RCT: Grape and blueberry extract improves cognitive health in ageing consumers

Polyphenols are a large family of naturally occurring organic compounds found in plants, and results from epidemiological studies have found their intake is associated with a reduced risk of cognitive decline. 

Two commonly consumed polyphenol-rich foods, include grapes and blueberries. In a systematic review​ of eight studies, preliminary results suggested that grapes improved some aspects of cognition (executive function, processing speed, and spatial memory) after chronic interventions, although differences in study designs, dosages, and outcome measures impacted the strength of conclusions.

The effects of a polyphenol-rich grape and blueberry extract (Memophonol, 600 mg) on cognition have been examined in two clinical studies. Its acute administration in 30 healthy students ​aged between 18 and 25 years improved performance on a rapid visual information processing task and in healthy older-age adults aged 60 to 70 years, it improved visuospatial and verbal recognition memory in “cognitive decliners.”​

This result suggests that the supplement may have greater benefits for individuals experiencing some form of cognitive impairment, therefore the current 24-week, two-arm, parallel-group, randomised, double-blind, placebo-controlled trial was carried out to examine the effects of Memophenol in older adults with MCI. 

The study, funded by Activ’Inside, the makers of Memophenol, concludes that supplementation with 300 mg of Memophenol in people with MCI for 24 weeks was associated with improvements in the speed of information processing, visuospatial learning, and self-reported executive functions.

However, no between-group differences in other cognitive domains were identified, including episodic memory (the primary outcome measure). The preliminary positive results of this unique polyphenol-rich extract require further investigation in robust clinical trials.

The study

A total of 143 volunteers aged between 60 and 80 were recruited between June and December 2021.

The screening questionnaire assessed self-reported memory problems; medication use; medical or psychiatric disorder history; alcohol, nicotine, and other drug use; and herbal and nutraceutical intake. To assess depressive and anxiety symptoms, respondents completed the 4-item Patient Health Questionnaire (PHQ-4) and the Geriatric Depression Scale – Short Form (GDS-SF). 

Eligible and consenting participants were then allocated randomly to one of two groups (Memophenol or placebo; 1:1 ratio).

All volunteers were instructed to take 1 capsule, twice daily with food, for 24 weeks, delivering 300 mg daily of Memophenol. Although it is difficult to accurately estimate, based on the total polyphenol content, this daily dose is equivalent to eating approximately 185 g of grapes (35 to 40 grapes) or 34 g of blueberries (65 to 70 blueberries) a day.

Capsule adherence was evaluated by asking participants to estimate the consistency of capsule intake (0 to 100%) every 4 weeks and by the return of unused capsules at the week 12 and 24 assessments. 

The Computerized Mental Performance Assessment System (COMPASS), the cognitive failures questionnair (CFQ), the behaviour rating inventory of executive function-adult version (BRIEF-A), and the control, autonomy, self-realization, and pleasure (CASP-19) test were completed onsite at weeks 0, 12, and 24.

Food diaries were filled out in the three days leading up to the 0, 12, and 24 week assessments to assess polyphenol consumption.

Resulting data suggest the administration of Memophenol was associated with "significantly greater improvements" in the speed of information processing and visuospatial learning compared with the placebo.

However, there were no significant between-group differences in episodic memory, working memory, or accuracy in attention.

The authors note: "Despite no change in episodic memory (primary outcome measure), working memory, or accuracy of attention, Memophenol was associated with improvements in reaction time/speed of information processing, and visuospatial learning (measured using the location learning task).

"It is important to note that the greater improvement in reaction time/speed of information processing in the Memophenol group was primarily due to a statistically significant between-group difference in the reaction time for the picture recognition task and, to a lesser extent, a trend of between-group differences on the reaction time for the word recognition task." 

Discussing limitations and future research opportunities, the authors note that more comprehensive dietary assessments may be required to provide a more valid measure of long-term dietary intake.

Objective outcome measures and more comprehensive and sensitive neuropsychological assessments will also help to substantiate the results from self-report and computer-based cognitive tasks.

These include measuring blood markers of oxidative stress, inflammation, and neurogenesis, and neural imaging to identify changes in brain centres associated with memory and cognitive performance. A more comprehensive assessment of MCI will also be important, as MCI in this study was diagnosed using the telephone version of the MoCA. 

Source: Frontiers in Nutrition

https://doi.org/10.3389/fpsyg.2023.1144231​

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

Authors: Lopresti Adrian L., Smith Stephen J., Pouchieu Camille, Pourtau Line, Gaudout David, Pallet Véronique, Drummond Peter D.