Psychological factors, particularly anxiety, increased risk for developing infectious gastroenteritis, which in turn increased risk for postinfectious irritable bowel syndrome, according to new research data.
IBS “is a common condition with large socio-economic costs, yet there is so much that still remains to be discovered about the causes,” Guy Boeckxstaens, MD, PhD, from the University Hospital of Leuven in Belgium, said in a press release. “Our investigation found that anxiety or depression alters the immune response towards a gastrointestinal infection, which can result in more severe symptoms and the development of chronic [IBS].”
In December 2010, 18,620 residents of two small Belgian villages were exposed to drinking water contaminated with multiple pathogens, causing an outbreak of gastroenteritis. Boeckxstaens and colleagues studied the epidemiology and long-term outcome of the outbreak to assess the link between psychological factors, immune response in the acute infectious phase and risk for developing infectious gastroenteritis and/or postinfectious IBS. Furthermore, they aimed to examine the possible role of persistent immune activation in patients who developed postinfectious IBS.
“The water contamination in Schelle and Hemiksem was an ‘accidental experiment’ on a scale rarely possible in medical research,” Adrian Liston, PhD, from University of Leuven and VIB, said in the release. “By following the patients from the initial contamination to a year after the outbreak we were able to find out what factors altered the risk of long-term complications.”
Demographic, psychological and clinical factors were evaluated by questionnaire during the outbreak and 1 year later. Immune function was evaluated by peripheral blood and rectal biopsies in a subgroup of patients.
Of the 1,379 participants who completed questionnaires during the outbreak, 968 were included in the analysis, 28% of whom developed infectious gastroenteritis. Independent risk factors for developing infectious gastroenteritis included younger age (OR = 0.98; 95% CI, 0.97-0.99), pre-existing dyspepsia-like symptoms (OR = 1.1; 95% CI, 1-1.1), drinking tap water (OR = 2.6; 95% CI, 1.8-3.7) and anxiety (OR = 1.1; 95% CI, 1-1.1).
The researchers observed a significant inverse correlation between baseline anxiety scores and interleukin-2-expressing CD4+ T cells (P = .01).
At follow-up, 19.8% of 172 patients with infectious gastroenteritis developed IBS compared with 7% of 366 exposed participants who did not develop infectious gastroenteritis (P < .0001). Independent risk factors for developing postinfectious IBS included age (OR = 0.95; 95% CI, 0.91-0.99), somatization (OR = 1.16; 95% CI, 1.03-1.31) and dyspepsia-like symptoms (OR = 1.17; 95% CI, 1.05-1.3).
The researchers also observed increased numbers of Th2 cells at the time of infection in patients who developed postinfectious IBS (P = .02), and with the exception of increased numbers of B cells, there was no evidence for persistent immune activation in blood or rectal biopsies in postinfectious IBS at follow-up.
“Our study indicates that [infectious gastroenteritis] and psychological factors (anxiety and somatization, but not depression) are associated with an increased risk to develop [postinfectious IBS],” the researchers wrote. “Of interest though, we showed that anxiety and somatization are also risk factors to develop [infectious gastroenteritis], thereby indirectly adding to the increased risk to develop IBS.”
“These results once again emphasize the importance of mental health care and social support services,” Liston said in the release. “We need to understand that health, society and economics are not independent, and ignoring depression and anxiety results in higher long-term medical costs.”
“Altogether, our study shows that the increased risk of patients with psychological comorbidity to develop [postinfectious IBS] is partly due to an increased susceptibility to develop [infectious gastroenteritis],” the researchers concluded. “Moreover, we provide evidence to speculate that subjects who develop a predominant Th2 response against the infectious agent are prone to develop a humoral immune response and subsequently [postinfectious IBS].” – by Adam Leitenberger
Disclosure: The researchers report no relevant financial disclosures.