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Bifidobacterium longum 1714™ Strain Modulates Brain Activity of Healthy Volunteers During Social Stress

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  • DSM shanghai

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Objectives: Accumulating evidence indicates that the gut microbiota communicates with the central nervous system, possibly through neural, endocrine, and immune pathways, and influences brain function. B. longum 1714™ has previously been shown to attenuate cortisol output and stress responses in healthy subjects exposed to an acute stressor. However, the ability of B. longum 1714™ to modulate brain function in humans is unclear. Methods: In a randomized, double-blinded, placebo-controlled trial, the effects of B. longum 1714™ on neural responses to social stress, induced by the "Cyberball game," a standardized social stress paradigm, were studied. Forty healthy volunteers received either B. longum 1714™ or placebo for 4 weeks at a dose of 1 × 10 cfu/d. Brain activity was measured using magnetoencephalography and health status using the 36-item short-form health survey. Results: B. longum 1714™ altered resting-state neural oscillations, with an increase in theta band power in the frontal and cingulate cortex (P < 0.05) and a decrease in beta-3 band in the hippocampus, fusiform, and temporal cortex (P < 0.05), both of which were associated with subjective vitality changes. All groups showed increased social stress after a 4-week intervention without an effect at behavioral level due to small sample numbers. However, only B. longum 1714™ altered neural oscillation after social stress, with increased theta and alpha band power in the frontal and cingulate cortex (P < 0.05) and supramarginal gyrus (P < 0.05). Discussion: B. longum 1714™ modulated resting neural activity that correlated with enhanced vitality and reduced mental fatigue. Furthermore, B. longum 1714™ modulated neural responses during social stress, which may be involved in the activation of brain coping centers to counter-regulate negative emotions.
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Bifidobacterium longum 1714Strain Modulates Brain
Activity of Healthy Volunteers During Social Stress
Huiying Wang, PhD
1
,
2
,
3
, Christoph Braun, PhD
2
,
4
, Eileen F. Murphy, PhD
5
and Paul Enck, PhD
1
OBJECTIVES: Accumulating evidence indicates that the gut microbiota communicates with the central nervous
system, possibly through neural, endocrine, and immune pathways, and influences brain function.
B. longum 1714has previously been shown to attenuate cortisol output and stress responses in
healthy subjects exposed to an acute stressor. However, the ability of B. longum 1714to modulate
brain function in humans is unclear.
METHODS: In a randomized, double-blinded, placebo-controlled trial, the effects of B. longum 1714on neural
responses to social stress, induced by the Cyberball game,a standardized social stress paradigm,
were studied. Forty healthy volunteers received either B. longum 1714or placebo for 4 weeks at
a dose of 1 310
9
cfu/d. Brain activity was measured using magnetoencephalography and health status
using the 36-item short-form health survey.
RESULTS: B. longum 1714altered resting-state neural oscillations, with an increase in theta band power in the
frontal and cingulate cortex (P<0.05) and a decrease in beta-3 band in the hippocampus, fusiform, and
temporal cortex (P<0.05), both of which were associated with subjective vitality changes. All groups
showed increased social stress after a 4-week intervention without an effect at behavioral level due to
small sample numbers. However, only B. longum 1714altered neural oscillation after social stress,
with increased theta and alpha band power in the frontal and cingulate cortex (P<0.05) and
supramarginal gyrus (P<0.05).
DISCUSSION: B. longum 1714modulated resting neural activity that correlated with enhanced vitality and reduced
mental fatigue. Furthermore, B. longum 1714modulated neural responses during social stress,
which may be involved in the activation of brain coping centers to counter-regulate negative emotions.
SUPPLEMENTARY MATERIAL accompanies this paper at http://links.lww.com/AJG/A163
Am J Gastroenterol 2019;00:111. https://doi.org/10.14309/ajg.0000000000000203
INTRODUCTION
The existence of bidirectional communication between the gut
and brain has long been established. Recently, a body of work has
suggested that the commensal gut microbiota plays an important
role in modulating the gut-brain axis, possibly through immune,
endocrine, and neural system pathways (1). This has led to in-
creased interest in modulating the gut microbiota to target central
nervous system (CNS) functions and improve human behavior
especially in areas such as stress, mood, anxiety, and cognition.
