The list of associated problems in TS continues to increase. It has become clear that the presence of psychopathology is more pervasive than was previously estimated. The presence of a child with TS in the home, especially one with behavioral comorbidity, can have a significant negative effect on the parents. Several common comorbid problems include obsessive-compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), mood disorder, episodic outbursts, and academic difficulties:
OCD - The incidence of obsessive-compulsive behaviors (OCB) in TS is typically reported to be in the range of 40-50 percent Some studies report up to 60-89 percent. Obsessive behaviors generally emerge several years after the onset of tics, usually during early adolescence. Behaviors can include a need for order or routine and a requirement for things to be symmetrical or "just right." Thus, compulsions typically involve arranging, ordering, hoarding, touching, tapping, rubbing, counting, checking for errors and evening-up rituals (performing activities until things are symmetrical or feel/look just right). It has been suggested that tics and compulsions represent a clinical spectrum in TS with symptoms sharing many overlapping features.
ADHD - Attention deficit hyperactivity disorder is characterized by impulsivity, hyperactivity and a decreased ability to maintain attention. The disorder is common in TS patients and is reported to affect about 50 percent of referred TS cases. ADHD typically begins between ages four and five and usually precedes the onset of tics by two to three years in TS patients.
Depression and Anxiety - Some investigators believe depression positively correlates with earlier onset and longer duration of tics, whereas others find no correlations between depression and the number of tics.
Rage Attacks - Rage attacks and difficulties with aggression have been described in patients with TS. Whether these problems are etiologically related to TS or other comorbid conditions is under review.
Academic Difficulties - Severe tics, psychosocial problems, ADHD, OCD, learning disabilities, and medications can result in poor school performance in children. Individuals with TS typically have normal intellectual functioning, although there may be executive dysfunction, discrepancies between performance and verbal IQ, impairments of visual perceptual achievement or a decrease in visual-motor skills.