Striatal transcriptome changes linked to drug-induced repetitive behaviors.

Disruptive or excessive repetitive motor patterns (stereotypies) are cardinal symptoms in numerous neuropsychiatric disorders. Stereotypies are also evoked by psychomotor stimulants such as amphetamine. The acquisition of motor sequences is paralleled by changes in activity patterns in the striatum, and stereotypies have been linked to abnormal plasticity in these reinforcement-related circuits. Here, we designed experiments in mice to identify transcriptomic changes that underlie striatal plasticity occurring alongside the development of drug-induced stereotypic behavior. We identified three schedules of amphetamine treatment inducing different degrees of stereotypy and used bulk RNAseq to compare striatal gene expression changes among groups of mice treated with the different drug-dose schedules and vehicle-treated, cage-mate controls. Mice were identified as naïve, sensitized, or tolerant to drug-induced stereotypy. All drug-treated groups exhibited expression changes in genes that encode members of the extracellular signal-regulated kinase (ERK) cascades known to regulate psychomotor stimulant responses. In the sensitized group with the most prolonged stereotypy, we found dysregulation of 20 genes that were not changed in other groups. Gene set enrichment analysis indicated highly significant overlap with genes regulated by neuregulin 1 (Nrg1). Nrg1 is known to be a schizophrenia and autism susceptibility gene that encodes a ligand for Erb-B receptors, which are involved in neuronal migration, myelination, and cell survival, including that of dopamine-containing neurons. Stimulant abuse is a risk factor for schizophrenia onset, and these two disorders share behavioral stereotypy phenotypes. Our results raise the possibility that drug-induced sensitization of the Nrg1 signaling pathway might underlie these links.

Pharmacotherapy of restricted/repetitive behavior in autism spectrum disorder:a systematic review and meta-analysis.

BACKGROUND: This paper is a systematic review and meta-analysis of the efficacy of available medications for the treatment of restricted/repetitive behavior (RRBs) in Autism Spectrum Disorder (ASD). METHOD: We searched MEDLINE, Embase, PsycINFO, The Cochrane Library (Cochrane Database of Systematic Reviews (CDRS), the Cochrane Central Register of Controlled Trials (CENTRAL), database of Abstracts of Reviews of Effects (DARE)), Scopus, Epistimonikos, Clinicaltrials.gov, and included all randomized controlled trials published after 1993 that were directed at RRBs in patients with ASD of all ages. We extracted the relevant data from the published studies with a predefined data extraction form and assessed the risk of bias. The primary outcomes were change in restricted/repetitive behavior. We performed a meta-analysis using the random effect model and included studies with given mean and standard deviation. This study is registered with PROSPERO number CRD42018092660). RESULTS: We identified 14 randomized controlled trials that met initial inclusion criteria. After closer inspection, nine trials - involving 552 patients in total - were included in the final analysis. The meta-analysis found no significant difference between medications (including fluvoxamine, risperidone, fluoxetine, citalopram, oxytocin, N-Acetylcysteine, buspirone) and placebo in the treatment of RRBs in ASD (P = 0.20). Similarly, the sub-group meta-analysis also showed no significant difference between Selective Serotonin Reuptake Inhibitor (SSRIs) and placebo in the treatment of RRBs in ASD (P = 0.68). There was no evidence of publication bias. CONCLUSION: This meta-analysis finds little support for the routine use of medications to treat restricted/repetitive behaviors in Autism Spectrum Disorder. Further research of large, balanced trials with precise assessment tools and long-term follow-up are needed. TRIAL REGISTRATION: The study protocol is registered in PROSPERO (Reference number: CRD42018092660).

Cortico-basal ganglia white matter microstructure is linked to restricted repetitive behavior in autism spectrum disorder.

