Public health significance of tic disorders in children and adolescents.

In conclusion, data from community surveys suggest that tic disorders, including TS, exist on a spectrum from transient to persistent, multiple motor, and vocal tics that interfere with activities of daily living. The presence of isolated and transitory tics is common and appears to be of minimal consequence. On the other hand, persistent tics, even mild tics, appear to be associated with ADHD, disruptive behavior, and learning problems (though not necessarily formal learning disability). The presence of ADHD with tics increases the likelihood of disruptive behavior and learning problems, but learning problems can be observed in community samples of children with tic disorders, even in the absence of ADHD. To date, few studies have clearly defined the nature of the learning problems in children with tic disorders. Nonetheless, the data do suggest that having chronic tics is associated with impairment independent of ADHD. Community samples and recent investigations in clinical samples confirm that the presence of ADHD predicts greater disability than that associated with tic disorders alone.