Psychopharmacologic interventions for repetitive behaviors in autism spectrum disorders

Molecular Docking and Dynamics Simulation Studies Predict Potential Anti-ADAR2 Inhibitors: Implications for the Treatment of Cancer, Neurological, Immunological and Infectious Diseases

Altered RNA editing has been linked to several neurodevelopmental disorders, including autism spectrum disorder (ASD) and intellectual disability, in addition to depression, schizophrenia, some cancers, viral infections and autoimmune disorders. The human ADAR2 is a potential therapeutic target for managing these various disorders due to its crucial role in adenosine to inosine editing. This study applied consensus scoring to rank potential ADAR2 inhibitors after performing molecular docking with AutoDock Vina and Glide (Maestro), using a library of 35,161 compounds obtained from traditional Chinese medicine. A total of 47 compounds were predicted to be good binders of the human ADAR2 and had insignificant toxicity concerns. Molecular dynamics (MD) simulations, including the molecular mechanics Poisson–Boltzmann surface area (MM/PBSA) procedure, also emphasized the binding of the shortlisted compounds. The potential compounds had plausible binding free energies ranging from −81.304 to −1068.26 kJ/mol from the MM/PBSA calculations. ZINC000085511995, a naphthoquinone had more negative binding free energy (−1068.26 kJ/mol) than inositol hexakisphosphate (IHP) [−873.873 kJ/mol], an agonist and a strong binder of ADAR2. The potential displacement of IHP by ZINC000085511995 in the IHP binding site of ADAR2 could be explored for possible deactivation of ADAR2. Bayesian-based biological activity prediction corroborates the neuropharmacological, antineoplastic and antiviral activity of the potential lead compounds. All the potential lead compounds, except ZINC000014612330 and ZINC000013462928, were predicted to be inhibitors of various deaminases. The potential lead compounds also had probability of activity (Pa) > 0.442 and probability of inactivity (Pi) < 0.116 values for treating acute neurologic disorders, except for ZINC000085996580 and ZINC000013462928. Pursuing these compounds for their anti-ADAR2 activities holds a promising future, especially against neurological disorders, some cancers and viral infections caused by RNA viruses. Molecular interaction, hydrogen bond and per-residue decomposition analyses predicted Arg400, Arg401, Lys519, Trp687, Glu689, and Lys690 as hot-spot residues in the ADAR2 IHP binding site. Most of the top compounds were observed to have naphthoquinone, indole, furanocoumarin or benzofuran moieties. Serotonin and tryptophan, which are beneficial in digestive regulation, improving sleep cycle and mood, are indole derivatives. These chemical series may have the potential to treat neurological disorders, prion diseases, some cancers, specific viral infections, metabolic disorders and eating disorders through the disruption of ADAR2 pathways. A total of nine potential lead compounds were shortlisted as plausible modulators of ADAR2.

Role of Gut Microbiome in Autism Spectrum Disorder and Its Therapeutic Regulation

Autism spectrum disorder (ASD) is a neurological disorder that affects normal brain development. The recent finding of the microbiota–gut–brain axis indicates the bidirectional connection between our gut and brain, demonstrating that gut microbiota can influence many neurological disorders such as autism. Most autistic patients suffer from gastrointestinal (GI) symptoms. Many studies have shown that early colonization, mode of delivery, and antibiotic usage significantly affect the gut microbiome and the onset of autism. Microbial fermentation of plant-based fiber can produce different types of short-chain fatty acid (SCFA) that may have a beneficial or detrimental effect on the gut and neurological development of autistic patients. Several comprehensive studies of the gut microbiome and microbiota–gut–brain axis help to understand the mechanism that leads to the onset of neurological disorders and find possible treatments for autism. This review integrates the findings of recent years on the gut microbiota and ASD association, mainly focusing on the characterization of specific microbiota that leads to ASD and addressing potential therapeutic interventions to restore a healthy balance of gut microbiome composition that can treat autism-associated symptoms.

Fluoxetine exposure throughout neurodevelopment differentially influences basilar dendritic morphology in the motor and prefrontal cortices

The significance of serotonin (5HT) in mental health is underscored by the serotonergic action of many classes of psychiatric medication. 5HT is known to have a significant role in neurodevelopment, thus 5HT disruption during development may have a long term impact on brain structure and circuits. We previously generated a model of 5HT alteration throughout neurodevelopment by maternal administration of the selective serotonin reuptake inhibitor fluoxetine. We found resulting social behavior alterations in the offspring during both postnatal and adult ages. Previous work by others has indicated that early 5HT disruption influences neuronal morphology. Therefore, in the current study we sought to determine if dendritic morphological changes occur in areas involved in the social behavior deficits we previously observed, specifically the primary motor (M1) and medial prefrontal (mPFC) cortices. We quantified dendritic morphology of projection neurons in M1 and mPFC at postnatal day (P)10 and P79 in mice exposed to fluoxetine. Basilar dendritic complexity and spine density were persistently decreased in M1 fluoxetine-exposed neurons while in the mPFC, similar reductions were observed at P79 but were not present at P10. Our findings underscore that the developing brain, specifically the projection cortex, is vulnerable to 5HT system perturbation, which may be related to later behavioral disruptions.