BACKGROUND: Restricted repetitive behavior (RRB) is one of two behavioral domains required for the diagnosis of autism spectrum disorder (ASD). Neuroimaging is widely used to study brain alterations associated with ASD and the domain of social and communication deficits, but there has been less work regarding brain alterations linked to RRB. METHODS: We utilized neuroimaging data from the National Institute of Mental Health Data Archive to assess basal ganglia and cerebellum structure in a cohort of children and adolescents with ASD compared to typically developing (TD) controls. We evaluated regional gray matter volumes from T1-weighted anatomical scans and assessed diffusion-weighted scans to quantify white matter microstructure with free-water imaging. We also investigated the interaction of biological sex and ASD diagnosis on these measures, and their correlation with clinical scales of RRB. RESULTS: Individuals with ASD had significantly lower free-water corrected fractional anisotropy (FAT) and higher free-water (FW) in cortico-basal ganglia white matter tracts. These microstructural differences did not interact with biological sex. Moreover, both FAT and FW in basal ganglia white matter tracts significantly correlated with measures of RRB. In contrast, we found no significant difference in basal ganglia or cerebellar gray matter volumes. LIMITATIONS: The basal ganglia and cerebellar regions in this study were selected due to their hypothesized relevance to RRB. Differences between ASD and TD individuals that may occur outside the basal ganglia and cerebellum, and their potential relationship to RRB, were not evaluated. CONCLUSIONS: These new findings demonstrate that cortico-basal ganglia white matter microstructure is altered in ASD and linked to RRB. FW in cortico-basal ganglia and intra-basal ganglia white matter was more sensitive to group differences in ASD, whereas cortico-basal ganglia FAT was more closely linked to RRB. In contrast, basal ganglia and cerebellar volumes did not differ in ASD. There was no interaction between ASD diagnosis and sex-related differences in brain structure. Future diffusion imaging investigations in ASD may benefit from free-water estimation and correction in order to better understand how white matter is affected in ASD, and how such measures are linked to RRB.

Relations of Restricted and Repetitive Behaviors to Social Skills in Toddlers with Autism.

We examined the relations of restricted and repetitive behaviors (RRB; insistence on sameness, repetitive sensory-motor, self-injurious behavior) to social skills overall and aspects that comprise social skills as measured by the VABS-II (coping skills, play/leisure time, interpersonal relationships) in 24- (n = 63) and 36-month old (n = 35), high-familial-risk toddlers with ASD. Hierarchical linear regression results indicated that repetitive sensory-motor was the best predictor of social skills overall. Secondary results indicated that all three RRB subtypes were associated with each subdomain of social skills; however, repetitive sensory-motor was the strongest and most consistent among these effects. While our results suggests a general negative relation of subtypes of RRB to aspects of adaptive social function, repetitive sensory-motor behaviors may be of particular relevance to the development of social skills during toddlerhood.

The Role of Ion Channel-Related Genes in Autism Spectrum Disorder: A Study Using Next-Generation Sequencing.

The clinical heterogeneity of autism spectrum disorder (ASD) is closely associated with the diversity of genes related to ASD pathogenesis. With their low effect size, it has been hard to define the role of common variants of genes in ASD phenotype. In this study, we reviewed genetic results and clinical scores widely used for ASD diagnosis to investigate the role of genes in ASD phenotype considering their functions in molecular pathways. Genetic data from next-generation sequencing (NGS) were collected from 94 participants with ASD. We analyzed enrichment of cellular processes and gene ontology using the Database for Annotation, Visualization, and Integrated Discovery (DAVID). We compared clinical characteristics according to genetic functional characteristics. We found 266 genes containing nonsense, frame shift, missense, and splice site mutations. Results from DAVID revealed significant enrichment for "ion channel" with an enrichment score of 8.84. Moreover, ASD participants carrying mutations in ion channel-related genes showed higher total IQ (p = 0.013) and lower repetitive, restricted behavior (RRB)-related scores (p = 0.003) and mannerism subscale of social responsiveness scale scores, compared to other participants. Individuals with variants in ion channel genes showed lower RRB scores, suggesting that ion channel genes might be relatively less associated with RRB pathogenesis. These results contribute to understanding of the role of common variants in ASD and could be important in the development of precision medicine of ASD.

