Attention, Memory, Mental Fatigue, Mood
Conditions
Keywords
n-3 PUFAs, Fish oil, Cognitive function, Healthy young adults
Brief summary
To date, the relationship between omega-3 polyunsaturated fatty acids (n-3 PUFAs) in cognitively intact individuals has only been examined in a limited number of studies; it is at present unknown whether supplementation with n-3 PUFAs can improve cognitive function and mood in this population. Further to this, it still remains to be established whether a relationship exists between peripheral fatty acid status-reflective of dietary n-3 PUFA intake-and cognitive function in this population. The current study therefore aims to address this issue by exploring the relationship between serum PUFAs and specific cognitive functions in a sample of healthy adults. To this end, participants will complete a range of cognitive tasks evaluating performance across the domains of attention, memory and executive function. Self-report mood assessments will be included as secondary measures.
Interventions
None listed
Sponsors
Northumbria University
Study design
Time perspective
CROSS_SECTIONAL
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Male/Female * 18-35 years * Healthy * No herbal supplements/prescription medications (excl. contraceptive pill) * Non smoker * Native English speaker
Exclusion criteria
* BMI ≥ 30
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Word Recognition (Episodic Memory) | Single visit | The original 15 words plus 15 distractor words were presented one at a time in a random order. For each word the participant indicated whether or not it was included in the original list of words by pressing appropriate 'yes' and 'no' keys as quickly as possible. Stimuli remained on screen until an appropriate response had been made. |
| Simple Reaction Time (Attention) | Single visit | The participant was instructed to press the 'space bar' on the laptop keyboard as quickly as possible every time an upwards pointing arrow appeared on screen. Fifty stimuli were presented with an inter-stimulus duration that varied randomly between 1 and 3.5 seconds. |
| Choice Reaction Time (Attention) | Single visit | An arrow appeared on the screen pointing to the left or to the right. Participants responded with a left or right key press corresponding to the direction of the arrow. There was a randomly varying inter-stimulus interval of between 1 and 3 seconds for a total of fifty stimuli. |
| Four Choice Reaction Time (Attention) | Single visit | A visual representation of the four direction arrow keys of a standard keyboard was presented on screen. The arrows 'lit up' at random on screen until the corresponding key press was made. In all, each arrow was the target stimulus 12 times, forming a total of 48 stimuli for this task in all. |
| Numeric Working Memory (Working Memory) | Single visit | — |
| Alphabetic Working Memory (Working Memory) | Single visit | Five random letters (A-Z) were presented sequentially for the participant to hold in memory. This was followed by a series of 30 probe digits (15 targets and 15 distractors) for each of which the participant indicated whether or not it had been in the original series by a simple key press. The task consisted of 3 separate trials. |
| Corsi Blocks Span (Spatial Working Memory) | Single visit | In this task nine identical blue squares appeared on screen in non-overlapping random positions. A set number of blocks changed colour from blue to red in a randomly generated sequence. Participants were instructed to repeat the sequence by clicking on the blocks using the mouse and cursor. The task was repeated five times at each level of difficulty. The sequence span increased from 4, until the participant could no longer correctly recall the sequence, resulting in a span measure of nonverbal working memory, calculated by averaging the level of the last five correctly completed trials. |
| 3-back Task (Working Memory) | Single visit | A continuous string of letters (upper and lower case; inter-stimulus interval of 2.5 seconds) was presented; 45 letters in total with 15 target pairs. For each stimulus, participants were instructed to indicate whether this was the same letter that appeared three letters before. |
| Immediate Word Recall (Episodic Memory) | Single visit | A unique set of fifteen words is presented. Words were selected at random from a large bank of words derived from the MRC Psycholinguistic Database matched for word length, frequency, familiarity and concreteness. Stimulus duration was one second, as was the inter-stimulus duration. Following word presentation, the participant was allowed 60 seconds to write down as many of the words as possible. |
| Delayed Word Recall (Episodic Memory) | Single visit | The participant was again given 60 seconds to write down as many of the words presented previously as possible. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Depression, Anxiety and Stress Scale (DASS) | Single visit-90 minutes | The DASS is a set of three self-report scales designed to measure the negative emotional states of depression, anxiety and stress. Each of the three DASS scales contains 14 items. Subjects are asked to use 4-point (0-3) severity/frequency scales to rate the extent to which they have experienced each state over the past week. Scores for Depression, Anxiety and Stress (0-42) are calculated by summing the scores for the relevant items, with higher scores indicating higher incidence of negative emotional symptoms. A total score can be derived by adding scores from each of the subscales (0-126). |
Countries
United Kingdom
Participant flow
Recruitment details
Recruitment took place on the Northumbria University campus via posted adverts and email messages sent using the university distribution lists. Recruitment took place in 2 waves; the first taking place between July 31 - November 8 2007, and the second between March 26 - September 9 2008.
Pre-assignment details
Participants from whom a venous blood sample could not be obtained were not entered into the analysis.
