Distinct Patterns of Atypical Functional Connectivity in Lower-Functioning Autism.

Area of Science:

• Neuroscience
• Developmental Psychology
• Medical Imaging

Background:

• Autism spectrum disorder (ASD) research has primarily focused on individuals with average intelligence.
• Functional network connectivity in lower-functioning individuals with ASD remains poorly understood.
• It is unclear if lower-functioning ASD exhibits exacerbated or distinct connectivity abnormalities compared to higher-functioning ASD.

Purpose of the Study:

• To investigate functional network connectivity differences in lower- and higher-functioning individuals with autism spectrum disorder (ASD).
• To compare connectivity patterns between ASD subgroups and typically developing controls.
• To determine if ASD connectivity abnormalities vary based on general cognitive ability.

Main Methods:

• Resting-state functional magnetic resonance imaging (fMRI) data from 88 children (44 ASD, 44 controls) were analyzed.
• ASD participants were stratified into lower-functioning (mean IQ=77) and higher-functioning (mean IQ=123) groups.
• Whole-brain functional connectivity was contrasted across groups using seed regions in key brain networks.

Main Results:

• Lower-functioning ASD participants showed underconnectivity in default mode and ventral visual networks compared to higher-functioning ASD.
• Higher-functioning ASD participants exhibited decreased anticorrelations between default mode, salience, and task-positive networks.
• Large effect sizes (Cohen's d > 1.46) indicated significant differences in connectivity patterns.

Conclusions:

• Individuals with ASD display distinct functional connectivity patterns based on their cognitive functioning level.
• Lower-functioning ASD is characterized by reduced network integration, while higher-functioning ASD shows reduced network segregation.
• Stratification by general functional level is crucial for future functional connectivity studies in ASD.