The Development, Reliability, and Validity of the Social Impact of Repetitive Behavior Scale in Children with Autism Spectrum Disorder.

Introduction: Current measures of restrictive and repetitive behavior (RRB) in people with autism focus on severity and intensity and, to some degree, the global interference of the behavior. In this study we developed the Social Impact of Repetitive Behavior Scale (SIRBS) to capture several different contexts in which repetitive behavior is likely to occur and interfere. Methods: SIRBS items were selected through reviewing the RRB literature, participant chart reviews, and consensus among authors, followed by an initial piloting and further refinement of the tool. Caregivers completed the SIRBS a total of 400 times. Results: Subscales showed high internal consistency and good test-retest reliability, moderate concurrent validity, and average to excellent inter-rater reliability. Conclusion: The SIRBS is a psychometrically reliable and valid measure of the social impact of repetitive behavior with children with autism. Additional research is needed to independently validate it and conduct an initial exploratory factor analysis of subscales.

A Comparison of Children Born Preterm and Full-Term on the Autism Spectrum in a Prospective Community Sample.

Introduction: Previous research suggests children diagnosed with autism spectrum disorder (ASD or "autism") born extremely and very preterm face substantially delayed development than their peers born full-term. Further, children born preterm are proposed to show a unique behavioral phenotype, which may overlap with characteristics of autism, making it difficult to disentangle their clinical presentation. To clarify the presentation of autism in children born preterm, this study examined differences in key indicators of child development (expressive language, receptive language, fine motor, and visual reception) and characteristics of autism (social affect and repetitive, restricted behaviors). Materials and Methods: One fifty-eight children (136 full-term, twenty-two preterm) diagnosed with autism, aged 22-34 months, were identified prospectively using the Social Attention and Communication Surveillance tools during community-based, developmental surveillance checks in the second year of life. Those identified at "high likelihood" of an autism diagnosis were administered the Mullen Scales of Early Learning and the Autism Diagnostic Observation Schedule. Results: The children born preterm and full-term did not differ significantly in their fine motor, visual reception, expressive language, or receptive language skills. No significant differences in social affect and repetitive and restrictive behavior traits were found. Discussion: The findings of this study differs from previous research where children diagnosed with autism born very or extremely preterm were developmentally delayed and had greater autistic traits than their term-born peers. These null findings may relate to the large proportion of children born moderate to late preterm in this sample. This study was unique in its use of a community-based, prospectively identified sample of children diagnosed with autism at an early age. It may be that children in these groups differ from clinic- and hospital-based samples, that potential differences emerge later in development, or that within the autism spectrum, children born preterm and full-term develop similarly. It was concluded that within the current sample, at 2 years of age, children diagnosed with autism born preterm are similar to their peers born full-term. Thus, when clinicians identify characteristics of autism in children born preterm, it is important to refer the child for a diagnostic assessment for autism.

Gender differences in restricted and repetitive behaviors and interests in youth with autism.

Previous work has found gender differences in restricted and repetitive behaviors and interests (RRBI) for autism spectrum disorder (ASD). Compared to girls, affected boys have increased stereotyped and restricted behaviors; however much less is known about gender differences in other areas of RRBI. This study aims to identify whether specific RRBI (i.e., stereotyped, self-injurious, compulsive, insistence on sameness, ritualistic, and restricted), as measured by item-level data on the Repetitive Behavior Scale-Revised (RBS-R), can distinguish girls from boys with ASD. Participants included 615 individuals with ASD (507 boys; 82.4%), ages 3-18 years of age (M = 10.26, SD = 4.20), who agreed to share data with the National Database for Autism Research (NDAR). Multivariate analysis of variance and discriminant function analysis (DFA) were used to determine whether item-level RBS-R data could correctly classify cases by gender. DFA results suggest that RBS-R items significantly differentiate gender. Strongly differentiating RBS-R items had greater success in correctly classifying affected boys (67.90%) than girls (61.00%). Items that best-discriminated gender were heightened stereotyped behaviors and restricted interests items in boys and compulsive, sameness, restricted, and self-injurious behavior items in girls. This study is the first to find that girls with ASD may have increased compulsive, sameness, and restricted RRBI compared to boys. Additionally, findings support heightened self-injurious behaviors in affected girls. Future research should disentangle whether elevated rates of RRBI in girls are central to the presentation of ASD in girls or an epiphenomenon of the high rates of co-occurring disorders (e.g., anxiety) noted in girls. Autism Res 2019, 12: 274-283 © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: This study is the first to examine a comprehensive measure of repetitive behavior in children with autism, with findings of increased compulsive, insistence on sameness, and self-injurious behavior characterizing girls and increased stereotyped and restricted behavior characterizing boys. Future research should determine whether these elevated behaviors in girls are directly part of the autism presentation in girls or symptoms of co-occurring psychopathology. It is important for autism diagnostic measures to best capture the types of repetitive behavior girls may demonstrate.

