Abstract
- Background
Population-based studies consistently demonstrate positive associations between dietary anthocyanin and blueberry intakes and preserved cognitive function, while randomized controlled trials have reported cognitive benefits in adults presenting with self-perceived or clinical cognitive dysfunction. However, the neurocognitive and psychological effects of blueberries in adults diagnosed with metabolic syndrome (MetS) but lacking overt cognitive impairment remain significantly understudied.
- Objectives
This secondary analysis aimed to rigorously evaluate cognitive performance, subjective mood states, alertness, and sleep quality as secondary endpoints in participants with metabolic syndrome, assessing both acute postprandial responses (over a 24-hour period) and chronic adaptations following a 6-month continuous blueberry intervention.
- Methods
A double-blind, randomized controlled trial was conducted to examine the primary effects of consuming freeze-dried wild blueberry powder compared to a matched isocaloric placebo on cardiometabolic health over a 6-month period and a 24-hour postprandial phase at baseline. Data from participants completing comprehensive mood, alertness, cognition, and sleep evaluations were analyzed ($n = 115$ for the 6-month chronic study; $n = 33$ for the 24-hour postprandial study). Assessments utilized: 1) Bond-Lader self-rated mood scales, 2) a computerized electronic cognitive test battery evaluating attention, working memory, episodic memory, memory retrieval speed, executive function, and picture recognition, and 3) the Leeds Sleep Evaluation Questionnaire. Furthermore, urinary and serum anthocyanin metabolites were quantified, and host apolipoprotein E (APOE) genotype status was determined.
- Results
Acute postprandial evaluations revealed a statistically significant improvement in self-rated calmness following the consumption of 1 cup of blueberries ($P = 0.01$; $q = 0.04$; reflecting an 11.6% improvement compared to baseline across the 0- to 24-hour window). However, all other measured parameters concerning mood, sleep quality, and cognitive function remained unaffected following both acute postprandial and 6-month chronic blueberry interventions. Despite the lack of broad direct cognitive enhancements, correlation analyses across the ½-cup and 1-cup active treatment groups demonstrated that circulating and urinary microbial metabolites of anthocyanins and chlorogenic acid—including hydroxycinnamic acids, benzoic acids, phenylalanine derivatives, hippuric acids, and catechin—were significantly associated with favorable chronic and postprandial memory, attention, executive function, and calmness scores.
- Conclusions
Although acute blueberry intake significantly enhanced self-rated postprandial calmness and meaningful correlations emerged between cognitive performance and specific circulating bioactive metabolites, overall findings did not demonstrate robust, widespread improvements in general cognitive function, mood, alertness, or sleep quality in participants with metabolic syndrome following the blueberry intervention.
https://pmc.ncbi.nlm.nih.gov/articles/PMC10972710/