White matter changes with rehabilitation in children with Co-occurring autism spectrum disorder and developmental coordination disorder.

Purpose: Up to 88 % of children with autism spectrum disorder (ASD) experience motor difficulties consistent with developmental coordination disorder (DCD). Cognitive Orientation to daily Occupational Performance (CO-OP) intervention is effective for children with co-occurring ASD and DCD to learn motor skills, but it is unknown if treatment-induced brain changes occur in this clinical population. Our objectives were to: (1) investigate changes in white matter microstructure in children with ASD + DCD after CO-OP intervention; (2) determine whether these brain changes are maintained three months after intervention; and (3) explore the relationship of white matter changes with improvements in motor function. Methods: In this quasi-experimental study, 24 children with ASD + DCD (aged 8-12 years) underwent an initial MRI and were randomly assigned to either a treatment or waitlist group. The treatment group received CO-OP intervention (once weekly for 10 weeks), had a second MRI post-intervention, and a follow-up scan three months later. The waitlist group waited three months for their second MRI, received the intervention, and then had a post-treatment scan. Diffusion tensor imaging data were analyzed using tract-based spatial statistics. Results: Children with ASD + DCD showed increased fractional anisotropy in cerebellar white matter in vermal lobule VI and middle cerebellar peduncle after CO-OP (Cohen's d = 0.88 and 0.85, respectively). Brain changes were maintained three months post-intervention. Regression analysis found no relationship between white matter changes and motor outcomes. Conclusions: Improvements in cerebellar white matter pathways in children with ASD + DCD highlight the efficacy of CO-OP interventions as a therapeutic approach for this clinical population. Clinical trials registration: ClinicalTrials.gov ID: NCT04119492.