What is generalized anxiety disorder?

Generalized, persistent, and free-floating anxiety was first described by Freud in 1894, although the diagnostic term generalized anxiety disorder (GAD) was not included in classification systems until 1980 (Diagnostic and Statistical Manual for Mental Disorders, Third Edition [DSM-III]). Initially considered a residual category to be used when no other diagnosis could be made, it is now widely accepted that GAD represents a distinct diagnostic category. Since 1980, revisions to the diagnostic criteria for GAD in the DSM-III-R and DSM-IV classifications have markedly redefined this disorder, increasing the duration criterion to 6 months and increasing the emphasis on worry and psychic symptoms. This article reviews the development of the diagnostic criteria for defining GAD from Freud to DSM-IV and compares the DSM-IV criteria with the criteria set forth in the tenth revision of the International Classification of Diseases. The impact of the changes in diagnostic criteria on research into GAD, and on diagnosis, differential diagnosis, and treatment of GAD, will be discussed.