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

This brain imaging study looked at 61 boys aged 9-18 with either fragile X syndrome or autism. Researchers found that boys with fragile X had thicker brain tissue in areas that process basic sight and sound compared to boys with autism. This suggests these conditions affect the brain differently, even though they can look similar behaviourally. Understanding these brain differences could help develop better targeted treatments for each condition.

This neuroimaging study compared brain structure in 61 male children (9-18 years) with fragile X syndrome (FXS) or autism spectrum disorder (ASD). Using high-resolution MRI, researchers measured cortical thickness and myelination markers across the brain. Boys with FXS showed significantly thicker cortex compared to those with ASD, particularly in early sensory processing areas including visual and auditory regions spanning occipital, parietal, and temporal cortices. No differences in myelination were found between groups.

These findings suggest distinct neurobiological mechanisms underlying sensory processing differences between FXS and ASD, despite similar behavioral presentations. The research provides neuroanatomical evidence for developing more targeted, disorder-specific interventions.

Findings support developing disorder-specific interventions despite similar behavioral presentations. Thicker sensory cortex in fragile X syndrome suggests different sensory processing mechanisms that may require tailored therapeutic approaches. Results emphasize need for personalized interventions based on underlying neurobiology rather than behavioral similarities alone.

Study limited to males aged 9-18 years only. Cross-sectional design cannot show developmental changes over time. Pooling of autism participants from multiple studies may introduce variability. Does not include females or examine comorbid conditions.

An estimated 30%-50% of male individuals with fragile X syndrome (FXS) meet criteria for autism spectrum disorder (ASD), indicating phenotypic overlap but potentially distinct neurobiology. Here, we aimed to characterize shared and divergent cortical features between FXS and ASD. High-resolution, motion-corrected quantitative MRI was used to compare cortical morphometry and relaxometry in 61 male participants (9-18 years) with FXS or ASD. To increase power, ASD participants were pooled from multiple MPnRAGE studies and harmonized across protocols using ComBat.

Cortical thickness and R1 (longitudinal relaxation rate; proxy for myelination) were computed across the cerebral cortex. Relative to ASD, FXS exhibited greater cortical thickness predominantly in early sensory cortices implicated in low-level visual and auditory processing spanning occipital, parietal, and temporal regions. No significant group differences in R1 were found. Thicker cortex in FXS within primary and early associative sensory areas suggests divergent early sensory processing mechanisms between FXS and ASD.

Characterizing different neuroanatomical features between the two disorders provides a grounding to develop more disorder-specific interventions despite similar behavioral difficulties. Future work should test developmental trajectories, include females and comorbidities, and link imaging markers to individual sensory/clinical profiles to inform and improve personalized therapies and interventions.