ADHD, Subtypes and Cognitive Performance: WISC-V as a Support Tool for Diagnostic Assessment

BACKGROUND: Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental condition characterized by impairments in working memory (WM) and processing speed (PS). Previous studies using earlier editions of the Wechsler Intelligence Scale for Children (WISC) have identified a cognitive response pattern defined by lower Cognitive Proficiency Index (CPI). However, evidence using the Wechsler Intelligence Scale for Children-Fifth Edition (WISC-V) remains limited. This study aimed to examine whether the WISC-V identifies a characteristic cognitive profile in ADHD and to evaluate its discriminative capacity. METHODS: The sample consisted of 188 participants aged 6-16 years, including a control group (n = 56) and two clinical ADHD groups: The combined presentation of ADHD (ADHD-C; n = 57) and the predominantly inattentive presentation of ADHD (ADHD-I; n = 75). Cognitive functioning was assessed using the WISC-V. Group differences were examined using Multivariate and Univariate Analyses of Covariance (MANCOVA/ANCOVA). Binary logistic regression analyses were conducted to evaluate the predictive capacity of WISC-V. RESULTS: Compared with controls, the clinical ADHD group showed significant multivariate differences. Univariate analyses revealed significantly lower performance in the working memory index (WMI; p < 0.001), processing speed index (PSI; p < 0.001), CPI (p < 0.001), and Full-Scale Intelligence Quotient (FSIQ; p = 0.005), in the clinical ADHD group. Differences between ADHD-C and ADHD-I were observed, with the ADHD-I group showing lower scores in WMI (p = 0.016), PSI (p < 0.001), CPI (p < 0.001), and FSIQ (p = 0.016). Logistic regression analyses indicated that WMI (B = -0.067; p < 0.001), PSI (B = -0.043; p = 0.007), and CPI (B = -0.091; p < 0.001) significantly predicted control versus clinical ADHD group membership. When comparing ADHD presentations, PSI (B = -0.055; p = 0.001) and CPI (B = -0.063; p < 0.001) emerged as significant predictors. CONCLUSIONS: The findings support the use of the WISC-V as a complementary tool in the diagnostic assessment of ADHD.