The Effects of a Single Dose of Wild Blueberries on Mood and Cognition in Healthy Young Adults
- Conditions
- MoodAffectCognition
- Interventions
- Dietary Supplement: Wild blueberry powderDietary Supplement: Placebo powder
- Registration Number
- NCT04935099
- Lead Sponsor
- University of Reading
- Brief Summary
This study aims to investigate whether consuming a drink containing powdered blueberries (equivalent to 150 g fresh fruit) can improve mood and cognition in healthy young adults. Blood biomarkers of inflammation and neurotransmitter turnover will be analyzed as well as responses to computer-based cognitive tasks designed to measure verbal memory, executive function, and emotional processing.
- Detailed Description
The present study will examine the psychological effects of a single dose of freeze-dried wild blueberries using a randomized, double-blind, placebo-controlled, counterbalanced, crossover design. A total of 30 healthy young adults will consume two drinks: one containing 22 g blueberry powder and the other containing 22 g matched placebo powder in counterbalanced order one week apart. The investigators will assess changes in transient mood, cognitive-emotional function, and serum biomarkers of inflammation, neuroplasticity, and monoamine metabolism from baseline to 2 hours post-ingestion.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 33
- 18 to 25 years of age
- Willingness to provide blood samples
- Allergy to blueberries or any other Vaccinium species
- Diagnosis or symptoms of anxiety, depression, or other mental health conditions
- Any medically significant condition (e.g. anemia, gastrointestinal disorders, diabetes)
- Use of psychoactive medication or recreational drugs in the last two weeks
- Current use of medication that could interact with the intervention (e.g. antibiotics)
- Obesity or underweight
- Participation in other interventional studies in the last month
- Pregnancy or lactation
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- CROSSOVER
- Arm && Interventions
Group Intervention Description Placebo/Blueberry Wild blueberry powder In this arm, participants will receive the placebo first, followed by the blueberry intervention one week later. Placebo/Blueberry Placebo powder In this arm, participants will receive the placebo first, followed by the blueberry intervention one week later. Blueberry/Placebo Placebo powder In this arm, participants will receive the blueberry intervention first, followed by the placebo one week later. Blueberry/Placebo Wild blueberry powder In this arm, participants will receive the blueberry intervention first, followed by the placebo one week later.
- Primary Outcome Measures
Name Time Method Negative interpretation bias 2 hours post-ingestion A negative interpretation bias is defined as a tendency to interpret ambiguous information in a consistently threatening or negative manner, thus serving as an objective indicator of affective state. In this task, participants will be asked to categorize facial expressions of anger, happiness, and surprise as either positive or negative. Interpretation bias will be operationalized as the percent of trials in which surprised faces were rated as negative, out of the total number of surprise trials (48 trials).
Global transient mood as measured by PANAS-X 2 hours post-ingestion The Positive and Negative Affect Schedule - Expanded Form (PANAS-X) is a validated, self-rated measure of affective state, encompassing two general dimensions (positive and negative affect). These will be calculated separately by adding the values of the individual items (21 positive and 25 negative items). Thus, the scales will range from 0 to 84 points for positive affect and from 0 to 100 for negative affect, with a higher score indicating greater positive or negative affect. Positive affect will be considered the primary measure
Cognitive flexibility (accuracy on post-switch trials) 2 hours post-ingestion A task-switching test will be used to assess cognitive performance when switching between two predictable tasks requiring simple numerical decisions. The main outcome of interest is the average accuracy of responses to post-switch trials (those immediately following a switch to a new task).
Delayed verbal memory on RAVLT 2 hours post-ingestion The Rey Auditory Verbal Learning Test (RAVLT) is a standard neuropsychological assessment designed to evaluate verbal memory. The participant hears a list of 15 words and is asked to recall as many words as possible. This procedure is repeated five times. The main outcome of interest is the number of correctly recalled words 20 minutes after the last presentation of the list of words (Trial A7).
