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Epidemiologic studies of modifiable factors associated with cognition and dementia: systematic review and meta-analysis
Beydoun MA, Beydoun HA, Gamaldo AA, Teel A, Zonderman AB, Wang Y.. BMC public health, 2014-06-24
Topic: Risk, prevention and care in population studies
Background Cognitive impairment, including dementia, is a major health concern with the increasing aging population. Preventive measures to delay cognitive decline are of utmost importance. Alzheimer's disease (AD) is the most frequent cause of dementia, increasing in prevalence from 40% above 85 years of age. Methods We systematically reviewed selected modifiable factors such as education, smoking, alcohol, physical activity, caffeine, antioxidants, homocysteine (Hcy), n-3 fatty acids that were studied in relation to various cognitive health outcomes, including incident AD. We searched MEDLINE for published literature (January 1990 through October 2012), including cross-sectional and cohort studies (sample sizes > 300). Analyses compared study finding consistency across factors, study designs and study-level characteristics. Selecting studies of incident AD, our meta-analysis estimated pooled risk ratios (RR), population attributable risk percent (PAR%) and assessed publication bias. Results In total, 247 studies were retrieved for systematic review. Consistency analysis for each risk factor suggested positive findings ranging from ~38.9% for caffeine to ~89% for physical activity. Education also had a significantly higher propensity for "a positive finding" compared to caffeine, smoking and antioxidant-related studies. Meta-analysis of 31 studies with incident AD yielded pooled RR for low education (RR = 1.99; 95% CI: 1.30-3.04), high Hcy (RR = 1.93; 95% CI: 1.50-2.49), and current/ever smoking status (RR = 1.37; 95% CI: 1.23-1.52) while indicating protective effects of higher physical activity and n-3 fatty acids. Estimated PAR% were particularly high for physical activity (PAR% = 31.9; 95% CI: 22.7-41.2) and smoking (PAR% = 31.09%; 95% CI: 17.9-44.3). Overall, no significant publication bias was found. Conclusions Higher Hcy levels, lower educational attainment, and decreased physical activity were particularly strong predictors of incident AD. Further studies are needed to support other potential modifiable protective factors, such as caffeine.
Key findings
- Results In total, 247 studies were retrieved for systematic review.
- Education also had a significantly higher propensity for "a positive finding" compared to caffeine, smoking and antioxidant-related studies.
- Overall, no significant publication bias was found.
Why it matters
This systematic review and meta-analysis examined modifiable factors such as education, smoking, alcohol, physical activity, caffeine, antioxidants, homocysteine, and n-3 fatty acids in relation to cognitive health and incident Alzheimer's disease. It summarizes consistency across studies rather than proving that changing any of these factors prevents or treats dementia.
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Study details
- Study designsystematic review
- Effect size38.9%; RR = 1.99; RR = 1.93
- Evidence strengthHigh
How this study scored 74/100
Published in a peer-reviewed journal, and it is a systematic review of all the studies on the question. Scored zero for sample size and studied in people because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (BMC public health) |
| Journal's citation record | 3 / 4 | BMC Public Health: journal h-index 289 (OpenAlex, 2026-10-29) |
| Study design | 12 / 12 | A systematic review of all the studies on the question |
| Strength of evidence | 5 / 5 | Rated “high” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 2014 — within 20 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 3 / 3 | Effect reported with a statistic (interval, p-value, ratio or similar) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | A review of other studies — randomisation is not credited here |
| Times cited | 6 / 7 | Cited 672 times (OpenAlex, 2026-10-10) |
| Citations per year | 4 / 5 | 48.0 citations a year over 14 year(s) since 2014 |
| Impact for its field and year | 4 / 6 | Cited 9.3× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 4 / 6 | Cited by 33 other studies in this library |
| Still being cited | 3 / 4 | Cited 105 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 3 / 4 | Last-listed author Youfa Wang: h-index 74 (OpenAlex, whole career) |
| Institution's track record | 3 / 3 | National Institutes of Health: institution h-index 2,723 (OpenAlex) |
| Multi-centre collaboration | 2 / 3 | OpenAlex lists 5 institution(s) in 1 country |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 24962204) |
| Free to read | 2 / 2 | Free to read |
| Total | 74 / 100 | — |
What each of these 20 components measures, and what this score is not →
Read the original
- DOI: 10.1186/1471-2458-14-643
- PubMed: 24962204
- Original source →
- Free full text: BMC Public Health →
Full text: free to read — OpenAlex lists this copy as free to read: the link above (checked 6 Feb 1020).
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. Check the citation against the original before you use it.
APA 7th
Beydoun, M. A., Beydoun, H. A., Gamaldo, A. A., Teel, A., Zonderman, A. B., & Wang, Y. (2014). Epidemiologic studies of modifiable factors associated with cognition and dementia: systematic review and meta-analysis. BMC public health. https://doi.org/10.1186/1471-2458-14-643
Vancouver
Beydoun MA, Beydoun HA, Gamaldo AA, Teel A, Zonderman AB, Wang Y. Epidemiologic studies of modifiable factors associated with cognition and dementia: systematic review and meta-analysis. BMC public health. 2014. doi:10.1186/1471-2458-14-643. PMID: 24962204.
BibTeX
@article{beydoun2014-24962204,
author = {Beydoun, M. A. and Beydoun, H. A. and Gamaldo, A. A. and Teel, A. and Zonderman, A. B. and Wang, Y.},
title = {{Epidemiologic studies of modifiable factors associated with cognition and dementia: systematic review and meta-analysis}},
journal = {BMC public health},
year = {2014},
doi = {10.1186/1471-2458-14-643},
pmid = {24962204},
url = {https://doi.org/10.1186/1471-2458-14-643}
}
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