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

Beatrice Bortolato; Cristiano A. Köhler; Evangelos Evangelou; Jordi León-Caballero; Marco Solmi; Brendon Stubbs; Lazaros Belbasis; Isabella Pacchiarotti; Lars V. Kessing; Michael Berk; Eduard Vieta; André F. Carvalho

doi:10.1111/bdi.12490

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

Beatrice Bortolato, Cristiano A. Köhler, Evangelos Evangelou, Jordi León-Caballero, Marco Solmi, Brendon Stubbs, Lazaros Belbasis, Isabella Pacchiarotti, Lars V. Kessing, Michael Berk, Eduard Vieta, André F. Carvalho^*

^*Corresponding author for this work

Department of Clinical Medicine

52 Citations (Scopus)

Abstract

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.

Original language	English
Journal	Bipolar Disorders
Volume	19
Issue number	2
Pages (from-to)	84-96
Number of pages	13
ISSN	1399-5618
DOIs	https://doi.org/10.1111/bdi.12490
Publication status	Published - Mar 2017

Keywords

aetiology
bipolar disorder
depression
mania
meta-analysis
mood disorder
psychiatry
risk factor
systematic review

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1111/bdi.12490

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Bortolato, B., Köhler, C. A., Evangelou, E., León-Caballero, J., Solmi, M., Stubbs, B., Belbasis, L., Pacchiarotti, I., Kessing, L. V., Berk, M., Vieta, E., & Carvalho, A. F. (2017). Systematic assessment of environmental risk factors for bipolar disorder: an umbrella review of systematic reviews and meta-analyses. Bipolar Disorders, 19(2), 84-96. https://doi.org/10.1111/bdi.12490

Bortolato, B, Köhler, CA, Evangelou, E, León-Caballero, J, Solmi, M, Stubbs, B, Belbasis, L, Pacchiarotti, I, Kessing, LV, Berk, M, Vieta, E & Carvalho, AF 2017, 'Systematic assessment of environmental risk factors for bipolar disorder: an umbrella review of systematic reviews and meta-analyses', Bipolar Disorders, vol. 19, no. 2, pp. 84-96. https://doi.org/10.1111/bdi.12490

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

abstract = "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.",

keywords = "aetiology, bipolar disorder, depression, mania, meta-analysis, mood disorder, psychiatry, risk factor, systematic review",

author = "Beatrice Bortolato and K{\"o}hler, {Cristiano A.} and Evangelos Evangelou and Jordi Le{\'o}n-Caballero and Marco Solmi and Brendon Stubbs and Lazaros Belbasis and Isabella Pacchiarotti and Kessing, {Lars V.} and Michael Berk and Eduard Vieta and Carvalho, {Andr{\'e} F.}",

year = "2017",

month = mar,

doi = "10.1111/bdi.12490",

language = "English",

volume = "19",

pages = "84--96",

journal = "Bipolar Disorders (English Edition, Online)",

issn = "1399-5618",

publisher = "Wiley-Blackwell",

number = "2",

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TY - JOUR

T1 - Systematic assessment of environmental risk factors for bipolar disorder

T2 - an umbrella review of systematic reviews and meta-analyses

AU - Bortolato, Beatrice

AU - Köhler, Cristiano A.

AU - Evangelou, Evangelos

AU - León-Caballero, Jordi

AU - Solmi, Marco

AU - Stubbs, Brendon

AU - Belbasis, Lazaros

AU - Pacchiarotti, Isabella

AU - Kessing, Lars V.

AU - Berk, Michael

AU - Vieta, Eduard

AU - Carvalho, André F.

PY - 2017/3

Y1 - 2017/3

N2 - 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.

AB - 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.

KW - aetiology

KW - bipolar disorder

KW - depression

KW - mania

KW - meta-analysis

KW - mood disorder

KW - psychiatry

KW - risk factor

KW - systematic review

U2 - 10.1111/bdi.12490

DO - 10.1111/bdi.12490

M3 - Review

C2 - 28470927

AN - SCOPUS:85018781743

SN - 1399-5618

VL - 19

SP - 84

EP - 96

JO - Bipolar Disorders (English Edition, Online)

JF - Bipolar Disorders (English Edition, Online)

IS - 2

ER -

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

Abstract

Keywords

UN SDGs

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