Discovery of G Protein-Biased Ligands against 5-HT7R

There has been significant attention concerning the biased agonism of G protein-coupled receptors (GPCRs), and it has resulted in various pharmacological benefits. 5-HT₇R belongs to a GPCR, and it is a promising pharmaceutical target for the treatment of neurodevelopmental and neuropsychiatric disorders. Based on our previous research, we synthesized a series of 6-chloro-2'-methoxy biphenyl derivatives 1, 2, and 3 with a variety of amine scaffolds. These compounds were evaluated for their binding affinities to 5-HTR subtypes and their functional selectivity toward the Gs protein and the β-arrestin signaling pathways of 5-HT₇R. Among them, 2-(6-chloro-2'-methoxy-[1,1'-biphenyl]-3-yl)-N-ethylethan-1-amine, 2b, was found to be a G-protein-biased ligand of 5-HT₇R. In an in vivo study with Shank3 transgenic mice, the self-grooming behavior test was performed with 2b, which increased the duration of self-grooming. The experiments further suggested that 5-HT₇R is associated with autism spectrum disorders (ASDs) and could be a therapeutic target for the treatment of stereotypy in ASDs.

Behavioral Tests for Mouse Models of Autism: An Argument for the Inclusion of Cerebellum-Controlled Motor Behaviors

Mouse models of Autism Spectrum Disorder (ASD) have been interrogated using a variety of behavioral tests in order to understand the symptoms of ASD. However, the hallmark behaviors that are classically affected in ASD - deficits in social interaction and communication as well as the occurrence of repetitive behaviors - do not have direct murine equivalents. Thus, it is critical to identify the caveats that come with modeling a human disorder in mice. The most commonly used behavioral tests represent complex cognitive processes based on largely unknown brain circuitry. Motor impairments provide an alternative, scientifically rigorous approach to understanding ASD symptoms. Difficulties with motor coordination and learning - seen in both patients and mice - point to an involvement of the cerebellum in ASD pathology. This brain area supports types of motor learning that are conserved throughout vertebrate evolution, allowing for direct comparisons of functional abnormalities between humans with autism and ASD mouse models. Studying simple motor behaviors provides researchers with clearly interpretable results. We describe and evaluate methods used on mouse behavioral assays designed to test for social, communicative, perseverative, anxious, nociceptive, and motor learning abnormalities. We comment on the effectiveness and validity of each test based on how much information its results give, as well as its relevance to ASD, and will argue for an inclusion of cerebellum-supported motor behaviors in the phenotypic description of ASD mouse models. LAY SUMMARY: Mouse models of Autism Spectrum Disorder help us gain insight about ASD symptoms in human patients. However, there are many differences between mice and humans, which makes interpreting behaviors challenging. Here, we discuss a battery of behavioral tests for specific mouse behaviors to explore whether each test does indeed evaluate the intended measure, and whether these tests are useful in learning about ASD.

Effect of Fluoxetine on Obsessive-Compulsive Behaviors in Children and Adolescents With Autism Spectrum Disorders: A Randomized Clinical Trial

IMPORTANCE

Selective serotonin receptor inhibitors are prescribed to reduce the severity of core behaviors of autism spectrum disorders, but their efficacy remains uncertain.

OBJECTIVE

To determine the efficacy of fluoxetine for reducing the frequency and severity of obsessive-compulsive behaviors in autism spectrum disorders.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter, randomized, placebo-controlled clinical trial. Participants aged 7.5-18 years with autism spectrum disorders and a total score of 6 or higher on the Children's Yale-Brown Obsessive Compulsive Scale, modified for pervasive developmental disorder (CYBOCS-PDD) were recruited from 3 tertiary health centers across Australia. Enrollment began November 2010 and ended April 2017. Follow-up ended August 2017.

INTERVENTIONS

Participants were randomized to receive fluoxetine (n = 75) or placebo (n = 71). Study medication was commenced at 4 or 8 mg/d for the first week, depending on weight, and then titrated to a maximum dose of 20 or 30 mg/d over 4 weeks. Treatment duration was 16 weeks.

MAIN OUTCOMES AND MEASURES

The primary outcome was the total score on the CYBOCS-PDD (scores range from 0-20; higher scores indicate higher levels of maladaptive behaviors; minimal clinically important difference, 2 points) at 16 weeks postrandomization, analyzed with a linear regression model adjusted for stratification factors (site, age at baseline, and intellectual disability), with an additional prespecified model that included additional adjustment for baseline score, sex, communication level, and imbalanced baseline and demographic variables.

RESULTS

Among the 146 participants who were randomized (85% males; mean age, 11.2 years), 109 completed the trial; 31 in the fluoxetine group and 21 in the placebo group dropped out or did not complete treatment. The mean CYBOCS-PDD score from baseline to 16 weeks decreased in the fluoxetine group from 12.80 to 9.02 points (3.72-point decrease; 95% CI, -4.85 to -2.60) and in the placebo group from 13.13 to 10.89 points (2.53-point decrease; 95% CI, -3.86 to -1.19). The between-group mean difference at 16 weeks was -2.01 (95% CI, -3.77 to -0.25; P = .03) (adjusted for stratification factors), and in the prespecified model with further adjustment, it was -1.17 (95% CI, -3.01 to 0.67; P = .21).

