Environmental risk factors and Parkinson's disease: An umbrella review of meta-analyses

Bellou, Vanesa; Belbasis, Lazaros; Tzoulaki, Ioanna; Εvangelou, Εvangelos; Ioannidis, John P. A.

doi:10.1016/j.parkreldis.2015.12.008

Cited by 325 publications

(316 citation statements)

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“…We combined schizophrenia and affective psychoses and then meta-analyzed the IRR of each 10-year age range (vs. other ages), and the IRR of males (vs. females, globally and within each 10-year age range). Since age and gender were considered as basic factors and excluded by previous reviews on psychosis 8,9 and by umbrella reviews on other neuropsychiatric conditions 23,25,27 , these analyses were considered exploratory.…”

Section: Discussionmentioning

confidence: 99%

“…Specifically, the incidence in each location was (logistic) regressed by the latitude or GNI, obtaining the OR of 108 increase in latitude or 10,000 USD increase in GNI. These results were also considered exploratory because they are based on ecological analyses rather than individual-level data, and were traditionally excluded from previous umbrella reviews of risk factors 23,25,27 . Complementary analyses included: a) an Egger test to assess small-study effects that lead to potential reporting or publication bias 68 ; b) a test of excess significance bias 69 as described below, and c) an OR equivalent.…”

Section: Discussionmentioning

confidence: 99%

“…Umbrella reviews can overcome these problems by assessing the level of the evidence provided by systematic reviews and meta-analyses 14 for each risk or protective factor, through strict criteria that probe a standard list of potential biases. These criteria have been extensively validated in various areas of medicine, such as neurology, oncology, nutrition medicine, internal medicine, psychiatry, paediatrics, dermatology and neurosurgery [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] . In the current study, we applied the umbrella review approach to the published evidence on risk or protective factors for psychotic disorders.…”

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What causes psychosis? An umbrella review of risk and protective factors

et al. 2018

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Psychosis is a heterogeneous psychiatric condition for which a multitude of risk and protective factors have been suggested. This umbrella review aimed to classify the strength of evidence for the associations between each factor and psychotic disorders whilst controlling for several biases. The Web of Knowledge database was searched to identify systematic reviews and meta-analyses of observational studies which examined associations between socio-demographic, parental, perinatal, later factors or antecedents and psychotic disorders, and which included a comparison group of healthy controls, published from 1965 to January 31, 2017. The literature search and data extraction followed PRISMA and MOOSE guidelines. The association between each factor and ICD or DSM diagnoses of non-organic psychotic disorders was graded into convincing, highly suggestive, suggestive, weak, or non-significant according to a standardized classification based on: number of psychotic cases, random-effects p value, largest study 95% confidence interval, heterogeneity between studies, 95% prediction interval, small study effect, and excess significance bias. In order to assess evidence for temporality of association, we also conducted sensitivity analyses restricted to data from prospective studies. Fifty-five meta-analyses or systematic reviews were included in the umbrella review, corresponding to 683 individual studies and 170 putative risk or protective factors for psychotic disorders. Only the ultra-high-risk state for psychosis (odds ratio, OR59.32, 95% CI: 4.91-17.72) and Black-Caribbean ethnicity in England (OR54.87, 95% CI: 3.96-6.00) showed convincing evidence of association. Six factors were highly suggestive (ethnic minority in low ethnic density area, second generation immigrants, trait anhedonia, premorbid IQ, minor physical anomalies, and olfactory identification ability), and nine were suggestive (urbanicity, ethnic minority in high ethnic density area, first generation immigrants, North-African immigrants in Europe, winter/spring season of birth in Northern hemisphere, childhood social withdrawal, childhood trauma, Toxoplasma gondii IgG, and non-right handedness). When only prospective studies were considered, the evidence was convincing for ultra-high-risk state and suggestive for urbanicity only. In summary, this umbrella review found several factors to be associated with psychotic disorders with different levels of evidence. These risk or protective factors represent a starting point for further etiopathological research and for the improvement of the prediction of psychosis.

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What causes psychosis? An umbrella review of risk and protective factors

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“…Environmental risks are from a number of sources that include most commonly pesticide exposure, living in rural settings, well water consumption, herbicide exposure and living in proximity to industrial plants or quarries. Bellou et al reported that environmental factors such as dietary factors, drugs, medical history or comorbid diseases, exposure to toxic environmental agents and habits have been substantially associated with Parkinson's disease in 21 of 75 metaanalyses (more than 1000 cases) [35].…”

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confidence: 99%

OMICS as Therapeutic Platform: Environmental Factors to Parkinson’s Disease

Kim¹,

Warner²

2016

J Microb Biochem Technol

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“…Bellou et al 35 offer words of caution in the strength of inference that is offered by many of the meta-analytical studies on PQ-PD associations. An additional problem is that there is a tendency to treat hypotheses as the 'data' for inferring a more inclusive hypothesis.…”

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confidence: 99%