The early development of 33 boys with Duchenne muscular dystrophy (DMD) was assessed at the Institute of Medical Genetics, University of Wales College of Medicine, Heath Park, Cardiff, Wales. The average age of entry into the study was 3.4 years (range 0.8 to 6.7). The Griffiths Developmental Scales, The Reynell Language Scales and the British Picture Vocabulary Scales were used at three evaluations at 6 monthly intervals over a one year period. Compared to a control group the boys with DMD showed developmental delay which was most severe in the locomotor and language areas. Locomotor quotients deteriorated over time and behavior problems were probably secondary to the developmental delay. 
COMMENT: Unexplained developmental delays should prompt a neurological evaluation to exclude Duchenne muscular dystrophy in boys. Young children with DMD have significant problems with motor, speech and behavioral disorders before muscle weakness becomes an obvious clinical sign.
The etiology of intellectual impairment in Duchenne muscular dystrophy was investigated by MRI studies at Jordan University, Amman, Jordan . Four DMD patients were studied prospectively by cranial MRI, DNA deletion analysis, clinical evaluation and IQ testing. There was no significant correlation between verbal IQ and MRI findings, DNA deletion or the clinical severity of the disease. Other than mild atrophy in two patients, no significant anatomical brain lesion was discovered. Previous reports have attributed intellectual impairment in DMD to anatomic brain changes, abnormal dendritic development, and migrational lesions. Others have described a direct relation between the severity of clinical disease and impairment of IQ.