Tourette Syndrome is a debilitating tic disorder characterized by frequent motor and phonic tics. Diagnostic criteria include onset before the age of 21; recurrent, involuntary, rapid, purposeless motor movements affecting multiple muscle groups; one or more vocal tics; variations in the intensity of the symptoms over weeks to months; and duration of more than one year.
People suffering from TS commonly experience other behavioral and neurological complaints such as attention deficits, depression, self-injurious behaviors, obsessive-compulsive behaviors, and irritability. These neurological symptoms are thought to be due to the same central nervous system (brain and spinal cord) malfunction that causes TS: alterations of dopamine and serotonin levels in the brain.
While researchers generally consider TS to be a genetic disorder, approximately 15% of patients do not show any relationship with the disorder through genetics. Consequently, researchers have focused upon stressful events during perinatal or early life that may trigger the onset of TS. Traumatic head injury (during birth, falls, accidents, etc.) has been implicated as a possible trigger of TS. Evidence supports that trauma increases the risk of TS onset. Following the trauma, tics can be triggered immediately or can take months or years to develop.