CONCLUSIONS AND RELEVANCE

In this preliminary study of children and adolescents with autism spectrum disorders, treatment with fluoxetine compared with placebo resulted in significantly lower scores for obsessive-compulsive behaviors at 16 weeks. Interpretation is limited by the high dropout rate, null findings of prespecified analyses that accounted for potentially confounding factors and baseline imbalances, and CIs for the treatment effect that included the minimal clinically important difference.

TRIAL REGISTRATION

anzctr.org.au Identifier: ACTRN12608000173392.

Vortioxetine Reduces Marble Burying but Only Transiently Enhances Social Interaction Preference in Adult Male BTBR T+Itpr3tf/J Mice

Vortioxetine is a multimodal antidepressant with agonist activity at serotonin (5-HT)_1A and 5-HT_1B receptors that blocks the 5-HT transporter (SERT). Previously in male BTBR T⁺Itpr3^tf/J (BTBR) mice, the 5-HT_1A partial agonist buspirone and SERT blocker fluoxetine enhanced social interaction but did not reduce marble burying. We hypothesized that vortioxetine through its actions at SERT and 5-HT_1A could improve BTBR sociability and via 5-HT_1B could reduce burying better than sertraline, a selective SERT blocker. Vortioxetine (5-10 mg/kg) or sertraline (2 mg/kg) was administered 30 min presociability and 75 min prior to marble burying tests. Vortioxetine (10 mg/kg) occupancy (%) was 84 ± 1 for SERT, 31 ± 12 for 5-HT_1A, and 80 ± 5 for 5-HT_1B in brain at 110 min postinjection, and serum oxytocin was 24% lower (p < 0.01) in vortioxetine-treated mice. Vortioxetine reduced novel object investigation, whereas sertraline enhanced overall sociability. However, the vortioxetine-induced increase in social sniffing was transient, as it was lost with 60-120 min presociability test delays in subsequent experiments. Vortioxetine and sertraline both reduced BTBR marble burying. Based on vortioxetine occupancy, actions at SERT and/or 5-HT_1B are more likely to underlie its behavioral effects than 5-HT_1A. Overall, vortioxetine has great potential for suppressing restrictive-repetitive behaviors, but it appears less promising as a sociability enhancer.

Citalopram attenuates social behavior deficits in the BTBR T+Itpr3tf/J mouse model of autism

Autism spectrum disorder (ASD) is diagnosed by two core symptoms: impaired social communication and the presence of repetitive, stereotyped behaviors and/or restricted interests. Alterations in serotonergic signaling are involved in the genesis of ASD. Selective serotonin reuptake inhibitors (SSRIs) have been reported to reduce repetitive behaviors and rescue social deficits in ASD mouse models and patients. In the present study, we examined the potential of citalopram (a representative selective serotonin reuptake inhibitor) on sociability and repetitive behaviors in the BTBR T⁺Itpr3^tf/J (BTBR) mouse model of ASD. We found that the deficits of sociability in the BTBR mice were reversed by a 20 mg/kg dose of citalopram treatment without any adverse effects on locomotor activity or anxiety level. In addition, both high (20 mg/kg) and low (10 mg/kg) doses decreased the repetitive behavior of marble burying but did not affect self-grooming behavior. Furthermore, both doses were shown to have antidepressant-like activity in both the B6 and the BTBR mice in the tail suspension test. Taken together, these findings further demonstrate that citalopram can alleviate behavioral abnormalities in the BTBR autism model and lend support to the hypothesis that SSRIs may be potential therapeutic drugs for the treatment of behavioral dysfunctions in ASD.

Dissecting the roles of β-arrestin2 and GSK-3 signaling in 5-HT1BR-mediated perseverative behavior and prepulse inhibition deficits in mice

Serotonin-1B receptors (5-HT1BRs) modulate perseverative behaviors and prepulse inhibition (PPI) in humans and mice. These inhibitory G-protein-coupled receptors signal through a canonical G-protein-coupled pathway that is modulated by GSK-3β, and a noncanonical pathway mediated by the adaptor protein β-arrestin2 (Arrb2). Given the development of biased ligands that differentially affect canonical versus noncanonical signaling, we examined which signaling pathway mediates 5-HT1BR agonist-induced locomotor perseveration and PPI deficits, behavioral phenotypes observed in both obsessive-compulsive disorder (OCD) and autism spectrum disorder (ASD). To assess the role of canonical 5-HT1BR signaling, mice received acute pretreatment with a GSK-3 inhibitor (SB216763 or AR-A014418) and acute treatment with the 5-HT1A/1B receptor agonist RU24969 prior to assessing perseverative locomotor behavior in the open field, and PPI. To determine the role of noncanonical 5-HT1BR signaling, Arrb2 wild-type (WT), heterozygous (HT), and knockout (KO) mice received acute RU24969 treatment prior to behavioral testing. GSK-3 inhibition increased locomotor perseveration overall, and also failed to influence the RU24969-induced perseverative locomotor pattern in the open field. Yet, GSK-3 inhibition modestly reduced RU24969-induced PPI deficits. On the other hand, Arrb2 HT and KO mice showed reduced locomotion and no changes in perseveration overall, in addition to modest reductions in RU24969-induced locomotion and PPI deficits. In conclusion, our data do not support use of either GSK-3 inhibitors or β-arrestin2 inhibition in treatment of perseverative behaviors.

