The Effects of a Single Dose of Wild Blueberries on Mood and Cognition in Healthy Young Adults: a Randomized, Double-blind, Placebo-controlled, Crossover Study
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Sponsor
- University of Reading
- Enrollment
- 33
- Locations
- 1
- Primary Endpoint
- Negative interpretation bias
Study Overview
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.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Crossover
- Primary Purpose
- Treatment
- Masking
- Triple (Participant, Investigator, Outcomes Assessor)
Eligibility Criteria
- Ages
- 18 Years to 25 Years (Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •18 to 25 years of age
- •Willingness to provide blood samples
Exclusion Criteria
- •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
Arms & Interventions
Blueberry/Placebo
In this arm, participants will receive the blueberry intervention first, followed by the placebo one week later.
Intervention: Wild blueberry powder (Dietary Supplement)
Blueberry/Placebo
In this arm, participants will receive the blueberry intervention first, followed by the placebo one week later.
Intervention: Placebo powder (Dietary Supplement)
Placebo/Blueberry
In this arm, participants will receive the placebo first, followed by the blueberry intervention one week later.
Intervention: Wild blueberry powder (Dietary Supplement)
Placebo/Blueberry
In this arm, participants will receive the placebo first, followed by the blueberry intervention one week later.
Intervention: Placebo powder (Dietary Supplement)
Outcomes
Primary Outcomes
Negative interpretation bias
Time Frame: 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
Time Frame: 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)
Time Frame: 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
Time Frame: 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)
Time Frame: 2 hours post-ingestion
Serum levels of BDNF will be analyzed using enzyme-linked immunosorbent assay (ELISA).
Global transient mood as measured by PANAS-X
Time Frame: baseline
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.
Negative interpretation bias
Time Frame: baseline
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).
Cognitive flexibility (accuracy on post-switch trials)
Time Frame: baseline
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
Time Frame: baseline
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)
Time Frame: baseline
Serum levels of BDNF will be analyzed using enzyme-linked immunosorbent assay (ELISA).
Secondary Outcomes
- Choice reaction time (remaining trials of task-switching test)(2 hours post-ingestion)
- Distinct affective states as measured by PANAS-X subscales(2 hours post-ingestion)
- Reaction time to positive stimuli(2 hours post-ingestion)
- Recall of interference list on RAVLT(2 hours post-ingestion)
- Serum monoamine oxidase B (MAO-B) inhibition(2 hours post-ingestion)
- Reaction time to negative stimuli(2 hours post-ingestion)
- Attentional bias to emotional information(2 hours post-ingestion)
- Choice reaction time (post-switch trials)(2 hours post-ingestion)
- Cognitive flexibility (accuracy on remaining trials of task-switching test)(2 hours post-ingestion)
- Immediate recall on RAVLT(2 hours post-ingestion)
- Proactive interference on RAVLT(2 hours post-ingestion)
- Retroactive interference on RAVLT(2 hours post-ingestion)
- Final acquisition on RAVLT (Trial 5)(2 hours post-ingestion)
- Retention on RAVLT(2 hours post-ingestion)
- Serum interleukin-6 (IL-6)(2 hours post-ingestion)
- Serum C-reactive protein (CRP)(2 hours post-ingestion)
- Serum 3,4-dihydroxyphenylglycol (DHPG)(2 hours post-ingestion)
- Recall of interference list on RAVLT(baseline)
- Distinct affective states as measured by PANAS-X subscales(baseline)
- Reaction time to positive stimuli(baseline)
- Reaction time to negative stimuli(baseline)
- Attentional bias to emotional information(baseline)
- Cognitive flexibility (accuracy on remaining trials of task-switching test)(baseline)
- Choice reaction time (post-switch trials)(baseline)
- Choice reaction time (remaining trials of task-switching test)(baseline)
- Final acquisition on RAVLT (Trial 5)(baseline)
- Immediate recall on RAVLT(baseline)
- Proactive interference on RAVLT(baseline)
- Retroactive interference on RAVLT(baseline)
- Retention on RAVLT(baseline)
- Serum monoamine oxidase B (MAO-B) inhibition(baseline)
- Serum 3,4-dihydroxyphenylglycol (DHPG)(baseline)
- Serum interleukin-6 (IL-6)(baseline)
- Serum C-reactive protein (CRP)(baseline)
Investigators
Prof Claire Williams
Professor
University of Reading