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Co-occurring conditions

Because people with milder symptoms are unlikely to be referred to specialty clinics, studies of Tourette's have an inherent bias towards more severe cases. When symptoms are severe enough to warrant referral to clinics, ADHD and OCD are often also found. In specialty clinics, 30% of those with TS also have mood or anxiety disorders or disruptive behaviors. In the absence of ADHD, tic disorders do not appear to be associated with disruptive behavior or functional impairment, while impairment in school, family, or peer relations is greater in those who have more comorbid conditions. When ADHD is present along with tics, the occurrence of conduct disorder and oppositional defiant disorder increases. Aggressive behaviors and angry outbursts in people with TS are not well understood; they are not associated with severe tics, but are connected with the presence of ADHD. ADHD may also contribute to higher rates of anxiety, and aggression and anger control problems are more likely when both OCD and ADHD co-occur with Tourette's.