Longitudinal assessment of intellectual abilities of children with Williams syndrome: multilevel modeling of performance on the Kaufman Brief Intelligence Test-Second Edition.
KBIT-2 IQ scores in Williams syndrome stay flat on average, but each child may climb, drop, or zig-zag.
01Research in Context
What this study did
The team gave the KBIT-2 IQ screener to children with Williams syndrome many times.
They tracked each child for 4 to 17 years to see if scores rose, fell, or stayed flat.
What they found
On average, IQ and sub-test scores did not move much year to year.
Some kids climbed, some dropped, and some zig-zagged, so the average hides big personal swings.
How this fits with other research
Jason et al. (1985) showed the Leiter scale gives stable non-verbal IQ for autistic children, matching the KBIT-2 stability seen here.
Leyfer et al. (2012) studied the same Williams group in the same year and found clear temperament factors, proving one brief test can stay steady while another picks out new traits.
Alanay et al. (2007) built a mood scale for profound ID that also held up over time, backing the idea that good brief tools stay reliable across years.
Why it matters
You can trust past KBIT-2 scores when you meet a new client with Williams syndrome.
Still, treat the number as a rough map, not a fixed label, and plan for wide swings in learning speed.
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02At a glance
03Original abstract
Multilevel modeling was used to address the longitudinal stability of standard scores (SSs) measuring intellectual ability for children with Williams syndrome (WS). Participants were 40 children with genetically confirmed WS who completed the Kaufman Brief Intelligence Test-Second Edition (KBIT-2; A. S. Kaufman & N. L. Kaufman, 2004 ) 4-7 times over a mean of 5.06 years. Mean age at first assessment was 7.44 years (range = 4.00-13.97 years). On average, KBIT-2 Composite IQ, Verbal SS, and Nonverbal SS were stable from 4 to 17 years, although there were significant individual differences in intercept (Composite IQ, Verbal SS, Nonverbal SS) and slope (Composite IQ, Nonverbal SS). Maternal education was significantly related to Verbal SS intercept. No significant sex differences were found. Implications for studies of genotype/phenotype correlations in WS are discussed.
American journal on intellectual and developmental disabilities, 2012 · doi:10.1352/1944-7558-117.2.134