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Cortical Thickness Differences in Autistic Children With and Without Intellectual Disability.
Derek S Andrews1, Andrew J Dakopolos1, Joshua K Lee1
1Department of Psychiatry & Behavioral Sciences, the MIND Institute, University of California, Davis, California, USA.
Summary
Autism spectrum disorder (ASD) and intellectual disability (ID) often co-occur. This study found unique cortical thickness patterns in autistic children, linking thinner cortex to higher IQ and thicker cortex in those with ID, highlighting potential neuroimaging biomarkers.
Area of Science:
- Neuroscience
- Developmental Psychology
- Medical Imaging
Background:
- Autism spectrum disorder (ASD) affects 1 in 36 US children, with nearly 40% also having intellectual disability (ID).
- Cortical thickness is a potential neuroimaging biomarker for ASD and ID, but studies often exclude individuals with ID.
- Limited research exists on cortical thickness across the full spectrum of intellectual abilities in autistic children.
Purpose of the Study:
- To investigate associations between full-scale IQ and cortical thickness in young autistic children and typically developing (TD) peers.
- To examine differences in cortical thickness between autistic children with and without intellectual disability.
- To explore the overlap between cortical thickness patterns, IQ, and autism symptom severity.
Main Methods:
- Magnetic Resonance Imaging (MRI) was used to assess cortical thickness in 88 autistic children (IQ 19-133) and 53 TD children (mean age ~5.3 years).
- Statistical analyses examined correlations between full-scale IQ and cortical thickness in both groups.
- Cortical thickness was compared between autistic children with ID (IQ ≤ 70) and those without, and associations with IQ and Autism Diagnostic Observation Schedule (ADOS) Calibrated Severity Scores were analyzed.
Main Results:
- Autistic children showed significant negative associations between IQ and cortical thickness in regions including the entorhinal cortex, fusiform gyrus, and temporal gyri, unlike TD children.
- Autistic children with ID exhibited significantly thicker cortex in these regions compared to autistic children without ID.
- Cortical thickness patterns associated with IQ and autism symptom severity showed significant overlap across the cortex.
Conclusions:
- Cortical thickness variations are associated with intellectual ability in autistic children, differing from typically developing peers.
- Specific cortical regions may serve as neuroimaging markers for intellectual functioning within the autism spectrum.
- Findings suggest a complex interplay between brain structure, intellectual ability, and autism symptomology.
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Intellectual disability (ID) is a neurodevelopmental condition characterized by deficits in intellectual and adaptive functioning that manifest during the developmental period. This condition encompasses challenges in reasoning, memory, problem-solving, and learning, accompanied by impairments in everyday life skills, such as communication, self-care, and social interactions. Intellectual disability affects approximately 1% of the population in the United States, impacting an estimated 5...
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