The most disabling aspect of Tourette syndrome is that in 90% of cases, it exists in conjunction with another disorder. The most frequent co-occurring condition in people with Tourette is attention deficit hyperactivity disorder (ADHD), though the cause of this association is uncertain. Having one disorder can be disabling enough, but having two means coping with more than twice the disability.
New research published in the April 13 edition of the Journal of Developmental and Behavioural Pediatrics by University of Calgary and University of Toronto researchers looked at nearly 400 children with Tourette syndrome to try to understand the connection between these two disorders. Their findings show that while Tourette and ADHD have a major genetic component, there are potentially preventable perinatal factors that increase the risk of a co-occurring diagnosis of ADHD in children with Tourette.
"We know that perinatal stress is a risk factor for ADHD alone. If you were low birth weight, if your mother smoked during pregnancy, or if you were born prematurely, all these things increase the risk of ADHD," says Dr. Tamara Pringsheim, Director, Calgary Tourette Syndrome Clinic, a University of Calgary Faculty of Medicine professor and lead author on the study.
To examine the link between Tourette and ADHD, the researchers looked at a population of children that had Tourette syndrome with or without ADHD and compared rates of perinatal risk factors such as low birth weight, prematurity, and maternal smoking in each group. Researchers found that the children exposed to these perinatal risks were two to three times as likely to develop Tourette syndrome with ADHD, suggesting that these factors play a role in the development of ADHD in children with Tourette as well.
Pringsheim, a neurologist and researcher says the important information from this research is for people at risk genetically for Tourette syndrome to take precautions when planning a family by "not smoking, trying to ensure a healthy weight for the baby, and receiving appropriate medical care." Quality of life in children with Tourette syndrome is most importantly determined by the severity of ADHD symptoms; anything one can do to minimize the chances of a co-occurring diagnosis of ADHD will allow children a greater chance of success and happiness in their life.
Laura Locke is a board member of the Tourette Syndrome Foundation of Canada and became involved with the foundation when her son was diagnosed with Tourette syndrome at the age of 10. "Research into Tourette syndrome is vital. We have seen the difference it can make to have accurate information about this disorder and better medications," she says.
Tourette syndrome has a great spectrum of severity. People with Tourette have motor and vocal tics -- rapid, repetitive, meaningless movements and sounds. Common motor tics include forceful blinking, opening the eyes wide, head shaking and grimacing, while the most common vocal tics are sniffing, throat clearing and grunting. Some people are very mildly affected, while others have more severe symptoms which make the disorder more noticeable and disabling. It is believed that Tourette syndrome affects about 1 in 100 people; however, many people do not seek medical attention for the disorder because the symptoms are so mild.
"There are a lot of misconceptions out there about people who suffer from Tourette. The images we see on TV and movies are completely false. I have some patients who have severe tics, but less than 10% of patients with Tourette syndrome swear. It's uncommon," says Pringsheim.
Tamara Pringsheim is Director of the Calgary Tourette Syndrome Clinic and Clinical Assistant Professor with the Departments of Clinical Neurosciences and Pediatrics University of Calgary. She is also a member of the Institute for Child and Maternal Health at the U of C.
The study is funded by the Canadian Institute of Health Research (CIHR).
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