Generalized, persistent, and free-floating anxiety was first described by Freud in 1894. The diagnostic term generalized anxiety disorder (GAD) was not in classification systems until the publication of the diagnostic and statistical manual for mental disorders, third edition (DSM-III) in 1980. Initially considered a residual category to be used when no other diagnosis could be made. The term GAD is not accepted as a distinct diagnostic category yet. Since 1980, revisions to the diagnostic criteria for GAD in the DSM-III-R, DSM-IV and DSM-5 classifications have slightly redefined this disorder. The classification is fluid. This article reviews the development of diagnostic criteria for defining GAD from Freud to DSM-5. Excessive worrying impairs the individual's capacity to do things quickly and efficiently, whether at home or at work. The worrying takes time and energy; associated symptoms of feeling keyed up or edge, tiredness, difficulty concentrating, and depression. Individuals whose presentation meets criteria for GAD are likely to have met, or currently meet, criteria for unipolar depressive disorders. Comorbid depression are common in GAD and negatively impact treatment outcome.
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