Brief Report: Reduced Restricted and Repetitive Behaviors after Pivotal Response Treatment

Children with ASD show high frequency of restricted and repetitive behaviors (RRBs); however, higher-order RRBs, such as restricted interests, have remained largely resistant to treatment. This study evaluated change in severity of RRBs following a 16-weeks open trial of Pivotal Response Treatment (PRT). Participants included 15 children with ASD ages 4-7 years. RRBs, as measured by the repetitive behavioral scales-revised (RBS-R) and aberrant behaviors checklist, decreased significantly after treatment. These reductions remained significant after controlling for change in social communication skills. PRT shows promise in reducing RRBs; although PRT explicitly addresses pivotal social communication skills, there is a secondary and less direct effect on RRBs.

Pharmacogenomic testing: aiding in the management of psychotropic therapy for adolescents with autism spectrum disorders

Adolescents with autism have higher rates of anxiety than the general adolescent population. They often struggle to express psychological symptoms verbally where their symptoms may manifest as withdrawal and agitation. Adolescent patients with autism have higher rates of polypharmacy and high-risk psychiatric medication use (eg, atypical antipsychotics) than other patients with psychiatric illness. Primary care pediatricians are at the front lines of psychiatric management for patients with autism. Yet, they have inadequate access to pediatric psychiatry for complex medication management. Pharmacogenomic testing can provide personalized drug metabolism profiles for a majority of psychotropic medications. Primary care based pharmacogenomic testing for adolescents with autism on one or more psychiatric medications may help individualize and optimize complex medication regimens, while promoting drug safety.

Autism, intellectual disability, and a challenge to our understanding of proxy consent

This paper focuses on a hypothetical case that represents an intervention request familiar to those who work with individuals with intellectual disability. Stacy has autism and moderate intellectual disability. Her parents have requested treatment for her hand flapping. Stacy is not competent to make her own treatment decisions; proxy consent is required. There are three primary justifications for proxy consent: the right to an open future, substituted judgment, and the best interest standard. The right to an open future justifies proxy consent on the assumption of future autonomy whereas substituted judgment justifies proxy consent via reference to past autonomy. Neither applies. Stacy has not been, nor will she be, competent to make her own treatment decisions. The best interest standard justifies proxy consent on the grounds of beneficence. It is unlikely that hand flapping harms Stacy. None of the three primary means of justifying proxy consent apply to Stacy's case.

Acetylcysteine for treatment of autism spectrum disorder symptoms

PURPOSE

Successful use of acetylcysteine to control irritability and aggressive behaviors in a hospitalized adolescent patient with autism spectrum disorder (ASD) is described.

SUMMARY

A 17-year-old Hispanic male with ASD and intellectual disability was hospitalized for inpatient psychiatric treatment due to impulsive and violent behavior. Despite receiving various medications in the initial weeks of hospitalization, including intramuscular lorazepam and diphenhydramine injections (four days a week on average), the patient continued to exhibit aggressive and unpredictable behaviors. Treatment with 20% acetylcysteine oral solution was initiated at a dosage of 600 mg twice daily as an adjunct to quetiapine therapy. Over the next six weeks, reductions in the patient's aggressive behavior, tantrums, and irritability were noted. The use of as-needed medications to control aggression was decreased, and the dosage of quetiapine was lowered from 700 to 400 mg daily over the course of the hospitalization. Acetylcysteine was well tolerated, with no observed or reported adverse effects. Unlike clonidine or guanfacine (other medications used for ASD-related behavioral symptoms), acetylcysteine is not sedating; moreover, it lacks the metabolic, extrapyramidal, and endocrine adverse effects of atypical antipsychotics. Published data from small controlled trials and case reports suggest that acetylcysteine use is associated with improvements in irritability and aggression in prepubertal children with ASD; these therapeutic benefits may be associated with acetylcysteine's glutamatergic, dopaminergic, antioxidant, and anti-inflammatory properties.

CONCLUSION

Treatment with acetylcysteine improved ASD symptoms, including irritability and aggression, in a teenage patient.

Excitatory/inhibitory imbalance in autism spectrum disorders: Implications for interventions and therapeutics

OBJECTIVES

Imbalance between excitation and inhibition and increased excitatory-inhibitory (E-I) ratio is a common mechanism in autism spectrum disorders (ASD) that is responsible for the learning and memory, cognitive, sensory, motor deficits, and seizures occurring in these disorders. ASD are very heterogeneous and better understanding of E-I imbalance in brain will lead to better diagnosis and treatments.

METHODS

We perform a critical literature review of the causes and presentations of E-I imbalance in ASD.

RESULTS

E-I imbalance in ASD is due primarily to abnormal glutamatergic and GABAergic neurotransmission in key brain regions such as neocortex, hippocampus, amygdala, and cerebellum. Other causes are due to dysfunction of neuropeptides (oxytocin), synaptic proteins (neuroligins), and immune system molecules (cytokines). At the neuropathological level E-I imbalance in ASD is presented as a "minicolumnopathy". E-I imbalance alters the manner by which the brain processes information and regulates behaviour. New developments for investigating E-I imbalance such as optogenetics and transcranial magnetic stimulation (TMS) are presented. Non-invasive brain stimulation methods such as TMS for treatment of the core symptoms of ASD are discussed.

