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66/100

✓ Peer-reviewed alzhub usefulness score 66 out of 100. Prevention and risk

Reviewed as evidence on: Coffee / caffeine intake and dementia risk 3 studies (what the news said). Being listed means the study bears on the question, not that it agrees with the news.

Topic: Risk, prevention and care in population studies

Plain-language summary

Background Previous studies have revealed the involvement of coffee and tea in the development of stroke and dementia. However, little is known about the association between the combination of coffee and tea and the risk of stroke, dementia, and poststroke dementia. Therefore, we aimed to investigate the associations of coffee and tea separately and in combination with the risk of developing stroke and dementia. Methods and findings This prospective cohort study included 365,682 participants (50 to 74 years old) from the UK Biobank. Participants joined the study from 2006 to 2010 and were followed up until 2020. We used Cox proportional hazards models to estimate the associations between coffee/tea consumption and incident stroke and dementia, adjusting for sex, age, ethnicity, qualification, income, body mass index (BMI), physical activity, alcohol status, smoking status, diet pattern, consumption of sugar-sweetened beverages, high-density lipoprotein (HDL), low-density lipoprotein (LDL), history of cancer, history of diabetes, history of cardiovascular arterial disease (CAD), and hypertension. Coffee and tea consumption was assessed at baseline. During a median follow-up of 11.4 years for new onset disease, 5,079 participants developed dementia, and 10,053 participants developed stroke. The associations of coffee and tea with stroke and dementia were nonlinear (P for nonlinear Conclusions We found that drinking coffee and tea separately or in combination were associated with lower risk of stroke and dementia. Intake of coffee alone or in combination with tea was associated with lower risk of poststroke dementia.

What this study adds

Evidence grade: Moderate

This is a follow-up (cohort) study of 365,682 participants. In this large cohort, drinking coffee and tea, separately or together, was associated with a lower risk of stroke and dementia. These are observational associations, so they do not prove that drinking coffee or tea prevents dementia.

Taken from this record’s own fields, not from reading the paper. The grade is assigned from the abstract’s wording; what that means.

Cite this study APA, Vancouver, BibTeX · download .bib or .ris

APA 7th

Zhang, Y., Yang, H., Li, S., Li, W. D., & Wang, Y. (2021). Consumption of coffee and tea and risk of developing stroke, dementia, and poststroke dementia: A cohort study in the UK Biobank. PLoS medicine. https://doi.org/10.1371/journal.pmed.1003830

Vancouver

Zhang Y, Yang H, Li S, Li WD, Wang Y. Consumption of coffee and tea and risk of developing stroke, dementia, and poststroke dementia: A cohort study in the UK Biobank. PLoS medicine. 2021. doi:10.1371/journal.pmed.1003830. PMID: 34784347.

BibTeX

@article{zhang2021-34784347,
  author  = {Zhang, Y. and Yang, H. and Li, S. and Li, W. D. and Wang, Y.},
  title   = {{Consumption of coffee and tea and risk of developing stroke, dementia, and poststroke dementia: A cohort study in the UK Biobank}},
  journal = {PLoS medicine},
  year    = {2021},
  doi     = {10.1371/journal.pmed.1003830},
  pmid    = {34784347},
  url     = {https://doi.org/10.1371/journal.pmed.1003830}
}

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.

How to read this study

Design: this is a follow-up (cohort) study. People are observed over time and not assigned to anything, so an association can reflect other differences between groups. Look at how long follow-up lasted, how many dropped out, and whether the authors adjusted for age, education and other health conditions.
Size: the record lists 365,682 participants. Ask whether that is enough for the question, and who they were.
Effect: the record gives no effect size, so the summary above cannot say how large any difference was.

What the evidence grade means here

This page is graded moderate. alzhub.org assigns the grade automatically from keywords in the abstract, not from reading the paper. Moderate means the abstract mentions a cohort, case-control or longitudinal design. It can add at most 5 of the 100 points in the study score, and it is a label about design, not a verdict on whether the findings are true.

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Key findings

Background Previous studies have revealed the involvement of coffee and tea in the development of stroke and dementia.
The associations of coffee and tea with stroke and dementia were nonlinear (P for nonlinear Conclusions We found that drinking coffee and tea separately or in combination were associated with lower risk of stroke and dementia.
Intake of coffee alone or in combination with tea was associated with lower risk of poststroke dementia.

Why it matters

In this large cohort, drinking coffee and tea, separately or together, was associated with a lower risk of stroke and dementia. These are observational associations, so they do not prove that drinking coffee or tea prevents dementia.

New to this subject? Start with our plain-English guide: Prevention →

Study details

Study designcohort study
Participants365,682
Evidence strengthModerate

How this study scored 66/100

Published in a peer-reviewed journal, and it is a cohort study following people over time. Scored zero for effect reported and randomized / blinded because the record does not state it.

Component	Points	Why
Journal tier	7 / 10	Tier 3 — peer-reviewed journal (PLoS medicine)
Journal's citation record	3 / 4	PLoS Medicine: journal h-index 350 (OpenAlex, 2026-10-29)
Study design	7 / 12	A cohort study following people over time
Strength of evidence	3 / 5	Rated “moderate” in our summary
Peer-review validation	10 / 10	Peer-reviewed. Published as an article in a named peer-reviewed journal.
How recent	3 / 5	2021 — within 6 year(s) of the newest study here
Sample size	4 / 4	365,682 participants
Effect reported	0 / 3	No effect size reported — scores zero (not stated in the record — scored 0)
Studied in people	3 / 3	Studied in people (participant count stated)
Randomized / blinded	0 / 2	No randomization or blinding stated — scores zero (not stated in the record — scored 0)
Times cited	5 / 7	Cited 195 times (OpenAlex, 2026-10-10)
Citations per year	4 / 5	27.9 citations a year over 7 year(s) since 2021
Impact for its field and year	4 / 6	Cited 14.8× the average for papers of its field and year (OpenAlex FWCI)
Cited by studies here	2 / 6	Cited by 4 other studies in this library
Still being cited	3 / 4	Cited 129 times in 2024–2026 (2026 still in progress; OpenAlex)
Senior author's track record	1 / 4	Last-listed author Yaogang Wang: h-index 12 (OpenAlex, whole career)
Institution's track record	2 / 3	Yale University: institution h-index 1,927 (OpenAlex)
Multicenter collaboration	1 / 3	OpenAlex lists 2 institution(s) in 2 countries
Indexed in PubMed	2 / 2	Indexed in PubMed (PMID 34784347)
Free to read	2 / 2	Free to read
Total	66 / 100	—

What each of these 20 components measures, and what this score is not →

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