The aim of this study is to demonstrate the effects of 28-days supplementation with a novel probiotic formulation on mental fatigue following a cognitive load in healthy adults. Half of the participants will receive the probiotic formulation while the other half will receive placebo.
A total of 128 participants will be recruited to take part in this trial. The supplement contains selected strains of lactobacilli and bifidobacteria which have been well studied in human clinical trials. Previous clinical trials have demonstrated improvements in cognitive function and mood after supplementation with various combinations of lactobacilli and bifidobacteria. The specific strains present in the current investigation have been studied in a number of clinical trials in which no adverse events were linked to the strains. The benefits of probiotic supplements on health is well established, and has led to an increase in use, as well as the addition of probiotic strains in dietary supplements. Despite this, only a small number of controlled trials have directly investigated the cognitive benefits associated with probiotic supplementation. The current study therefore aims to investigate the anti-fatigue effects of a probiotic supplement after a period of cognitive demand. We will be measuring the effects of the probiotic supplement compared to a placebo using assessments of mental fatigue, cognition, memory and mood.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
TRIPLE
Enrollment
128
Probiotic capsule
Placebo capsule identical in taste and appearance to probiotic capsule
Centre for Human Psychopharmacology, Swinburne University of Technology
Hawthorn, Victoria, Australia
Mental fatigue score (VAS-mental fatigue)
Difference in mental fatigue score as the participant moves through six cycles of a cognitive demand battery (CDB). The cognitive demand battery consists of three tasks (RVIP, serial threes and serial sevens, described below), and is designed to increase cognitive load. Six cycles of the battery are completed in succession at each testing visit. The mental fatigue scale (VAS-mental fatigue) is completed after each cycle of the CDB (6 times over the course of one hour, per visit). Participants rate their level of mental fatigue on a 100-mm scale from "not at all" to "extremely". The primary outcome is difference in mental fatigue score (VAS-mental fatigue) as the participant moves through the six cycles of the CDB, (after cognitive load) absolute change from baseline (Visit 2) to 28 days (Visit 3) between the active vs placebo group.
Time frame: 28 days
RVIP number correct
Percentage of target strings correctly detected on the rapid visual information processing (RVIP) task throughout each of the six cycles of the CDB. In this task, which lasts for 5 minutes, a series of numbers rapidly appear on the screen one at a time. Participants are instructed to press the space bar whenever they detect a sequence of either 3 consecutive odd or 3 consecutive even numbers.
Time frame: 28 days
RVIP reaction time
Average reaction time for correct detections (RVIP) throughout each of the six cycles of the CDB.
Time frame: 28 days
RVIP false alarms
The number of false alarms (RVIP) throughout each of the six cycles of the CDB
Time frame: 28 days
Serial threes subtraction total
Total number of subtractions on the serial threes subtraction task, regardless of whether correct or incorrect, throughout each of the six cycles of the CDB. In this two minute task, participants are given a starting number and instructed to subtract three from this number. They must then type in the number they are left with and press enter. After this no numbers are visible but the participant must continue to subtract three and enter their responses.
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Time frame: 28 days
Serial threes errors
Total number of incorrect subtractions (serial threes subtraction task) throughout each of the six cycles of the CDB
Time frame: 28 days
Serial sevens total
Total number of subtractions (serial sevens subtraction task) throughout each of the six cycles of the CDB. This task is the same as the serial threes task, except that participants must subtract seven instead of three.
Time frame: 28 days
Serial sevens errors
Total number of errors (serial sevens subtraction task) throughout each of the six cycles of the CDB
Time frame: 28 days
Immediate word recall - correct
The number of correctly identified words in the immediate word recall task. Participants see a list of 15 words that they are instructed to remember. After seeing the last word, the participant has 60 seconds to write down as many of the words as they can remember.
Time frame: 28 days
Immediate word recall - errors
The number of errors in the immediate word recall task (words not included in the original list)
Time frame: 28 days
Immediate word recall - intrusions
The number of intrusions in the immediate word recall task (words similar to those included in the original list but not identical).
Time frame: 28 days
Delayed word recall - Correct
The number of correctly identified words in the delayed word recall task. After completing the CDB (approximately one hour after presentation of the 15 words), the participant has 60 seconds to write down as many of the words as they can remember from the original list.
