Patterns of change in nonverbal cognition in adolescents with Down syndrome.
In teens with Down syndrome, standard IQ freezes but raw nonverbal skill keeps climbing—track growth scores to see real progress.
01Research in Context
What this study did
Channell et al. (2014) tracked nonverbal thinking skills in teens with Down syndrome. They gave the same IQ test twice, three years apart. The team looked at both standard scores and raw growth scores to see what really changed.
What they found
Standard IQ numbers stayed flat. Raw ability scores went up. Gains showed up in some subtests more than others. The teens learned new skills even though their rank among peers did not move.
How this fits with other research
Couzens et al. (2011) saw the same flat line for language-heavy tasks and a slow rise for puzzles. Moore narrows the lens to adolescence and finds the same puzzle rise.
Sabat et al. (2019) add adaptive behavior data. They show social skills stay stronger than practical skills, matching the uneven cognitive pattern Moore found.
Alaimo et al. (2015) follow adults and see skill breadth shrink with age. Together the papers sketch a arc: raw skills grow in adolescence, then the menu of daily skills contracts in adulthood.
Why it matters
Stop waiting for IQ scores to jump. Plot raw growth scores instead to show families real gains. Pick goals in subtests that still rise, like pattern puzzles. Plan for a future where daily skills may narrow, so teach a wide menu now while the brain is still adding abilities.
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02At a glance
03Original abstract
This study was designed to examine longitudinal change in nonverbal cognitive abilities across adolescence for 20 males with Down syndrome (DS). We used hierarchical linear modeling to examine the rate of change in performance on the subtests of the Leiter-R Brief IQ across four annual time points and to determine the relation between maternal IQ and level and rate of change in performance. Results indicated no significant change in IQ (standard scores) with age in the sample, suggesting IQ stability during adolescence for individuals with DS, although several participants performed at floor level on the standard scores for the Leiter-R, limiting interpretation. Growth scores, however, provide a metric of absolute ability level, allow for the examination of change in Leiter-R performance in all participants, and minimize floor effects. Results from the analysis of growth scores indicated significant gain in absolute nonverbal cognitive ability levels (growth score values) over time for the adolescents with DS, although the growth varied by subdomain. Maternal IQ did not explain variability in cognitive performance or change in that performance over time in our sample of adolescents with DS.
Research in developmental disabilities, 2014 · doi:10.1016/j.ridd.2014.07.014