The Etiology of Phobias: An Evaluation of the Stress-Diathesis Model | Psychiatry | JAMA Psychiatry | JAMA Network
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Original Article
March 2002

The Etiology of Phobias: An Evaluation of the Stress-Diathesis Model

Author Affiliations

From the Virginia Institute for Psychiatric and Behavioral Genetics(Drs Kendler and Prescott and Mr Myers) and the Departments of Psychiatry(Drs Kendler and Prescott and Mr Myers) and Human Genetics (Dr Kendler), Medical College of Virginia of Virginia Commonwealth University, Richmond.

Arch Gen Psychiatry. 2002;59(3):242-248. doi:10.1001/archpsyc.59.3.242

Background  We evaluated for phobias the prediction of the stress-diathesis model that the magnitude of stress at onset is inversely proportional to the level of underlying diathesis.

Methods  In more than 7500 twins from a population-based registry, we assessed the personality trait of neuroticism—as an index of phobia-proneness—and the lifetime histories of 5 phobia subtypes (agoraphobia, social, animal, situational, and blood or injury) and their associated irrational fears. Interviewers classified the mode of acquisition of the fear in phobic twins into 5 possible categories: trauma to self (further divided by severity), observed trauma to others, observed fear in others, taught by others to be afraid, and no memory of how or why fear developed. Analyses were conducted by logistic regression and analysis of covariance.

Results  The mode of acquisition had moderate test-retest reliability and differed meaningfully across phobia subtypes. None of the 3 tests of the stress-diathesis model was confirmatory: (1) the risk of phobias was not elevated in co-twins of twins who had no memory of their mode of acquisition, (2) the risk of phobias was not decreased in co-twins of twins who had severe trauma to self, and(3) no significant relationship, in phobic twins, was found between levels of neuroticism and mode of acquisition.

Conclusions  These results are inconsistent with the traditional etiologic theories for phobias, which assume conditioning or social transmission. However, they are compatible with nonassociative models, which postulate that the vulnerability to phobias is largely innate and does not arise directly from environmental experiences. The stress-diathesis model may not be an appropriate paradigm for phobic disorders.