Substance Use Disorder in Adult Tourette Syndrome: Frequency, Profile, and Comorbidities

Introduction

Although defined by tics, Tourette syndrome (TS) is a complex neuropsychiatric disorder commonly featuring symptoms of obsessive-compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), and a variety of associated mood and behavioral disturbances. Multifaceted in its expression, TS has been conceptualized fundamentally as a disorder of inhibition. Thus, simple and complex motor and vocal tics may result from disordered inhibition of unwanted motor patterns. Associated failures of behavioral and affective inhibition frequently manifest as behavioral impulsivity, including nonobscene complex socially inappropriate behaviors, ADHD, explosive emotional outbursts or rage reactions, aggression, self-injurious behaviors, and conduct disorder.

Abstract

INTRODUCTION

Previous studies have suggested that substance use disorder (SUD) may be over-represented in patients with Tourette syndrome (TS). Nevertheless, this association has received relatively little attention, despite the presence in both conditions of psychic urges or cravings and the prominence in TS of symptoms commonly associated with addiction, including mood and impulse-control dysregulation. The profile of SUD in TS is of both theoretical and practical interest, in view of the differential impact of certain common drugs of abuse on tics and other TS-related symptomatology.

OBJECTIVES

To assess the frequency, pattern, and comorbidities of SUD in a clinic population of adult TS subjects.

METHODS

Clinical records of adult TS patients followed at a University neurology clinic, which included formal ratings of tic and OCD severity, as well as information from a modified version of the Centre for Addiction and Mental Health Concurrent Disorders Screener (CAMH-CDS), were reviewed retrospectively. Patients with and without a history of SUD were compared with respect to severity of tics and comorbid psychiatric disorders.

RESULTS

Fifteen of the 66 TS patients (23%) had a history of SUD. Abused substances included not only those which might alleviate tics, such as cannabis and benzodiazepines, but also cocaine, with its strong tic-aggravating potential. Mood and impulse dysregulation in the form of panic disorder and rage attacks predicted SUD. Obsessive-compulsive disorder was not associated with SUD, consistent with the conceptual separation of both substance and behavioral addictions from obsessive-compulsive spectrum disorders.

CONCLUSIONS

SUD, primarily involving non-alcoholic substances, may be twice as common in symptomatic TS adults as in the general population, may be predicted by mood and impulse dysregulation and, in specific instances, may either drive or be driven by tics. These findings are considered in the context of dysfunction involving frontal-subcortical circuits and their modulating neurotransmitter systems, a pathobiology common to TS, SUD and linked psychiatric disorders. Management implications for TS patients at potential risk for SUD are discussed.

Keywords

Tourette syndrome, Gilles de la Tourette's disorder, substance use disorder, addictions, frontal-subcortical circuits, dopamine, mood disorders, impulse control