Time frame: 28 days
Delayed word recall - errors
The number of errors in the delayed word recall task (words not included in the original list)
Time frame: 28 days
Delayed word recall - intrusions
The number of intrusions in the delayed word recall task (words similar to those included in the original list but not identical).
Time frame: 28 days
Delayed word recognition - reaction time
Mean reaction time to word recognition in delayed word recognition task following cognitive load. After participants have viewed the word list and completed the immediate word recall task, they complete the CDB which lasts for one hour. On completion of the CDB, participants complete a word recognition task. In this task, the original 15 target words plus an additional 15 distractor words are presented one at a time, in a randomized order. Participants are instructed to indicate whether or not they recognize the word from the original list by pressing the 'Yes' or 'No' button as appropriate as quickly as possible, mean reaction times are measured in msec.
Time frame: 28 days
Word recognition - original words accuracy
Accuracy of responses (%) to original target words in delayed word recognition task following cognitive load (CDB).
Time frame: 28 days
Word recognition - distractor words accuracy
Accuracy of responses (%) to novel distractor words in delayed word recognition following cognitive load (CDB).
Time frame: 28 days
Self-reported alertness score
Participants are presented with a number of 100-mm visual analogue scales (Bond-Lader mood scales) where they indicate their current feelings. The alertness score is calculated by averaging scores on lines anchored by alert-drowsy, attentive-dreamy, lethargic-energetic, muzzy-clearheaded, well-coordinated-clumsy, mentally slow-quick witted, strong-feeble, interested-bored, incompetent-proficient. This is completed before and after the CDB.
Time frame: 28 days
Self-reported contentment score
Participants are presented with a number of 100-mm visual analogue scales (Bond-Lader mood scales) where they indicate their current feelings. The contentment score is calculated by averaging scores on lines anchored by contented-discontented, troubled-tranquil, happy-sad, antagonistic-friendly, withdrawn-sociable. This is completed before and after the CDB.
Time frame: 28 days
Self-reported calmness score
Participants are presented with a number of 100-mm visual analogue scales (Bond-Lader mood scales) where they indicate their current feelings. The calmness score is calculated by averaging scores on lines anchored by calm-excited, tense-relaxed. This is completed before and after the CDB.
Time frame: 28 days
Difference in self-reported stress score (VAS-stress) before and after a cognitive load
The Stress Visual Analogue Scale (VAS-Stress) consists of a single 100 mm line with end-points labelled 'Not at all' and 'Very much so'. Participants are instructed to mark the line, depending on how "stressed" they feel at that point in time. This is completed twice in each session, once prior to the CDB, and once after the battery is complete. The difference between pre- and post-CDB score is calculated, and the difference is compared between baseline and 28 days.
Time frame: 28 days
Self-reported stress score (VAS-stress) - pre-CDB only
The Stress Visual Analogue Scale (VAS-Stress) consists of a single 100 mm line with end-points labelled 'Not at all' and 'Very much so'. Participants are instructed to mark the line, depending on how "stressed" they feel at that point in time. The pre-CDB score is compared between baseline and 28 days to provide an assessment of stress without cognitive load.
Time frame: 28 days
Difference in self-reported physical fatigue score (VAS-fatigue) before and after a cognitive load
The Physical Fatigue Visual Analogue Scale (VAS-fatigue) consists of a single 100 mm line with end-points labelled 'Not at all' and 'Very much so'. Participants are instructed to mark the line, depending on how "physically fatigued" they feel at that point in time. This is completed twice in each session, once prior to the CDB, and once after the battery is complete. The difference between pre- and post-CDB score is calculated, and the difference is compared between baseline and 28 days.
Time frame: 28 days
Self-reported physical fatigue score (VAS-fatigue) - pre-CDB only
The Physical Fatigue Visual Analogue Scale (VAS-Fatigue) consists of a 100 mm line with end-points labelled 'Not at all' and 'Very much so'. Participants are instructed to mark the line, depending on how "physically fatigued" they feel at that point in time. The pre-CDB score is compared between baseline and 28 days to provide an assessment of physical fatigue without cognitive load.
Time frame: 28 days
Self-reported state anxiety (STAI) before and after a cognitive load
The 'State' subscale of the STAI contains 20 items, and requires participants to rate how much they feel like each item at the time of response. The scale is scored on a 4-point scale ranging from 'not at all' to 'very much so'. Scores range from 20 to 80, with higher scores indicating higher levels of anxiety. Participants will be required to complete the state version of the STAI twice per session, once before the commencement of the CDB, and once at completion.
