Sex Differences in the Striatal Contributions to Longitudinal Fine Motor Development in Autistic Children.

Background: Fine motor challenges are prevalent in autistic populations. However, little is known about their neurobiological underpinnings or how their related neural mechanisms are influenced by sex. The dorsal striatum, comprised of the caudate nucleus and putamen, is associated with motor learning and control and may hold critical information. We investigated how autism diagnosis and sex assigned at birth influence associations between the dorsal striatum and fine motor development in autistic and non-autistic children.

Methods: We used multimodal assessment of striatal structures (volume and cortico-striatal white matter microstructure) and longitudinal assessment of fine motor skills, first at approximately 3 years of age (Time 1) and again 2-3 years later (Follow-up). Fine motor and magnetic resonance imaging (T1 and diffusion) data were collected at Time 1 from 356 children (234 autistic; 128 female) and at Follow-up from 195 children (113 autistic; 76 female).

Results: At Time 1, associations among fine motor skills, putamen volume, and sensorimotor-striatal fractional anisotropy (sensorimotor-affiliated dorsal striatal structures) were different in autistic boys compared to autistic girls and were not significant for non-autistic children. Further, Time 1 sensorimotor-striatal and prefrontal-striatal microstructure predicted fine motor development for autistic girls but not boys.

Conclusions: Sensorimotor-affiliated dorsal striatum structures may contribute to concurrent motor ability and predict fine motor improvement during critical windows of development in a sex-specific and diagnosis-dependent way. Moreover, the dorsal striatum may play a key role in the distinct neural mechanisms underlying motor challenges in autistic males and females.