CONCLUSIONS

Understanding E-I imbalance has important implications for developing better pharmacological and behavioural treatments for ASD, including TMS, new drugs, biomarkers and patient stratification.

An Orally Active Phenylaminotetralin-Chemotype Serotonin 5-HT7 and 5-HT1A Receptor Partial Agonist that Corrects Motor Stereotypy in Mouse Models

Stereotypy (e.g., repetitive hand waving) is a key phenotype of autism spectrum disorder, Fragile X and Rett syndromes, and other neuropsychiatric disorders, and its severity correlates with cognitive and attention deficits. There are no effective treatments, however, for stereotypy. Perturbation of serotonin (5-HT) neurotransmission contributes to stereotypy, suggesting that distinct 5-HT receptors may be pharmacotherapeutic targets to treat stereotypy and related neuropsychiatric symptoms. For example, preclinical studies indicate that 5-HT7 receptor activation corrects deficits in mouse models of Fragile X and Rett syndromes, and clinical trials for autism are underway with buspirone, a 5-HT1A partial agonist with relevant affinity at 5-HT7 receptors. Herein, we report the synthesis, in vitro molecular pharmacology, behavioral pharmacology, and pharmacokinetic parameters in mice after subcutaneous and oral administration of (+)-5-(2'-fluorophenyl)-N,N-dimethyl-1,2,3,4-tetrahydronaphthalen-2-amine ((+)-5-FPT), a new, dual partial agonist targeting both 5-HT7 (Ki = 5.8 nM, EC50 = 34 nM) and 5-HT1A (Ki = 22 nM, EC50 = 40 nM) receptors. Three unique, heterogeneous mouse models were used to assess the efficacy of (+)-5-FPT to reduce stereotypy: idiopathic jumping in C58/J mice, repetitive body rotations in C57BL/6J mice treated with the NMDA antagonist, MK-801, and repetitive head twitching in C57BL/6J mice treated with the 5-HT2 agonist, DOI. Systemic (+)-5-FPT potently and efficaciously reduced or eliminated stereotypy in each of the mouse models without altering locomotor behavior on its own, and additional tests showed that (+)-5-FPT, at the highest behaviorally active dose tested, enhanced social interaction and did not cause behaviors indicative of serotonin syndrome. These data suggest that (+)-5-FPT is a promising medication for treating stereotypy in psychiatric disorders.

Identifying individual differences of fluoxetine response in juvenile rhesus monkeys by metabolite profiling

Fluoxetine is the only psychopharmacological agent approved for depression by the US Food and Drug Administration for children and is commonly used therapeutically in a variety of neurodevelopmental disorders. Therapeutic response shows high individual variability, and severe side effects have been observed. In the current study we set out to identify biomarkers of response to fluoxetine as well as biomarkers that correlate with impulsivity, a measure of reward delay behavior and potential side effect of the drug, in juvenile male rhesus monkeys. The study group was also genotyped for polymorphisms of monoamine oxidase A (MAOA), a gene that has been associated with psychiatric disorders. We used peripheral metabolite profiling of blood and cerebrospinal fluid (CSF) from animals treated daily with fluoxetine or vehicle for one year. Fluoxetine response metabolite profiles and metabolite/reward delay behavior associations were evaluated using multivariate analysis. Our analyses identified a set of plasma and CSF metabolites that distinguish fluoxetine- from vehicle-treated animals and metabolites that correlate with impulsivity. Some metabolites displayed an interaction between fluoxetine and MAOA genotype. The identified metabolite biomarkers belong to pathways that have important functions in central nervous system physiology. Biomarkers of response to fluoxetine in the normally functioning brain of juvenile nonhuman primates may aid in finding predictors of response to treatment in young psychiatric populations and in progress toward the realization of a precision medicine approach in the area of neurodevelopmental disorders.

Evidence-based, parent-mediated interventions for young children with autism spectrum disorder: The case of restricted and repetitive behaviors

Restricted and repetitive behaviors represent a core symptom of autism spectrum disorders. While there has been an increase in research into this domain in recent years, compared to social-communication impairments experienced by children with autism spectrum disorders, much less is known about their development, etiology, and management. Parent-mediated interventions have become increasingly popular in the field, with a surge of studies reporting significant findings in social communication and cognitive development in early childhood. Restricted and repetitive behaviors are often not specifically targeted or measured as an outcome within these interventions. This article reviews how 29 parent-mediated interventions approached the management, treatment, and measurement of restricted and repetitive behaviors. Recommendations for research and practice are presented.

Fluoxetine for Autistic Behaviors (FAB trial): study protocol for a randomized controlled trial in children and adolescents with autism

BACKGROUND

Serotonin reuptake inhibitors (SSRIs) are commonly prescribed off-label for children with autism. To date, clinical trials examining the use of SSRIs in autism have been limited by small sample sizes and inconclusive results. The efficacy and safety of SSRIs for moderating autistic behaviors is yet to be adequately examined to provide evidence to support current clinical practice. The aim of the Fluoxetine for Autistic Behaviors (FAB) study is to determine the efficacy and safety of low dose fluoxetine compared with placebo, for reducing the frequency and severity of repetitive stereotypic behaviors in children and adolescents with an autism spectrum disorder (ASD). The relationship between the effectiveness of fluoxetine treatment and serotonin transporter genotype will also be explored.