Probiotics may represent a safe and eective way of targeting CNS
function. Indeed, an abundance of preclinical studies have shown
that probiotics acting through the gut-brain axis can aect brain
development, function, and behavior (2). However, the trans-
lation of promising preclinical signals into human subjects with
certain probiotic strains has proven challenging (3). Therefore,
there is a need for more detailed mechanistic insights into the
interaction between the gut microbiota and brain function in
humans.
One probiotic strain, Bidobacterium longu m 1714(Zenore),
has proven eective in modulating CNS functions in animals and
humans. B. longum 1714has been shown to reduce stress-related
behaviors in preclinical studies (4,5) and improve stress responses
and cognitive function in healthy volunteers (6). However, the
role of B. longum 1714in modulating brain function in humans
is unclear. Clinical studies with probiotics using neuroimaging
methods have started to emerge and provide insight into mod-
ulations of CNS functions in healthy volunteers (79) and in
patients with irritable bowel syndrome (IBS) (10). The rst study
to demonstrate neural eects of probiotics in humans used
functional MRI and showed that brain activations to emotional
1
Department of Psychosomatic Medicine and Psychotherapy, University of T ¨
ubingen, T ¨
ubingen, Germany;
2
MEG Center, University Hospital T ¨
ubingen, T ¨
ubingen,
Germany;
3
Graduate Training Center of Neuroscience, IMPRS for Cognitive and Systems Neuroscience, T ¨
ubingen, Germany;
4
CIMeC, Center for Mind/Bra in
Sciences, University of Trento, Trento, Italy;
5
Alimentary He alth Gr oup, Co rk Airport Business Park, Cork, Ireland. Correspondence: Paul Enck. E-mail:
paul.enck@uni-tuebingen.de.
Received August 12, 2018; accepted January 25, 2019; published online April 17, 2019
Copyright © 2019 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The American College of Gastroenterology The American Journal of GASTROENTEROLOGY
ARTICLE 1
FUNCTIONAL GI DISORDERS
faces were altered by a 4-week consumption of a fermented dairy
drink in comparison to placebo in healthy subjects (7). A more
recent study in healthy volunteers showed positive correlations
between psychometric measures and brain activity (8) as well as
altered functional connectivity (9) in response to emotional
processing after a 4-week intervention with a multi-strain pro-
biotic. Of interest, treatment of patients with IBS using B. longum
NCC3001 for 6 weeks resulted in an improvement in depressions
scores and reduction in limbic activity to negative emotional
stimuli, but had no eect on gut symptoms (10). Notably, these
previous studies used picture-viewing tasks during brain re-
cording that poorly reect behavioral changes found in animal
models, which are commonly used to screen the eects of pro-
biotics on stress and emotions. Furthermore, both studies in
healthy volunteers used multi-strain probiotic product making it
dicult to identify the bacterial strain responsible for the ob-
served eects and the pathways involved in strain-speciceects.
Therefore, further investigations are required using targeting
approaches and dierent stress paradigms.
In this study, we explored the eect of B. longum 1714on
brain function in response to social stress in a randomized,
double-blinded, placebo-controlled trial, using the neuroimaging
method magnetoencephalography (MEG). Social stress was in-
duced by social exclusion/rejection (11) through a standardized
paradigm, called Cyberball Game(CBG) (12). According to
a recent review summarizing previous neuroimaging studies on
the CBG, regions of the prefrontal cortex (PFC), anterior cingu-
late cortex (ACC), and temporal cortex are involved in neural
processing of this type of social stressor (13). Indeed, social stress
during the CBG is consistently associated with altered neural
oscillations in certain brain areas, such as alpha band power in
frontalcortex and theta band powerin the ACC and insula (1417).
In the current trial, we hypothesized that the probiotic strain
B. longum 1714alters resting-state brain activity and neuro-
physiological responses to CBG-induced social stress. We as-
sumed that during the CBG, stress-related neural oscillations of
the theta and alpha band power would be changed after probiotic
treatment. The results conrmed that B. longum 1714modu-
lated neural responses during social stress, suggesting counter-
regulation of negative emotions.
