Evidence map›Paper›PMID 25763939›Full record

SynthesisPloS one2015

Smoking is associated with an increased risk of dementia: a meta-analysis of prospective cohort studies with investigation of potential effect modifiers.

Guochao Zhong, Yi Wang, Yong Zhang, Jeff Jianfei Guo, Yong Zhao

Erratum issuedOpen access · goldAbstract readMeta-AnalysisReview
PubMed Full text at PMC Publisher
In one paragraph

Synthesis in PloS one, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. An erratum has been issued. Cited by 173 papers, 9 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
173citing papers in PubMed, 9 pooled it
11.6field-weighted citation impact, top 1% of its field
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

173 citing papers in PubMed, 9 syntheses or guidelines pooled it, 342 citations in OpenAlex.

  1. Pooled it
  2. Hypertensive disorders of pregnancy and the risk of dementia: a systematic review and meta-analysis of cohort studies.Hypertension research : official journal of the Japanese Society of Hypertension · 2024
    Pooled it
  3. Non-Genetic Risk Factors of Alzheimer's Disease: An Updated Umbrella Review.The journal of prevention of Alzheimer's disease · 2024
    Pooled it
  4. Pooled it
  5. Pooled it
  6. Pooled it
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  9. Pooled it
  10. Trial
  11. Trial
  12. Smoking Interacts WithBiological psychiatry global open science · 2026
    Article
  13. Review
  14. Article
  15. Article
  16. Article
  17. The landscape of dementia in India: Prevalence, risk factors, and opportunities ahead.Alzheimer's & dementia : the journal of the Alzheimer's Association · 2026
    Review
  18. Article
  19. Review
  20. Article

113 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

5 · Who and what money

Authors and funding

5 authors at 4 institutions in 2 countries.

Guochao ZhongThe Second College of Clinical Medicine, Chongqing Medical University, Chongqing, China.
Yi WangThe Second College of Clinical Medicine, Chongqing Medical University, Chongqing, China.
Yong ZhangSchool of Public Health and Management, Chongqing Medical University, Chongqing, China.
Jeff Jianfei GuoDivision of Pharmacy Practice and Administrative Sciences, College of Pharmacy, University of Cincinnati, Cincinnati, OH, 45221, United States of America.
Yong ZhaoSchool of Public Health and Management, Chongqing Medical University, Chongqing, China.
Chongqing Medical University · CNChongqing Public Health Medical Center · CNDalian Medical University · CNUniversity of Cincinnati · US

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundPrevious studies showed inconsistent results on the association of smoking with all-cause dementia and vascular dementia (VaD), and are limited by inclusion of a small number of studies and unexplained heterogeneity. Our review aimed to assess the risk of all-cause dementia, Alzheimer's disease (AD) and VaD associated with smoking, and to identify potential effect modifiers. METHODS AND

findingsThe PubMed, Embase, Cochrane Library and Psychinfo databases were searched to identify studies that provided risk estimates on smoking and incidence of dementia. A random-effects model was used to yield pooled results. Thirty-seven studies were included. Compared with never smokers, current smokers showed an increased risk of all-cause dementia (risk ratio (RR) 1.30, 95% confidence interval (CI) 1.18-1.45), AD (RR 1.40, 95% CI 1.13-1.73) and VaD (RR 1.38, 95% CI 1.15-1.66). For all-cause dementia, the risk increased by 34% for every 20 cigarettes per day (RR 1.34, 95% CI 1.25-1.43). Former smokers did not show an increased risk of all-cause dementia (RR 1.01, 95% CI 0.96-1.06), AD (RR 1.04, 95% CI 0.96-1.13) and VaD (RR 0.97, 95% CI 0.83-1.13). Subgroup analyses indicated that (1) the significantly increased risk of AD from current smoking was seen only in apolipoprotein E ε4 noncarriers; (2) current smokers aged 65 to 75 years at baseline showed increased risk of all-cause dementia and AD compared to those aged over 75 or under 65 years; and (3) sex, race, study location and diagnostic criteria difference in risk of dementia was not found.

conclusionsSmokers show an increased risk of dementia, and smoking cessation decreases the risk to that of never smokers. The increased risk of AD from smoking is more pronounced in apolipoprotein E ε4 noncarriers. Survival bias and competing risk reduce the risk of dementia from smoking at extreme age.

Indexed as

AgedAged, 80 and overAlzheimer DiseaseApolipoproteins EDementiaDementia, VascularFemaleHumansMaleMiddle AgedProspective StudiesRisk FactorsSmokingSurvival AnalysisApolipoproteins E

Identifiers

PMID25763939
PMCPMC4357455
OpenAlexW2027048227

What OpenQuestion holds

Textmetadata
LicenceCC BY
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.