Growth and Decline in Language and Phonological Memory Over Two Years Among Adolescents With Down Syndrome.

The study followed participants for only two years, so small or nonlinear changes could have been missed. The sample was modest, and the analyses of individual reliable change were exploratory because standard errors had to be estimated with compromises. Eligibility required English speech, adequate vision and hearing, and no autism spectrum disorder, so the results do not necessarily apply to all adolescents with Down syndrome. There was no same-age comparison group with another intellectual disability, so the pattern cannot be said to be specific to Down syndrome. There was no treatment, control group, or random assignment, so the study describes change over time rather than effects of therapy.

The article is listed as supported by NIH extramural research funding. The supplied text does not include a separate conflict-of-interest declaration.

Do not read the improvements in the younger group as proof that therapy caused them. The study assigned no treatment and had no control group, and the full sample showed no significant change in expressive vocabulary or digit memory.