Cerebral Cortex Morphometry and Relaxometry in Male Children With Fragile X Syndrome and Autism

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Neuroimaging

Background:

• Fragile X syndrome (FXS) and autism spectrum disorder (ASD) share phenotypic overlap, with 30-50% of males with FXS meeting ASD criteria.
• Distinct neurobiological underpinnings may exist despite behavioral similarities.

Purpose of the Study:

• To characterize shared and divergent cortical features between FXS and ASD.
• Investigate differences in cortical morphometry and relaxometry.

Main Methods:

• Used high-resolution, motion-corrected quantitative MRI in 61 male participants (9-18 years) with FXS or ASD.
• Harmonized ASD data from multiple MPnRAGE studies using ComBat.
• Computed cortical thickness and R1 (longitudinal relaxation rate) across the cerebral cortex.

Main Results:

• FXS exhibited significantly greater cortical thickness compared to ASD, particularly in early sensory cortices (occipital, parietal, temporal).
• These regions are implicated in low-level visual and auditory processing.
• No significant group differences were found in R1, a proxy for myelination.

Conclusions:

• Thicker cortex in FXS sensory areas suggests divergent early sensory processing mechanisms compared to ASD.
• Understanding these neuroanatomical differences can guide the development of disorder-specific interventions.
• Future research should explore developmental trajectories, include females and comorbidities, and link imaging markers to clinical profiles.