title: Onset and progression factors in Parkinson's disease: A systematic review.
abstract: Current research has identified several factors thought to be associated with the onset and progression of Parkinson's Disease (PD); however, whether certain factors contribute to or are protective against PD remains unclear. As such, a systematic search of the literature was performed using variations of MeSH and keyword search terms to identify and summarize systematic reviews and primary studies pertaining to factors associated with the onset and progression of PD. Factors referred to both traditional risk factors and prodromal markers. The following databases were searched: MEDLINE, MEDLINE In-Process, EMBASE, PsycINFO, Scopus, Web of Science, Cochrane Database of Systematic Reviews, Cumulative Index to Nursing and Allied Health Literature (CINAHL), ProQuest Dissertations & Theses, AARP AgeLine, and PDGene. A quality assessment of included systematic reviews was completed using the validated Assessment of the Methodological Quality of Systematic Reviews (AMSTAR) tool. Data extraction targeted reported factors, risk estimates, and 95% confidence intervals (CI). Findings identified 11 systematic reviews of sufficient quality reporting factors for PD onset, and no systematic reviews reporting factors for PD progression. In addition, 93 primary articles were identified, of which, 89 articles addressed factors related to PD onset and 4 articles addressed factors related to the PD progression. Pesticide exposure, rural living, well-water drinking, and farming occupation were consistently found to be positively associated with the onset of PD. Moreover, family history and polymorphisms to key genes were also found to be positively associated with the onset of PD. Conversely, coffee consumption, cigarette smoking, and some polymorphisms were consistently found to be negatively associated with the onset of PD. Urate was the only identified factor linked to the progression of PD; it was mostly found to be negatively associated with PD. In sum, the evidence was systematically found and summarized in the literature pertaining to factors related to the onset and progression of PD.
authors.affiliation: Department of Speech-Language Pathology, University of Toronto, Toronto, Canada; Rehabilitation Sciences Institute, University of Toronto, Toronto, Canada; Health Care and Outcomes Research, Krembil Research Institute, University Health Network, Toronto, Canada. Electronic address: rosemary.martino@utoronto.ca.
authors.forename: Rosemary
authors.initials: R
authors.lastname: Martino
authors.affiliation: Faculty of Health Sciences, University of Ontario Institute of Technology, Toronto, Canada.
authors.forename: Hamilton
authors.initials: H
authors.lastname: Candundo
authors.affiliation: Department of Speech-Language Pathology, University of Toronto, Toronto, Canada; Rehabilitation Sciences Institute, University of Toronto, Toronto, Canada; Department of Psychology, University of Toronto, Toronto, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada; Toronto Rehabilitation Institute, University Health Network, Toronto, Canada.
authors.forename: Pascal van
authors.initials: PV
authors.lastname: Lieshout
authors.affiliation: Faculty of Health Sciences, University of Ontario Institute of Technology, Toronto, Canada.
authors.forename: Sabina
authors.initials: S
authors.lastname: Shin
authors.affiliation: McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Canada.
authors.forename: James A G
authors.initials: JAG
authors.lastname: Crispo
authors.affiliation: Faculty of Health Sciences, University of Ontario Institute of Technology, Toronto, Canada.
authors.forename: Caroline
authors.initials: C
authors.lastname: Barakat-Haddad
mesh_terms: D017668:Age of Onset; D016206:Databases, Bibliographic / Q000706:statistics & numerical data; D018450:Disease Progression; D006801:Humans; D010300:Parkinson Disease / Q000453:epidemiology* / Q000209:etiology*; D012307:Risk Factors
keywords: Disease progression; Onset; Parkinson’s disease; Systematic review