What is the Diagnostic Criteria for Tourette Syndrome (TS)?
In order to be diagnosed with TS, a person must meet a set of conditions or diagnostic criteria. These criteria, found in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) are:
- At least two motor tics and at least one vocal tic (not necessarily at the same time);
- Tics persist for more than a year (tics can wax and wane during this period);
- Tics begin before age 18; and
- Tics are not caused by a substance or other condition (e.g., Huntington Disease, infection, head injury).
Currently there is no laboratory test or brain scan that conclusively shows a person has TS. The diagnosis is a clinical one, which means that it is based on a medical professional taking a medical history, observing the patient, and doing any necessary tests to rule out other conditions that may look like TS or that could cause tics.
Who can diagnose TS?
TS can be diagnosed by any medical professional who is familiar with Tourette Syndrome, including family doctors, neurologists, psychiatrists, and psychologists.
What is the prognosis?
TS is a chronic, life-long disorder that currently has no cure. However, it is not a degenerative condition and the severity and intensity of the tics generally decrease when the individual reaches their late teens or early 20s. Some individuals become tic-free by adulthood. Although the tic symptoms tend to decrease with age, the associated disorders (e.g. ADHD, OCD, neurobehavioural disorders) can persist throughout adulthood.
What is the prevalence of TS?
Although it was once considered rare, TS is a common medical condition. Approximately 1% of the population has TS; however, depending on the study, the prevalence rate can be as high as 3.8%. Studies also report that up to 24% of children develop tics during childhood at some point.
TS affects three to four times as many boys as girls. The tic symptoms can range from mild or severe. Tics will manifest differently between individuals.