Effect of Polyphenols on Cognitive Function: Evidence from Population-based Studies and Clinical Trials

Abstract

Due to progressive population aging, a new dementia case occurs at every 3 seconds, placing a heavy burden of disease. Identifying potential risk or preventive factors is emphasized owing to a lack of effective treatment for dementia. There has been emerging evidence on the link of certain dietary components, particularly polyphenols, to brain wellness and cognitive outcomes. Findings from animal and in vitro studies appear more consistent and conclusive. However, such an association has not been investigated in depth in human beings. In this review, we examined studies on the effect of dietary polyphenols (including flavonoids, curcumin, and resveratrol) on cognitive function. Intervention in early stages of dementia/Alzheimer’s disease might be a target to slow down age-related cognitive decline before disease onset. We summarized 28 epidemiological studies (8 cross-sectional and 20 cohort studies) and 55 trials in this review. Preliminary evidence from epidemiological data provides the necessity for intervention trials, even though the measures of polyphenol intake tend to be less precise. Clinical trials are in favor of the role of some polyphenols in benefiting specific domains of cognition. This review also describes the divergence of results and current limitations of research in this field.

Effects of a polyphenol-rich grape and blueberry extract (Memophenol™) on cognitive function in older adults with mild cognitive impairment: A randomized, double-blind, placebo-controlled study

“…In a systematic review and meta-analysis based on data from 44 randomized controlled trials, it was concluded that short-to-moderate-term polyphenol interventions might improve working and episodic memory in middle-to-older-aged adults; however, publication bias impacted on the robustness of conclusions ( De Vries et al, 2021 ). In another review based on 28 epidemiological studies (8 cross-sectional and 20 cohort studies) and 55 randomized trials, it was concluded that there was preliminary evidence to suggest a beneficial effect of polyphenol intake on cognitive function ( Yang et al, 2021 ). However, in a systematic review of 22 studies, it was concluded that the evidence was mixed and that further randomized-controlled trials were necessary before definitive conclusions could be made ( Colizzi, 2019 ).…”

A Dietary Supplement Containing Micronutrients, Phosphatidylserine, and Docosahexaenoic Acid Counteracts Cognitive Impairment in D-Galactose-Induced Aged Rats

“…Several human studies (4)(5)(6)(7)(8) and fundamental research (7,(9)(10)(11) have shown that some nutrients such as antioxidants, B vitamins, phosphatidylserine (PS), long-chain n-3 polyunsaturated fatty acids (n-3 PUFA) and polyphenols can ameliorate age-related cognitive decline and decrease the risk of dementia. Some underlying mechanisms that can potentially support the protective effects of these nutrients against brain aging are the restoration of the microstructural integrity of the hippocampus (12), prevention of glutamatergic synapse and astroglial aging (13), decreased oxidative stress and neuroinflammation (14), and increased expression of brain neurotrophins (15).…”

Polyphenols Targeting NF-κB Pathway in Neurological Disorders: What We Know So Far?

“…The advantages mentioned above may also have relevance for those in lower age groups, and there is much current study into the impact of consuming polyphenols on older persons who are at risk for dementia or AD. There is a potential correlation between the consumption of well-balanced and nourishing food and the potential improvement of age-related cognitive decline throughout the early stages of life 148 , 165 , 166 .…”