Relationship between abdominal pain subgroups in the community and psychiatric diagnosis and personality A birth cohort study Stuart Howell a , Ritchie Poulton b , Avshalom Caspi c , Nicholas J. Talley a, * a University of Sydney, Nepean Hospital, PO Box 63, Penrith NSW 2751, Australia b University of Otago Medical School, Dunedin, New Zealand c Kings College London and University of Wisconsin-Madison, Madison, WI, USA Received 18 January 2001; accepted 15 October 2002 Abstract Introduction: It is unclear if there is a causal link between psychiatric disorders and unexplained chronic gastrointestinal (GI) symptomatology. The role of personality is also in dispute. We aimed to assess the association of these factors with functional GI symptoms in a birth cohort study. Methods: The Dunedin birth cohort is well characterised and has been followed-up prospectively to age 26 (n = 980). Measured were upper and lower GI symptoms over the prior year at age 26 using a validated questionnaire, psychiatric diagnoses at ages 18 and 21 by standardised interview applying DSM-III-R criteria, and personality at age 18 using the Multidimensional Personality Questionnaire (MPQ). Natural symptom groupings were identi- fied using factor analysis and k-means clustering. The association of these clusters and psychiatric diagnoses or personality was assessed by logistic regression. Results: The k-means analysis produced a six-cluster solution, which was made up of a health group, and five ‘‘disease’’ clusters defined by higher than average scores on a single symptom. A diagnosis of depression at age 18 or 21 years was associated with increases in the odds of 1.69 (95% CI: 1.27 – 2.25) for all GI, of 2.16 (95% CI: 1.12 – 4.16) for dysmotility and of 2.07 (95% CI: 1.13 – 3.80) for constipation, but not with the other clusters. Similar results were observed with respect to anxiety disorders for the odds of GI overall (OR = 1.42, 95% CI: 1.01 – 1.99) and constipation (OR = 2.11, 95% CI: 1.17 – 3.79). The personality subscales were not strongly linked; membership of ‘‘any’’ diseased cluster was associated with a reduced odds of being in the fourth quartile for the well-being scale (OR = 0.64, 95% CI: 0.46 – 0.88) but increased odds of being in the fourth quartile for the social potency scale (OR = 1.64, 95% CI: 1.18 – 2.28). Conclusions: In a young adult community sample, unexplained GI symptoms appear to be linked to psychiatric disorders but personality differences were minimal. D 2003 Elsevier Inc. All rights reserved. Keywords: Functional disorders; Gastrointestinal symptoms; Personality; Psychiatric disorder Introduction Chronic unexplained gastrointestinal (GI) symptoms are now recognised to be highly prevalent in the general population but the pathogenesis of these symptoms remains in dispute. Selected personality characteristics [1–9] as well as psychological distress [10–15] have been linked to irritable bowel syndrome (IBS), which is one of the more widely recognised symptom complexes, characterised by abdominal pain or discomfort and disturbed defaecation linked to the pain. For example, outpatient and volunteer studies have reported that subjects with IBS tend to be significantly more neurotic and anxious than controls, applying standardised instruments such as the Eysenck Personality Inventory (EPI) [1,3], Spielberger Trait Anxiety Inventory [4–7] or the Minnesota Multiphasic Personality Inventory [7–9]. However, it remains unclear whether such personality scores are causally linked to IBS or other painful type GI symptoms. Alternative explanations include chronic symptoms increasing personality scores or psychological distress because of pain, or a selection bias whereby those 0022-3999/03/$ – see front matter D 2003 Elsevier Inc. All rights reserved. doi:10.1016/S0022-3999(02)00599-8 * Corresponding author. Tel.: +61-2-4734-2613; fax: +61-2-4734- 2614. E-mail address: ntalley@med.usyd.edu.au (N.J. Talley). Journal of Psychosomatic Research 55 (2003) 179 – 187