Increased prevalence of functional gastrointestinal disorders in panic disorder: clinical and theoretical implications.

BACKGROUND: Functional gastrointestinal disorders (FGID) are a group of disorders characterized by recurrent gastrointestinal distress for which no structural or biochemical cause can be discerned. Irritable bowel syndrome (IBS) is an FGID estimated to affect 10% to 25% of the United States population. IBS occurs in over 40% of individuals with panic disorder, and in patients with IBS, 25% to 30% have panic disorder, which has led to speculation about possible shared pathophysiology between the two. Less is known about the prevalence of other FGID in individuals with panic disorder.
OBJECTIVE: The purpose of this study was to examine the prevalence of IBS and all the other FGID in patients with current Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) panic disorder.
INTRODUCTION: We assessed FGIDs in 73 treatment-seeking DSM-IV panic disorder patients via the Diagnostic Interview Questions for Functional Gastrointestinal Disorders and made descriptive comparisons with a large convenience sample from an already-completed United States Household Survey (USHS), which employed the same diagnostic criteria.
RESULTS: The prevalence of IBS and other FGIDs in both men and women with panic disorder were substantially higher than in the USHS respondents. Women with panic disorder had significantly more functional chest pain than men, but there was no gender difference in IBS. With the exception of functional anorectal and biliary disorders, the FGID prevalences were comparatively higher in panic disorder versus the USHS respondents. DISCUSSION: This survey supports earlier reports of a high prevalence of IBS in individuals with panic disorder and also suggests that the prevalence of several other FGIDs were comparatively high as well. Methodological limitations precluded direct statistical analysis. It may be that commonly overlapping psychiatric and often-painful FGIDs, and extra-intestinal disorders increase the risk for comorbidity in already-affected individuals via shared pathophysiology. One potential model for which there is some evidence for a role in stress, panic disorder, FGIDs and several extra-intestinal functional conditions is dysregulation of corticotropin-releasing factor function.
CONCLUSION: The prevalence of FGIDs in DSM-IV panic disorder was comparatively higher than in USHS respondent community sample, which used similar FGID diagnostic criteria. The cause for the apparent close association of panic disorder with FGID may represent shared pathophysiology. Increased understanding of the mechanism of the overlap may allow for improved treatment of the significant proportion of the population suffering from comorbid psychiatric and functional medical conditions.