Evidence map›Paper›PMID 32462636›Full record

SynthesisPsychonomic bulletin & review2020

Does bilingualism protect against dementia? A meta-analysis.

John A E Anderson, Kornelia Hawrylewicz, John G Grundy

Abstract readMeta-Analysis
PubMed Publisher
In one paragraph

Synthesis in Psychonomic bulletin & review, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 35 papers, 3 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
35citing papers in PubMed, 3 pooled it
–field-weighted citation impact
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

35 citing papers in PubMed, 3 syntheses or guidelines pooled it.

  1. Pooled it
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  3. Pooled it
  4. The role of bilingualism on functional decline and neurodegeneration in distinct ADRD clinical syndromes.Alzheimer's & dementia : the journal of the Alzheimer's Association · 2025
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  7. The Association Between Multilingual Experience Factors and Cognitive Functioning in Older Adults: A Lifelines Study.The journals of gerontology. Series B, Psychological sciences and social sciences · 2025
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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

3 authors.

John A E AndersonCentre for Addiction and Mental Health, Kimel Imaging and Genetics Laboratory, Toronto, ON, Canada. johnaeanderson@gmail.com.
Kornelia HawrylewiczDepartment of Psychology, Faculty of Health, York University, Toronto, ON, Canada.
John G GrundyDepartment of Psychology, Iowa State University, Ames, IA, USA. grundy@iastate.edu.

Funding

CIHR 415116
6 · The paper itself

Abstract

Evidence suggests that bilingualism may contribute to neuroplasticity and cognitive reserve, allowing individuals to resist cognitive decline associated with Alzheimer's disease progression, although the idea remains controversial. Here, we argue that the reason for the discrepancy stems from conflating incidence rates of dementia and the age at which the symptoms first appear, as well as statistical and methodological issues in the study designs. To clarify the issues, we conducted a comprehensive meta-analysis on the available literature regarding bilingualism and Alzheimer's disease, including both retrospective and prospective studies, as well as age of onset and incidence rates. Results revealed a moderate effect size for the protective effect of bilingualism on age of onset of symptoms of Alzheimer's disease (Cohen's d = 0.32), and weaker evidence that bilingualism prevents the occurrence of disease incidence itself (Cohen's d = 0.10). Moreover, our results cannot be explained by SES, education, or publication bias. We conclude with a discussion on how bilingualism contributes to cognitive reserve and protects against Alzheimer's disease and recommend that future studies report both age of onset as well as incidence rates when possible.

Indexed as

Alzheimer DiseaseCognitive ReserveMultilingualismHumansProtective FactorsAlzheimer’s diseaseBilingualismDementiaMeta-analysis

Identifiers

PMID32462636

What OpenQuestion holds

Textmetadata
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.