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73/100

✓ Peer-reviewed alzhub usefulness score 73 out of 100. Prevention and risk

Topic: Risk, prevention and care in population studies

Background Observational studies of the Mediterranean diet suggest cognitive benefits, potentially reducing dementia risk. Objective We performed the first published review to our knowledge of randomized controlled trials (RCTs) investigating Mediterranean diet effects on cognition or brain morphology and function, with an additional focus on intervention diet quality and its relation to "traditional" Mediterranean dietary patterns. Design We searched 9 databases from inception (final update December 2017) for RCTs testing a Mediterranean compared with alternate diet for cognitive or brain morphology and function outcomes. Results Analyses were based on 66 cognitive tests and 1 brain function outcome from 5 included studies (n = 1888 participants). The prescribed Mediterranean diets varied considerably between studies, particularly with regards to quantitative food advice. Only 8/66 (12.1%) of individual cognitive outcomes at trial level significantly favored a Mediterranean diet for cognitive performance, with effect sizes (ESs) ranging from small (0.32) to large (1.66), whereas 2 outcomes favored controls. Data limitations precluded a meta-analysis. Of 8 domain composite cognitive scores from 2 studies, the 3 (Memory, Frontal, and Global function) from PREDIMED (PREvención con DIeta MEDiterránea) were significant, with ESs ranging from 0.39 to 1.29. A posttest comparison at a second PREDIMED site found that the Mediterranean diet modulates the effect of several genotypes associated with dementia risk for some cognitive outcomes, with mixed results. Finally, the risk of low-plasma brain-derived neurotrophic factor was reduced by 78% (OR = 0.22; 95% CI: 0.05, 0.90) in those who consumed a Mediterranean diet compared to control diet at 3 y in this trial. There was no benefit of the Mediterranean diet for incident cognitive impairment or dementia. Conclusions Five RCTs of the Mediterranean diet and cognition have been published to date. The data are mostly nonsignificant, with small ESs. However, the significant improvements in cognitive domain composites in the most robustly designed study warrant additional research.

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APA 7th

Radd-Vagenas, S., Duffy, S. L., Naismith, S. L., Brew, B. J., Flood, V. M., & Fiatarone Singh, M. A. (2018). Effect of the Mediterranean diet on cognition and brain morphology and function: a systematic review of randomized controlled trials. The American journal of clinical nutrition. https://doi.org/10.1093/ajcn/nqx070

Vancouver

Radd-Vagenas S, Duffy SL, Naismith SL, Brew BJ, Flood VM, Fiatarone Singh MA. Effect of the Mediterranean diet on cognition and brain morphology and function: a systematic review of randomized controlled trials. The American journal of clinical nutrition. 2018. doi:10.1093/ajcn/nqx070. PMID: 29566197.

BibTeX

@article{raddvagenas2018-29566197,
  author  = {Radd-Vagenas, S. and Duffy, S. L. and Naismith, S. L. and Brew, B. J. and Flood, V. M. and Fiatarone Singh, M. A.},
  title   = {{Effect of the Mediterranean diet on cognition and brain morphology and function: a systematic review of randomized controlled trials}},
  journal = {The American journal of clinical nutrition},
  year    = {2018},
  doi     = {10.1093/ajcn/nqx070},
  pmid    = {29566197},
  url     = {https://doi.org/10.1093/ajcn/nqx070}
}

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Key findings

Design We searched 9 databases from inception (final update December 2017) for RCTs testing a Mediterranean compared with alternate diet for cognitive or brain morphology and function outcomes.
Results Analyses were based on 66 cognitive tests and 1 brain function outcome from 5 included studies (n = 1888 participants).
Only 8/66 (12.1%) of individual cognitive outcomes at trial level significantly favored a Mediterranean diet for cognitive performance, with effect sizes (ESs) ranging from small (0.32) to large (1.66), whereas 2 outcomes favored controls.
Of 8 domain composite cognitive scores from 2 studies, the 3 (Memory, Frontal, and Global function) from PREDIMED (PREvención con DIeta MEDiterránea) were significant, with ESs ranging from 0.39 to 1.29.
A posttest comparison at a second PREDIMED site found that the Mediterranean diet modulates the effect of several genotypes associated with dementia risk for some cognitive outcomes, with mixed results.

Why it matters

In a systematic review of 5 randomized controlled trials with 1,888 participants, only 8 of 66 individual cognitive outcomes significantly favored a Mediterranean diet, while 2 favored controls. Data limitations prevented a meta-analysis, and the prescribed Mediterranean diets varied considerably between studies.

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Study details

Study designmeta-analysis
Participants1,888
Effect size12.1%; reduced by 78%; OR = 0.22
Evidence strengthHigh

How this study scored 73/100

Published in a peer-reviewed journal, and it is a meta-analysis pooling many studies.

Component	Points	Why
Journal tier	7 / 10	Tier 3 — peer-reviewed journal (The American journal of clinical nutrition)
Journal's citation record	3 / 4	American Journal of Clinical Nutrition: journal h-index 499 (OpenAlex, 2026-10-29)
Study design	12 / 12	A meta-analysis pooling many studies
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	2 / 5	2018 — within 10 year(s) of the newest study here
Sample size	3 / 4	1,888 participants
Effect reported	3 / 3	Effect reported with a statistic (interval, p-value, ratio or similar)
Studied in people	3 / 3	Studied in people (participant count stated)
Randomized / blinded	0 / 2	A review of other studies — randomization is not credited here
Times cited	5 / 7	Cited 176 times (OpenAlex, 2026-10-10)
Citations per year	3 / 5	17.6 citations a year over 10 year(s) since 2018
Impact for its field and year	3 / 6	Cited 4.3× the average for papers of its field and year (OpenAlex FWCI)
Cited by studies here	3 / 6	Cited by 12 other studies in this library
Still being cited	3 / 4	Cited 54 times in 2024–2026 (2026 still in progress; OpenAlex)
Senior author's track record	3 / 4	Last-listed author Maria A. Fiatarone Singh: h-index 56 (OpenAlex, whole career)
Institution's track record	1 / 3	The University of Sydney: institution h-index 1,466 (OpenAlex)
Multicenter collaboration	2 / 3	OpenAlex lists 9 institution(s) in 2 countries
Indexed in PubMed	2 / 2	Indexed in PubMed (PMID 29566197)
Free to read	0 / 2	Behind a paywall — scores zero
Total	73 / 100	—

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