Executive function in fluency and recall measures among children with Tourette syndrome or ADHD

This study assessed two relevant aspects of executive dysfunction in childr en with either Tourette syndrome (TS) or ADHD. Process variables derived fr om existing neuropsychological measures were used to clarify the executive function construct. Clustering of responses on measures of verbal fluency, figural fluency, and verbal learning was examined to assess strategic respo nse organization. Rule breaks, intrusions, and repetition errors were recor ded to assess inhibition errors. No significant differences were found amon g the three groups (TS, ADHD, and controls) on tasks of response organizati on (clustering). In our sample, both the ADHD and the TS groups were largel y free from executive function impairment. and their performance on thr flu ency and list learning tasks was in the average range. There was a signific ant group difference on one of the disinhibition variables, with both TS an d ADHD groups showing significantly more intrusions on verbal list learning trials than controls. When more traditional total score variables were ana lyzed among the three groups, there were no significant differences; howeve r, analysis of effect size revealed medium-to-large effect sizes for Letter Word Fluency total score differences (ADHD vs. controls), and for Semantic Word Fluency total score differences (ADHD vs. TS), with the ADHD group ha ving weaker performance in both comparisons. Results provide some support f or the use and analysis of process variables-particularly those related to inhibition and intrusion errors, in addition to the total score variables w hen assessing executive function deficits in children with ADHD and TS. Whi le group differences may be found, children with uncomplicated TS should no t routinely be considered to have significant executive function impairment s, and when deficits are found, they may be attributable to other comorbid disorders.