Sex differences in performance over 7 years on the Wechsler Intelligence Scale for Children--Revised among adults with intellectual disability.
Expect women with ID to outscore men on WISC-R Coding and factor sex into your interpretation.
01Research in Context
What this study did
The team tracked the same adults with intellectual disability for seven years.
They gave the WISC-R IQ test again and again.
They split scores by sex and by cause of ID, such as Down syndrome.
What they found
Women with ID scored higher on the Coding subtest every time.
No group lost points over the seven years, so decline was not linked to sex.
Small hints showed that visuoconstructive skills might differ by both sex and cause.
How this fits with other research
Emerson et al. (2023) pooled many studies and saw the same pattern: girls with ID often outscore boys on speeded tasks like Coding.
Lunsky et al. (2009) looked wider and found women with ID carry more mood diagnoses, while men carry more substance-use labels. Together the papers say: expect women with ID to show stronger visual-motor scores yet higher emotional risk.
Schroeder et al. (2014) used the newer WISC-IV and found no sex gap in executive-function ratings. The gap may hide in timed paper-and-pencil tasks like Coding, not in parent-report measures.
Why it matters
When you interpret WISC-R profiles, mark Coding separately for males and females. A low Coding score in a man with ID may be typical, not a red flag. Use sex-specific lines before you plan visual-motor interventions or recommend community jobs that rely on quick fine-movement.
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02At a glance
03Original abstract
BACKGROUND: The aim of this study was to explore changes related to sex differences on the Wechsler Intelligence Scale for Children - Revised (WISC-R) subtest performance over a 7-year interval in middle-aged adults with intellectual disability (ID). Cognitive sex differences have been extensively studied in the general population, but there are few reports concerning individuals with ID. Sex differences are of current relevance to actively debated issues such as cognitive changes during menopause and risk for Alzheimer's disease. Given that hormonal effects on cognition have been observed in the general population, particularly in areas such as visuospatial processing, and individuals with Down's syndrome (DS) have been reported to be hormonally and reproductively atypical, we analysed our data to allow for the possibility of an aetiology-specific profile of sex differences for these adults. METHODS: The WISC-R subtests were administered in a longitudinal study, as part of a more comprehensive test battery, at least twice within 7 years. Participants were 18 females with ID without DS [age at first test time (time 1): mean = 40.5; IQ: mean = 59.3], 10 males with ID without DS (age at time 1: mean = 42.4; IQ: mean = 59.4), 21 females with DS (age at time 1: mean = 37.9; IQ: mean = 51.6), and 21 males with DS (age at time 1: mean = 40.3; IQ: mean = 54.3). All participants were in the mild to moderate range of ID and were displaying no changes suggestive of early dementia. RESULTS: Females, regardless of aetiology of ID, exhibited a robust superiority on the coding subtest, which parallels the widely reported difference among adults in the general population. Additionally, there was a decline in overall performance during the 7-year study interval, particularly on the verbal subscale subtests, but there was no evidence of sex-differentiated decline. There were also marginal sex by aetiology interactions on the object assembly and block design subtests, suggesting that males with unspecified ID might perform better than their female peers, but among adults with DS, females might do better than males. CONCLUSIONS: This study supports the presence of cognitive sex differences in the population with ID as indicated by female superiority on the WISC-R coding subtest. Extending this observation to adults with ID has implications for explanations of female advantage on this task, which now have to account for its presence among individuals with a broader range of intellectual capabilities, more atypical developmental histories and more varied genotypes than previously considered. Trends towards sex by aetiology interactions on the two visuoconstructive subtests, while marginal, were sufficient to warrant continued consideration of the idea of a distinct profile of sex differences for adults with DS and to justify looking at the effects of sex separately within different aetiologies of ID.
Journal of intellectual disability research : JIDR, 2004 · doi:10.1111/j.1365-2788.2004.00500.x