Systematic Review With Meta-analysis

The Prevalence of Anxiety and Depression in Patients With Irritable Bowel Syndrome

Mohammad Zamani; Shaghayegh Alizadeh-Tabari; Vahid Zamani

Disclosures

Aliment Pharmacol Ther. 2019;50(2):132-143. 

In This Article

Discussion

In this study, we found considerable prevalence rates of anxiety and depressive symptoms and disorders in IBS patients. It was also shown that the risk of the mentioned psychiatric problems is significantly higher in IBS patients in comparison with healthy control subjects. To the best of our knowledge, this was the first comprehensive systematic review and meta-analysis assessing the prevalence of anxiety or depression in IBS patients, and comparing the data with healthy subjects. Recent meta-analyses evaluated the levels, but not prevalence rates, of anxiety and depression in IBS patients and healthy controls by comparing the standardized mean difference (SMD) of the levels between the two groups. The meta-analysis by Fond et al[8] on 10 studies revealed significant higher levels of anxiety (pooled SMD = 0.76) and depression (pooled SMD = 0.80) in IBS patients versus controls. A newer systematic review by Lee et al,[9] which included 27 studies, similarly indicated that the levels of anxiety (pooled SMD = 0.84) and depression (pooled SMD = 0.76) were significantly higher in IBS patients than in healthy controls. A review by Zhang et al[7] performed on 24 comparative studies indicated that depressive symptoms are significantly more severe (SMD = 2.02) and more frequent (OR = 9.21) in IBS patients compared with controls. The results retrieved by us and other authors are in agreement with the theory that patients with IBS are associated with degrees of anxiety and depression.

The explanation of the relationship between IBS and psychiatric comorbidities is probably related to the "brain-gut" interactions. Psychophysiological and neuroimaging studies have stated that dysfunction of brain-gut axis, which is a bidirectional neurological connecting pathway between brain and digestive system, leads to presentation of IBS. According to this model, abdominal symptoms influence anxiety and depression, and on the other hand, the psychological factors physiologically increase risk of IBS symptoms.[92,93] It is not difficult to accept that chronic IBS symptoms can have a destabilising impact on quality of life, and be associated with stress, work impairment and cost, and these factors aggravate mental disorders. Considering these theories and the results supporting the positive relationship of IBS with the psychiatric problems, it can also be hypothesised that treatment of IBS symptoms in the patients with anxiety and depression can improve their psychiatric symptoms as well. It is recommended that these comorbidities be systematically checked and treated in IBS patients. Also, it is recommended that the physicians treating the patients with anxiety and depression, assess them in terms of IBS as well. If the co-existence gastrointestinal disorder diagnosed and treated, it would speed up improvement of the psychiatric comorbidities too. Several published systematic reviews summarised the efficacy of antidepressants and psychological therapies in patients with IBS.[94,95]

Subgroup analysis in the present study showed that patients IBS-C type had highest prevalence rates of both anxiety and depressive symptoms. Although the number of papers representing the data related to different IBS subgroups were few, we are able to somewhat explain the results and compare them with other studies. There are different reports about which IBS type is more associated with anxiety and depression than other types. In the meta-analysis by Lee et al,[9] IBS-C patients indicated the highest SMD for anxiety and depression, and it was explained that this is probably due to an imbalance of 5-hydroxytryptamine (5-HT) secretion, leading to constipation in these patients. 5-HT belongs to the intestinal serotonin system helping better gastrointestinal motility, which is also present in the central nervous system as a neurotransmitter contributing in mental health.[96,97] So, it is probable that the low responsiveness of 5-HT in both of the central and peripheral regions lead to the psychiatric problems in IBS-C patients. However, all types of IBS had high prevalence of anxiety and depression in our study.

According to the results, anxiety and depressive symptoms were not more prevalent in females than in males. Generally, females are more prone to worse mental health than males.[98,99] This is related to inner and outer factors. Inner factors are mainly related to hormonal effects. Oestrogen and progesterone are involved in stability of mental health and fluctuations in their level over the females' life, like puberty, menstrual cycle, pregnancy and menopause, can trigger changes in their mental health. Environmental factors are also linked to females' mental health.[100–102] Lower social power and higher stress lead females to be more prone to mental disorders.[99] However, more studies are suggested to investigate the gender differences in depression and anxiety among IBS patients.

A limitation of this systematic review pertains to the high heterogeneity between the studies. According to meta-regression, gender (% male) and publication year cannot justify the heterogeneity. The high heterogeneity could be probably due to differences in study place and/or diagnostic methods for IBS and the psychiatric comorbidities. Publication bias assessment did not show significant bias among the studies on anxiety and depressive disorders or symptoms, therefore, heterogeneity between studies may not be due to publication or reporting bias, but to other factors. On the other hand, there was a significant publication bias for anxiety symptom studies, hence, heterogeneity may be due to publication or reporting bias. Prevalence of anxiety and depression can vary according to the cultural region, which can result from actual differences in prevalence and discrepancies in measurement (due to translation, and limited validation of questionnaires).[9] Variations in cut-offs of elevated symptoms for the same instruments were other potential reason of heterogeneity. Altogether, such high heterogeneity in prevalence meta-analyses is not unexpected.[103] However, the results of the present study should be interpreted with caution.

The main strong point of this study is the wide range of reports, and the large total number of patients analysed. The selected studies relate to control groups of healthy subjects, without reported IBS.

Conclusions

This systematic review and meta-analysis shows that the prevalence of anxiety or depressive symptoms and disorders are considerable in IBS patients. In addition, we found that IBS patients are more at risk of the given psychiatric comorbidities compared with control subjects. It is recommended that gastroenterologists and other physicians, who are responsible for treatment of IBS patients, pay attention to and assess the concurrent presence of anxiety or depression in the patients as well, and consider specialist treatment for the psychiatric disorder. Also, it is recommended that those physicians treating patients with anxiety and depression also assess them in terms of IBS as well. If the co-existence gastrointestinal disorder is diagnosed and treated, it could also speed the improvement of the psychiatric comorbidities.

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