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[evol-psych] Fears and phobias: reliability and heritability

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  • Ian Pitchford
    Psychological Medicine (1999), 29:539-553. Cambridge University Press. http://www.journals.cup.org/owa_dba/owa/issues?sjid=PSM&svid=29&siid=3 Copyright © 1999
    Message 1 of 1 , Aug 10, 1999
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      Psychological Medicine (1999), 29:539-553. Cambridge University Press.
      http://www.journals.cup.org/owa_dba/owa/issues?sjid=PSM&svid=29&siid=3
      Copyright © 1999 Cambridge University Press

      Fears and phobias: reliability and heritability

      K. S. KENDLER a1 c1, L. M. KARKOWSKI a1 and C. A. PRESCOTT a1
      a1Virginia Institute for Psychiatric and Behavioral Genetics and the
      Departments of Psychiatry and Human Genetics, Medical College of Virginia of
      Virginia Commonwealth University, VA, USA

      Abstract

      Background. Familial factors, which are partly genetic, influence risk for
      phobias. Prior family and twin studies, however, were based on a single
      lifetime assessment, which may be only moderately reliable.

      Methods. We obtained, 8 years apart, two assessments of lifetime history of
      five unreasonable fears and phobias (agoraphobia and social, situational,
      animal and blood-injury phobia) from face-to-face and telephone interviews from
      1708 individual female twins from a population-based registry. We also
      obtained, 1 month apart, test-retest reliability on 192 twins. We fitted, using
      the program Mx, a measurement model that estimates the role of genetic and
      environmental risk factors correcting for measurement error.

      Results. Short-term reliability of the five phobias was modest (mean
      [kappa]=0·46), but higher than long-term stability (mean [kappa]=0·30).
      Unreliability occurred both for subject recall of unreasonable fears and for
      interviewer assessment of which fears constituted phobias. Examining fears and
      phobias together, in a multiple threshold model, results suggested that twin
      resemblance was due solely to genetic factors, with estimated total
      heritabilities, corrected for unreliability, of: any 43%, agoraphobia 67%,
      animal 47%, blood/injury 59%, situational 46% and social 51%. With the
      exception of animal phobia, similar results were obtained analysing phobias
      alone.

      Conclusions. Lifetime histories of unreasonable fears and phobias assessed at
      personal interview have substantial unreliability. Correcting for
      unreliability, the liability to fears and their associated phobias is
      moderately heritable. Individual-specific environmental experiences play an
      important role in the development of phobias, while familial-environmental
      factors appear to be of little aetiological significance.

      Correspondence:

      c1Address for correspondence: Professor K. S. Kendler, Virginia Institute for
      Psychiatric and Behavioral Genetics, PO Box 980126, Richmond, VA 23298-0126,
      USA.
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