Psychomotor development in infants and young children with Down syndrome-A prospective, repeated measure, post-hoc analysis.

Children with Down syndrome (DS) show delayed acquisition of cognitive and functional skills compared to typically developing children. The objective of this study was to accurately describe early development of infants and young children (children hereafter) with DS based on a large recent sample. We carried out repeated measure analysis of the global development quotient (GDQ) and developmental age using data from the Assessment of Systematic Treatment with Folinic Acid and Thyroid Hormone on Psychomotor Development of Down Syndrome Young Children (ACTHYF) study (NCT01576705). Because there was no statistically significant difference in the primary endpoint between active treatment and placebo, data from all treatment groups were pooled for post-hoc analysis. Data of 141 children with DS aged 6-18 months at inclusion were analyzed. Mean GDQ decreased over the study period, especially in the youngest age classes ([6-9] and [9-12] months), indicating that acquisition of skills occurred at a slower pace compared to typically developing children. Strongest deficits were observed for motor and hearing and language skills. Only GDQ at baseline correlated significantly with evolution of GDQ. Future studies should aim at elucidating the mechanisms underlying motor and language development. Early pharmacological interventions together with early childhood therapies might be necessary to improve the developmental trajectory of children with DS.