Alternative Diagnoses in the Work-Up of Down Syndrome Regression Disorder

This retrospective study evaluated 266 individuals referred for developmental regression in Down syndrome and identified that 20% had alternative diagnoses, most commonly autism spectrum disorder. Individuals with confirmed Down Syndrome Regression Disorder showed distinct clinical patterns including rapid symptom onset and preceding triggers, while those with alternative diagnoses were more likely to have earlier-onset, long-standing symptoms and histories of epilepsy or prematurity.