Time frame: 28 days
Mental fatigue score on the Chalder Fatigue Scale
The 14-item Chalder Fatigue Scale (CFS) measures both physical and mental fatigue, as well as a total fatigue rating, on a 4-point scale ranging from 'better than usual' to 'much worse than usual'.
Time frame: 28 days
Physical fatigue score on the Chalder Fatigue Scale
The 14-item CFS measures both physical and mental fatigue, as well as a total fatigue rating, on a 4-point scale ranging from 'better than usual' to 'much worse than usual'.
Time frame: 28 days
Total fatigue score on the Chalder Fatigue Scale
The 14-item CFS measures both physical and mental fatigue, as well as a total fatigue rating, on a 4-point scale ranging from 'better than usual' to 'much worse than usual'.
Time frame: 28 days
Self-reported sleep quality - total score
The Pittsburgh Sleep Quality Index (PSQI) was originally designed to measure sleep quality and disturbance in clinical populations, and has been subsequently utilized in a number of research settings. The PSQI is a self-rated scale measured over a one-month interval. The scale is comprised of 19 individual items that generate 7 "component" scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleep medications, and daytime dysfunction. The scale also has five items to be answered by a bed partner, if applicable, but these answers are not included in the scoring of the scale. For the current study, these five questions will be removed from the scale.
Time frame: 28 days
Self-reported duration of sleep score
The Pittsburgh Sleep Quality Index (PSQI) was originally designed to measure sleep quality and disturbance in clinical populations, and has been subsequently utilized in a number of research settings. The PSQI is a self-rated scale measured over a one-month interval. The scale is comprised of 19 individual items that generate 7 "component" scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleep medications, and daytime dysfunction. The scale also has five items to be answered by a bed partner, if applicable, but these answers are not included in the scoring of the scale. For the current study, these five questions will be removed from the scale.
Time frame: 28 days
Self-reported sleep disturbance score
The Pittsburgh Sleep Quality Index (PSQI) was originally designed to measure sleep quality and disturbance in clinical populations, and has been subsequently utilized in a number of research settings. The PSQI is a self-rated scale measured over a one-month interval. The scale is comprised of 19 individual items that generate 7 "component" scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleep medications, and daytime dysfunction. The scale also has five items to be answered by a bed partner, if applicable, but these answers are not included in the scoring of the scale. For the current study, these five questions will be removed from the scale.
Time frame: 28 days
Self-reported sleep latency score
The Pittsburgh Sleep Quality Index (PSQI) was originally designed to measure sleep quality and disturbance in clinical populations, and has been subsequently utilized in a number of research settings. The PSQI is a self-rated scale measured over a one-month interval. The scale is comprised of 19 individual items that generate 7 "component" scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleep medications, and daytime dysfunction. The scale also has five items to be answered by a bed partner, if applicable, but these answers are not included in the scoring of the scale. For the current study, these five questions will be removed from the scale.
Time frame: 28 days
Self-reported daytime dysfunction score
The Pittsburgh Sleep Quality Index (PSQI) was originally designed to measure sleep quality and disturbance in clinical populations, and has been subsequently utilized in a number of research settings. The PSQI is a self-rated scale measured over a one-month interval. The scale is comprised of 19 individual items that generate 7 "component" scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleep medications, and daytime dysfunction. The scale also has five items to be answered by a bed partner, if applicable, but these answers are not included in the scoring of the scale. For the current study, these five questions will be removed from the scale.
Time frame: 28 days
Self-reported habitual sleep efficiency score
The Pittsburgh Sleep Quality Index (PSQI) was originally designed to measure sleep quality and disturbance in clinical populations, and has been subsequently utilized in a number of research settings. The PSQI is a self-rated scale measured over a one-month interval. The scale is comprised of 19 individual items that generate 7 "component" scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleep medications, and daytime dysfunction. The scale also has five items to be answered by a bed partner, if applicable, but these answers are not included in the scoring of the scale. For the current study, these five questions will be removed from the scale.
