Measures of executive functions predicting Attention-Deficit/Hyperactivity Disorder core symptoms

Attention-deficit/hyperactivity disorder (ADHD) is a common childhood disorder, and in many children, ADHD is thought to be aggravated by a deficit in executive functions (EFs). This study tried to establish whether commonly used neuropsychological tests of EF also predicted the core symptoms of ADHD, namely hyperactivity/impulsiveness (H/I) and inattention, as well as total ADHD symptomatology, according to the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR). The participants were children from the Limpopo province, South Africa, aged from 6 to 15 years (M = 11.7 years; SD = 1.7). One hundred and fifty-six children (51.3% girls) were assessed by neuropsychological tests of EFs: the Tower of London (ToL), Digits Forward and Digits Backward, Trails-A and Trails-B and Wisconsin Card Sorting Test (WCST). Forward stepwise regression analysis was employed to predict H/I and inattention, as well as total ADHD symptomatology, based on DSM-IV-TR criteria. All the tests, except Trails-A, were found to predict ADHD symptomatology. The WCST (total errors) was the best predictor of all the ADHD symptoms and also for H/I and inattention separately, followed by Trails-B and Digits Backwards, which were found to predict more symptoms of inattention than H/I. Perseverative errors on the WCST predicted more H/I symptomatology, whilst non-perseverating errors were more associated with inattention. The ToL and Digits Forward predicted fewer ADHD symptoms. The ToL seemed more sensitive to inattention, whilst Digits Forward showed a stronger association with H/I. The WCST, Digits Backwards and Trails-B may be used to measure EF to support the diagnosis of ADHD in a clinical setting and to indicate cognitive impairment.