Irritable Bowel Syndrome is Strongly Associated with Generalized Anxiety Disorder: A Community Study

S. Lee; J. Wu; Y. L. Ma; A. Tsang; W.-J. Guo; J. Sung


Aliment Pharmacol Ther. 2009;30(6):643-651. 

In This Article

Abstract and Introduction


Background No previous study has examined the comorbidity of Irritable Bowel Syndrome (IBS) and Generalized Anxiety Disorder (GAD) in a general population using standardized diagnostic methods.
Aim To examine the prevalence, comorbidity and risk correlates of IBS and GAD in a general population.
Methods A random community-based telephone survey was conducted. The questionnaire covered symptoms of IBS, GAD, core depressive symptoms, help-seeking behaviour and functional impairment on the Sheehan Disability Scale.
Results A total of 2005 participants completed the interview. The current prevalence of IBS was 5.4% and the 12-month prevalence of GAD was 4%. GAD was five times more common among IBS respondents than non-IBS respondents (OR: 5.84, P < 0.001), whereas IBS was 4.7 times more common among GAD respondents than among non-GAD respondents (OR: 6.32, P < 0.001). Core depressive symptoms (OR: 6.25, P < 0.01) and education level (OR: 5.918, P = 0.021) were risk correlates of GAD among IBS respondents. Comorbid respondents were more impaired than respondents having either disorder alone, but were not more likely to seek professional help than IBS-only respondents.
Conclusion Irritable Bowel Syndrome and GAD comorbidity was common and added to impairment in the community. The strong association between psychiatric morbidity and IBS observed in referral centres was not a consequence of increased help-seeking behaviour.


Irritable Bowel Syndrome (IBS) is a common functional bowel disorder with a 12-month prevalence of about 20% in Western countries[1] and 2–7% in Asian communities.[2–4] It is typically a chronic and relapsing condition that is both distressing and disabling to its sufferers.[5] Reasons for the chronicity and often unsatisfactory treatment response of IBS are complex, but may partly be mediated by undetected comorbid mental disorders.

Studies on the relationship between IBS and mental disorders are relatively few and often confined to referral centres. A clinical study which did not adopt Rome criteria for IBS reported a strong correlation between IBS symptoms and anxiety-depression in patients with recurrent depression.[6] Another clinical study found that 94% of IBS patients had lifetime mental disorders.[7] Specifically, the lifetime prevalence of generalized anxiety disorder (GAD), as defined by the Diagnostic and Statistics Manual of Mental Disorders, third edition revision (DSM-III-R),[8] was 34% among these patients. As psychological distress could motivate individuals with IBS to seek treatment, the association between IBS and psychiatric disorders found in referral centres might inflate the degree of their association in the community because of selection bias. However, community-based studies of IBS and psychiatric disorders are limited. Using stratified random sampling, one general population study which did not adopt Rome criteria for IBS found that panic disorder and agoraphobia were found in 9.3% and 33.1% of people with IBS.[3] Hazlett-Stevens et al.[9] examined the relationship between IBS and GAD among college students rather than a general population. Nonetheless, they found that 21.5% of those with IBS had GAD compared to 7% of controls. These preliminary community studies suggest that there might be a significant association between IBS and anxiety disorders.

Of the different types of anxiety disorders, GAD may be particularly associated with IBS. Like IBS, GAD is typically a chronic relapsing illness. It is characterized by the core symptom of pathological worry and other anxiety symptoms including restlessness, easy fatigue, sleep disturbance, muscle tension, difficulty concentrating and irritability. Both IBS and GAD are reactive to stress[10–12] and are likely to involve central and/or peripheral serotonergic disturbances.[13,14] They also bring about anticipatory worries and avoidance behaviour that impair functioning in everyday life.[8,15] The two illnesses add to health-care cost and poor quality of life.[16,17]

To our knowledge, no previous research has studied, using standardized diagnostic criteria, the relationship between IBS and GAD in a community-based sample. Therefore, we set out to examine the prevalence, comorbidity and risk correlates of IBS and GAD in a general population.


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