. Thus, early behavioral interventions rely on neurocircuitry that may function atypically in at least a subset of individuals with ASD. Recent work has investigated physiological, behavioral, and neural responses to reinforcers to uncover differences in motivation and learning in ASD. We will synthesize this work to identify promising avenues for future research that ultimately can be used to enhance the efficacy of early intervention.

Severity of Autism Spectrum Disorders: Current Conceptualization, and Transition to DSM-5

Mirroring the evolution of the conceptualization of autism has been changes in the diagnostic process, including the most recent revisions to the DSM-5 and the addition of severity-based diagnostic modifiers assigned on the basis of intensity of needed supports. A review of recent literature indicates that in research stratifying individuals on the basis of autism severity, core ASD symptomology is the primary consideration. This conceptualization is disparate from the conceptualization put forth in DSM-5 in which severity determination is based on level of needed support, which is also impacted by cognitive, language, behavioral, and adaptive functioning. This paper reviews literature in this area and discusses possible instruments that may be useful to inform clinical judgment in determining ASD severity levels.

Atypical Amygdala Response to Fear Conditioning in Autism Spectrum Disorder

BACKGROUND

Anxiety is the most common comorbid psychiatric concern in individuals diagnosed with autism spectrum disorder (ASD) and can cause significant functional impairment. Fear conditioning tasks offer a useful neurodevelopmental model for anxiety, yet there are no published neuroimaging studies of fear conditioning using ASD samples.

METHODS

Twenty adults diagnosed with ASD and 19 healthy adult control subjects completed a standard fear conditioning and extinction paradigm while undergoing functional magnetic resonance imaging scanning. A burst of air on the base of the neck was the unconditioned stimulus. Participants returned 1 day later for scanning during an extinction recall phase. A priori regions of interest were analyzed with a familywise error correction rate < 0.05.

RESULTS

All regions of interest demonstrated significantly greater response to threat than safe conditions during initial fear acquisition. Compared with age-matched control subjects, the ASD group showed a significantly decreased differential response to threat versus safe cues in right amygdala during the initial fear acquisition phase and decreased response in left amygdala during the first run of extinction recall on the second day of scanning.

CONCLUSIONS

Symptoms of severe anxiety in ASD may arise from atypical neural mechanisms especially related to the differentiation of threat versus safe cues. An inability to effectively identify safety contexts may underlie chronically increased levels of anxiety in many individuals diagnosed with ASD.

From Autism to Eating Disorders and More: The Role of Oxytocin in Neuropsychiatric Disorders

Oxytocin (oxy) is a pituitary neuropeptide hormone synthesized from the paraventricular and supraoptic nuclei within the hypothalamus. Like other neuropeptides, oxy can modulate a wide range of neurotransmitter and neuromodulator activities. Additionally, through the neurohypophysis, oxy is secreted into the systemic circulation to act as a hormone, thereby influencing several body functions. Oxy plays a pivotal role in parturition, milk let-down and maternal behavior and has been demonstrated to be important in the formation of pair bonding between mother and infants as well as in mating pairs. Furthermore, oxy has been proven to play a key role in the regulation of several behaviors associated with neuropsychiatric disorders, including social interactions, social memory response to social stimuli, decision-making in the context of social interactions, feeding behavior, emotional reactivity, etc. An increasing body of evidence suggests that deregulations of the oxytocinergic system might be involved in the pathophysiology of certain neuropsychiatric disorders such as autism, eating disorders, schizophrenia, mood, and anxiety disorders. The potential use of oxy in these mental health disorders is attracting growing interest since numerous beneficial properties are ascribed to this neuropeptide. The present manuscript will review the existing findings on the role played by oxy in a variety of distinct physiological and behavioral functions (Figure 1) and on its role and impact in different psychiatric disorders. The aim of this review is to highlight the need of further investigations on this target that might contribute to the development of novel more efficacious therapies. Figure 1

Are ASD and ADHD a Continuum? A Comparison of Pathophysiological Similarities Between the Disorders

OBJECTIVE

The objective of this study was to review and compare the similarities between autism spectrum disorder (ASD) and ADHD with regard to symptomatology, neurological deficits, metabolic and endocrine-related conditions, and brain pathology.

