Longitudinal trajectories of intellectual and adaptive functioning in adolescents and adults with Williams syndrome.
In Williams syndrome, daily living skills slip even when IQ holds steady—so keep adaptive training across the lifespan.
01Research in Context
What this study did
The team followed 44 people with Williams syndrome for up to nine years. Ages ranged from 12 to 52.
Every two years they gave the same IQ test and the Vineland Adaptive Behavior Scales. They wanted to see if scores changed over time.
What they found
IQ scores stayed almost the same. Adaptive behavior scores dropped. The drop was biggest in daily living skills like cooking, money, and hygiene.
By the final visit, most adults needed more help than they did as teens.
How this fits with other research
Deserno et al. (2017) saw the same IQ-adaptive gap in adults with autism. Both studies show bright adults falling behind in real-life skills.
Pathak et al. (2019) found the gap starts in childhood for autism. H et al. now show it keeps widening into adulthood for Williams syndrome.
Schaaf et al. (2015) warned that new DSM rules can remove the autism label from high-IQ clients. Together these papers tell us: high IQ does not protect anyone from daily-living deficits.
Why it matters
If you serve teens or adults with Williams syndrome, keep teaching adaptive skills even when IQ looks strong. Schedule periodic Vineland checks and write goals for money, cooking, and self-care. Do not fade services just because the person scores in the average IQ range.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Pull your oldest Williams client, run a quick Vineland, and add one adaptive goal for money or hygiene.
02At a glance
03Original abstract
BACKGROUND: Williams syndrome (WS) is associated with a distinct cognitive-behavioural phenotype including mild to moderate intellectual disability, visual-spatial deficits, hypersociability, inattention and anxiety. Researchers typically characterise samples of individuals with WS by their intellectual functioning and adaptive behaviour. Because of the low prevalence of the syndrome, researchers often include participants with WS across a broad age range throughout childhood and adulthood and assume participants demonstrate consistent cognitive development across ages. Indeed, IQ scores are generally stable for children and adolescents with WS, although there are significant individual differences. It is less clear whether this pattern of stable intellectual ability persists into adulthood. Furthermore, while adaptive behaviour is an important indicator of an individual's ability to apply their conceptual skills to everyday functioning, conflicting findings on the trajectories of adaptive behaviour in adolescents and adults with WS have been reported. The current study examined longitudinal profiles of cognitive and adaptive functioning in adolescents and adults with WS. METHOD: To examine cognitive functioning, participants included 52 individuals with WS (51.9% men) who were assessed with the Kaufman Brief Intelligence Test, 2nd edition (KBIT-2) between two and seven times. At their first assessment, participants had a mean age of 25.4 years (SD = 8.4), ranging in age from 14.2 to 48.9 years. To assess adaptive behaviour, participants included a subset of 28 individuals with WS whose parents completed the Vineland Adaptive Behavior Scale, 2nd edition (VABS-II) between two and five times. At their initial administration, participants ranged from 17.1-40.2 years of age, with a mean age of 26.5 years (SD = 7.3). A series of multilevel models were used to examine changes in KBIT-2 Composite IQ, Verbal IQ and Nonverbal IQ standard scores over time, as well as the Adaptive Behavior Composite, and the Communication, Daily Living Skills and Socialization subdomains of the VABS-II. RESULTS: Consistent with the WS cognitive profile, IQ scores were significantly lower than the general population IQ score of 100, and there was significant variability in individual IQ scores and slopes. KBIT-2 IQ scores were generally stable across adolescents and adults with WS. Adaptive behaviour scores were significantly lower than the population mean score of 100, and there was significant variability in individuals' adaptive behaviour scores but not trajectories. However, in contrast to the findings with the KBIT-2, VABS-II scores were observed to significantly decrease over time. CONCLUSION: Findings suggest that while intellectual functioning remains stable, adaptive functioning does not remain stable across adolescence and adulthood in individuals with WS. Implications for the relation between cognitive and adaptive functioning across development are discussed, with a focus on how this relates to specific aspects of the WS phenotype.
Journal of intellectual disability research : JIDR, 2016 · doi:10.1111/jir.12303