The Relevance of Personality Assessment in Patients With Hyperventilation Symptoms Mieke Decuyper and Marleen De Bolle Ghent University Eva Boone AZ Sint-Jan A.V., Bruges, Belgium Filip De Fruyt Ghent University Objective: Relatively few data are available concerning the relations between hyperventilation symptoms and general personality traits in clinical populations. A clear picture of the personality traits associated with hyperventilation symptoms could enhance early detection of those individuals who are at risk for developing hyperventilation. The aim of this study was to investigate the role of general personality in hyperventilation syndrome. Method: Patients (N = 364) with symptoms not explained by an organic disease and supposedly caused by hyperventilation completed the NEO Five-Factor Inventory, the General Health Questionnaire—12, and the Nijmegen Questionnaire. Patients were also subjected to a hyperventilation provocation test and transcutaneous carbon dioxide (TcPCO 2 ) values were registered. Results: The results showed that patients with hyperventilation obtained mean Neuroticism scores above the normative mean. Moreover, only Neuroticism was positively linked with self-reported hyperventi- lation symptoms, and personality traits were more strongly related to self-reported complaints than to objective physical information. Neuroticism clearly differentiated between different diagnostic groups on the basis of Nijmegen Questionnaire and TcPCO 2 values, and an additional small effect of Agreeableness was observed. Conclusions: The present study contributes to the evidence that Neuroticism is strongly associated with self-reported hyperventilation symptoms, and provides substantial evidence that Neu- roticism is a vulnerability factor in the development of hyperventilation. Therefore, personality assess- ment may be helpful in advancing the understanding and the early detection of hyperventilation symptoms. Keywords: personality, neuroticism, hyperventilation, hypocapnia Hyperventilation syndrome is a common, frightening disorder and involves various somatic and psychological symptoms that appear to be a consequence of episodes of hyperventilation with no known organic basis (Shu et al., 2007). This syndrome is defined as breathing in excess of metabolic needs that acutely leads to a reduction in the level of arterial pCO 2 (hypocapnia; Wilhelm, Gerlach, & Roth, 2001). Most psychiatrists have viewed hyper- ventilation as one of the concurrent physiological effects of anx- iety, and they have placed it at the somatic end of the somatic– psychiatric anxiety continuum (Shu et al., 2007). The literature has shown no consensus on the exact diagnostic criteria for the hyper- ventilation syndrome. The term hyperventilation syndrome is used in so many different contexts that its usefulness as a single entity can be questioned. Gardner (1996) stated that regarding hyperven- tilation as a simple manifestation is incorrect because a complex interaction often occurs among organic respiratory, psychiatric, and physiological disturbances. The incidence of hyperventilation syndrome is estimated to be between 6% and 11% of the general population, and this syndrome may mimic diverse organic diseases (Coffman, 2002). The acute manifestation of hyperventilation can easily be diagnosed, but its recognition in more subtle forms requires a particular alertness on the part of the clinician and the general practitioner (Lachman, Gielis, Thys, Lorimier, & Sergysels, 1992). Hyperventilation oc- curs in acute and chronic forms (Gardner, 1996). Acute hyperven- tilation is a more manifest form because of the obvious rapid breathing or tachypnea. Most cases occur in the form of chronic hyperventilation in which a modest increase in respiratory rate or tidal volume may occur that may not even be apparent to the patient or a medical observer. Because of the subtlety of chronic hyperventilation, many patients are admitted and undergo exten- sive testing in an attempt to discover organic causes of the com- plaints. The current medical approach toward patients with unexplained physical complaints, including hyperventilation, does not suffice, and medical consumption and costs remain high (Serlie et al., 1996). Because many patients with hyperventilation symptoms have a long medical history of visiting different specialists and undergo expensive, unnecessary medical examinations before they This article was published Online First December 12, 2011. Mieke Decuyper, Marleen De Bolle, and Filip De Fruyt, Department of Developmental, Personality, and Social Psychology, Ghent University, Ghent, Belgium; Eva Boone, Department of Clinical Psychology, AZ Sint-Jan A.V., Bruges, Belgium. Correspondence concerning this article should be addressed to Mieke Decuyper, Department of Developmental, Personality, and Social Psychol- ogy, Ghent University, Henri Dunantlaan 2, B-9000 Ghent, Belgium. E-mail: Mieke.Decuyper@Ugent.be Health Psychology © 2011 American Psychological Association 2012, Vol. 31, No. 3, 316 –322 0278-6133/11/$12.00 DOI: 10.1037/a0026563 316