Cognitive inflexibility in Japanese adolescents and adults with autism spectrum disorders

Adolescent treadmill exercise enhances hippocampal brain-derived neurotrophic factor (BDNF) expression and improves cognition in autism-modeled rats

Autism spectrum disorder (ASD) is a prevalent neurodevelopmental disorder characterized by repetitive behaviors and altered communication abilities. Exercise is a low-cost intervention that could improve cognitive function and improve brain plasticity mechanisms. Here, the valproic acid (VPA) model was utilized to induce ASD-like phenotypes in rodents. Animals were exercised on a treadmill and performance was evaluated on a cognitive flexibility task. Biomarkers related to exercise and plasticity regulation were quantified from the prefrontal cortex, hippocampus, and skeletal muscle. Exercised VPA animals had higher levels of hippocampal BDNF compared to sedentary VPA animals and upregulated antioxidant enzyme expression in skeletal muscle. Cognitive improvements were demonstrated in both sexes, but in different domains of cognitive flexibility. This research demonstrates the benefits of exercise and provides evidence that molecular responses to exercise occur in both the central nervous system and in the periphery. These results suggest that improving regulation of BDNF via exercise, even at low intensity, could provide better synaptic regulation and cognitive benefits for individuals with ASD.

Aerobic Exercise Improves Cognitive Flexibility and Modulates Regional Volume Changes in a Rat Model of Autism

Gestational exposure to valproic acid (VPA) is a risk factor for autism spectrum disorder (ASD). Rodents exposed to VPA in utero display common features of ASD, including volumetric dysregulation in higher-order cognitive regions like the medial prefrontal cortex (mPFC), the anterior cingulate cortex (ACC), and the hippocampus. Exercise has been shown in elderly populations to boost cognition and to buffer against brain volume losses with age. This study employed an adolescent treadmill exercise intervention to facilitate cognitive flexibility and regional brain volume regulation in rats exposed to VPA during gestation. It was found that exercise improved performance on extra-dimensional shifts of attention on a set-shifting task, which is indicative of improved cognitive flexibility. Exercise decreased frontal cortex volume in females, whereas in males exercise increased the ventral hippocampus. These findings suggest that aerobic exercise may be an effective intervention to counteract the altered development of prefrontal and hippocampal regions often observed in ASD.

Comparison of Mathematics Problem-Solving Abilities in Autistic and Non-autistic Children: the Influence of Cognitive Profile

This study examines relationships between mathematical problem-solving performance (in terms of strategies used and accuracy) and the main cognitive domains associated with mathematical learning (i.e. executive functions, verbal comprehension and social perception) of children with and without autism spectrum disorder (ASD and non-ASD resp.). The study involved 26 ASD and 26 non-ASD children without intellectual disabilities, between 6 and 12 years old, matched by sex, age and school (grade and classroom). The results show a higher percentage of ASD children with problem solving difficulties than non-ASD (57% vs. 23% resp.). Poor performing ASD children showed comparatively lower scores in inhibition, theory of mind and verbal comprehension. Implications for the design of mathematical interventions for ASD students are discussed.

Differences between subclinical attention-deficit/hyperactivity and autistic traits in default mode, salience, and frontoparietal network connectivities in young adult Japanese

Attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are associated with attentional impairments, with both commonalities and differences in the nature of their attention deficits. This study aimed to investigate the neural correlates of ADHD and ASD traits in healthy individuals, focusing on the functional connectivity (FC) of attention-related large-scale brain networks (LSBNs). The participants were 61 healthy individuals (30 men; age, 21.9 ± 1.9 years). The Adult ADHD Self-Report Scale (ASRS) and Autism Spectrum Quotient (AQ) were administered as indicators of ADHD and ASD traits, respectively. Performance in the continuous performance test (CPT) was used as a behavioural measure of sustained attentional function. Functional magnetic resonance imaging scans were performed during the resting state (Rest) and auditory oddball task (Odd). Considering the critical role in attention processing, we focused our analyses on the default mode (DMN), frontoparietal (FPN), and salience (SN) networks. Region of interest (ROI)-to-ROI analyses (false discovery rate < 0.05) were performed to determine relationships between psychological measures with within-network FC (DMN, FPN, and SN) as well as with between-network FC (DMN-FPN, DMN-SN, and FPN-SN). ASRS scores, but not AQ scores, were correlated with less frequent commission errors and shorter reaction times in the CPT. During Odd, significant positive correlations with ASRS were demonstrated in multiple FCs within DMN, while significant positive correlations with AQ were demonstrated in multiple FCs within FPN. AQs were negatively correlated with FPN-SN FCs. During Rest, AQs were negatively and positively correlated with one FC within the SN and multiple FCs between the DMN and SN, respectively. These findings of the ROI-to-ROI analysis were only partially replicated in a split-half replication analysis, a replication analysis with open-access data sets, and a replication analysis with a structure-based atlas. The better CPT performance by individuals with subclinical ADHD traits suggests positive effects of these traits on sustained attention. Differential associations between LSBN FCs and ASD/ADHD traits corroborate the notion of differences in sustained and selective attention between clinical ADHD and ASD.