METHOD

A comprehensive review of the relevant research literature was carried out.

RESULTS

A number of important similarities between ASD and ADHD were identified, including recent increases in prevalence, male-biased incidence, shared involvement of sensory processing, motor and impulse control, abnormal patterns of neural connectivity, and sleep disturbances. Studies suggest involvement of androgen metabolism, impaired methylation, and heavy metal toxicity as possible contributing factors for both disorders.

CONCLUSION

ASD and ADHD share a number of features and pathophysiological conditions, which suggests that the two disorders may be a continuum and have a common origin.

An update on anxiety in youth with autism spectrum disorders

PURPOSE OF REVIEW

Anxiety is one of the most common co-occurring psychiatric conditions in youth with autism spectrum disorders (ASDs). This article reviews recent evidence as well as earlier relevant studies regarding the characteristics, assessment, and treatment of anxiety in youth with ASD.

RECENT FINDINGS

It is well established that the prevalence of anxiety in youth with an ASD is significantly greater than the prevalence of anxiety in the general population. Recent studies have highlighted the importance of informant, method, and instrument when measuring anxiety in this population. Despite the high prevalence, findings to date have been unable to identify any consistent risk factors for anxiety. New psychological treatments, including modified cognitive behavioral therapy for youth with high functioning ASD and co-occurring anxiety, are emerging. Pharmacological data, however, are scant. Existing studies show that youth with ASD are at increased risk for behavioral activation when taking SSRIs.

SUMMARY

Clinicians working with youth with ASD are encouraged to routinely screen for anxiety. Until further data are available, clinical judgment is needed when prescribing treatments, particularly selective serotonin reuptake inhibitors, which require close monitoring of side-effects. Research on risk factors, pathophysiology, and treatment of this condition is needed.

Abnormal emotional learning in a rat model of autism exposed to valproic acid in utero

Autism Spectrum Disorders (ASD) are complex neurodevelopmental disorders characterized by repetitive behavior and impaired social communication and interactions. Apart from these core symptoms, a significant number of ASD individuals display higher levels of anxiety and some ASD individuals exhibit impaired emotional learning. We therefore sought to further examine anxiety and emotional learning in an environmentally induced animal model of ASD that utilizes the administration of the known teratogen, valproic acid (VPA) during gestation. Specifically we exposed dams to one of two different doses of VPA (500 and 600 mg/kg) or vehicle on day 12.5 of gestation and examined the resultant progeny. Our data indicate that animals exposed to VPA in utero exhibit enhanced anxiety in the open field test and normal object recognition memory compared to control animals. Animals exposed to 500 mg/kg of VPA displayed normal acquisition of auditory fear conditioning, and exhibited reduced extinction of fear memory and normal litter survival rates as compared to control animals. We observed that animals exposed to 600 mg/kg of VPA exhibited a significant reduction in the acquisition of fear conditioning, a significant reduction in social interaction and a significant reduction in litter survival rates as compared to control animals. VPA (600 mg/kg) exposed animals exhibited similar shock sensitivity and hearing as compared to control animals indicating the fear conditioning deficit observed in these animals was not likely due to sensory deficits, but rather due to deficits in learning or memory retrieval. In conclusion, considering that progeny from dams exposed to rather similar doses of VPA exhibit striking differences in emotional learning, the VPA model may serve as a useful tool to explore the molecular and cellular mechanisms that contribute to not only ASD, but also emotional learning.

