Pharmacology of autism

Chemical Modulators for Targeting Autism Spectrum Disorders: From Bench to Clinic

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by diverse behavioral symptoms such as repetitive behaviors, social deficits, anxiety, hyperactivity, and irritability. Despite their increasing incidence, the specific pathological mechanisms of ASD are still unknown, and the degree and types of symptoms that vary from patient to patient make it difficult to develop drugs that target the core symptoms of ASD. Although various atypical antipsychotics and antidepressants have been applied to regulate ASD symptoms, these drugs can only alleviate the symptoms and do not target the major causes. Therefore, development of novel drugs targeting factors directly related to the onset of ASD is required. Among the various factors related to the onset of ASD, several chemical modulators to treat ASD, focused on serotonin (5-hydroxytryptamine, 5-HT) and glutamate receptors, microbial metabolites, and inflammatory cytokines, are explored in this study. In particular, we focus on the chemical drugs that have improved various aspects of ASD symptoms in animal models and in clinical trials for various ages of patients with ASD.

Pharmacological management of core and comorbid symptoms in autism-spectrum disorder

In this article we review the evidence base and practical experience supporting the use of psychopharmacological treatments for autism-spectrum disorders across the lifespan. Recent advances in knowledge are highlighted, as are the shortcomings of published data in this field. Psychosocial and educational interventions remain the core of treatment, but there is now evidence that medication management is a good option for certain domains of behaviour. We discuss the evidence in terms of symptom clusters, including the underlying social deficit of autism and common psychiatric comorbidities.

Review article: intestinal barrier dysfunction and central nervous system disorders--a controversial association

BACKGROUND

Central nervous system (CNS) development and physiopathology are greatly affected by environmental stimuli. The intestinal barrier restricts the entrance of toxins, pathogens, and antigens while modulating the expression of various neuroactive compounds. The existence of a rich gut-to-brain communication raises the possibility that intestinal barrier alterations may take part in the pathophysiology of CNS disorders.

AIM

To review evidence associating intestinal barrier dysfunction with the development of CNS disorders.

METHODS

Literature search was conducted on PubMed using the following terms: intestinal barrier, intestinal permeability, central nervous system, mental disorders, schizophrenia, autism, stress, anxiety, depression, and neurodegeneration.

RESULTS

Clinical and animal model studies of the association between intestinal barrier and schizophrenia, autism spectrum disorders, neurodegenerative diseases or depression were reviewed. The majority of reports concentrated on schizophrenia and autism spectrum disorders. About half of these described increased intestinal permeability/mucosal damage in patients compared with healthy controls, with up to 43% of children with autism spectrum disorders and up to 35% of schizophrenia patients displaying abnormally high urinary excretion of the sugars used as permeability markers. However, another substantial group of studies did not find such differences. In autism spectrum disorders, some reports show that the use of diets such as the gluten-free casein-free diet may contribute to the normalisation of lactulose/mannitol ratio, but to date there is no adequately controlled study showing improvement in behavioural symptoms following these dietary interventions.

CONCLUSIONS

Evidence of altered intestinal permeability in individuals suffering from CNS disorders is limited and cannot be regarded as proven. Moreover the efficacy of targeting gut barrier in the management of neurological and behavioural aspects of CNS disorders has not yet been established, and needs further investigation.

Issues in the management of challenging behaviours of adults with autism spectrum disorder

Autism spectrum disorder (ASD) is a particularly important risk factor for challenging behaviours such as aggression, tantrums, self-injury and pica. Adults with ASD have rarely been studied with respect to these problems. This is particularly disconcerting since there are far more adults than children with ASD. In addition, because of adults' increased physical size and longer history of these problems, treating these behaviours effectively is important. Psychological methods, particularly applied behaviour analysis, and pharmacotherapy have been the most frequently addressed treatments for challenging behaviours associated with ASD in the research literature. In many cases, challenging behaviours have clear environmental antecedents. In these cases, behavioural interventions, such as applied behaviour analysis, should be used to reduce the behaviours. When environmental factors cannot be identified or when challenging behaviours are very severe, pharmacological treatments may be necessary in combination with behavioural interventions. Newer antipsychotics are the most researched medications for use with this population. Currently, risperidone and aripiprazole are the only medications that have US FDA approval for the treatment of behaviours associated with ASD, specifically irritability; however, they are indicated for use in children not adults. It is important not to use medications unnecessarily, due to possible side effects associated with their use. Based on available research, some recommendations for the treatment of challenging behaviours of adults (and children) with ASD include the use of functional assessment, side-effect monitoring of medications and behavioural methods whenever possible. Additionally, future research in this area needs to focus more on adults, as most current research has used child samples.

A review of behavioral treatments for self-injurious behaviors of persons with autism spectrum disorders

Autism spectrum disorders (ASD) are considered to be among the most serious of the mental health conditions. Concomitant with many cases of ASD is intellectual disability. Further compounding the disability is the fact that both conditions are known risk factors for self-injurious behavior (SIB). To date, the most effective intervention methods, based on the available data, appear to be variants of behavior modification. This article provides an overview of the current status of learning-based interventions for SIB in ASD and provides a review of specific studies. Although most studies describe some combination of reinforcement and punishment procedures, efforts are under way to develop more positively oriented strategies, such as functional assessment, to decrease the use of punishment. However, almost all the treatment studies employ single case designs, thus preventing a comparison of treatment efficacy. These issues are discussed along with other strengths, weaknesses, and future directions for clinical practice and treatment.