Measuring flexibility in autistic adults: Exploring the factor structure of the flexibility scale self report

Cognitive flexibility differences are common for autistic individuals and have an impact on a range of clinical outcomes. However, there is currently a lack of well validated measurement tools to assess flexibility in adulthood. The Flexibility Scale was originally designed as a parent-report measure of real-world flexibility challenges in youth. The original Flexibility Scale provides a total score and five subscales: Routines and Rituals, Transitions and Change, Special Interests, Social Flexibility, and Generativity. In this study, we evaluate the factorial validity of the Flexibility Scale as a self-report (Flexibility Scale Self Report) measure of cognitive flexibility, adapted from the original Flexibility Scale, for use by autistic adults. This study includes both a primary sample (n = 813; mean age = 40.3; 59% female) and an independently recruited replication sample (n = 120; mean age = 32.8; 74% female) of individuals who completed the Flexibility Scale Self Report. The analysis consisted of an initial confirmatory factor analysis (CFA) of the original Flexibility Scale structure, followed by exploratory factor analysis (EFA) and factor optimization within a structural equation modeling framework to identify the optimal structure for the questionnaire in adults. The identified structure was then replicated through CFA in the replication sample. Our results indicate an alternative optimal scale structure from the original Flexibility Scale, which includes fewer items, and only three (Routines/Rituals, Transitions and Change, Special Interests) of the five subscales contributing to the flexibility total score. Comparisons revealed no structural differences within the scale based on sex assigned at birth. Here the Generativity and Social Flexibility scales are treated as independent but related scales. The implications for measurement of cognitive flexibility in clinical and research settings, as well as theoretical underpinnings are discussed.

Computer-Based Assessment and Self-Report Measures of Executive Functions in High-Functioning Adults with Autism

This study analyzes the profile of executive functions (EF) in high-functioning adults with autism (HFA), both in terms of performance on four computer-based tasks, as well as how these functions are perceived by the individuals through self-reporting measures. The study included 64 participants: 32 individuals with HFA, and 32 typically developing controls. Four CANTAB tasks were used (assessing spatial working memory, planning, visual memory, and inhibition), as well as a self-reported measure of executive functions (BDEFS) and a scale for the severity of autism symptoms (RAADS-R). The participants in the ASD group performed significantly lower than the control group on all four computer-based tasks, as measured by the total number of errors made (for the spatial working memory, visual memory, and inhibition tasks) and the number of problems solved at the first choice (for the planning task). No correlation was found in the ASD group between the severity of autism symptoms and the computer-based measures. These findings provide evidence that HFA adults may have various executive functioning impairments, and subsequent daily life problems, but these deficits do not necessarily correlate with the severity of core ASD symptoms.

Atypically slow processing of faces and non-faces in older autistic adults

Face recognition is a fundamental function that requires holistic processing. Differences in face processing have been consistently identified in autistic children, but it is unknown whether these differences persist across the adult lifespan. Using event-related functional magnetic resonance imaging, we measured holistic face processing with a rapid Mooney faces task in 50 autistic and 49 non-autistic participants (30–74 years). Behavioral tasks included a self-paced version of the same paradigm and a global–local processing task (Navon). Reduced detection rates for faces, but not non-faces, were found in autistic adults, including slower responses on all conditions. Without time constraints, differences in accuracy disappeared between groups, although reaction times in correctly identifying faces remained higher in autistic adults. The functional magnetic resonance imaging results showed lower activation in the left and right superior frontal gyrus in the autism group but no age-related differences. Overall, our findings point toward slower information processing speed rather than a face recognition deficit in autistic adults. This suggests that face-processing differences are not a core feature of autism across the adult lifespan.

