Premonitory Urges

It is easy to think of Tourette syndrome (TS) as nothing more than the involuntary movements and sounds (see List of Possible Tics) that are the noticeable part of a tic from the perspective of an outside observer. However, before the movement or sound occurs, many individuals experience a premonitory urge. The premonitory urge is a feeling of tension or discomfort that comes before the visible tic. If the tic is delayed, the urge tends to go up, increasing discomfort. Once the tic is performed, the urge goes away either partially or completely. Unfortunately for individuals with TS the urge, along with the discomfort, keeps coming back and the tic is performed again and again (see What it is Like to Have a Tic).

Premonitory urges are a major factor in a process called reinforcement that makes certain tics habitual. Reinforcement describes the principle where an animal increases any action that immediately increases pleasure or decreases discomfort. For example, if a pigeon is rewarded with food every time it pecks a button, it will quickly learn to peck the button again and again. In the case of tics, humans with TS learn to make a specific movement or sound to relieve the discomfort of the premonitory urge. The more the tic is performed when the urge is present, the stronger the connection between the tic and the urge. The behavioral treatment, Habit Reversal Training (HRT/CBIT) teaches individual to break the connection between the tic and the urge. Certain medications can decrease the premonitory urge and subsequent tic behavior.