Does a grape and blueberry extract sharpen memory in early decline?
Six months of a grape-and-blueberry extract did not improve episodic memory in older adults with mild cognitive impairment more than a placebo, although it was linked to faster processing, better location learning and better self-rated executive function.
Source
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
Study at a glance
- Design
- RCT — 24-week, two-arm, parallel-group, randomized, double-blind trial of 300 mg/day Memophenol versus maltodextrin placebo; cognition tested at weeks 0, 12 and 24
- N
- Planned recruitment of 70 per group; 14 placebo and 9 Memophenol participants withdrew. The exact number randomized is given only in a flow figure not included in the text; analyses were intention-to-treat
- Population
- Adults aged 60-80 in Australia with self-reported memory and attention difficulties and a telephone MoCA-BV score in the mild cognitive impairment range (13-18), without dementia
- Outcome
- Primary: COMPASS episodic memory; secondary: working memory, attention accuracy, processing speed, location (visuospatial) learning, BRIEF-A executive function, Cognitive Failures Questionnaire, CASP-19 well-being
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What they did
Older adults aged 60 to 80 with mild cognitive impairment were randomly assigned to take either 300 mg a day of a polyphenol-rich grape and wild blueberry extract (Memophenol) or identical-looking placebo capsules for 24 weeks. Neither participants nor investigators knew who got what. Computer-based cognitive tests were given at the start, at 12 weeks and at 24 weeks, with episodic memory as the main outcome, and participants also completed questionnaires on everyday executive function, cognitive failures and well-being.
What they found
Episodic memory improved by a similar amount in both groups (about 4% with the extract and about 3.4% with placebo), so there was no treatment effect on the primary outcome; working memory and attention accuracy also did not differ. Reaction times fell by about 9.5% in the extract group versus 3.3% on placebo, the extract group learned object locations faster at 24 weeks, and self-rated executive function improved more with the extract (about 5.9% versus 1.9%), mainly on the metacognition index. Everyday cognitive failures dropped in both groups, well-being did not change, and the extract was well tolerated.
The limits
What it doesn't show
The main memory outcome was null, and the positive results come from secondary and exploratory measures tested without correction for multiple comparisons, so some may be false positives. The processing-speed benefit was driven mostly by one task (picture recognition), and three of the six speed tasks showed no improvement with the extract. Both groups improved on several measures, showing strong practice and placebo effects. MCI was identified only by a telephone screening test, the trial was funded by the extract's manufacturer with company employees as co-authors, and six months is too short to say anything about slowing progression to dementia.
Key terms
- Mild cognitive impairment (MCI)
- A decline in memory or thinking greater than expected for age that does not yet interfere enough with daily life to count as dementia.
- Polyphenols
- A large family of plant compounds, including flavonoids in grapes and berries, proposed to protect the brain through antioxidant and anti-inflammatory effects.
- Primary outcome
- The single main result a trial is designed and powered to test, here episodic memory; secondary outcomes are more likely to produce chance findings.
- Practice effect
- Improvement on a test simply from taking it again, which is why a placebo group is needed to judge a treatment.
- Intention-to-treat analysis
- Analysing all randomized participants in their original groups, regardless of dropout or adherence, to preserve the benefits of randomization.
- Metacognition index (BRIEF-A)
- A self-report score of how well someone can initiate, plan, organize and monitor their own thinking and tasks.
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Quiz yourself
What happened to episodic memory, the primary outcome?
Common questions
If memory improved in the extract group, why is that not a positive result?
Memory improved almost as much in the placebo group, most likely from practice and expectation. A treatment only counts as working if it beats the placebo, and here the group-by-time interaction for memory was not significant.
Should the positive speed and learning results be trusted?
Cautiously. They were secondary outcomes, no correction for multiple tests was applied, and the speed effect was driven largely by one task, so they need replication in a trial designed to test them.
Does the industry funding invalidate the study?
Not automatically; the design was randomized and double-blind and the funder reportedly did not handle data. But company employees were co-authors and supplied the capsules, which is a reason for independent replication.
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