Autism, autistic traits and creativity: a systematic review and meta-analysis

Psychometric, historiometric and psychiatric studies are controversial on a hypothetical link between psychopathology and creativity. In this study, we will try to contribute to this debate by analysing the case of autism. Is there a relationship between autism and creativity? If so, can we find the same relationship in a watered-down form in subjects with autistic traits? In order to answer these questions, we carried out a systematic literature review of the studies on this topic published in the last 10 years. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We also conducted a meta-analysis of data. We found that in the clinical population there are fewer creative performances than in control groups; nonetheless, it is possible to delineate a medium creative profile of subjects with autism. The average creative profile of people with autism shows that they are inhibited in fluency and flexibility, but that they display a high level of detail and a particularly high level of originality in works either generated during tests or created in private time. In particular, the level of detail reached in the latter condition seems to be higher in the autistic population than in the control groups. Better linguistic skills appear to be linked to better creative performances. Linguistic tests, if compared with visual and performative tests, seem to favour the expression of originality in subjects with autism. Although our data on autistic traits are compatible with the hypothesis that a high level of autistic traits is a watered-down replica of the cognitive profile of subjects with autism, we have no sufficient data to support this hypothesis.

Frontoparietal Network in Executive Functioning in Autism Spectrum Disorder

Higher cognitive functions in autism spectrum disorder (ASD) are characterized by impairments in executive functions (EF). While some research attributes this to an overreliance of the prefrontal cortex (PFC), others demonstrate poor recruitment of the PFC in individuals with ASD. In order to assess the emerging consensus across neuroimaging studies of EF in ASD, the current study used a coordinate-based activation likelihood estimation (ALE) analysis of 16 functional magnetic resonance imaging (fMRI) studies, resulting in a meta-analysis of data from 739 participants (356 ASD, 383 typically developing [TD] individuals) ranging from 7 to 52 years of age. Within-group analysis of EF tasks revealed that both TD and ASD participants had significant activity in PFC regions. Analysis of group differences indicated greater activation in ASD, relative to TD participants, in the right middle frontal gyrus and the anterior cingulate cortex, and lesser activation in the bilateral middle frontal, left inferior frontal gyrus, right inferior parietal lobule, and precuneus. Although both ASD and TD participants showed similar PFC activation, there was differential recruitment of wider network of EF regions such as the IPL in ASD participants. The under-recruitment of parietal regions may be due to poor connectivity of the frontoparietal networks with other regions during EF tasks or a restricted executive network in ASD participants which is limited primarily to the PFC. These results support the executive dysfunction hypothesis of ASD and suggests that poor frontoparietal recruitment may underlie some of the EF difficulties individuals with ASD experience. LAY SUMMARY: This study reports a meta-analysis of 16 brain imaging studies of executive functions (EF) in individuals with autism spectrum disorder (ASD). While parts of the brain's EF network is activated in both ASD and control participants, the ASD group does not activate a wider network of EF regions such as the parietal cortex. This may be due to poor EF network connectivity, or a constrained EF network in ASD participants. These results may underlie some of the EF difficulties individuals with ASD experience. Autism Res 2020, 13: 1762-1777. © 2020 International Society for Autism Research and Wiley Periodicals LLC.

Resting-state abnormalities of posterior cingulate in autism spectrum disorder

The posterior cingulate cortex (PCC) plays pivotal roles in cognitive, social and emotional processing, as well as early neural development that supports complex interactions among different neural networks. Alterations in its local and long-range connectivity during resting state are often implicated in neuropathology of neurodevelopmental disorders such as autism spectrum disorder (ASD). ASD is characterized by social and communication deficits, as well as restricted and repetitive behaviors and interests. Individuals with ASD demonstrate persistent disturbances in cognitive and social-emotional functioning, and their PCC exhibits both local and long-range resting state abnormalities compared to typically developing healthy controls. In terms of regional metrics, only the dorsal part of the PCC showed local underconnectivity. As to long-range connectivity measures, the most replicated finding in ASD studies is the reduced functional coupling between the PCC and medial prefrontal cortex (MPFC), which may represent a core neuropathology of ASD unrelated to medication effects. Functional importance of these resting state abnormalities to ASD and directions of future study are discussed at the end of this chapter.