METHODS
Participants
Healthy adults were recruited to the study. Criteria for inclusion
were (i) man or woman aged 1850 years; (ii) nonsmoker for at
least 3 months; (iii) a body mass index of 1830; (iv) no chronic
allergies; (v) willing to discontinue their normal consumption
of probiotics and probiotic-containing foods or potentially
immune-enhancing dietary supplements; (vi) receiving no
immune-suppressing intervention and not having any immu-
nosuppressive illness within the past year; (vii) receiving no
antibiotic therapy within the past 2 months; (viii) having no
chronic psychiatric or gastrointestinal disorder; and (ix) having
no nonremovable metal parts in the body. Informed consent was
obtained from all participants before joining the study. Partic-
ipants were screened for IBS and psychiatric disorders using the
Rome III criteria (18) and the Patient Health Questionnaire (19).
During the intervention period, participants were instructed to
avoid consumption of food containing probiotics/prebiotics or
potentially immune-enhancing dietary supplements. This was
supported by providing them with a list of prohibitedfoods
(see Information 1, Supplementary Digital Content 1, http://
links.lww.com/AJG/A163). Demographic and baseline psycho-
logical information was also recorded. The protocol was ap-
proved by the Ethics Board of the University of T ¨
ubingen Medical
School (No. 503/2015BO1, as of August 26, 2015) and registered
at ClinicalTrials.gov (identier No. NCT02793193).
Design
A randomized, double-blinded, parallel-group design was used.
After screening, participants were randomly allocated to the
probiotic or placebo group for 4 weeks. At baseline (visit 1) and 1
day after completion of the intervention period (visit 2), meas-
urements of resting-state MEG, MEG during CBG, and related
questionnaires to measure the level of distress were performed.
Structural MR images were acquired on a dierent day, regardless
of the intervention schedule. To record participants health and
quality of life status, participants completed the 36-item short-
form health survey (SF36) (20) at the beginning of each of the 2
visits. The SF36 includes 8 subscales: physical functioning, bodily
pain, role limitations due to physical health problems, role limi-
tations due to personal or emotional problems, emotional well-
being, social functioning, energy/vitality, and general health
perceptions. The randomization scheme was only unblinded after
completion of the experiment and complete data evaluation.
Materials
The probiotic and placebo preparations were provided by
Alimentary Health Group, Cork, Ireland. Participants were ran-
domized to receive sachets containing either probiotic (1 310
9
CFU of B. longum 1714in 2 g of maltodextrin) or placebo (2 g of
maltodextrin). Probiotic and placebo were identically packaged.
Participants were instructed to consume one sachet every
morning by mixing the content into 50 mL of water. Both subjects
and investigators were blinded to the regime administered.
CBG
The CBG was used to study the eects of social stress and ex-
clusion as outlined previously by Wang et al. (21). Briey, during
the CBG, participants were asked to play a virtual ball-tossing
game with 2 other virtual players programmed. The CBG involves
2 conditions, the so-called inclusion and exclusion. Figure 1
presents a single trial from 1 player throwing the ball to another
(Figure 1) (see Information 2, Supplementary Digital Content 1,
http://links.lww.com/AJG/A163 for more detail).
CBG questionnaires
After the CBG exclusion or inclusion periods, participants
completed 3 questionnaires to assess the level of acute distress.
We employed the self-report measures of the Need Threat Scale
(NTS), the Mood Questionnaire (MQ), and the Subjective Ex-
clusion Perception(SEP) (see Information 3, Supplementary
Digital Content 1, http://links.lww.com/AJG/A163); all these
scales are validated standards for the CBG (12,22). The NTS is
designed to measure the feelings and emotional consequences of
social rejection, and higher scores related to higher distress level.
