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2022-01-26Zeitschriftenartikel DOI: 10.18452/24425
The Effect of Polyphenols on Working and Episodic Memory in Non-pathological and Pathological Aging: A Systematic Review and Meta-Analysis
dc.contributor.authorde Vries, Karin
dc.contributor.authorMedawar, Evelyn
dc.contributor.authorKorosi, Aniko
dc.contributor.authorWitte, A. Veronica
dc.date.accessioned2022-03-31T11:16:09Z
dc.date.available2022-03-31T11:16:09Z
dc.date.issued2022-01-26none
dc.date.updated2022-02-12T16:50:34Z
dc.identifier.urihttp://edoc.hu-berlin.de/18452/25080
dc.description.abstractLife expectancy steadily increases, and so do age-associated diseases, leading to a growing population suffering from cognitive decline and dementia. Impairments in working memory (WM) and episodic memory (EM) are associated with an increased risk of developing dementia. While there are no effective pharmacological therapies to preserve or enhance cognition and to slow down the progression from mild memory complaints to dementia so far, plant-based nutrients including polyphenols have been suggested to exert beneficial effects on brain aging. This review studies whether supplementary polyphenols are effective in preserving or enhancing memory in both non-pathological and pathological aging, and whether there are polyphenol efficiency differences between WM and EM. A systematic literature search was conducted and 66 out of 294 randomized clinical trials with 20 participants or more per group, aged 40 years or older were included. These covered a daily intake of 35–1,600 mg polyphenols, e.g., flavonols, flavonoids, isoflovones, anthocyanins, and/or stilbenes, over the course of 2 weeks to 6.5 years duration. In total, around half of the studies reported a significantly improved performance after polyphenol administration compared to control, while three studies reported a worsening of performance, and the remainder did not observe any effects. According to pooled WM and EM meta-analysis of all memory outcomes reported in 49 studies, overall effect size for WM and EM indicated a significant small positive effect on EM and WM with similar estimates (b ~ 0.24, p < 0.001), with large study heterogeneity and significant Funnel asymmetry tests suggesting a positivity bias. These results remained similar when excluding studies reporting extremely large positive effect sizes from the meta-analyses. While Ginkgo biloba and isoflavones did not show benefits in subgroup meta-analyses, those suggested some effects in extracts containing anthocyanins, other flavonoids and resveratrol, again potentially resulting from publication bias. To conclude, a systematic review and meta-analysis indicate that short- to moderate-term polyphenol interventions might improve WM and EM in middle-to older aged adults, however, publication bias in favor of positive results seems likely, rendering definite conclusions difficult. Future studies with larger, more diverse samples and sensitive monitoring of cardiovascular, metabolic and beginning brain pathologies as well as longer follow-up are needed to better understand the impact of age, (beginning) pathologies, gender, and long-term use on polyphenol action.eng
dc.language.isoengnone
dc.publisherHumboldt-Universität zu Berlin
dc.rights(CC BY 4.0) Attribution 4.0 Internationalger
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectpolyphenoleng
dc.subjectRCT—randomized controlled trialeng
dc.subjectagingeng
dc.subjectepisodic memoryeng
dc.subjectworking memoryeng
dc.subject.ddc150 Psychologienone
dc.titleThe Effect of Polyphenols on Working and Episodic Memory in Non-pathological and Pathological Aging: A Systematic Review and Meta-Analysisnone
dc.typearticle
dc.identifier.urnurn:nbn:de:kobv:11-110-18452/25080-3
dc.identifier.doihttp://dx.doi.org/10.18452/24425
dc.type.versionpublishedVersionnone
local.edoc.pages25none
local.edoc.type-nameZeitschriftenartikel
local.edoc.container-typeperiodical
local.edoc.container-type-nameZeitschrift
dc.description.versionPeer Reviewednone
dc.identifier.eissn2296-861X
dcterms.bibliographicCitation.doi10.3389/fnut.2021.720756none
dcterms.bibliographicCitation.journaltitleFrontiers in nutrition : FNUTnone
dcterms.bibliographicCitation.volume8none
dcterms.bibliographicCitation.articlenumber720756none
dcterms.bibliographicCitation.originalpublishernameFrontiers Medianone
dcterms.bibliographicCitation.originalpublisherplaceLausannenone
bua.departmentPhilosophische Fakultätnone

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