Children with autism spectrum disorder comorbid with attention-deficit/hyperactivity disorder examined by the Wisconsin card sorting test: Analysis by age-related differences

The DSM-5 confirmed that autism spectrum disorder (ASD) might be comorbid with attention-deficit/hyperactivity disorder (ADHD). This study investigated the executive function of ASD comorbid with ADHD (ASD + ADHD), ASD, and typically developed (TD) children using the Keio version of the modified Wisconsin card sorting test (KWCST). Children with ASD + ADHD (n = 43), ASD (n = 69), and TD (n = 69) were examined in two age groups: 5-9 years and 10-15 years. Both of the younger clinical groups showed significantly unfavorable scores for many indices in the second step compared to the TD group. As for the older groups, the ASD children showed significantly unfavorable scores in total errors in the second step, while the ASD + ADHD children did not show significant differences in either step. However, some index scores of the two older clinical groups were comparable to the older TD group in the second step. For the cognitive differences between clinical groups, the younger ASD + ADHD showed unfavorable scores in numbers of response cards until the first category achieved in the second step, while the older ASD showed unfavorable scores in categories achieved and perseverative errors of Nelson in the first step. For the degree of improvements in the second step, the older groups did not show significant group differences, while the younger ASD group showed significantly fewer improvements compared to the TD group. Based on these results, it is presumed that younger ASD + ADHD individuals are not sufficiently able to sustain attention and/or memory, and that the older ASD patients have difficulty in terms of flexibility.

A Meta-Analysis of Relationships between Measures of Wisconsin Card Sorting and Intelligence

The Wisconsin Card Sorting Test (WCST) represents a widely utilized neuropsychological assessment technique for executive function. This meta-analysis examined the discriminant validity of the WCST for the assessment of mental shifting, considered as an essential subcomponent of executive functioning, against traditional psychometric intelligence tests. A systematic search was conducted, resulting in 72 neuropsychological samples for the meta-analysis of relationships between WCST scores and a variety of intelligence quotient (IQ) domains. The study revealed low to medium-sized correlations with IQ domains across all WCST scores that could be investigated. Verbal/crystallized IQ and performance/fluid IQ were indistinguishably associated with WCST scores. To conclude, the WCST assesses cognitive functions that might be partially separable from common conceptualizations of intelligence. More vigorous initiatives to validate putative indicators of executive function against intelligence are required.

Inflexibility in Autism Spectrum Disorder: Need for certainty and atypical emotion processing share the blame

Although ASD (Autism Spectrum Disorder) diagnosis requires the co-occurrence of socio-emotional deficits and inflexible behaviors, the interaction between these two domains remains unexplored. We used an emotional Wisconsin Card Sorting Test adapted to fMRI to explore this question. ASD and control participants matched a central card (a face) with one of four surrounding cards according to one of three rules: frame color, facial identity or expression. Feedback informed participants on whether to change or maintain the current sorting rule. For each rule, we modeled feedback onsets to change, switch (confirming the newly found rule) and maintenance events. "Bias error", which measures participants' willingness to switch, was larger in ASD participants for the emotional sorting rule. Brain activity to change events showed no group differences. In response to switch events significantly larger activity was observed for ASD participants in bilateral Inferior Parietal Sulci. Inflexibility in ASD appears characterized by the unwillingness to switch toward processing socio-emotional information, rather than a major disruption in cognitive flexibility. However, a larger activity to switch events in ASD highlights the need for a higher level of certainty before setting into a stable processing stage, which may be particularly detrimental in the highly changeable socio-emotional environment.

Clinical considerations for the inclusion of individuals with autism spectrum disorder in clinical trials

Diagnoses of autism spectrum disorder (ASD) have increased considerably over the past 20 years. Because of this rise and the inherent complexity of ASD, there is a need for an increased number of scientifically valid basic and clinical research studies addressing this disorder. This manuscript serves as an introduction to the clinical presentation of ASD as well as the unique challenges and modifications required to conduct clinical research with this population. This includes detailing the current diagnostic criteria, process of receiving an ASD diagnosis, information on assessment measures, and special considerations when developing research. It is the hope that this information will provide researchers interested in conducting clinical trials with those with ASD with baseline information and considerations when developing their research topics and methodology.