Time frame: 28 days
Subjective sleep quality score
The Pittsburgh Sleep Quality Index (PSQI) was originally designed to measure sleep quality and disturbance in clinical populations, and has been subsequently utilized in a number of research settings. The PSQI is a self-rated scale measured over a one-month interval. The scale is comprised of 19 individual items that generate 7 "component" scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleep medications, and daytime dysfunction. The scale also has five items to be answered by a bed partner, if applicable, but these answers are not included in the scoring of the scale. For the current study, these five questions will be removed from the scale.
Time frame: 28 days
Self-reported use of sleep medications score
The Pittsburgh Sleep Quality Index (PSQI) was originally designed to measure sleep quality and disturbance in clinical populations, and has been subsequently utilized in a number of research settings. The PSQI is a self-rated scale measured over a one-month interval. The scale is comprised of 19 individual items that generate 7 "component" scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleep medications, and daytime dysfunction. The scale also has five items to be answered by a bed partner, if applicable, but these answers are not included in the scoring of the scale. For the current study, these five questions will be removed from the scale.
Time frame: 28 days
Self-reported vitality score (SF-36)
The SF-36 is a 36-item survey of health and well-being. The scale consists of eight domains: vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning and mental health. The SF-36 will be completed once per session.
Time frame: 28 days
Self-reported physical functioning score (SF-36)
The SF-36 is a 36-item survey of health and well-being. The scale consists of eight domains: vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning and mental health. The SF-36 will be completed once per session.
Time frame: 28 days
Self-reported bodily pain score (SF-36)
The SF-36 is a 36-item survey of health and well-being. The scale consists of eight domains: vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning and mental health. The SF-36 will be completed once per session.
Time frame: 28 days
Self-reported general health perceptions score (SF-36)
The SF-36 is a 36-item survey of health and well-being. The scale consists of eight domains: vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning and mental health. The SF-36 will be completed once per session.
Time frame: 28 days
Self-reported physical role functioning score (SF-36)
The SF-36 is a 36-item survey of health and well-being. The scale consists of eight domains: vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning and mental health. The SF-36 will be completed once per session.
Time frame: 28 days
Self-reported emotional role functioning score (SF-36)
The SF-36 is a 36-item survey of health and well-being. The scale consists of eight domains: vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning and mental health. The SF-36 will be completed once per session.
Time frame: 28 days
Self-reported social role functioning score (SF-36)
The SF-36 is a 36-item survey of health and well-being. The scale consists of eight domains: vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning and mental health. The SF-36 will be completed once per session.
Time frame: 28 days
Self-reported mental health score (SF-36)
The SF-36 is a 36-item survey of health and well-being. The scale consists of eight domains: vitality, physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning and mental health. The SF-36 will be completed once per session.
Time frame: 28 days
Self-reported depression score (DASS-21)
The Depression, Anxiety and Stress scale (DASS-21) is a 21-item questionnaire that is split into three factors: depression, anxiety and stress. The DASS-21 is made up of affect-related questions pertaining to both physical (e.g. 'dry mouth') and mood symptoms (e.g. 'down-hearted'). Each item is scored on a 4-point scale from 0 to 3, with higher scores indicating a higher degree of dysfunction. It is important to note that lower scores reflect a lack of symptoms and not a more positive mood. Furthermore, as the experience of such symptoms is common in every-day life, the DASS-21 is considered suitable for use in non-clinical settings.
Time frame: 28 days
Self-reported anxiety score (DASS-21)
The Depression, Anxiety and Stress scale (DASS-21) is a 21-item questionnaire that is split into three factors: depression, anxiety and stress. The DASS-21 is made up of affect-related questions pertaining to both physical (e.g. 'dry mouth') and mood symptoms (e.g. 'down-hearted'). Each item is scored on a 4-point scale from 0 to 3, with higher scores indicating a higher degree of dysfunction. It is important to note that lower scores reflect a lack of symptoms and not a more positive mood. Furthermore, as the experience of such symptoms is common in every-day life, the DASS-21 is considered suitable for use in non-clinical settings.
Time frame: 28 days
Self-reported stress score (DASS-21)
The Depression, Anxiety and Stress scale (DASS-21) is a 21-item questionnaire that is split into three factors: depression, anxiety and stress. The DASS-21 is made up of affect-related questions pertaining to both physical (e.g. 'dry mouth') and mood symptoms (e.g. 'down-hearted'). Each item is scored on a 4-point scale from 0 to 3, with higher scores indicating a higher degree of dysfunction. It is important to note that lower scores reflect a lack of symptoms and not a more positive mood. Furthermore, as the experience of such symptoms is common in every-day life, the DASS-21 is considered suitable for use in non-clinical settings.