Visual Exploration in Autism Spectrum Disorder: Exploring Age Differences and Dynamic Features Using Recurrence Quantification Analysis.

Eye-tracking studies have demonstrated that individuals with autism spectrum disorder sometimes show differences in attention and gaze patterns. This includes preference for certain nonsocial objects, heightened attention to detail, and more difficulty with attention shifting and disengagement, which may be associated with restricted and repetitive behaviors. This study utilized a visual exploration task and replicates findings of reduced number of objects explored and increased fixation duration on high autism interest objects in a large sample of individuals with autism spectrum disorder (n = 129, age 6-54 years) in comparison with a typically developing group. These findings correlated with parent-reported repetitive behaviors. Additionally, we applied recurrent quantification analysis to enable identification of new eye-tracking features, which accounted for temporal and spatial differences in viewing patterns. These new features were found to discriminate between autism spectrum disorder and typically developing groups and were correlated with parent-reported repetitive behaviors. Original and novel eye-tracking features identified by recurrent quantification analysis differed in their relationships to reported behaviors and were dependent on age. Trial Registration: NCT02299700. Autism Research 2018, 11: 1554-1566. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Using eye-tracking technology and a visual exploration task, we showed that people with autism spectrum disorder (ASD) spend more time looking at particular kinds of objects, like trains and clocks, and look at fewer objects overall than people without ASD. Where people look and the order in which they look at objects were related to the restricted and repetitive behaviors reported by parents. Eye-tracking may be a useful addition to parent reports for measuring changes in behavior in individuals with ASD.

Decrease in endogenous brain allopregnanolone induces autism spectrum disorder (ASD)-like behavior in mice: A novel animal model of ASD.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with core symptoms of social impairments and restrictive repetitive behaviors. Recent evidence has implicated a dysfunction in the GABAergic system in the pathophysiology of ASD. We investigated the role of endogenous allopregnanolone (ALLO), a neurosteroidal positive allosteric modulator of GABAA receptors, in the regulation of ASD-like behavior in male mice using SKF105111 (SKF), an inhibitor of type I and type II 5α-reductase, a rate-limiting enzyme of ALLO biosynthesis. SKF impaired sociability-related performance, as analyzed by three different tests; i.e., the 3-chamber test and social interaction in the open field and resident-intruder tests, without affecting olfactory function elucidated by the buried food test. SKF also induced repetitive grooming behavior without affecting anxiety-like behavior. SKF had no effect on short-term spatial working memory or long-term fear memory, but enhanced latent learning ability in male mice. SKF-induced ASD-like behavior in male mice was abolished by the systemic administration of ALLO (1mg/kg, i.p.) and methylphenidate (MPH: 2.5mg/kg, i.p.), a dopamine transporter inhibitor. The effects of SKF on brain ALLO contents in male mice were reversed by ALLO, but not MPH. On the other hand, SKF failed to induce ASD-like behavior or a decline in brain ALLO contents in female mice. These results suggest that ALLO regulates episodes of ASD-like behavior by positively modulating the function of GABAA receptors linked to the dopaminergic system. Moreover, a sex-dependently induced decrease in brain ALLO contents may provide an animal model to study the main features of ASD.