Increased psychiatric symptoms in university students with autism spectrum disorder are associated with reduced adaptive behavior

High variability in adaptive behavior in cognitively-able adults with autism spectrum disorder has been previously reported, and may be caused by the high prevalence of psychiatric comorbidity in this population. This study's goals were to examine self-reported psychiatric symptoms in students with ASD, and to identify their relative contribution to the variance in adaptive behaviors. The study population included 95 students: 55 diagnosed with ASD (4 females; age range 18-34) who participated in a university integration program (ASD group), and 40 regularly matriculated students (non-ASD group, 7 females; age range 20-36). The ASD group showed a lower adaptive skill level than the non-ASD group as measured by the Adaptive Behavior Assessment System (GAC-ABAS). Significantly higher scores for the ASD group were found for social anxiety, trait anxiety, obsessive-compulsive symptoms, and depression symptoms. The level of adaptive skills correlated negatively and significantly with the severity of social anxiety symptoms in both groups and with severity of obsessive-compulsive symptoms only in the ASD group. Additionally, in a regression model, significant contributions of having an ASD diagnosis and severity of social anxiety explained 41.7% of the variance in adaptive skills. Adequate evaluation and treatment, if needed, are recommended in this population.

Subtyping cognitive profiles in Autism Spectrum Disorder using a Functional Random Forest algorithm

DSM-5 Autism Spectrum Disorder (ASD) comprises a set of neurodevelopmental disorders characterized by deficits in social communication and interaction and repetitive behaviors or restricted interests, and may both affect and be affected by multiple cognitive mechanisms. This study attempts to identify and characterize cognitive subtypes within the ASD population using our Functional Random Forest (FRF) machine learning classification model. This model trained a traditional random forest model on measures from seven tasks that reflect multiple levels of information processing. 47 ASD diagnosed and 58 typically developing (TD) children between the ages of 9 and 13 participated in this study. Our RF model was 72.7% accurate, with 80.7% specificity and 63.1% sensitivity. Using the random forest model, the FRF then measures the proximity of each subject to every other subject, generating a distance matrix between participants. This matrix is then used in a community detection algorithm to identify subgroups within the ASD and TD groups, and revealed 3 ASD and 4 TD putative subgroups with unique behavioral profiles. We then examined differences in functional brain systems between diagnostic groups and putative subgroups using resting-state functional connectivity magnetic resonance imaging (rsfcMRI). Chi-square tests revealed a significantly greater number of between group differences (p < .05) within the cingulo-opercular, visual, and default systems as well as differences in inter-system connections in the somato-motor, dorsal attention, and subcortical systems. Many of these differences were primarily driven by specific subgroups suggesting that our method could potentially parse the variation in brain mechanisms affected by ASD.

Frontal theta activation during motor synchronization in autism

Autism is characterized by two primary characteristics: deficits in social interaction and repetitive behavioral patterns. Because interpersonal communication is extremely complicated, its underlying brain mechanisms remain unclear. Here we showed that both characteristics can be explained by a unifying underlying mechanism related to difficulties with irregularities. To address the issues, we measured electroencephalographm during a cooperative tapping task, which required participants to tap a key alternately and synchronously with constant rhythmic a PC program, a variable rhythmic PC program, or a human partner. We found that people with autism had great difficulty synchronizing tapping behavior with others, and exhibited greater than normal theta-wave (6 Hz) activity in the frontal cortex during the task, especially when their partner behaved somewhat irregularly (i.e. a variable rhythmic PC program or a human partner). Importantly, the higher theta-wave activity was related to the severity of autism, not the performance on the task. This indicates that people with autism need to use intense cognition when trying to adapt to irregular behavior and can easily become overtaxed. Difficulty adapting to irregular behavior in others is likely related to their own tendencies for repetitive and regular behaviors. Thus, while the two characteristics of autism have been comprehended separately, our unifying theory makes understanding the condition and developing therapeutic strategies more tractable.

Problem-solving styles in autism spectrum disorder and the development of higher cognitive functions

The Vygotsky Blocks Test assesses problem-solving styles within a theoretical framework for the development of higher mental processes devised by Vygotsky. Because both the theory and the associated test situate cognitive development within the child's social and linguistic context, they address conceptual issues around the developmental relation between language and thought that are pertinent to development in autism. Our aim was to document the performance of adults with autism spectrum disorder on the Vygotsky Blocks Test, and our results showed that they made more errors than the typically developing participants and that these errors correlated with performance IQ. The autism spectrum disorder group also required more cues than the typically developing group to discern the conceptual structure of the blocks, a pattern that correlated with Autism Diagnostic Observational Schedule-Communication and Imagination/Creativity sub-scales. When asked to categorize the blocks in new ways, the autism spectrum disorder participants developed fewer principles on which to base new categorizations, which in contrast to the typically developing group correlated with verbal IQ and with the Imagination/Creativity sub-scale of the ADOS. These results are in line with a number of existing findings in the autism spectrum disorder literature and confirm that conceptualization in autism spectrum disorder seems to rely more on non-verbal and less on imaginative processes than in typically developing individuals. The findings represent first steps to the possibility of outlining a testable account of psychological development in autism spectrum disorder that integrates verbal, non-verbal and social factors into the transition from elementary to higher level processes.

