children with tic disorders are more likely to experience attention-deficit/hyperactivity
disorder (ADHD), obsessive-co mpulsive disorder (OCD), and separation anxiety disorder
than are teenagers and adults, who are more li kely to experience the new onset of major
depressive disorder, substance use disorder, or bipolar disorder.
Risk and Prognostic Factors 
Temperamental. Tics are worsened by anxiety, excitement, and exhaustion and are better
during calm, focused activities. Individuals ma y have fewer tics when engaged in schoolwork
or tasks at work than when relaxing at home after school or in the evening. Stressful/exciting
events (e.g., taking a test, participating in exciting activities) often make tics worse. 
Environmental. Observing a gesture or sound in another person may result in an indi-
vidual with a tic disorder making a simila r gesture or sound, which may be incorrectly
perceived by others as purposeful. This can be a particular problem when the individual is
interacting with authority figures (e .g., teachers, supe rvisors, police).
Genetic and physiological. Genetic and environmental factors influence tic symptom
expression and severity. Important risk allele s for Tourette’s disorder and rare genetic
variants in families with tic disorders have  been identified. Obstetrical complications,
older paternal age, lower birth weight, and maternal smoking during pregnancy are as-
sociated with worse tic severity.
Culture-Related Diagnostic Issues
Tic disorders do not appear to vary in clinical  characteristics, course , or etiology by race,
ethnicity, and culture. However, race, ethnici ty, and culture may impa ct how tic disorders
are perceived and managed in the family an d community, as well as influencing patterns
of help seeking, and choices of treatment.