Endorsement frequencies and factor structure of DSM-III-R and DSM-IV Generalized Anxiety Disorder symptoms in women: implications for future research, classification, clinical practice and comorbidity

Authors

  • Thomas S. Kubarych,

    Corresponding author
    1. Department of Psychiatry, Virginia Commonwealth University, Richmond, Virginia, USA
    • Department of Psychiatry, Virginia Commonwealth University, PO Box 980126, Richmond VA 23298-1026, USA.
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  • Steven H. Aggen,

    1. Department of Psychiatry, Virginia Commonwealth University, Richmond, Virginia, USA
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  • John M. Hettema,

    1. Department of Psychiatry, Virginia Commonwealth University, Richmond, Virginia, USA
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  • Kenneth S. Kendler,

    1. Department of Psychiatry, Virginia Commonwealth University, Richmond, Virginia, USA
    2. Department of Human Genetics, Virginia Commonwealth University, Richmond, Virginia, USA
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  • Michael C. Neale

    1. Department of Psychiatry, Virginia Commonwealth University, Richmond, Virginia, USA
    2. Department of Human Genetics, Virginia Commonwealth University, Richmond, Virginia, USA
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Abstract

We investigated dimensions of liability to Generalized Anxiety Disorder (GAD) and whether evidence exists for distinct pathological versus normal clusters in the population. Structured interviews were administered to a general population sample of 2,163 female twins in a cross-sectional design. Endorsement rates were estimated using full information maximum likelihood factor analyses of the DSM-III-R and DSM-IV GAD symptoms, which provides appropriate treatment of the stem-probe structure of the clinical interview.

Endorsement rates were highest for symptoms retained in DSM-IV. For both DSM-III-R and DSM-IV, a two-factor model fit the data better than a single-factor model. There was no evidence for non-normality in the liability to GAD. For DSM-III-R, autonomic symptoms loaded on a factor with panic disorder, while fatiguability, difficulty concentrating and hypervigilance loaded on a factor with major depression. For DSM-IV, all items loaded on one factor, and muscle tension also loaded on a second. Major depression, panic, phobias and alcohol dependence diagnoses also loaded on the first factor. Conclusions: future research involving structured interviews should take into account the stem-and-probe format and focus on common factors rather than separate disorders; GAD is not a unidimensional construct and pathological anxiety may differ only quantitatively from normal anxiety. Copyright © 2005 Whurr Publishers Ltd.

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