Its 4 items (rated between 1 and 5 for weakto strong) com-
prised self-esteem, belonging, meaningful existence, and control,
and combined ratings have been used as a measure of social
distress in previous studies. The MQ is used to assess mood, using
8 questions (are you feeling bad, good, happy, sad, pleasant, an-
gry, friendly, and unfriendly), all rated between 1 and 5. The SEP
The American Journal of GASTROENTEROLOGY VOLUME 00 | MONTH 2019 www.amjgastro.com
FUNCTIONAL GI DISORDERS
Wang et al.2
is used to record participantsfeeling of being included/ostracized
by asking them to rate 2 statements (I was ignoredand I was
excluded) between 1 and 5.
MEG recording
Brain magnetic elds were measured with a 275-channel whole-
head MEG (CTF Omega, Port Coquitlam, Canada). Participants
Figure 1. Schematic outline of a trial in the Cyberball Game (CBG).
Figure 2. The CONSORT flow diagram of the clinical trial. Reprinted from Schulz et al. Copyright BMJ (48). All permission requestsfor this image should be
made to the copyright holder.
Copyright © 2019 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The American College of Gastroenterology The American Journal of GASTROENTEROLOGY
FUNCTIONAL GI DISORDERS
Bifidobacterium longum 1714ÔStrain Modulates Brain Activity 3
were studied in sitting position. During each session, 5 minutes
resting state was recorded before playing the CBG. During the
resting state, participants were instructed to move as little as
possible and to stay alert while keeping their eyes closed. During
the CBG, task instructions were projected onto a screen in front of
the participants using a video projector and a mirror system.
MEG signals were sampled at a rate of 585.94 Hz with an anti-
aliasing lter set to 146.49 Hz.
To overlay the brain activity derived from MEG on anatomical
scans, high-resolution (1 mm, isotropic) T1-weighted structural
MR images were acquired using an MPRAGE sequence with
a Siemens MAGNETOM Trio 3T scanner (Siemens AG, Erlan-
gen, Germany) (12-channel array head coil) for each participant,
but at a separate occasion.
Data analysis
Power calculation. The primary endpoint was change in brain
activity. Based on previously published data (7), we estimated
thatwith a power of 0.95 for a 2 32 repeated measure
ANOVAa minimum sample size of 28 was required to dem-
onstrate an eect size f50.23 at a50.05 in a parallel-group
designed study (see Information 4, Supplementary Digital Con-
tent 1, http://links.lww.com/AJG/A163 for more detail).
Data analysis: MEG
Analysis of the MEG data was performed using MATLAB
(Mathworks, Natick, MA) and the open-source toolboxes Field-
Trip (23). Data from the resting state and during the CBG were
analyzed, respectively, after procedures of preprocessing (trial
segmentation and artifacts rejection)Time-frequency analysis
(multitaper windowed fast Fourier transform)Source analysis
(dynamic imaging of cortical sources: DICS)Source statistics
(cluster-based permutation statistics).
Data analysis: Questionnaires
Data analysis was conducted using SPSS 21 (IBM, Armonk, NY).
To examine whether there was a signicant dierence in health
Table 1. Demographic and baseline information
B. longum 1714Placebo Pvalue
Sex
Male N 57N57ns
Female N 513 N 513
Birth delivery
Caesarean section N 52N52ns
Vaginal delivery N 518 N 518
Age 31.00 62.28 33.00 62.83 0.45
BMI 23.00 60.68 22.00 60.55 0.26
SF36
Physical functioning 96.84 61.03 97.63 60.80 0.71
Role limitations due to physical health 100.00 60.00 100.00 60.00 1.00
Role limitations due to emotion problems 100.00 60.00 95.00 65.00 0.81
Energy/vitality 72.25 62.42 75.25 62.94 0.57
Emotional well-being 85.78 61.22 84.42 61.75 0.52
Social functioning 100.00 60.00 94.74 62.20 0.20
Pain 88.75 62.67 89.75 62.80 0.84
General health 82.50 62.31 87.37 62.40 0.11
CBG
NTS
Inclusion 228.30 63.55 236.90 62.28
Exclusion 14.33 64.55 26.90 63.48 P
intervention
50.59
MQ
Inclusion 13.80 61.47 18.03 60.99
Exclusion 2.38 62.25 25.48 62.17 P
intervention
50.21
SEP
Inclusion 24.68 60.28 25.30 60.21
Exclusion 0.15 60.92 2.23 60.61 P
intervention
50.15
BMI, body mass index; CBG, Cyberball Game; MQ, mood questionnaire; ns, not significant; NTS, Need Threat Scale; SEP, subjective exclusion perception; SF36, 36-item
short-form health survey.
