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Published on: December 7, 2018
Shared Brain Connectivity Issues, Symptoms, and Comorbidities in Autism Spectrum Disorder, Attention
Janet K Kern1, David A Geier1, Paul G King2
11 Institute of Chronic Illnesses, Inc. , Silver Spring, Maryland.
Insights
Autism spectrum disorder (ASD), attention deficit/hyperactivity disorder (ADHD), and Tourette syndrome (TS) may represent a spectrum of neurodevelopmental disorders. These conditions share similar neuropathology, characterized by abnormal brain connectivity, and potentially a common etiology.
Area of Science:
- Neuroscience
- Developmental Biology
- Genetics
Background:
- The prevalence of neurodevelopmental disorders, including autism spectrum disorder (ASD), attention deficit/hyperactivity disorder (ADHD), and Tourette syndrome (TS), has significantly increased.
- Approximately one in six children in the U.S. receives a neurodevelopmental disorder diagnosis.
- These disorders share overlapping symptoms, comorbidities, and neuropathological features.
Purpose of the Study:
- To critically examine the evidence supporting ASD, ADHD, and TS as part of a broader neurodevelopmental illness spectrum.
- To investigate the neuropathological basis of abnormal brain connectivity (long-range underconnectivity and short-range overconnectivity) in these disorders.
- To explore potential shared etiologies and the role of axonal injury and regeneration.
Main Methods:
- Literature review and critical analysis of existing evidence.
- Examination of neuropathological findings related to brain connectivity.
- Discussion of potential biological mechanisms and etiological factors.
Main Results:
- Evidence suggests ASD, ADHD, and TS share similar neuropathology, specifically abnormal connectivity patterns.
- These disorders exhibit considerable overlap in symptomatology and comorbid conditions.
- Potential biological underpinnings include neurotoxicity, neuroinflammation, and oxidative stress.
Conclusions:
- ASD, ADHD, and TS may be classified as a spectrum of neurodevelopmental disorders, termed abnormal connectivity spectrum disorder.
- Shared neuropathology and potential common etiology warrant further investigation.
- Understanding axonal injury and regeneration is crucial for elucidating connectivity issues.
Abstract:
The prevalence of neurodevelopmental disorders, including autism spectrum disorder (ASD), attention deficit/hyperactivity disorder (ADHD), and Tourette syndrome (TS), has increased over the past two decades. Currently, about one in six children in the United States is diagnosed as having a neurodevelopmental disorder. Evidence suggests that ASD, ADHD, and TS have similar neuropathology, which includes long-range underconnectivity and short-range overconnectivity. They also share similar symptomatology with considerable overlap in their core and associated symptoms and a frequent overlap in their comorbid conditions. Consequently, it is apparent that ASD, ADHD, and TS diagnoses belong to a broader spectrum of neurodevelopmental illness. Biologically, long-range underconnectivity and short-range overconnectivity are plausibly related to neuronal insult (e.g., neurotoxicity, neuroinflammation, excitotoxicity, sustained microglial activation, proinflammatory cytokines, toxic exposure, and oxidative stress). Therefore, these disorders may a share a similar etiology. The main purpose of this review is to critically examine the evidence that ASD, ADHD, and TS belong to a broader spectrum of neurodevelopmental illness, an abnormal connectivity spectrum disorder, which results from neural long-range underconnectivity and short-range overconnectivity. The review also discusses the possible reasons for these neuropathological connectivity findings. In addition, this review examines the role and issue of axonal injury and regeneration in order to better understand the neuropathophysiological interplay between short- and long-range axons in connectivity issues.
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