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Systematic assessment of environmental risk factors for bipolar disorder: an umbrella review of systematic reviews and meta-analyses

Version 2 2024-06-06, 09:34
Version 1 2017-05-11, 15:20
journal contribution
posted on 2024-06-06, 09:34 authored by B Bortolato, CA Köhler, E Evangelou, J León-Caballero, M Solmi, B Stubbs, L Belbasis, I Pacchiarotti, LV Kessing, Michael BerkMichael Berk, E Vieta, AF Carvalho
OBJECTIVES: The pathophysiology of bipolar disorder is likely to involve both genetic and environmental risk factors. In our study, we aimed to perform a systematic search of environmental risk factors for BD. In addition, we assessed possible hints of bias in this literature, and identified risk factors supported by high epidemiological credibility. METHODS: We searched the Pubmed/MEDLINE, EMBASE and PsycInfo databases up to 7 October 2016 to identify systematic reviews and meta-analyses of observational studies that assessed associations between putative environmental risk factors and BD. For each meta-analysis, we estimated its summary effect size by means of both random- and fixed-effects models, 95% confidence intervals (CIs), the 95% prediction interval, and heterogeneity. Evidence of small-study effects and excess of significance bias was also assessed. RESULTS: Sixteen publications met the inclusion criteria (seven meta-analyses and nine qualitative systematic reviews). Fifty-one unique environmental risk factors for BD were evaluated. Six meta-analyses investigated associations with a risk factor for BD. Only irritable bowel syndrome (IBS) emerged as a risk factor for BD supported by convincing evidence (k=6; odds ratio [OR]=2.48; 95% CI=2.35-2.61; P<.001), and childhood adversity was supported by highly suggestive evidence. Asthma and obesity were risk factors for BD supported by suggestive evidence, and seropositivity to Toxoplasma gondii and a history of head injury were supported by weak evidence. CONCLUSIONS: Notwithstanding that several environmental risk factors for BD were identified, few meta-analyses of observational studies were available. Therefore, further well-designed and adequately powered studies are necessary to map the environmental risk factors for BD.

History

Journal

Bipolar Disorders

Volume

19

Pagination

84-96

Location

Denmark

ISSN

1398-5647

eISSN

1399-5618

Language

English

Publication classification

C Journal article, C1 Refereed article in a scholarly journal

Copyright notice

2017, John Wiley & Sons A/S.

Issue

2

Publisher

WILEY