Investigating the effects of tic suppression on premonitory urge ratings in children and adolescents with Tourette's syndrome.

Tics represent a complex class of behaviors that have a neurobiological origin and are influenced by factors both internal and external to the individual. One factor that has gained recent attention is the premonitory urge. Contemporary behavioral models suggest that some tics are preceded by aversive somatic urges that increase in severity when tics are suppressed and are attenuated by performance of the tic. It has been proposed that the removal of premonitory urges may strengthen or maintain tics via negative reinforcement. This investigation is the first to empirically evaluate the effect of tic suppression on the premonitory urge phenomenon. Five children and adolescents, ages 8-17years, participated in the study. Using an ABAB reversal design, tic frequency and subjective premonitory urge ratings were recorded under conditions of free-to-tic baseline (BL) and reinforced tic suppression (differential reinforcement of zero-rate behavior). Results show that four of the five children demonstrated reliable suppression. Of the four children who achieved suppression, three demonstrated a pattern in which subjective urge ratings were higher during suppression than during BL. Results provide preliminary support for the negative reinforcement view of tic function for some children.