title: Intakes of fish and polyunsaturated fatty acids and mild-to-severe cognitive impairment risks: a dose-response meta-analysis of 21 cohort studies.
abstract: BACKGROUND
  The intake of fish and polyunsaturated fatty acids (PUFAs) may benefit cognitive function. However, optimal intake recommendations for protection are unknown.
  
  
  OBJECTIVE
  We systematically investigated associations between fish and PUFA intake and mild-to-severe cognitive impairment risk.
  
  
  METHODS
  Studies that reported risk estimates for mild cognitive impairment (MCI), cognitive decline, dementia, Alzheimer disease (AD), or Parkinson disease (PD) from fish, total PUFAs, total n-3 (ω-3) PUFAs, or at least one n-3 PUFA were included. Study characteristics and outcomes were extracted. The pooled RR was estimated with the use of a random-effects model meta-analysis. A dose-response analysis was conducted with the use of the 2-stage generalized least-squares trend program.
  
  
  RESULTS
  We included 21 studies (181,580 participants) with 4438 cases identified during follow-up periods (2.1-21 y). A 1-serving/wk increment of dietary fish was associated with lower risks of dementia (RR: 0.95; 95% CI: 0.90, 0.99; P = 0.042, I(2) = 63.4%) and AD (RR: 0.93; 95% CI: 0.90, 0.95; P = 0.003, I(2) = 74.8%). Pooled RRs of MCI and PD were 0.71 (95% CI: 0.59, 0.82; P = 0.733, I(2) = 0%) and 0.90 (95% CI: 0.80, 0.99; P = 0.221, I(2) = 33.7%), respectively, for an 8-g/d increment of PUFA intake. As an important source of marine n-3 PUFAs, a 0.1-g/d increment of dietary docosahexaenoic acid (DHA) intake was associated with lower risks of dementia (RR: 0.86; 95% CI: 0.76, 0.96; P < 0.001, I(2) = 92.7%) and AD (RR: 0.63; 95% CI: 0.51, 0.76; P < 0.001, I(2) = 94.5%). Significant curvilinear relations between fish consumption and risk of AD and between total PUFAs and risk of MCI (both P-nonlinearity < 0.001) were observed.
  
  
  CONCLUSIONS
  Fishery products are recommended as dietary sources and are associated with lower risk of cognitive impairment. Marine-derived DHA was associated with lower risk of dementia and AD but without a linear dose-response relation.
authors.affiliation: Department of Food Science and Nutrition, College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, China; and.
authors.forename: Yu
authors.identifier: http://orcid.org/0000-0003-1025-906X
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Food Science and Nutrition, College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, China; and.
authors.forename: Jingnan
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Nutrition, and.
authors.forename: Jieni
authors.initials: J
authors.lastname: Qiu
authors.affiliation: Department of Epidemiology and Health Statistics, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Yingjun
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Epidemiology and Health Statistics, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Jianbing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Nutrition, and jingjingjiao@zju.edu.cn.
authors.forename: Jingjing
authors.identifier: http://orcid.org/0000-0003-4167-1567
authors.initials: J
authors.lastname: Jiao
mesh_terms: D000544:Alzheimer Disease / Q000453:epidemiology / Q000503:physiopathology / Q000517:prevention & control; D000818:Animals; D003072:Cognition Disorders / Q000453:epidemiology / Q000503:physiopathology / Q000517:prevention & control; D060825:Cognitive Dysfunction / Q000453:epidemiology / Q000503:physiopathology / Q000517:prevention & control*; D003704:Dementia / Q000453:epidemiology / Q000503:physiopathology / Q000517:prevention & control*; D004032:Diet / Q000009:adverse effects; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D019587:Dietary Supplements / Q000009:adverse effects; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D005399:Fishes; D006801:Humans; D012307:Risk Factors; D017747:Seafood / Q000009:adverse effects; D012720:Severity of Illness Index
chemical_list: D004042:Dietary Fats, Unsaturated; D015525:Fatty Acids, Omega-3
keywords: Alzheimer disease; cognitive impairment; dementia; fish; polyunsaturated fatty acids