The Tourette Syndrome Association (TSA) Classification Study Group, representing a large number of investigators and medical institutions, arrived at a consensus statement titled "Definitions and Classification of Tic Disorders" that was published in the Archives.1
Since then the American Psychiatric Association has published the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV).2 Their Task Force introduced several changes: (1) Tics are described as "rapid." (2) Tourette syndrome (TS) cannot be diagnosed if there is a remission of more than 3 months in the first 12 months.2 (3) The disturbance causes marked distress or significant impairment in social, occupational, or other important areas of functioning.
We strongly prefer the TSA classification to that of DSM-IV for the following reasons:
1. The TSA classification depends on diagnosis by objective documentation of history,3 not "significant impairment or distress" as in criterion 3 of DSM-IV. For epidemiological, clinical,