Two longitudinal studies of the abilities of people with Down's syndrome.
Better services hardly moved test scores in two nine-year Down syndrome cohorts.
01Research in Context
What this study did
Researchers followed two groups of people with Down syndrome for nine years. Group one started in 1986. Group two started in 1991.
Both groups took the same language, memory, and problem-solving tests every year. The second group had better schools, more therapy, and new laws on their side.
What they found
Only one test score improved between the two groups. It was a picture-vocabulary test. Every other skill stayed flat.
Better services did not speed up development. The kids still gained skills, but at the same slow pace as before.
How this fits with other research
Brinton et al. (1996) looks like it clashes with this paper. Their parent-training program cut problem behavior in half for kids with Down syndrome. The difference is focus: Shepperdson (1995) counted test scores; Brinton et al. (1996) counted real-life behavior.
Koegel et al. (1992) backs up the slow-gain picture. Seven social-intelligence tests stayed stable in teens with ID, just like the Down syndrome skills tracked here.
Vassos et al. (2023) updates the story. Their new 18-item emotional-development scale is reliable for adults with ID. It gives you a sharper tool today than the 1995 battery.
Why it matters
Do not expect bigger test jumps just because services look better on paper. Keep your goals tight and concrete. Use brief probes every session to see real progress instead of waiting for big score leaps that may never come.
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02At a glance
03Original abstract
A cohort of subjects with Down's syndrome born in South Wales, UK, in 1964, 1965 and 1966, and living at home, was studied as infants, teenagers and young adults (the original cohort). Carers were interviewed and the abilities of the subjects assessed, using a variety of measures. Average scores of the cohort improved over the years, although the rate of progress slowed down between the teenage and adult years. Scores were related to social class, stimulation given in the home, and at older ages, maternal age at the birth of the subject. This latter finding was unexpected. A comparative cohort of subjects with Down's syndrome from South Wales born in 1973, 1974 and 1975 was studied as infants and teenagers. They were at the same stage as the original cohort as infants and teenagers, but living 9 years later. In spite of the comparative cohort coming from a favoured background, in terms of social class and having access to improved services, mean scores at the teenage stage were only significantly better on one test of language than those of the original cohort at the same age. Most studies find that females with Down's syndrome have higher abilities than males: this was the case for the original cohort, but not for the comparative cohort.
Journal of intellectual disability research : JIDR, 1995 · doi:10.1111/j.1365-2788.1995.tb00546.x