Across a range of neurodevelopmental conditions, a diagnosis of attention deficit hyperactivity disorder (ADHD) has been shown to be associated with executive function impairment. However, the DSM-V emphasis upon viewing psychological characteristics as existing on a continuous distributed quantitative dimension has enabled the opportunity to consider the influence of sub-diagnostic or sub-referral levels of these psychological characteristics upon cognitive function. This study adopted a continuum approach to the consideration of this ADHD influence and examined the extent to which the difference in parental reported executive functions between children with Tourette syndrome (TS) or typically developing children could be mediated by a concurrent group difference in the possession of sub-referral levels of ADHD-like characteristics. A total of 146 children, 58 with reported TS diagnosis, participated. Parental report measures of ecological executive functioning, the Child Executive Functioning Inventory, and the Vanderbilt ADHD Diagnostic Parent Rating Scale were employed. The analyses with a full sample and a sub-referral sample revealed significant group differences in most of the key measures. In addition, these measures were highly correlated even when controlling for age and gender. A series of mediation analyses indicated that in all models, the ADHD-like measures significantly mediated the group difference in executive function. These results suggest that sub-referrals levels of ADHD-like characteristics continue to contribute to executive challenges in TS. Future intervention research targeting these executive functions should consider the presence of ADHD-like characteristics at sub-referral levels of possession.
Keywords: ADHD-like characteristics; Children; Tourette syndrome; executive function; mediation analyses.