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Brain reserve and dementia: a systematic review
Valenzuela MJ, Sachdev P.. Psychological medicine, 2005-10-06
Topic: Risk, prevention and care in population studies
Background Behavioural brain reserve is a property of the central nervous system related to sustained and complex mental activity which can lead to differential expression of brain injury. Behavioural brain reserve has been assessed using autobiographical data such as education levels, occupational complexity and mentally stimulating lifestyle pursuits. So far there have been several epidemiological reports but no systematic review to put conflicting results into context. Our aim was to quantitatively review evidence for the effect of brain reserve on incident dementia. Method Cohort studies of the effects of education, occupation, premorbid IQ and mental activities on dementia risk were of interest. Abstracts were identified in MEDLINE (1966-September 2004), CURRENT CONTENTS (to September, 2004), PsychINFO (1984-September 2004), Cochrane Library Databases and reference lists from relevant articles. Twenty-two studies met inclusion criteria. Key information was extracted by both reviewers onto a standard template with a high level of agreement. Studies were combined through a quantitative random-effects meta-analysis. Results Higher brain reserve was associated with a lowered risk for incident dementia (summary odds ratio, 0.54; 95% confidence interval, 0.49-0.59). This effect was found over a median of 7.1 years follow-up and resulted from integrating data across more than 29000 individuals. Notably, increased complex mental activity in late life was associated with lower dementia rates independent of other predictors; a dose-response relationship was also evident between extent of complex mental activities in late life and dementia risk. Conclusions This study demonstrates robust evidence that complex patterns of mental activity in the early, mid- and late-life stages is associated with a significant reduction in dementia incidence. Randomized control trials based on brain-reserve principles are now required.
Key findings
- So far there have been several epidemiological reports but no systematic review to put conflicting results into context.
- Results Higher brain reserve was associated with a lowered risk for incident dementia (summary odds ratio, 0.54; 95% confidence interval, 0.49-0.59).
- Notably, increased complex mental activity in late life was associated with lower dementia rates independent of other predictors; a dose-response relationship was also evident between extent of complex mental activities in late life and dementia risk.
- Conclusions This study demonstrates robust evidence that complex patterns of mental activity in the early, mid- and late-life stages is associated with a significant reduction in dementia incidence.
Why it matters
This systematic review found that higher brain reserve, assessed through education, occupation, premorbid IQ and mental activities, was associated with a lowered risk for incident dementia, with increased complex mental activity in late life linked to lower dementia rates independent of other predictors. It reports an association only and no treatment or cure.
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Study details
- Study designsystematic review
- Participants29,000
- 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 effect reported because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Psychological medicine) |
| Journal's citation record | 3 / 4 | Psychological Medicine: journal h-index 331 (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 | 2006 — older than 20 years, still counted |
| Sample size | 4 / 4 | 29,000 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) |
| Randomised / blinded | 0 / 2 | A review of other studies — randomisation is not credited here |
| Times cited | 6 / 7 | Cited 937 times (OpenAlex, 2026-10-10) |
| Citations per year | 4 / 5 | 42.6 citations a year over 22 year(s) since 2006 |
| Impact for its field and year | 4 / 6 | Cited 8.6× 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 121 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 4 / 4 | Last-listed author Perminder Singh Sachdev: h-index 147 (OpenAlex, whole career) |
| Institution's track record | 1 / 3 | UNSW Sydney: institution h-index 1,101 (OpenAlex) |
| Multi-centre collaboration | 1 / 3 | OpenAlex lists 3 institution(s) in 1 country |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 16207391) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 74 / 100 | — |
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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
Valenzuela, M. J., & Sachdev, P. (2006). Brain reserve and dementia: a systematic review. Psychological medicine. https://doi.org/10.1017/s0033291705006264
Vancouver
Valenzuela MJ, Sachdev P. Brain reserve and dementia: a systematic review. Psychological medicine. 2006. doi:10.1017/s0033291705006264. PMID: 16207391.
BibTeX
@article{valenzuela2006-16207391,
author = {Valenzuela, M. J. and Sachdev, P.},
title = {{Brain reserve and dementia: a systematic review}},
journal = {Psychological medicine},
year = {2006},
doi = {10.1017/s0033291705006264},
pmid = {16207391},
url = {https://doi.org/10.1017/s0033291705006264}
}
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