Combining modifiable risk factors and risk of dementia: a systematic review and meta-analysis. Issue 1 (25th January 2019)

• Record Type: Journal Article
• Authors: Peters, Ruth; Booth, Andrew; Rockwood, Kenneth; Peters, Jean; D'Este, Catherine; Anstey, Kaarin J
• Is Part Of: BMJ open. Volume 9:Issue 1(2019)
• Publication Date: 2019-01-25
• Subjects: dementia -- risk factors -- cognitive decline -- scores -- clustering; Medicine -- Research -- Periodicals; 610.72
• DOI: 10.1136/bmjopen-2018-022846
• Languages: English
• ISSNs: 2044-6055

Abstract

Abstract : Objective: To systematically review the literature relating to the impact of multiple co-occurring modifiable risk factors for cognitive decline and dementia. Design: A systematic review and meta-analysis of the literature relating to the impact of co-occurring key risk factors for incident cognitive decline and dementia. All abstracts and full text were screened independently by two reviewers and each article assessed for bias using a standard checklist. A fixed effects meta-analysis was undertaken. Data sources: Databases Medline, Embase and PsycINFO were searched from 1999 to 2017. Eligibility criteria: For inclusion articles were required to report longitudinal data from participants free of cognitive decline at baseline, with formal assessment of cognitive function or dementia during follow-up, and an aim to examine the impact of additive or clustered comorbid risk factor burden in with two or more core modifiable risk factors. Results: Seventy-nine full-text articles were examined. Twenty-two articles (18 studies) were included reporting data on >40 000 participants. Included studies consistently reported an increased risk associated with greater numbers of intraindividual risk factors or unhealthy behaviours and the opposite for healthy or protective behaviours. A meta-analysis of studies with dementia outcomes resulted in a pooled relative risk for dementia of 1.20 (95% CI 1.04 to 1.39) for one risk factor, 1.65 (95% CI 1.40 to 1.94) for two and 2.21 (95% CI 1.78 to 2.73) for three or more, relative to no risk factors. Limitations include dependence on published results and variations in study outcome, cognitive assessment, length of follow-up and definition of risk factor exposure. Conclusions: The strength of the reported associations, the consistency across studies and the suggestion of a dose response supports a need to keep modifiable risk factor exposure to a minimum and to avoid exposure to additional modifiable risks. Further research is needed to establish whether particular combinations of risk factors confer greater risk than others. PROSPERO registration number: 42016052914.