Associations of acute and chronic stress hormones with cognitive functions in autism spectrum disorder

Extensive studies have reported cognitive abnormalities in neurodevelopmental disorders, such as autism spectrum disorder (ASD). Another line of evidence suggests that stress also affects cognitive functions. In this study, we investigated whether there were associations between stress hormones and cognitive functions in ASD and typically developing (TD) children. Cognitive functions in ASD and TD children were evaluated with a battery of psychological tests for working memory, behavioral flexibility, and social cognition for emotional assessments of others. ASD children exhibited higher hair and salivary cortisol, which reflects chronic and acute stress hormone levels of subjects, respectively, than TD children. Autism-spectrum quotient (AQ) was positively correlated with hair cortisol and the scores of Spence Children's Anxiety Scale in ASD children. In addition, a negative correlation was present between spatial working memory performance and hair cortisol in ASD, but not in TD, children. These results suggest that chronic stress hormone elevation may have relationships with some aspects of cognitive dysfunction in ASD subjects.

The set-shifting profiles of anorexia nervosa and autism spectrum disorder using the Wisconsin Card Sorting Test: a systematic review and meta-analysis

Difficulties in set-shifting are commonly reported in both autism spectrum disorder (ASD) and anorexia nervosa (AN) populations. Despite this, it is not known whether this cognitive profile persists across different ages, or whether the profiles seen in ASD and AN are comparable. This systematic review and meta-analyses aimed to compare the set-shifting profiles, as measured by the Wisconsin Card Sorting Test (WCST) in adults and younger people with either ASD or AN, relative to healthy controls (HCs) and to statistically compare performance on the WCST between ASD and AN. In all, 24 studies on ASD and 22 studies on AN were identified. In ASD, there were significant differences between the clinical group and HCs, with the ASD group making significantly more perseverative errors, indicating greater difficulty in set-shifting [pooled effect size of d = 0.67, 95% confidence interval (CI) 0.53-0.81, p ⩽ 0.001]. This effect was consistent across the age span. For AN studies, there was a significant difference between adults with AN and HCs (d = 0.52, 95% CI 0.36-0.68, p ⩽ 0.001) but a non-significant effect in child studies (d = 0.25, 95% CI -0.05 to 0.55, z = 1.66, p = 0.096). Meta-regression indicated no effect of diagnosis (AN or ASD) on performance in adult studies but there was a non-significant trend (p = 0.053) towards children with ASD performing worse than children with AN. While difficulties with set-shifting appear to be stable in ASD, there may be differences between children and adults with AN, which warrant further investigation.

Deletion of CTNNB1 in inhibitory circuitry contributes to autism-associated behavioral defects

Mutations in β-catenin (CTNNB1) have been implicated in cancer and mental disorders. Recently, loss-of-function mutations of CTNNB1 were linked to intellectual disability (ID), and rare mutations were identified in patients with autism spectrum disorder (ASD). As a key regulator of the canonical Wnt pathway, CTNNB1 plays an essential role in neurodevelopment. However, the function of CTNNB1 in specific neuronal subtypes is unclear. To understand how CTNNB1 deficiency contributes to ASD, we generated CTNNB1 conditional knockout (cKO) mice in parvalbumin interneurons. The cKO mice had increased anxiety, but had no overall change in motor function. Interestingly, CTNNB1 cKO in PV-interneurons significantly impaired object recognition and social interactions and elevated repetitive behaviors, which mimic the core symptoms of patients with ASD. Surprisingly, deleting CTNNB1 in parvalbumin-interneurons enhanced spatial memory. To determine the effect of CTNNB1 KO in overall neuronal activity, we found that c-Fos was significantly reduced in the cortex, but not in the dentate gyrus and the amygdala. Our findings revealed a cell type-specific role of CTNNB1 gene in regulation of cognitive and autistic-like behaviors. Thus, this study has important implications for development of therapies for ASDs carrying the CTNNB1 mutation or other ASDs that are associated with mutations in the Wnt pathway. In addition, our study contributes to a broader understanding of the regulation of the inhibitory circuitry.

