Type D personality: predictor of general psychological distress after military deployment?
Londen, F.A. van
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Introduction: the current thesis examines the question whether type D personality is a risk factor in military personnel for an increase in psychological symptoms post deployment after controlling for psychological symptoms predeployment. Type D personality is defined as a distressed personality type, which consists of the combination of Negative Affectivity (the tendency to experience negative emotions) and Social Inhibition (the tendency to inhibit self-expression in social interaction). Previous research is concentrated on the predictive power of type D personality in worse health outcomes after myocardial infarct. Could type D personality also prospective play a role in the experience of more psychological symptoms post deployment? Methods: this thesis was part of the large prospective Dutch study PRISMO, concerning psychological and immunological effects of deployment. This thesis concentrated on the role of personality traits in the experience of mental and physical symptoms pre- and post deployment. Symptoms were measured with the SCL-90 and type D personality was measured with the DS14. Because the DS14 is a recently developed questionnaire and has not been used on military personnel before, reliability tests and a factor analysis will be conducted. Hypotheses: Individuals with type D personality were expected to show more symptoms predeployment, and therefore also more symptoms post deployment, but as an effect of deployment there would be a larger increase in symptoms than in the non-type D group. Another hypothesis was that type D is a (prospective) predictor for the level of symptoms after deployment, controlled for level of symptoms post deployment. Other important hypotheses were that type D personality is less prevalent in military personnel than in a general healthy Dutch population and that it is a stable trait in this cohort because this research concerns a healthy, selected, stable population. Results: Individuals with type D personality had more symptoms pre- and postdeployment, and there was no effect of deployment on level of symptoms. Exceptions were the subscales ‘interpersonal sensitivity and paranoid ideation’ where there was an effect of deployment, and ‘sleeping problems’where there was an additional interaction effect on level of symptoms post deployment. After controlling for predeploment symptoms, type D personality had a unique contribution of 2%. This effect was significant, but the clinical implications are questionable. Furthermore, type D personality was less prevalent in military personnel than in civilians. As expected, type D personality was stable over time and therefore was found to be a trait.