There is a probable biological relationship between OCD and Tourette’s disorder because individuals with Tourette’s disorder are more likely to have OCD than are individuals with most other mental health disorders.
Tourette’s is a tic disorder, and tics, according to the DSM-IV-TR (2000), are “sudden, rapid, recurrent, nonrhythmic, stereotyped motor movements or vocalizations.” The tics are classified as either simple or complex, depending on the amount of time it takes to complete the tic or how involved the tic is (such as an eye blink versus an entire bodily movement).
To differentiate Tourette’s and OCD, we need to look at the defining characteristics of the two disorders. For OCD, the ritual must be done as a response to an obsession or according to strict rules. A tic, on the other hand, is performed to relieve some type of physical tension that is occurring.
If there is an obsession, it’s OCD. If there is no obsession, but the behavior is still very purposeful and follows very set rules, then OCD is also warranted. If the behavior is performed out of the blue for no purpose other than to relieve tension, then it is probably a tic and is probably part of Tourette’s or one of the other tic disorders (chronic motor or vocal tic disorder, transient tic disorder, or tic disorder not otherwise specified).
If both criteria are met, a diagnosis of both OCD and Tourette’s disorder is possible. The criteria for Tourette’s disorder, according to the DSM-IV-TR (2000), are as follows:
1. Multiple motor tics and one or more vocal tics
2. The tics occur many times a day or nearly every day over the course of a year, with no more than a three-month tic-free period.
3. The onset is before the age of 18.
4. The Tourette’s is not better accounted for by the effects of a substance or a medical condition.
So, an individual may have motor and vocal tics that they perform in addition to the occurrence of obsessions or compulsions. If this were to happen, then the diagnosis of both disorders would be in order.