title: The epidemiology of pure and comorbid generalized anxiety disorder: a review and evaluation of recent research.
abstract: OBJECTIVE
  Research documenting high rates of comorbidity among patients with generalized anxiety disorder (GAD) has led to the suggestion that GAD might best be conceptualized as a prodrome, residual or severity marker of other disorders. Recent research investigating this suggestion is reviewed in this report.
  
  
  METHODS
  A computer search cross-classified the terms 'Generalized Anxiety' and 'Comorbidity'.
  
  
  RESULTS
  Results arguing that GAD is an independent disorder include the finding that GAD is usually temporally primary in cases of comorbidity with major depression, that primary GAD is a significant predictor of subsequent depression and that the course of GAD is independent of comorbidity. Studies in both patient and community samples show that the impairment associated with pure GAD is equivalent to the impairment associated with pure depression.
  
  
  CONCLUSIONS
  The results reviewed here support the view that GAD as an independent disorder is a major public health problem.
authors.affiliation: Department of Health Care Policy, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Kessler
mesh_terms: D001008:Anxiety Disorders / Q000150:complications / Q000453:epidemiology*; D015897:Comorbidity; D003866:Depressive Disorder / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D011634:Public Health