title: Association between BDNF levels and suicidal behaviour: a systematic review protocol.
abstract: BACKGROUND
  Suicide is a worldwide public health concern that claims close to 1 million lives each year. Suicidal behaviour is a significant risk factor for completed suicide and is much more prevalent than completed suicide. Many internal and external factors contribute to the risk of suicidal behaviour. Recent research has focused on biological markers in suicide risk, including brain-derived neurotrophic factor (BDNF). BDNF is a protein involved in the growth, function, and maintenance of the nervous system. It has been implicated in psychiatric disorders and suicide. While some evidence suggests that reduced levels of BDNF are associated with suicide, the precise relationship has yet to be determined. The aim of this study is to review the literature examining the relationship between levels of BDNF and suicidal behaviour.
  
  
  METHODS
  A predefined search strategy will be implemented to search the following electronic databases: PubMed/MEDLINE, Excerpta Medica Database (EMBASE), PsycINFO, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) from inception. The articles will be screened by two independent authors (RE and SP) using predetermined inclusion and exclusion criteria. Discrepancies will be resolved by consensus, or by a third author (ZS) in cases of disagreement. The primary outcome will be the association between levels of BDNF and suicidal behaviour. A meta-analysis will be conducted if appropriate. Quality of evidence and risk of bias will be evaluated.
  
  
  CONCLUSIONS
  The findings of this review will assist in identifying and treating individuals at increased risk of suicide.
  
  
  BACKGROUND
  PROSPERO CRD42015015871 .
authors.affiliation: MiNDS Neuroscience Graduate Program, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. eisenrb@mcmaster.ca.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Eisen
authors.affiliation: Health Research Methodology Graduate Program, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. pererasm@mcmaster.ca.|Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. pererasm@mcmaster.ca.
authors.forename: Stefan
authors.initials: S
authors.lastname: Perera
authors.affiliation: MiNDS Neuroscience Graduate Program, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. baworm@mcmaster.ca.|Population Genomics Program, Chanchlani Research Centre, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. baworm@mcmaster.ca.
authors.forename: Monica
authors.initials: M
authors.lastname: Bawor
authors.affiliation: Health Sciences Library, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. banfie@mcmaster.ca.
authors.forename: Laura
authors.initials: L
authors.lastname: Banfield
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. anglinr@mcmaster.ca.|Department of Medicine, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. anglinr@mcmaster.ca.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Anglin
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. minuzzi@mcmaster.ca.|Women's Health Concerns Clinic, St. Joseph's Healthcare Hamilton, 50 Charlton Avenue East, Hamilton, ON, L8N 4A6, Canada. minuzzi@mcmaster.ca.
authors.forename: Luciano
authors.initials: L
authors.lastname: Minuzzi
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. samaanz@mcmaster.ca.|Population Genomics Program, Chanchlani Research Centre, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. samaanz@mcmaster.ca.|Department of Psychiatry and Behavioural Neurosciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. samaanz@mcmaster.ca.|Peter Boris Centre for Addiction Research, St. Joseph's Healthcare Hamilton, 100 West 5th Street, Hamilton, ON, L8P 3R2, Canada. samaanz@mcmaster.ca.
authors.forename: Zainab
authors.initials: Z
authors.lastname: Samaan
mesh_terms: D015415:Biomarkers / Q000032:analysis; D001923:Brain Chemistry; D019208:Brain-Derived Neurotrophic Factor / Q000032:analysis*; D006801:Humans; D012107:Research Design; D012307:Risk Factors; D059020:Suicidal Ideation; D013406:Suicide, Attempted; D000078202:Systematic Reviews as Topic
chemical_list: D015415:Biomarkers; D019208:Brain-Derived Neurotrophic Factor