Long-term exposure to intranasal oxytocin in a mouse autism model

Oxytocin (OT) is a neuropeptide involved in mammalian social behavior. It is currently in clinical trials for the treatment of autism spectrum disorder (ASD). Previous studies in healthy rodents (prairie voles and C57BL/6J mice) have shown that there may be detrimental effects of long-term intranasal administration, raising the questions about safety and efficacy. To investigate the effects of OT on the aspects of ASD phenotype, we conducted the first study of chronic intranasal OT in a well-validated mouse model of autism, the BTBR T+ Itpr3tf/J inbred strain (BTBR), which displays low sociability and high repetitive behaviors. BTBR and C57BL/6J (B6) mice (N=94) were administered 0.8  IU/kg of OT intranasally, daily for 30 days, starting on day 21. We ran a well-characterized set of behavioral tasks relevant to diagnostic and associated symptoms of autism, including juvenile reciprocal social interactions, three-chambered social approach, open-field exploratory activity, repetitive self-grooming and fear-conditioned learning and memory, some during and some post treatment. Intranasal OT did not improve autism-relevant behaviors in BTBR, except for female sniffing in the three-chambered social interaction test. Male saline-treated BTBR mice showed increased interest in a novel mouse, both in chamber time and sniffing time, whereas OT-treated male BTBR mice showed a preference for the novel mouse in sniffing time only. No deleterious effects of OT were detected in either B6 or BTBR mice, except possibly for the lack of a preference for the novel mouse's chamber in OT-treated male BTBR mice. These results highlight the complexity inherent in understanding the effects of OT on behavior. Future investigations of chronic intranasal OT should include a wider dose range and early developmental time points in both healthy rodents and ASD models to affirm the efficacy and safety of OT.

Pten haploinsufficient mice show broad brain overgrowth but selective impairments in autism-relevant behavioral tests

Accelerated head and brain growth (macrocephaly) during development is a replicated biological finding in a subset of individuals with autism spectrum disorder (ASD). However, the relationship between brain overgrowth and the behavioral and cognitive symptoms of ASD is poorly understood. The PI3K-Akt-mTOR pathway regulates cellular growth; several genes encoding negative regulators of this pathway are ASD risk factors, including PTEN. Mutations in PTEN have been reported in individuals with ASD and macrocephaly. We report that brain overgrowth is widespread in Pten germline haploinsufficient (Pten(+/-)) mice, reflecting Pten mRNA expression in the developing brain. We then ask if broad brain overgrowth translates into general or specific effects on the development of behavior and cognition by testing Pten(+/-) mice using assays relevant to ASD and comorbidities. Deficits in social behavior were observed in both sexes. Males also showed abnormalities related to repetitive behavior and mood/anxiety. Females exhibited circadian activity and emotional learning phenotypes. Widespread brain overgrowth together with selective behavioral impairments in Pten(+/-) mice raises the possibility that most brain areas and constituent cell types adapt to an altered trajectory of growth with minimal impact on the behaviors tested in our battery; however, select areas/cell types relevant to social behavior are more vulnerable or less adaptable, thus resulting in social deficits. Probing dopaminergic neurons as a candidate vulnerable cell type, we found social behavioral impairments in mice with Pten conditionally inactivated in dopaminergic neurons that are consistent with the possibility that desynchronized growth in key cell types may contribute to ASD endophenotypes.

The amygdala and the relevance detection theory of autism: an evolutionary perspective

In the last few decades there has been increasing interest in the role of the amygdala in psychiatric disorders and, in particular, in its contribution to the socio-emotional impairments in autism spectrum disorders (ASDs). Given that the amygdala is a component structure of the "social brain," several theoretical explanations compatible with amygdala dysfunction have been proposed to account for socio-emotional impairments in ASDs, including abnormal eye contact, gaze monitoring, face processing, mental state understanding, and empathy. Nevertheless, many theoretical accounts, based on the Amygdala Theory of Autism, fail to elucidate the complex pattern of impairments observed in this population, which extends beyond the social domain. As posited by the Relevance Detector theory (Sander et al., 2003), the human amygdala is a critical component of a brain circuit involved in the appraisal of self-relevant events that include, but are not restricted to, social stimuli. Here, we propose that the behavioral and social-emotional features of ASDs may be better understood in terms of a disruption in a "Relevance Detector Network" affecting the processing of stimuli that are relevant for the organism's self-regulating functions. In the present review, we will first summarize the main literature supporting the involvement of the amygdala in socio-emotional disturbances in ASDs. Next, we will present a revised version of the Amygdala Relevance Detector hypothesis and we will show that this theoretical framework can provide a better understanding of the heterogeneity of the impairments and symptomatology of ASDs. Finally, we will discuss some predictions of our model, and suggest new directions in the investigation of the role of the amygdala within the more generally disrupted cortical connectivity framework as a model of neural organization of the autistic brain.

A potentiated startle study of uncertainty and contextual anxiety in adolescents diagnosed with autism spectrum disorder

Background

Beyond the core symptoms of autism spectrum disorder (ASD), associated symptoms of anxiety can cause substantial impairment for individuals affected by ASD and those who care for them.

