This study aims to investigate the acute and chronic effects of an 8 week probiotic intervention (Ecologic Barrier©) on mood and cognitive outcomes in healthy adults.
This study will employ a double-blind, randomised, placebo-controlled crossover design to investigate the acute and chronic effects of an 8 week probiotic intervention (Ecologic Barrier©) on mood and cognitive outcomes in healthy older adults. A total of 30 participants will be enrolled and counterbalanced to receive the active probiotic treatment (2g per day Ecologic Barrier©) or a matched placebo in the first arm, before having a 4 week washout period and continuing with 8 weeks of the second treatment not consumed within the first arm. Outcome measures will be assessed at baseline, 24 hours and 8 weeks within each arm. These will include cognitive measures of affective processing, immediate and delayed verbal memory, visuospatial working memory and executive functions, and mood measures of depressive symptoms, cognitive reactivity, anxiety, stress and general mood. In addition, faecal samples will be collected at all timepoints in order to explore faecal microbiota profiles before and after probiotic treatment.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
30
5x10\^9 CFU/ 2g per day of Ecologic Barrier©
matched placebo
School of Psychology and Clinical Languages
Reading, United Kingdom
Change in Corsi Block Tapping Test performance
A standardised assessment of visuospatial working memory. The task comprises nine identical squares fixed in a random arrangement on a screen. Participants observe sequences of between two and nine blocks, which they then reproduce as accurately as possible. The dependent variable is the number of blocks pointed out in the correct order. Four versions of each sequence length are presented during the task. A novel sequence will be presented on each occasion, the order of which will be counterbalanced across participants.
Time frame: Baseline, 24 hours and 8 weeks
Change in Immediate Word Recall from the Rey Auditory Verbal Learning Task
Participants will be presented with a sequential list of 15 words, at a rate of 1 word per second. The participant will then have 60s to say out loud as many of these words as possible, with the resulting score recorded as a percentage of accuracy.
Time frame: Baseline, 24 hours and 8 weeks
Rey Auditory Verbal Learning Task - Delayed Word Recall
After a period of time subject are asked to recall as many words as possible from list A
Time frame: Baseline, 24 hours and 8 weeks
Rey Auditory Verbal Learning Task - Word Recognition
Following the delayed word recall, words from list A, list B and novel words are displayed sequentially on the screen and participants are asked to indicate which words were from list A only.
Time frame: Baseline, 24 hours and 8 weeks
Switching task
This task requires executive function and sustained attention, and provides a measure of cognitive flexibility. Participants view a circle with 8 equally spaced radii 2 of which form a bold bisecting line. Numbers are chosen randomly from a set of 1-4 \& 6-9 and displayed sequentially in a clockwise direction. A response of higher or lower than 5 is made for trials below the bold line, and even or odd for numbers above the line. Outcome measures include overall accuracy and reaction time (RT) on correct trials, as well as accuracy and RT on trials where there is a 'switch cost' from stimuli moving from below to above the bold line and vice versa.
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Time frame: Baseline, 24 hours and 8 weeks
Go/No Go task
This task measures executive function - specifically the ability to inhibit or withhold a response to no-go stimuli. Both a neutral block (white circles) and an emotional block (happy and fearful faces from the FACES database) are included here, in order to explore any additional influence of emotional stimuli on inhibitory responses. Outcome measures include accuracy and reaction time (RT). Accuracy and reaction times in the emotional blocks may also be correlated with responses to mood measures.
Time frame: Baseline, 24 hours and 8 weeks
Leiden Index of Depression Sensitivity revised (LEIDS-r)
A validated questionnaire measure of cognitive reactivity. The LEIDS-r comprises of 34 items which the participant rate on a scale from 0-4 to indicate how strongly each statement applied to them when they are feeling somewhat sad.
Time frame: Baseline, 24 hours and 8 weeks
Positive and Negative Affect Schedule expanded (PANAS-x)
A validated self-report measure of affective state. The PANAS comprises of two distinct affective states (positive and negative), as well as 11 individual affective states (fear, guilt, sadness, surprise, hostility, shyness, joviality, self-assurance, attentiveness, fatigue and serenity. Subjects use a likert scale from 1 - 5 to indicate how the word relates to how they are currently feeling. As this analysis is exploratory all affective states will be explored.
Time frame: Baseline, 24 hours and 8 weeks
State Trait Anxiety Inventory
A well validated scale for assessing self-reported state and trait anxiety. In line with the study objectives, only the state items will be used to assess current feelings of anxiety in the participants. This includes 10 items which are rated using a 4-point likert scale.
Time frame: Baseline, 24 hours and 8 weeks
Perceived Stress Scale
A validated 10 item scale for self-reporting levels of perceived stress over the last month. Items are rated using a 5-point likert scale.
Time frame: Baseline and 8 weeks
Centre for Epidemiological Studies Depression Scale (CESD)
A validated, brief self report measure of depressive symptoms commonly used to assess sub-clinical levels of low mood. Items are responded to using a 4-point likert scale. Scores range from 0 to 60, with high scores indicating greater depressive symptoms.
Time frame: Baseline and 8 weeks