Tourette's Syndrome is a neurological condition in which many of the symptoms of ADHD are present. It has been diagnosed with increasing frequency in recent years, and there is variability in how the diagnosis is made by different physicians.
Classically, it is characterized by:
Tics - defined in DSM IV as " sudden, rapid, recurrent, non-rhythmic stereotyped motor movement or vocalization". These tics may be motor, vocal, or emotional.
Onset prior to 18 and tics occurring nearly daily and never free of tics for more than 3 consecutive months
Impaired function or significant distress
Ritalin and other stimulants used to treat ADHD may produce an increased incidence of tics in
some people. This remains an area of active investigation.