Methods

We utilized a potentiated startle paradigm with a puff of air to the neck as the unconditioned stimulus in order to investigate differences between response to cued fear and contextual anxiety among cognitively able adolescents diagnosed with ASD and an age- and IQ-matched typically developing group.

Results

In a threat-modulated startle paradigm, response patterns to neutral, predictable, and unpredictable conditions were comparable across typically developing and ASD youth in terms of startle response magnitude and latency. However, the ASD group showed significantly greater absolute startle responsivity at baseline and throughout the experiment, suggesting possibly enhanced general sensitivity to threatening contexts. The ASD group, but not the control group, demonstrated moderate to strong negative correlations between psychophysiological response to unpredictable threats (uncertainty) and questionnaire measures of generalized anxiety, intolerance of uncertainty, and repetitive behavior.

Conclusions

Our data suggest enhanced general reactivity among the ASD group, possibly reflecting greater sensitivity to the threatening context of the startle paradigm. Associations with the response to uncertainty may help explain shared neurobehavioral mechanisms in ASD and anxiety. This task can provide useful targets for future neuroimaging and genetics studies as well as specific avenues for intervention. We emphasize the importance of further basic and clinical research into links among these important constructs.

Cued and contextual fear conditioning in BTBR mice is improved with training or atomoxetine

The BTBR T+tf/J (BTBR) strain of mice is a model for autism spectrum disorders (ASDs). These mice display reduced social behavior, altered communication, and high levels of repetitive behavior. BTBR mice have shown a deficit in learning cued and contextual fear conditioning. In this study, experiments were conducted to determine if either changes in training or drug administration would improve learning in BTBR mice when compared to C57BL/6 (B6) mice in contextual and cued fear conditioning. The first experiment examined the effects of three conditioned stimulus-unconditioned stimulus (CS-US) training paradigms; a 1P (1 CS-US pairing), 4P (4 CS-US pairings), and 10P (10 CS-US pairings). Increasing the number of CS-US pairings to 10 caused an increase in freezing behavior by the BTBR mice in contextual and cued conditioning indicating that more training facilitated BTBR learning. B6 mice had a more complex reaction to the increased training; the mice increased freezing behavior in the cued fear conditioning but not contextual fear conditioning. The second experiment determined whether atomoxetine, a noradrenergic reuptake inhibitor that has been shown to improve attention and decrease hyperactivity, impulsivity, and social withdrawal, would enhance learning. There was a significant increase in freezing behavior in contextual fear conditioning following atomoxetine administration in BTBR mice but not in B6 mice. Our data demonstrates that contextual and cued learning in BTBR mice is facilitated by increased training. Furthermore, contextual learning is improved in BTBR mice with use of atomoxetine, which helps to improve attention. Both increased training and pharmacological intervention improved learning in the BTBR mice suggesting a role for the combination of the two.

Deletion of glutamate delta-1 receptor in mouse leads to enhanced working memory and deficit in fear conditioning

Glutamate delta-1 (GluD1) receptors are expressed throughout the forebrain during development with high levels in the hippocampus during adulthood. We have recently shown that deletion of GluD1 receptor results in aberrant emotional and social behaviors such as hyperaggression and depression-like behaviors and social interaction deficits. Additionally, abnormal expression of synaptic proteins was observed in amygdala and prefrontal cortex of GluD1 knockout mice (GluD1 KO). However the role of GluD1 in learning and memory paradigms remains unknown. In the present study we evaluated GluD1 KO in learning and memory tests. In the eight-arm radial maze GluD1 KO mice committed fewer working memory errors compared to wildtype mice but had normal reference memory. Enhanced working memory in GluD1 KO was also evident by greater percent alternation in the spontaneous Y-maze test. No difference was observed in object recognition memory in the GluD1 KO mice. In the Morris water maze test GluD1 KO mice showed no difference in acquisition but had longer latency to find the platform in the reversal learning task. GluD1 KO mice showed a deficit in contextual and cue fear conditioning but had normal latent inhibition. The deficit in contextual fear conditioning was reversed by D-Cycloserine (DCS) treatment. GluD1 KO mice were also found to be more sensitive to foot-shock compared to wildtype. We further studied molecular changes in the hippocampus, where we found lower levels of GluA1, GluA2 and GluK2 subunits while a contrasting higher level of GluN2B in GluD1 KO. Additionally, we found higher postsynaptic density protein 95 (PSD95) and lower glutamate decarboxylase 67 (GAD67) expression in GluD1 KO. We propose that GluD1 is crucial for normal functioning of synapses and absence of GluD1 leads to specific abnormalities in learning and memory. These findings provide novel insights into the role of GluD1 receptors in the central nervous system.

