by George T. Capone, M.D.

The term development usually encompasses many different aspects of a child's maturation and can be divided into six separate streams or domains, including: gross motor, fine motor, visual motor problem-solving, expressive language, receptive language, and social-adaptive/self-help skills. Developmental progress is frequently measured by recording when specific "milestones" are achieved. The rate of developmental progress and the ultimate level of developmental competence are a reflection of complex interactions among neuromaturational processes, genetic factors, individual temperament, environmental stimulation, and educational opportunities. Overreliance on one particular milestone or a handful of milestones, averaged to yield a single developmental age, can lead to an inaccurate description of the child's developmental level. A developmental assessment during infancy or childhood should yield a comprehensive overview of the pattern that the process of development is following in any particular child. Variations among the different streams of development are usually indicative of a particular child's strengths and weaknesses and may confirm the presence of a specific developmental diagnosis.

In children with Down syndrome, as with any child, developmental progress cannot be accurately forecast or predicted in advance. Because the rate of development is more variable in Down syndrome children compared to other children, a broader time span of milestone achievement is seen. Thus, when quoting the age for milestone attainment in this booklet, a range of ages rather than an average age is used.

Intellectual or cognitive skills are most accurately examined by measuring expressive/receptive language and visual motor problem-solving skills. When a child's cognitive skills (mental age) fall below 70% of his/her chronologic age and this is accompanied by similar delays in social-adaptive/self-help skills, a diagnosis of mental retardation is made. Most children with Down syndrome test in the mild to moderate range of mental retardation (IQ 70–40) with social adaptive/self-help skills being somewhat higher.

Formal psychological testing is usually administered between 2 and 3 years of age or just prior to placement in preschool. Testing is used to identify relative strengths and weaknesses in a child's abilities.

The article above is reproduced from the Down Syndrome Guide disseminated by the Down Syndrome Clinic at Kennedy Krieger Institute. In accordance with federal copyright restrictions, the contents of this booklet may not be reproduced by photocopying or any other means without written permission from the copyright holder. © 1999 George Capone, M.D.


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