Time frame: 28 days
Self-reported confrontive coping score (WAYS)
The Ways of Coping Questionnaire (WAYS) is a 66-item scale designed to measure an individual's ability to cope with stress over the past week. The scale measures coping processes, not coping styles. The scale is divided into 8 subscales; confrontive coping, distancing, self-controlling, seeking social support, accepting responsibility, escape-avoidance, planful problem solving, positive re-appraisal. The scale is completed once per session.
Time frame: 28 days
Self-reported distancing score (WAYS)
The Ways of Coping Questionnaire (WAYS) is a 66-item scale designed to measure an individual's ability to cope with stress over the past week. The scale measures coping processes, not coping styles. The scale is divided into 8 subscales; confrontive coping, distancing, self-controlling, seeking social support, accepting responsibility, escape-avoidance, planful problem solving, positive re-appraisal. The scale is completed once per session.
Time frame: 28 days
Self-reported self-controlling score (WAYS)
The Ways of Coping Questionnaire (WAYS) is a 66-item scale designed to measure an individual's ability to cope with stress over the past week. The scale measures coping processes, not coping styles. The scale is divided into 8 subscales; confrontive coping, distancing, self-controlling, seeking social support, accepting responsibility, escape-avoidance, planful problem solving, positive re-appraisal. The scale is completed once per session.
Time frame: 28 days
Self-reported seeking social support score (WAYS)
The Ways of Coping Questionnaire (WAYS) is a 66-item scale designed to measure an individual's ability to cope with stress over the past week. The scale measures coping processes, not coping styles. The scale is divided into 8 subscales; confrontive coping, distancing, self-controlling, seeking social support, accepting responsibility, escape-avoidance, planful problem solving, positive re-appraisal. The scale is completed once per session.
Time frame: 28 days
Self-reported accepting responsibility score (WAYS)
The Ways of Coping Questionnaire (WAYS) is a 66-item scale designed to measure an individual's ability to cope with stress over the past week. The scale measures coping processes, not coping styles. The scale is divided into 8 subscales; confrontive coping, distancing, self-controlling, seeking social support, accepting responsibility, escape-avoidance, planful problem solving, positive re-appraisal. The scale is completed once per session.
Time frame: 28 days
Self-reported escape-avoidance score (WAYS)
The Ways of Coping Questionnaire (WAYS) is a 66-item scale designed to measure an individual's ability to cope with stress over the past week. The scale measures coping processes, not coping styles. The scale is divided into 8 subscales; confrontive coping, distancing, self-controlling, seeking social support, accepting responsibility, escape-avoidance, planful problem solving, positive re-appraisal. The scale is completed once per session.
Time frame: 28 days
Self-reported planful problem-solving score (WAYS)
The Ways of Coping Questionnaire (WAYS) is a 66-item scale designed to measure an individual's ability to cope with stress over the past week. The scale measures coping processes, not coping styles. The scale is divided into 8 subscales; confrontive coping, distancing, self-controlling, seeking social support, accepting responsibility, escape-avoidance, planful problem solving, positive re-appraisal. The scale is completed once per session.
Time frame: 28 days
Self-reported positive re-appraisal score (WAYS)
The Ways of Coping Questionnaire (WAYS) is a 66-item scale designed to measure an individual's ability to cope with stress over the past week. The scale measures coping processes, not coping styles. The scale is divided into 8 subscales; confrontive coping, distancing, self-controlling, seeking social support, accepting responsibility, escape-avoidance, planful problem solving, positive re-appraisal. The scale is completed once per session.
Time frame: 28 days
Positive effects of on-trial experiences
At the completion of the trial, participants will be asked an open-ended question about any positive effects they may have experienced on their physical or mental health during the study, to allow qualitative analysis of on-trial experiences.
Time frame: 28 days
Negative effects of on-trial experiences
At the completion of the trial, participants will be asked an open-ended question about any negative effects they may have experienced on their physical or mental health during the study, to allow qualitative analysis of on-trial experiences.
Time frame: 28 days
Unusual effects of on-trial experiences
At the completion of the trial, participants will be asked an open-ended question about any unusual effects they may have experienced on their physical or mental health during the study, to allow qualitative analysis of on-trial experiences.
Time frame: 28 days