Executive function is affected in autism spectrum disorder, but does not correlate with intelligence

INTRODUCTION

Studies of executive function in autism spectrum disorder without intellectual disability (ASD-WID) patients are contradictory. We assessed a wide range of executive functioning cognitive domains in a sample of children and adolescents with ASD-WID and compared them with age-, sex-, and intelligence quotient (IQ)-matched healthy controls.

METHODS

Twenty-four ASD-WID patients (mean age 12.8±2.5 years; 23 males; mean IQ 99.20±18.81) and 32 healthy controls (mean age 12.9±2.7 years; 30 males; mean IQ 106.81±11.02) were recruited.

RESULTS

Statistically significant differences were found in all cognitive domains assessed, with better performance by the healthy control group: attention (U=185.0; P=.0005; D=0.90), working memory (T51.48=2.597; P=.006; D=0.72), mental flexibility (U=236.0; P=.007; D=0.67), inhibitory control (U=210.0; P=.002; D=0.71), and problem solving (U=261.0; P=0.021; D=0.62). These statistically significant differences were also found after controlling for IQ.

CONCLUSION

Children and adolescents with ASD-WID have difficulties transforming and mentally manipulating verbal information, longer response latency, attention problems (difficulty set shifting), trouble with automatic response inhibition and problem solving, despite having normal IQ. Considering the low executive functioning profile found in those patients, we recommend a comprehensive intervention including work on non-social problems related to executive cognitive difficulties.

Synaptic P-Rex1 signaling regulates hippocampal long-term depression and autism-like social behavior

Autism spectrum disorders (ASDs) are a group of highly inheritable mental disorders associated with synaptic dysfunction, but the underlying cellular and molecular mechanisms remain to be clarified. Here we report that autism in Chinese Han population is associated with genetic variations and copy number deletion of P-Rex1 (phosphatidylinositol-3,4,5-trisphosphate-dependent Rac exchange factor 1). Genetic deletion or knockdown of P-Rex1 in the CA1 region of the hippocampus in mice resulted in autism-like social behavior that was specifically linked to the defect of long-term depression (LTD) in the CA1 region through alteration of AMPA receptor endocytosis mediated by the postsynaptic PP1α (protein phosphase 1α)-P-Rex1-Rac1 (Ras-related C3 botulinum toxin substrate 1) signaling pathway. Rescue of the LTD in the CA1 region markedly alleviated autism-like social behavior. Together, our findings suggest a vital role of P-Rex1 signaling in CA1 LTD that is critical for social behavior and cognitive function and offer new insight into the etiology of ASDs.

Whole-exome sequencing and neurite outgrowth analysis in autism spectrum disorder

Autism spectrum disorder (ASD) is a complex group of clinically heterogeneous neurodevelopmental disorders with unclear etiology and pathogenesis. Genetic studies have identified numerous candidate genetic variants, including de novo mutated ASD-associated genes; however, the function of these de novo mutated genes remains unclear despite extensive bioinformatics resources. Accordingly, it is not easy to assign priorities to numerous candidate ASD-associated genes for further biological analysis. Here we developed a convenient system for identifying an experimental evidence-based annotation of candidate ASD-associated genes. We performed trio-based whole-exome sequencing in 30 sporadic cases of ASD and identified 37 genes with de novo single-nucleotide variations (SNVs). Among them, 5 of those 37 genes, POGZ, PLEKHA4, PCNX, PRKD2 and HERC1, have been previously reported as genes with de novo SNVs in ASD; and consultation with in silico databases showed that only HERC1 might be involved in neural function. To examine whether the identified gene products are involved in neural functions, we performed small hairpin RNA-based assays using neuroblastoma cell lines to assess neurite development. Knockdown of 8 out of the 14 examined genes significantly decreased neurite development (P<0.05, one-way analysis of variance), which was significantly higher than the number expected from gene ontology databases (P=0.010, Fisher's exact test). Our screening system may be valuable for identifying the neural functions of candidate ASD-associated genes for further analysis and a substantial portion of these genes with de novo SNVs might have roles in neuronal systems, although further detailed analysis might eliminate false positive genes from identified candidate ASD genes.