Studies do not show a strong relationship between ADHD and tics or Tourette's Disorder. Some studies have shown slightly higher evidence of tics in children with ADHD, but studies do not show any evidence of higher rates of Tourette's Disorder in children with ADHD.  A simple tic is an involuntary body movement or vocal sound that can be temporary or chronic. This commonly presents as behaviors such as eye blinking, throat clearing, head rolling, repeatedly licking lips, shoulder shrugging, and others. Many children will demonstrate transient simple tics at some point in childhood, with up to 20% demonstrating at least one tic at some point in childhood. Tourette's disorder, on the other hand, is a chronic psychological disorder characterized by the presence of frequent motor and vocal tics over a period lasting at least a year. In addition to simple motor tics, children with Tourette's Disorder may demonstrate complex motor or vocal tics. Complex motor tics may include hand gestures, jumping, stomping, physical routines, unusual physical postures, or other combinations. Complex vocal tics may include combinations of vocal sounds or repeated uttering of specific words or combinations of words. Only in very rare cases do vocal tics include obscenities.

Stimulant  Medication and Tics

Development of simple motor tics appears to be a somewhat rare side effect of stimulant medication. However, most studies indicate that stimulant tics stop when stimulant medications are used, except in cases where the child has a preexisting tic disorder. Recent research indicates that stimulant medications may be safely used for children with co-occurring ADHD and tic disorders, but that increased monitoring of tics is recommended. Studies have shown that some children with co-occurring ADHD and tic disorders do experience an increase in tic frequency or severity, but that most are able to safely tolerate stimulant medications. Stimulant medication may also be combined with medications demonstrated to be effective at reducing tics if children experience an increase in frequency or severity of tics. Additionally, the development of tics should be monitored in all children using stimulant medications. If tics become severe or impairing, appropriate action should be taken.