The Interplay between Emotion and Cognition in Autism Spectrum Disorder: Implications for Developmental Theory

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that is clinically defined by abnormalities in reciprocal social and communicative behaviors and an inflexible adherence to routinised patterns of thought and behavior. Laboratory studies repeatedly demonstrate that autistic individuals experience difficulties in recognizing and understanding the emotional expressions of others and naturalistic observations show that they use such expressions infrequently and inappropriately to regulate social exchanges. Dominant theories attribute this facet of the ASD phenotype to abnormalities in a social brain network that mediates social-motivational and social-cognitive processes such as face processing, mental state understanding, and empathy. Such theories imply that only emotion related processes relevant to social cognition are compromised in ASD but accumulating evidence suggests that the disorder may be characterized by more widespread anomalies in the domain of emotions. In this review I summarize the relevant literature and argue that the social-emotional characteristics of ASD may be better understood in terms of a disruption in the domain-general interplay between emotion and cognition. More specifically I will suggest that ASD is the developmental consequence of early emerging anomalies in how emotional responses to the environment modulate a wide range of cognitive processes including those that are relevant to navigating the social world.

Role of metabotropic glutamate receptor 7 in autism spectrum disorders: a pilot study

AIMS

The presence of genetic variants for autism spectrum disorders (ASDs) was investigated for the metabotropic glutamate receptor 7 (GRM7) gene in a case-control study.

MAIN METHODS

Employing Affymetrix SNP microarrays, 297 single nucleotide polymorphisms (SNPs) covering the GRM7 gene were selected and analyzed in ASD patients (n=22), non-ASD patients [n=14, including seven patients with development delay (DD)/mental retardation (MR), four patients with language delay (LD), and three patients with attention deficit hyperactivity disorder (ADHD)] and normal control subjects (n=18).

KEY FINDINGS

Twenty-one statistically significant SNPs with different inheritance models (recessive, dominant and allele) were demonstrated in three groups (ASDs vs. combined controls, ASDs vs. normal controls, ASDs vs. non-ASD patients). Associations of rs779867 and rs6782011 with ASDs were significant in all three groups and independent associations of rs779867 and rs6782011 with ASDs were found in the ASD vs. combined controls group, which are in modest linkage disequilibrium (D'>0.5). Further haplotype analysis showed that rs6782011/rs779867 (T-C) was statistically significantly related to ASDs in both the ASD vs. combined controls and ASD vs. normal controls groups (bootstrap P value=0.013, permutation P value=0.013 for the former group and bootstrap P value=0.002, permutation P value=0.020 for the latter).

SIGNIFICANCE

These findings support a role for genetic variants within the GRM7 gene in 3p26.1 in ASDs.

Prenatal exposure to valproic acid enhances synaptic plasticity in the medial prefrontal cortex and fear memories

The prefrontal cortex has been extensively implicated in autism to explain deficits in executive and other higher brain functions related to cognition, language, sociability and emotion. Hyper-connectivity and hyper-plasticity at the level of the neuronal microcircuit in the medial prefrontal cortex (mPFC) in the valproic acid (VPA) animal model of autism has been suggested. However, the possible alterations at the system levels are not well understood. The present study investigated the basal synaptic transmission and synaptic plasticity in the mPFC in vivo in the VPA rat model of autism. Furthermore, short-term and long-term retention of fear memories were also examined. The findings displayed that paired-pulse facilitation (PPF) and long-term potentiation (LTP), representing short- and long-term synaptic plasticity, were enhanced by the prenatal exposure to VPA. In addition, the short- and long-term fear memories were enhanced. These results suggest that enhanced synaptic plasticity in the mPFC and fear memories might be one of the mechanisms underlying some symptoms of autism.