Serum brain-derived neurotrophic factor (BDNF) 2 hours post-ingestion Serum levels of BDNF will be analyzed using enzyme-linked immunosorbent assay (ELISA).
- Secondary Outcome Measures
Name Time Method Distinct affective states as measured by PANAS-X subscales 2 hours post-ingestion The following affective states will be examined separately as defined by the PANAS-X subscales: Joviality (Happiness), Self-Assurance, Attentiveness, Fatigue, Serenity. Higher scores will indicate greater intensity of the respective affective state.
Reaction time to positive stimuli 2 hours post-ingestion The average reaction time to correctly categorized happy faces in the facial expression task.
Recall of interference list on RAVLT 2 hours post-ingestion The number of correctly retrieved words from the interference list (List B) of the Rey Auditory Verbal Learning Test.
Serum monoamine oxidase B (MAO-B) inhibition 2 hours post-ingestion The activity of the enzyme MAO-B in serum will be analyzed using a fluorometric assay.
Reaction time to negative stimuli 2 hours post-ingestion The average reaction time to correctly categorized angry faces in the facial expression task.
Attentional bias to emotional information 2 hours post-ingestion Attentional bias to emotional information will be operationalized as the average reaction time to correctly categorized angry faces divided by the average reaction time to correctly categorized happy faces. Thus, a higher value indicates a tendency to attend to and process positive information over negative information.
Choice reaction time (post-switch trials) 2 hours post-ingestion The average reaction time of correct responses to post-switch trials of the task-switching test.
Choice reaction time (remaining trials of task-switching test) 2 hours post-ingestion The average reaction time of correct responses to remaining trials of the task-switching test.
Cognitive flexibility (accuracy on remaining trials of task-switching test) 2 hours post-ingestion The average accuracy (in %) of responses to the remaining trials of the task-switching test will be measured as a secondary outcome. In this task, participants have to switch between two predictable tasks requiring simple numerical decisions.
Immediate recall on RAVLT 2 hours post-ingestion The number of correctly recalled words on the Rey Auditory Verbal Learning Test 2 minutes after the final presentation of List A (and following the presentation and recall of List B).
Proactive interference on RAVLT 2 hours post-ingestion Proactive interference on the Rey Auditory Verbal Learning Test is defined as the number of correctly recalled words from the interference List B divided by the number of correctly recalled words on Trial 1 of List A (B1/A1). A higher score indicates less proactive interference.
Retroactive interference on RAVLT 2 hours post-ingestion Retroactive interference on the Rey Auditory Verbal Learning Test is defined as the number of correctly recalled words on Trial 6 of List A (the free recall trial after the interference List B) divided by the number of correctly recalled words on Trial 5 of List A (A6/A5). A higher score indicates less retroactive interference.
Final acquisition on RAVLT (Trial 5) 2 hours post-ingestion The number of correctly retrieved words on Trial 5 (List A) of the Rey Auditory Verbal Learning Test.
Retention on RAVLT 2 hours post-ingestion Retention on the Rey Auditory Verbal Learning Test is defined as the number of correctly recalled words on Trial 7 of List A (the delayed recall trial at 20 minutes) divided by the number of correctly retrieved words on Trial 6 of List A (A7/A6). Thus, a higher score indicates a higher retention rate.
Serum interleukin-6 (IL-6) 2 hours post-ingestion Serum levels of IL-6 will be analyzed using enzyme-linked immunosorbent assay (ELISA) as an indication of systemic inflammation.
Serum C-reactive protein (CRP) 2 hours post-ingestion Serum levels of CRP will be analyzed using enzyme-linked immunosorbent assay (ELISA) as an indication of systemic inflammation.
Serum 3,4-dihydroxyphenylglycol (DHPG) 2 hours post-ingestion Serum levels of DHPG will be analyzed using liquid chromatography-mass spectrometry (LS-MS) to indirectly determine monoamine oxidase A (MAO-A) activity.
Trial Locations
- Locations (1)
School of Psychology and Clinical Languages, University of Reading
🇬🇧Reading, Berkshire, United Kingdom