METHODS/DESIGN

The FAB study is a multicenter, double-blinded, randomized controlled trial, funded by the Australian Government's National Health and Medical Research Council (NHMRC) grant. Participants will be aged between 7.5 and 17 years with a confirmed diagnosis of ASD. Eligible participants will be randomized to either placebo or fluoxetine for a 16-week period. Medication will be titrated over the first four weeks. Reponses to medication will be monitored fortnightly using the Clinical Global Impressions Scale (CGI). The primary outcome measure is the Children's Yale-Brown Obsessive Compulsive Scale-Modified for Pervasive Developmental Disorders (CYBOCS-PDD), administered at baseline and 16 weeks. Secondary outcome measures include the Aberrant Behaviour Scale (ABC), the Spence Children's Anxiety Scale Parent Report (SCAS-P), and the Repetitive Behaviors Scale (RBS-R), measured at baseline and 16 weeks. Participants will be invited to undergo genetic testing for SLC6A4 allele variants using a cheek swab. Continuous outcomes, including the primary outcome will be compared between the active and placebo groups using unadjusted linear regression. Binary outcomes will be compared using unadjusted logistic regression.

DISCUSSION

The FAB study is a large clinical trial to specifically investigate the efficacy of low dose fluoxetine for restricted, repetitive, and stereotyped behaviors in ASD. The outcomes of this study will contribute to evidence-based interventions used in clinical practice to assist children with ASD.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry ACTRN12608000173392; registered on 9 April, 2008.

The role of ionotropic glutamate receptors in childhood neurodevelopmental disorders: autism spectrum disorders and fragile x syndrome

Autism spectrum disorder (ASD) and Fragile X syndrome (FXS) are relatively common childhood neurodevelopmental disorders with increasing incidence in recent years. They are currently accepted as disorders of the synapse with alterations in different forms of synaptic communication and neuronal network connectivity. The major excitatory neurotransmitter system in brain, the glutamatergic system, is implicated in learning and memory, synaptic plasticity, neuronal development. While much attention is attributed to the role of metabotropic glutamate receptors in ASD and FXS, studies indicate that the ionotropic glutamate receptors (iGluRs) and their regulatory proteins are also altered in several brain regions. Role of iGluRs in the neurobiology of ASD and FXS is supported by a weight of evidence that ranges from human genetics to in vitro cultured neurons. In this review we will discuss clinical, molecular, cellular and functional changes in NMDA, AMPA and kainate receptors and the synaptic proteins that regulate them in the context of ASD and FXS. We will also discuss the significance for the development of translational biomarkers and treatments for the core symptoms of ASD and FXS.

TARGETED TREATMENTS IN AUTISM AND FRAGILE X SYNDROME

Autism is a neurodevelopmental disorder consisting of a constellation of symptoms that sometimes occur as part of a complex disorder characterized by impairments in social interaction, communication and behavioral domains. It is a highly disabling disorder and there is a need for treatment targeting the core symptoms. Although autism is accepted as highly heritable, there is no genetic cure at this time. Autism is shown to be linked to several genes and is a feature of some complex genetic disorders, including fragile X syndrome (FXS), fragile X premutation involvement, tuberous sclerosis and Rett syndrome. The term autism spectrum disorders (ASDs) covers autism, Asperger syndrome and pervasive developmental disorders (PDD-NOS) and the etiologies are heterogeneous. In recent years, targeted treatments have been developed for several disorders that have a known specific genetic cause leading to autism. Since there are significant molecular and neurobiological overlaps among disorders, targeted treatments developed for a specific disorder may be helpful in ASD of unknown etiology. Examples of this are two drug classes developed to treat FXS, Arbaclofen, a GABA(B) agonist, and mGluR5 antagonists, and both may be helpful in autism without FXS. The mGluR5 antagonists are also likely to have a benefit in the aging problems of fragile X premutation carriers, the fragile X -associated tremor ataxia syndrome (FXTAS) and the Parkinsonism that can occur in aging patients with fragile X syndrome. Targeted treatments in FXS which has a well known genetic etiology may lead to new targeted treatments in autism.

Oxytocin role in enhancing well-being: a literature review

OBJECTIVES

Oxytocin (OT) has long been implicated in maternal bonding, sexual behavior and social affiliation behaviors. This paper reviews the wide effects of oxytocin and its key role in well-being.

METHODS

Studies were identified through Medline, Pubmed, and PsychINFO search of the English-language literature from the past sixty years (1959 to 2009) using the key word "oxytocin" in human studies. Of the 287 articles identified, 102 were selected for review.

RESULTS

OT induces a general sense of well-being including calm, improved social interactions, increased trust, and reduced fear as well as endocrine and physiological changes. Some central effects of OT are temporary and its release is associated with induction of secondary biochemical actions which mediate long-term benefits including blood pressure reduction, calm and affiliative behavior. As OT release is augmented by touch and physiological support so the hormone is involved in both the cause and benefits of social interactions. Just as OT has widespread effects in factors encompassing well-being, its dysfunction is associated with morbidity and decreased quality of life as observed neuropsychiatric conditions such as autism, schizophrenia and social phobias.

