Objective:

This study examines the populations, treatment differences, and motor outcomes in children with Duchenne muscular dystrophy (DMD) and comorbid autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD).

Background:

Neurodevelopmental disorders (NDDs) are common in DMD, yet their impact on motor outcomes is underexplored. DMD clinical trials often exclude patients with severe NDDs, which leads to difficulties generalizing their results to all patients.

Design/Methods:

A retrospective analysis was conducted for ambulatory males aged 4 to 9 with DMD at the Children’s Hospital of Philadelphia from 01/2015 to 09/2023. The primary outcome was the rate of completion of standardized functional motor assessments. Secondary outcomes included the performance on these assessments, the correlation of NDDs with DMD mutations, and the rates of corticosteroid therapy.

Results:

The study analyzed 99 patients with DMD, involving 432 multidisciplinary clinic visits. Twenty-eight patients (28.3%) were diagnosed with autism and/or ADHD (the NDD group), accounting for 128 visits. The non-NDD group (n = 71, 71.7%) had 304 visits. The NDD group completed fewer functional motor assessments, with significant reductions in timed tests (p = 0.024), manual muscle testing (p < 0.001), and PUL tests (p = 0.008), though NSAA and ROM testing rates were similar. Performance outcomes were notably poorer in the NDD group, with significant deficits across timed tests, all quantitative strength measures, NSAA scores, and ankle dorsiflexion ROM (p < 0.001 to p = 0.039).

Conclusions:

Children with DMD and NDDs undergo less frequent motor assessments and have significantly worse motor outcomes. While children with severe NDDs are typically excluded from most clinical trials, our data indicates that an even greater number may be further excluded due to low baseline motor function assessments. This exclusion limits their access to potentially life-changing therapies and raises concerns about the applicability of trial findings to this vulnerable group.