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It is well established that people with irritable bowel syndrome (IBS) have higher levels of anxiety and depression compared with controls. However, the role of these as risk factors is less clearly established. The aims of this systematic review were to investigate: (1) whether anxiety and/or depression predict IBS onset; (2) the size of the relative risk (RR) of anxiety versus depression in IBS onset. Subgroup analyses explored if methodological factors affected the overall findings.
Method
Prospective cohort or case–control studies were included if they: (1) focused on the development of IBS in population-based or gastroenteritis cohorts; (2) explored the effects of anxiety and/or depression at baseline as predictors of IBS onset at a future point. In all, 11 studies were included of which eight recruited participants with a gastrointestinal infection. Meta-analyses were conducted.
Results
The risk of developing IBS was double for anxiety cases at baseline compared with those who were not [RR 2.38, 95% confidence interval (CI) 1.58–3.60]. Similar results were found for depression (RR 2.06, 95% CI 1.44–2.96). Anxiety and depression seemed to play a stronger role in IBS onset in individuals with a gastrointestinal infection although this could be attributed to other differences in methodology, such as use of diagnostic interviews rather than self-report.
Conclusions
The findings suggest that self-reported anxiety and depression provide a twofold risk for IBS onset. There is less support for the role of anxiety or depressive disorder diagnosed using clinical interview. These findings may have implications for the development of interventions focused on IBS prevention and treatment.
We have used in-situ scanning tunneling microscopy (STM) to study the formation and evolution of InAs islands on an InP (001) surface. The InAs islands are produced by (i) exchange of P-atoms with As-atoms or by (ii) direct deposition of In and As. In both cases InAs nanowires arem elongated along the [ī 10] direction with a length over 1 µm. We observe these nanowires to be stable under an arsenic environment while unstable with no arsenic flux, and eventually transform into a rectangular-based pyramid with a truncated top. These observations indicate that surface reconstruction can play a role in the selection of quantum wire or dot growth.