2018 Volume 59 Issue 2 Pages 187-198
The core symptoms of Attention-deficit/Hyperactivity Disorder (ADHD) are inattention, hyperactivity, and impulsivity. Among these, impulsivity has a particularly profound effect on daily life. The co-occurrence of Autism Spectrum Disorder (ASD) and ADHD was formally recognized as ADHD/ASD with the introduction of DSM-5. However, little is known on how the co-occurrence of ASD with ADHD affects impulsivity. Hence, in this study, we utilized near-infrared spectroscopy (NIRS) to assess the frontal lobe functions associated with impulsive behavior in patients with ADHD and ADHD/ASD. The study involved a group of 15 patients with ADHD (mean age, 8.93 years), a group of 15 patients with ADHD/ASD (mean age, 8.64 years), and a control group of 15 subjects of corresponding age, sex, and intelligence quotients. Utilizing the Stroop Color- Word Test as an activation task, we compared the ADHD and ADHD/ASD groups by measuring changes in prefrontal cortex oxyhemoglobin during task performance. As results, the ADHD and ADHD/ ASD groups showed significantly lower values compared to the control group for channels 5, 15, 16, and 23 among the 24 channels of the frontal region. Similarly, the ADHD group showed significantly lower values than the control group for channel 11, and the ADHD/ASD group showed significantly lower values than controls for channel 12. Furthermore, both the ADHD and ADHD/ASD groups provided significantly fewer correct responses and significantly more incorrect responses than the control group. These results suggest there is no difference between the ADHD and ADHD/ASD groups regarding executive function failure including impulsivity, based on hemodynamic responses in the prefrontal cortex and Stroop color-word task performance.