Participants by arm
| Arm | Count |
|---|---|
| Healthy Participants Participants declared themselves as healthy, a non-smoker and prescription and herbal medication free. | 283 |
| Total | 283 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Overall Study | Blood sample could not be obtained | 44 |
Baseline characteristics
| Characteristic | Healthy Participants |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 0 Participants |
| Age, Categorical Between 18 and 65 years | 283 Participants |
| Age Continuous | 22.47 years STANDARD_DEVIATION 3.95 |
| Region of Enrollment United Kingdom | 283 participants |
| Sex: Female, Male Female | 187 Participants |
| Sex: Female, Male Male | 96 Participants |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | — / — |
| other Total, other adverse events | 0 / 283 |
| serious Total, serious adverse events | 0 / 283 |
Outcome results
Primary
3-back Task (Working Memory)
A continuous string of letters (upper and lower case; inter-stimulus interval of 2.5 seconds) was presented; 45 letters in total with 15 target pairs. For each stimulus, participants were instructed to indicate whether this was the same letter that appeared three letters before.
Time frame: Single visit
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Participants | 3-back Task (Working Memory) | 80.89 percent of correct responses | Standard Error 1.04 |
Primary
Alphabetic Working Memory (Working Memory)
Five random letters (A-Z) were presented sequentially for the participant to hold in memory. This was followed by a series of 30 probe digits (15 targets and 15 distractors) for each of which the participant indicated whether or not it had been in the original series by a simple key press. The task consisted of 3 separate trials.
Time frame: Single visit
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Participants | Alphabetic Working Memory (Working Memory) | 94.5 percent of correct responses | Standard Error 0.3 |
Primary
Choice Reaction Time (Attention)
An arrow appeared on the screen pointing to the left or to the right. Participants responded with a left or right key press corresponding to the direction of the arrow. There was a randomly varying inter-stimulus interval of between 1 and 3 seconds for a total of fifty stimuli.
Time frame: Single visit
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Participants | Choice Reaction Time (Attention) | 412.79 ms | Standard Error 3.75 |
Primary
Corsi Blocks Span (Spatial Working Memory)
In this task nine identical blue squares appeared on screen in non-overlapping random positions. A set number of blocks changed colour from blue to red in a randomly generated sequence. Participants were instructed to repeat the sequence by clicking on the blocks using the mouse and cursor. The task was repeated five times at each level of difficulty. The sequence span increased from 4, until the participant could no longer correctly recall the sequence, resulting in a span measure of nonverbal working memory, calculated by averaging the level of the last five correctly completed trials.
Time frame: Single visit
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Participants | Corsi Blocks Span (Spatial Working Memory) | 5.90 Blocks remembered in sequence | Standard Error 0.08 |
Primary
Delayed Word Recall (Episodic Memory)
The participant was again given 60 seconds to write down as many of the words presented previously as possible.
Time frame: Single visit
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Participants | Delayed Word Recall (Episodic Memory) | 4.73 Number of words recalled | Standard Error 0.16 |
Primary
Four Choice Reaction Time (Attention)
A visual representation of the four direction arrow keys of a standard keyboard was presented on screen. The arrows 'lit up' at random on screen until the corresponding key press was made. In all, each arrow was the target stimulus 12 times, forming a total of 48 stimuli for this task in all.
Time frame: Single visit
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Participants | Four Choice Reaction Time (Attention) | 499.52 ms | Standard Error 5.84 |
Primary
Immediate Word Recall (Episodic Memory)
A unique set of fifteen words is presented. Words were selected at random from a large bank of words derived from the MRC Psycholinguistic Database matched for word length, frequency, familiarity and concreteness. Stimulus duration was one second, as was the inter-stimulus duration. Following word presentation, the participant was allowed 60 seconds to write down as many of the words as possible.
Time frame: Single visit
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Participants | Immediate Word Recall (Episodic Memory) | 6.21 Number of words recalled | Standard Error 0.16 |
Primary
Numeric Working Memory (Working Memory)
Time frame: Single visit
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Participants | Numeric Working Memory (Working Memory) | 95.57 percent of correct responses | Standard Error 0.34 |
Primary
Simple Reaction Time (Attention)
The participant was instructed to press the 'space bar' on the laptop keyboard as quickly as possible every time an upwards pointing arrow appeared on screen. Fifty stimuli were presented with an inter-stimulus duration that varied randomly between 1 and 3.5 seconds.
Time frame: Single visit
Population: Only those participants for whom a venous blood sample was obtained (N=239) were entered into the analysis. A further 20 participants were excluded on the basis that their BMI exceeded 30, and could not be considered 'healthy individuals'.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Participants | Simple Reaction Time (Attention) | 287.7 ms | Standard Error 2.67 |
Primary
Word Recognition (Episodic Memory)
The original 15 words plus 15 distractor words were presented one at a time in a random order. For each word the participant indicated whether or not it was included in the original list of words by pressing appropriate 'yes' and 'no' keys as quickly as possible. Stimuli remained on screen until an appropriate response had been made.
Time frame: Single visit
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Participants | Word Recognition (Episodic Memory) | 80.35 percent of correct responses | Standard Error 0.68 |
Secondary
Depression, Anxiety and Stress Scale (DASS)
The DASS is a set of three self-report scales designed to measure the negative emotional states of depression, anxiety and stress. Each of the three DASS scales contains 14 items. Subjects are asked to use 4-point (0-3) severity/frequency scales to rate the extent to which they have experienced each state over the past week. Scores for Depression, Anxiety and Stress (0-42) are calculated by summing the scores for the relevant items, with higher scores indicating higher incidence of negative emotional symptoms. A total score can be derived by adding scores from each of the subscales (0-126).
Time frame: Single visit-90 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Healthy Participants | Depression, Anxiety and Stress Scale (DASS) | 22.45 Scores on a scale | Standard Deviation 16.7 |