CONCLUSIONS

Oxytocin (OT) is of potential use in enhancing interpersonal and individual well-being, and might have more applications in neuropsychiatric disorders especially those characterized by persistent fear, repetitive behavior, reduced trust and avoidance of social interactions.

Differential Diagnosis and Treatment of Obsessive-Compulsive, Inattentive, and Sleep Symptoms in a 7-Year-Old With PDD-NOS

The overlap in symptoms among autism spectrum disorders (ASDs), anxiety disorders, and attention-deficit/hyperactivity disorder (ADHD) in youth can present diagnostic challenges for clinicians and researchers. Accurate diagnosis and comprehensive treatment can be facilitated by ongoing assessment and close collaboration among members of a multidisciplinary team. Specific treatment guidelines for reducing anxiety and/or inattentive behaviors in children with a primary ASD diagnosis are currently lacking. This case provides an example of how an empirically supported treatment for anxiety, exposure with response prevention (E/RP), in conjunction with pharmacotherapy, can be effective in reducing anxiety and ritualistic/compulsive behaviors in ASDs. This case also exemplifies how attention to and treatment of sleep problems can improve inattentive symptoms and overall functioning.

Psychopharmacology of autistic spectrum disorders in children and adolescents

This article provides an overview of the psychopharmacologic management of irritability, hyperactivity, and repetitive behaviors in children and adolescents with autism spectrum disorder. A review of the current literature on medications used to treat these conditions with emphasis on randomized controlled trials is presented.

Psychopharmacology in autism: an update

Autism spectrum disorders are characterized by impairment in social reciprocity, disturbances in language and communication, restricted interests and repetitive behaviors of various types, as defined by the DSM-IV. The neurobiological bases of these disorders are poorly understood, although several abnormalities have been found. Pharmacotherapy in autism spectrum disorders lacks a solid, reliable neurobiological basis and at present it is mainly directed at the so-called associated behavioral symptoms, with limited relevance to core symptoms. Atypical neuroleptics, especially risperidone, have been shown to be useful in the treatment of behavioral symptoms in autism. Recent trials with SSRIs did not show remarkable results, in spite of their promising potential role. Attention deficit and hyperactivity disorder medications may be useful for counteracting the additional features of hyperactivity and short attention span. Antiepileptics have shown promising results but there are no specific indications for them as of yet. Research is now directed at evaluating novel treatments and combined behavioral and pharmacologic treatments, since behavioral interventions are the mainstay of the early treatment of autism. An update of currently available pharmacological treatments is provided.

The effects of response interruption and redirection and sertraline on vocal stereotypy

Although response interruption and redirection (RIRD) has been shown to be successful in reducing vocal stereotypy, recent reports have suggested that selective serotonin reuptake inhibitors (SSRIs) may also reduce these behaviors. The purpose of the current investigation was to examine the effects of RIRD with and without sertraline on automatically maintained vocal stereotypy of a 4-year-old boy with autism. Results suggested that vocal stereotypy decreased when RIRD was implemented and that sertraline did not affect the participant's vocal stereotypy.

Central tetrahydrobiopterin concentration in neurodevelopmental disorders

Tetrahydrobiopterin (BH₄) is a naturally occurring cofactor essential for critical metabolic pathways. Studies suggest that BH₄ supplementation may ameliorate autism symptoms; the biological mechanism for such an effect is unknown. To help understand the relation between central BH₄ concentration and systemic metabolism and to develop a biomarker of central BH₄ concentration, the relationship between cerebrospinal fluid BH₄ concentration and serum amino acids was studied. BH₄ concentration was found to be distributed in two groups, a lower and higher BH₄ concentration group. Two serum amino acids, citrulline and methionine, differentiated these groups, and the ratio of serum citrulline-to-methionine was found to correlate with the cerebrospinal fluid BH₄ concentration (r = −0.67, p < 0.05). Both citrulline and methionine are substrates in inflammation and oxidative stress pathways – two pathways that utilize BH₄ and are abnormally activated in autism. These data suggests that central BH₄ concentration may be related to systemic inflammation and oxidative stress pathways.

Tetrahydrobiopterin as a novel therapeutic intervention for autism

Tetrahydrobiopterin (BH(4)) is an essential cofactor for several critical metabolic pathways that have been reported to be abnormal in autism spectrum disorder (ASD). In addition, the cerebrospinal fluid concentration of BH(4) is reported to be depressed in children with ASD. Over the past 25 years, several clinical trials have suggested that treatment with BH(4) improves ASD symptomatology in some individuals. Two ongoing clinical protocols may help further define the efficacy of BH(4) treatment in children with ASD. First, children with ASD who had low concentrations of cerebrospinal fluid or urine pterins were treated in an open-label manner with 20 mg/kg per day of BH(4). The majority of children (63%) responded positively to treatment, with minimal adverse events (AEs). Second, a double-blind placebo-controlled study examining the efficacy of 20 mg/kg per day of BH(4) treatment in children with ASD is currently underway. Safety studies from the commercially available forms of BH(4) document the low incidence of AEs, particularly serious AEs. Studies have also documented the ability of BH(4) to cross the blood-brain barrier. Based on the importance of BH(4) in neurodevelopmental metabolic pathways, the safety of BH(4) treatment, and the evidence for a therapeutic benefit of BH(4) treatment in children with ASD, we conclude that BH(4) represents a novel therapy for ASD, one that may gain wider use after further clinical studies have established efficacy and treatment guidelines.

