Affect, Cognition, Mood
Conditions
Keywords
blueberry, anthocyanins, flavonoids
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.
Interventions
DIETARY_SUPPLEMENTWild blueberry powder
22 g freeze-dried wild blueberry (Vaccinium angustifolium) powder, mixed with 250 ml water, and served in an opaque container.
DIETARY_SUPPLEMENTPlacebo powder
22 g placebo powder matched for macronutrients and flavor, mixed with 250 ml water, and served in an opaque container.
Sponsors
Wild Blueberry Association of North America
University of Reading
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 25 Years
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Global transient mood as measured by PANAS-X | 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 | 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) | 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 | 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) | baseline | Serum levels of BDNF will be analyzed using enzyme-linked immunosorbent assay (ELISA). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Choice reaction time (post-switch trials) | baseline | 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) | baseline | The average reaction time of correct responses to remaining trials of the task-switching test. |
| Final acquisition on RAVLT (Trial 5) | baseline | The number of correctly retrieved words on Trial 5 (List A) of the Rey Auditory Verbal Learning Test. |
| Recall of interference list on RAVLT | baseline | The number of correctly retrieved words from the interference list (List B) of the Rey Auditory Verbal Learning Test. |
| Immediate recall on RAVLT | baseline | 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 | baseline | 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 | baseline | 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. |
| Retention on RAVLT | baseline | 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 monoamine oxidase B (MAO-B) inhibition | baseline | The activity of the enzyme MAO-B in serum will be analyzed using a fluorometric assay. |
| Serum 3,4-dihydroxyphenylglycol (DHPG) | baseline | Serum levels of DHPG will be analyzed using liquid chromatography-mass spectrometry (LS-MS) to indirectly determine monoamine oxidase A (MAO-A) activity. |
| Serum interleukin-6 (IL-6) | baseline | 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) | baseline | Serum levels of CRP will be analyzed using enzyme-linked immunosorbent assay (ELISA) as an indication of systemic inflammation. |
| Distinct affective states as measured by PANAS-X subscales | baseline | 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 | baseline | The average reaction time to correctly categorized happy faces in the facial expression task. |
| Reaction time to negative stimuli | baseline | The average reaction time to correctly categorized angry faces in the facial expression task. |
| Attentional bias to emotional information | baseline | 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. |
| Cognitive flexibility (accuracy on remaining trials of task-switching test) | baseline | 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. |
Other
| Measure | Time frame | Description |
|---|---|---|
| Recognition memory on RAVLT | baseline | In the final task of the Rey Auditory Verbal Learning Test, participants need to recognize the 15 words from List A from a list of 50 words. Recognition memory is defined as the number of correctly recognized words out of the total number of words. |
Countries
United Kingdom
Outcome results
None listed