Comparative study of the behavioral and neuropsychologic characteristics of tic disorder with or without attention-deficit hyperactivity disorder (ADHD).

To study the nature of the comorbidity of tic disorder and attention-deficit hyperactivity disorder (ADHD), patients with tic disorder with or without ADHD were compared on the basis of clinical ratings and neuropsychologic tests. Seventy-eight children were involved in this study: 16 with tic disorder, 19 with comorbid tic disorder and ADHD, 21 with ADHD, and 22 normal controls. Rating scales for ADHD, the Child Behavior Checklist and the Yale Global Tic Severity Scale, were completed in clinical groups. To identify differences in neuropsychologic function among the four groups, the results of seven neuropsychologic tests of global cognitive abilities, attention, information-processing capacity, and fine motor skill were compared. On most behavioral and neuropsychologic tests, the tic disorder with ADHD and the ADHD groups demonstrated similar performance patterns and marked deficits compared with the tic disorder and the control groups, whereas in most of the attention tests, the ADHD group made more commission errors than the tic disorder with ADHD group. These findings suggest that the tic disorder with ADHD group has marked cognitive deficits and behavioral disturbance similar to the ADHD group, whereas the tic disorder group is more similar to the controls. The tic disorder with ADHD group might represent a true comorbidity of the two disorders.