About this Research Topic
Autism spectrum disorders (ASD) are currently viewed as a heterogeneous set of disorders, which can be caused by various genetic, epigenetic, and environmental factors. There are no current interventions that result in the complete resolution of ASD symptoms, due to the wide variability in the manifestations and severity of core and associated symptoms and to its unknown aetiology. Research has shown that there are genetic mutations associated with ASD, but these abnormal genetic markers do not fully explain the cause and wide variability of the features. Emerging evidence suggests that an imbalance between excitatory (glutamate) and inhibitory (-amino-butyric acid, GABA) neurotransmission may form a common pathway in ASD. In particular, defects in GABA transmission, leading to brain hyper-excitability, have been hypothesized to underlie the symptoms of ASD and might potentially be a novel therapeutic target for ASD. Glutamatergic abnormalities have been extensively documented in ASD and have paved the way to experimental trials that have shown mixed results in modifying core and associated symptoms in ASD. Clinical trials with targeted treatments directed to reduce excessive glutamatergic transmission have been carried out.
Neurobiological bases of ASD are being deeply investigated using mouse models bearing mutations in ASD-associated genes. Molecular, cellular, anatomical and behavioral studies performed on these models already contributed and will continue to identify molecular pathways disrupted in the disease, thus contributing to identify novel potential drug targets. Neurobiological studies also paved the way to identify potential molecular and structural biomarkers of the disorder. The quest for biomarkers of ASD is just started, and several potential candidates (from gene to brain network abnormalities) are currently being examined. ASD biomarker identification will improve prediction and stratification of ASD patients by severity and sub-type of the disorders, and allow a better monitoring of patients over time, especially in response to interventions. Furthermore, brain imaging can be used to generate biomarkers for selecting research participants based on their neural phenotype. If abnormalities in molecular and/or structural brain biomarkers were detected early in life, this would allow to prevent further unfolding of abnormal neural circuits. For infants and toddlers identified with specific sub-types of ASD defined by molecular and circuit abnormalities, pharmacological treatments will be directed to modify neural substrates while cognitive– behavioral treatments will be used to strengthen adaptive and social skills.
The present Research Topic will address all these aspects of current research in ASD, providing an updated overview on basic and clinical studies that aim to identify novel pathogenic mechanisms and therapeutic interventions for these neurodevelopmental disorders.
Keywords: autism spectrum disorders, developmental disorders, neurobiology, childhood and adolescence
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