For WISC-IV variables, there were significant multivariate effects for both independent variables: AE [F (4, 333) = 17.78, p < .001, partial η2 = 0.176] and ADHD [F (4, 333) = 11.96, p < .001, partial η2 = .126], and the covariates of Sex [F (4,333) = 8.88, p < .001, partial η2 = .096] and Age [F (4,333) = 2.68, p =.032), partial η2 = .031]. The AE × ADHD interaction was also significant [F (4, 333) = 3.33, p = .011, partial η2 = .038]. To probe the significant multivariate effects, we examined the between-subjects effects for each individual dependent variable. There were significant main effects of AE and ADHD diagnosis (ps < .001) on each of the WISC-IV index composite scores; Verbal Comprehension, Perceptual Reasoning, Working Memory, and Processing Speed indices (VCI, PRI, WMI, PSI). Heavy prenatal alcohol exposure was associated with lower WISC-IV scores, regardless of ADHD diagnosis. Also, children with ADHD exhibited lower scores on WISC-IV scores than children without ADHD, across levels of AE. The AE × ADHD diagnosis interaction effects were statistically significant