Diagnostik und Therapie von Autismus-Spektrum-Störungen im Kindesalter

Bei Autismus-Spektrum-Störungen (ASD) handelt es sich um komplexe Störungsbilder, die gerade im Kindesalter aufgrund der vielfältigen Differentialdiagnosen einer multidisziplinären und mehrschrittigen Diagnostik bedürfen. Eine Früherkennung autistischer Störungen ist ab dem zweiten Lebensjahr möglich. Standardisierte Verfahren verbessern die diagnostische Validität, erfordern jedoch eine fundierte kinder- und jugendpsychiatrische Expertise. Generell ist in der Behandlung ein ganzheitlicher, die Gesamtentwicklung des Kindes mit ASD umfassender Therapie- und Förderansatz zu verfolgen. Früh beginnende, intensive, verhaltenstherapeutische Interventionen unter Einbezug der Eltern haben sich als wirksam erwiesen. Die pharmakologische Behandlung von begleitenden Auffälligkeiten kann als ergänzende Maßnahme sinnvoll sein, da das Ansprechen auf pädagogische und psychotherapeutische Maßnahmen hierdurch verbessert werden kann.

CD38/cyclic ADP-ribose system: a new player for oxytocin secretion and regulation of social behaviour

Oxytocin is important for regulating a number of physiological processes. Disruption of the secretion, metabolism or action of oxytocin results in an impairment of reproductive function, social and sexual behaviours, and stress responses. This review discusses current views on the regulation and autoregulation of oxytocin release in the hypothalamic-neurohypophysial system, with special focus on the activity of the CD38/cADP-ribose system as a new component in this regulation. Data from our laboratories indicate that an impairment of this system results in alterations of oxytocin secretion and abnormal social behaviour, thus suggesting new clues that help in our understanding of the pathogenesis of neurodevelopmental disorders.

Behavioural intervention practices for stereotypic and repetitive behaviour in individuals with autism spectrum disorder: a systematic review

AIM

The purpose of this systematic review was to examine the quality of conduct of experimental studies contributing to our empirical understanding of function-based behavioural interventions for stereotypic and repetitive behaviours (SRBs) in individuals with autism spectrum disorders (ASDs).

METHOD

Systematic review methodology was used to identify relevant articles, to rate the level of evidence and quality of conduct of the studies, and to extract data systematically.

RESULTS

Ten single case studies examining 17 participants (14 males, 3 females; age 2y 11mo-26y) diagnosed with various ASDs were included. Overall, studies reported decreases in SRBs using behavioural interventions and some collateral increase in desirable behaviours.

INTERPRETATION

Only a small number of intervention studies for SRBs explicitly state the function of the behaviour; therefore, relatively little is known about the efficacy of SRB interventions in relation to the range of possible behavioural functions. Evidence supporting SRB interventions is preliminary in nature, and caution should be used in choosing and implementing SRB intervention practices for individuals with ASDs.

Repetitive self-grooming behavior in the BTBR mouse model of autism is blocked by the mGluR5 antagonist MPEP

Autism is a neurodevelopmental disorder characterized by abnormal reciprocal social interactions, communication deficits, and repetitive behaviors with restricted interests. BTBR T+tf/J (BTBR) is an inbred mouse strain that shows robust behavioral phenotypes with analogies to all three of the diagnostic symptoms of autism, including well-replicated deficits in reciprocal social interactions and social approach, unusual patterns of ultrasonic vocalization, and high levels of repetitive self-grooming. These phenotypes offer straightforward behavioral assays for translational investigations of pharmacological compounds. Two suggested treatments for autism were evaluated in the BTBR mouse model. Methyl-6-phenylethynyl-pyridine (MPEP), an antagonist of the mGluR5 metabotropic glutamate receptor, blocks aberrant phenotypes in the Fmr1 mouse model of Fragile X, a comorbid neurodevelopmental disorder with autistic features. Risperidone has been approved by the United States Food and Drug Administration for the treatment of irritability, tantrums, and self-injurious behavior in autistic individuals. We evaluated the actions of MPEP and risperidone on two BTBR phenotypes, low sociability and high repetitive self-grooming. Open field activity served as an independent control for non-social exploratory activity and motor functions. C57BL/6J (B6), an inbred strain with high sociability and low self-grooming, served as the strain control. MPEP significantly reduced repetitive self-grooming in BTBR, at doses that had no sedating effects on open field activity. Risperidone reduced repetitive self-grooming in BTBR, but only at doses that induced sedation in both strains. No overall improvements in sociability were detected in BTBR after treatment with either MPEP or risperidone. Our findings suggest that antagonists of mGluR5 receptors may have selective therapeutic efficacy in treating repetitive behaviors in autism.