The Basal Ganglia’s Relationship with Autistic Repetitive Motor Behaviors and Sex Assigned at Birth


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This project aimed to investigate the relationship between the volume of the caudate nucleus (CN) and repetitive motor behaviors (RMB) in an autistic sample, and whether sex assigned at birth moderates this relationship. Additionally, we explored the potential interactions of the ventromedial prefrontal cortex (vmPFC) with the caudate and RMB. We used structural MRI data and the Repetitive Behavior Scale-Revised (RBS-R) to measure CN volume and RMB, respectively. Our analysis revealed that only scan age and estimated full-scale IQ were significantly related to CN volume, while RMB and sex assigned at birth did not have a significant relationship. We also found a significant negative correlation between CN volume and estimated full-scale IQ. The independent samples t-tests revealed no significant difference between AFAB and AMAB groups in terms of RMB, but there was a difference in all normalized structural volumes, with a greater mean for the AMAB group. However, after controlling for confounding factors, sex assigned at birth was not significantly related to CN volume. Age was significantly correlated with RMB, with reported RMB decreasing as age increased; this relationship was further affected by sex assigned at birth. Our findings suggest that CN volume is related to estimated full-scale IQ in autistic individuals, but not to RMB or sex assigned at birth.