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-defici t hyperactivity disorder (ADHD), patients with tic disorder with or without ADHD were compared on the basis of clinical ratings and neuropsychologic t ests. Seventy-eight children were involved in this study: 16 with tic disor der, 19 with comorbid tic disorder and ADHD, 21 with ADHD, and 22 normal co ntrols. Rating scales for ADHD, the Child Behavior Checklist and the Yale G lobal Tic Severity Scale, were completed in clinical groups. To identify di fferences in neuropsychologic function among the four groups, the results o f seven neuropsychologic tests of global cognitive abilities, attention, in formation-processing capacity, and fine motor skill were compared. On most behavioral and neuropsychologic tests, the tic disorder with ADHD and the A DHD groups demonstrated similar performance patterns and marked deficits co mpared 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 d isorder 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 c ontrols. The tic disorder with ADHD group might represent a true comorbidit y of the two disorders.