Early learning and adaptive behaviour in toddlers with Down syndrome: evidence for an emerging behavioural phenotype?

Background: Though the Down syndrome behavioural phenotype has been described as involving relative strengths in visuo-spatial processing and sociability, and relative weaknesses in verbal skills and motor planning, the early emergence of this phenotypic pattern of strengths and weaknesses has not yet been fully explored.

Method: In this study, we compared the performance of eighteen 2 to 3-year-olds with Down syndrome to an MA-matched comparison group of nineteen 2 to 3-year-olds with mixed developmental disabilities, and an MA-matched comparison group of 24 children with typical development on two developmental measures: the Mullen Scales of Early Learning and the Vineland Adaptive Behaviour Scales.

Results: While the specificity of the Down syndrome profile was (for the most part) not yet evident, results showed that toddlers with Down syndrome in this study did show emerging areas of relative strength and weakness similar to that which has been described in older children and young adults with Down syndrome. This pattern included relatively stronger social skills, weaker expressive language, and poor motor coordination. When this pattern of strengths and weaknesses was compared to the developmental profiles of the two comparison groups, socialisation strengths differentiated the Down syndrome group from the mixed developmental disabilities group.