Validation of attention-deficit-hyperactivity disorder subtypes among Taiwanese children using neuropsychological functioning

Objective: The findings regarding the validity of attention-deficit-hyperactivity disorder (ADHD) subtypes using neuropsychological functioning have been inconsistent; and no such study has been conducted in an ethnic Chinese population. The aim of the present paper was therefore to examine the validity of attention tasks in distinguishing the ADHD-combined type (ADHD-C) from the ADHD-inattention type (ADHD-I), as compared to children without ADHD in Taiwan. Methods: Participants included 52 children with ADHD-C, 17 with ADHD-I, and 52 controls, aged 7-10 years. The clinical diagnosis of DSM-IV ADHD was further confirmed by a standardized psychiatric interview. Four attention components were examined: sensory selection, response selection, capacity/focus, and sustained attention, using the Cancellation Test, Digit Span, Trail-Making Test (TMT), Continuous Performance Test (CPT), and Circle-Tracing Test. Behaviour symptoms were rated by the parents, teachers, and investigators. Results: Compared to children without ADHD, children with ADHD scored significantly higher in parent-reported and investigator-rated behavioural symptoms, and performed worse in the four domains of attention. Multiple comparisons indicated that children with ADHD-C had a worse performance on most tests than children with ADHD-I, except that children with ADHD-I had more off-target errors on the TMT with alphanumeric sequencing than children with ADHD-C. Conclusions: Attention tests can distinguish Taiwanese children with ADHD from those without ADHD, and these tests also demonstrate different profiles between the ADHD-C and ADHD-I groups. Further investigation on this topic should include the ADHD-hyperactivity-impulsivity subtype (ADHD-HI) and increase sample sizes of the children with ADHD-I and ADHD-HI. (ClinicalTrials.gov number, NCT00494819.).