ABSTRACT
Tourette’s syndrome (TS) is characterized by the waxing and waning of signs and symptoms as a part of the natural history of the disease. External stressors, medications, and behavioral changes may all influence the expression of motor signs and symptoms in TS. Medication effects on TS may be helpful in elucidating the pathophysiology of the illness because certain mechanisms may be implicated by distinct classes of agents. Effects of stimulants on TS have been widely studied. Stimulants’ propensity to exacerbate or even induce symptoms of TS has provided important support for the hypothesis that the dopaminergic (DA) system plays a role in the development of tics. Although stimulants may induce or exacerbate tics in some patients with TS or attention-deficit/hyperactivity disorder (ADHD), not all patients experience this side effect. Stimulants also have effects other than simple potentiation of DA neurotransmission, and DA receptor antagonists are not always effective in management of tics in TS patients. Review of drugs that induce or exacerbate tics suggests that a complex interplay of neurotransmitter systems occurs, and that any effect on tics cannot be understood simply as potentiation of DA neurotransmission. This chapter reviews drug-induced exacerbation of tics in existing TS and drug-induced precipitation of tics.
