Influence of sympathetic autonomic arousal on Tics: Implications for a therapeutic behavioural intervention in Tourette syndrome

Abstract

Objectives: The pharmacological treatment of Tourette syndrome (TS) has improved due to the application of new medications and combinations of medications, coupled to greater phenomenological and neurobiological understanding of the condition. Nevertheless, for many individuals with TS, potentially troublesome tics persist despite optimized drug treatment. Anecdotally, a relationship is frequently described between tic frequency and states of bodily arousal and/or focused attention. The galvanic skin response (GSR) is an accessible and sensitive index of sympathetic nervous activity, reflecting centrally induced changes in peripheral autonomic arousal. Sympathetic nervous arousal, measured using GSR, has been shown to have an inverse relationship with an electroencephalographic index of cortical excitability (slow cortical potential), and GSR arousal biofeedback shows promise as an adjunctive therapy in management of treatment-resistant epilepsy. Method: We examined how changes in sympathetic arousal, induced using GSR biofeedback, impact on tic frequency in individuals with TS. Two different physiological states (sympathetic arousal and relaxation) were induced using GSR biofeedback in 15 individuals with a diagnosis of TS. During both biofeedback sessions, participants were videotaped to monitor the occurrence of tics. Results: We observed significantly lower tics during relaxation biofeedback compared to arousal biofeedback, with tic frequency positively correlating with sympathetic arousal during the arousal session. Conclusion: These findings indicate that the conjunction of focused attention to task and reduced peripheral sympathetic tone inhibits tic expression and suggests a potential therapeutic role of biofeedback relaxation training for tic management in patients with TS.