Relatively independent inhibitory control and cognitive flexibility deficits on the WCST in children with ADHD: age-related change patterns and cognitive profiles.

BACKGROUND: Debate persists regarding whether executive dysfunction in ADHD arises from a single core deficit or reflects impairments across multiple relatively independent components. Using the Wisconsin Card Sorting Test (WCST), this study examined the relative independence of inhibitory control and cognitive flexibility deficits, their age-related change patterns, and identifiable cognitive profiles in children with ADHD. METHODS: A total of 281 children with ADHD (aged 7-12 years) completed the WCST. Trial-level generalized linear mixed models examined predictors of response accuracy, and Gaussian mixture modeling identified cognitive profiles based on perseverative error rate (PER; inhibitory control) and shape rule disadvantage (SRD; cognitive flexibility). RESULTS: PER and SRD showed a weak positive correlation (r = .245, shared variance = 6.0%). Shape rule exerted a significant main effect on accuracy after controlling for covariates. A significant negative cross-sectional association with age was found for PER but not for SRD, although the age × deficit type interaction was not significant (p = .794). Two cognitive profiles were identified: a mild deficit profile (38.1%) with relatively preserved cognitive flexibility, and a dual deficit profile (61.9%) with concurrent impairments. CONCLUSIONS: Inhibitory control and cognitive flexibility deficits are relatively independent in children with ADHD, broadly consistent with multi-component frameworks of executive function. The identification of two cognitive profiles with distinct impairment patterns provides a foundation for comprehensive assessment, though these profiles require further validation through longitudinal and independent cohort studies.