The American Journal of GASTROENTEROLOGY VOLUME 00 | MONTH 2019 www.amjgastro.com
FUNCTIONAL GI DISORDERS
Wang et al.4
status between groups at baseline, scores of SF36 during the rst
visit were entered into a nonparametric independent-sample
Mann-Whitney Utest of Intervention as between factor (B. lon-
gum 1714vs placebo) because parametric assumptions of these
data were violated. To test the intervention-related changes in
participantshealth status scored by SF36, changes from before to
after the 4-week intervention were computed by subtracting the
baseline assessment from the corresponding postintervention
values. A nonparametric two-way independent-sample Mann-
Whitney Utest was used to examine the change of SF36 between
Intervention (B. longum 1714vs placebo).
To examine whether subjective ratings for the CBG were dierent
between groups at baseline, scores of NTS, MQ, and SEP acquired
during the rst visit were entered into an independent ttest with
Intervention as between factor (B. longum 1714vs placebo). To
control the intervention-related changes in the scores of the NTS,
MQ, and SEP during the CBG, changes after each intervention were
computed for each condition and entered into a 2 32 repeated
measure ANOVA with Intervention as a between-factor (B. longum
1714vs placebo) 3Condition as a within-factor (exclusion vs
inclusion). Where signicant main eects or interaction were ob-
served, pairwise post hoc comparisons were used with a Bonferroni-
adjusted threshold (a50.025). Mean data are reported as M 6s.d.
Correlation between stress measures and quality of life
assessments with MEG data
To investigate the relationship between changes in neural activity and
changes in subjective scores induced by B. longum 1714, correlation
analysis was performed for both, the change in brain activity in the
resting state and after the CBG. For the resting state, averaged source
power was calculated for the clusters that were signicantly dierent
between both visits. The averaged source power was correlated with
changes in health status (SF36) for each group separately. For the
CBG, for each condition and each intervention, source power within
clusters signicantly dierent between both visits was averaged. The
averaged source power was correlated with changes in the scores of
the NTS, MQ, and SEP separately for each condition and each group,
using Pearson correlations.
RESULTS
Subjects and baseline characteristics
A total of 40 healthy volunteers completed the study. After
screening, 43 subjects were randomized to either B. longum 1714
or placebo. Three subjects could not be included in the nal
analysis because of use of antibiotics during the intervention
period (Figure 2 for detailed trial prole). A total of 40 partic-
ipants were included in the analysis with n 520 per intervention
group. Sex of participants was matched between groups. Age and
body mass index of participants were not signicantly dierent
between groups (Table 1 for details).
Administration of social stress (CBG) altered brain activity in
healthy volunteers at baseline
At baseline, stress eects were analyzed across all participants.
No dierence between groups at baseline during rest was ob-
served in any frequency band. As expected, source statistics of
Figure 3. Neural activities in different frequency bands during exclusion vs inclusion condition. (a) Theta frequency band (6 Hz): increased power in the
bilateral cerebellum (CBL), right middle and inferior frontal cortex (MFC and IFC), left fusiform cortex (P50.004); decreased power in the left middle frontal
and bilateral superior frontal cortex (SFC) (P50.02). (b) Alpha frequency band (11 Hz): increased power in the bilateral CBL, left fusiform, right inferior
occipital cortex (P50.002); decreased power in the right SFC (P,0.05). (c) Beta-1 frequency band (16 Hz): increased power in the bilateral CBL, left
MFC, left inferior temporal, right middle and superior temporal cortex, and right parahippocampal (P50.004). (d) Beta-2 frequency band (21 Hz):
increased power in the right CBL, left IFC, right inferior and middle temporal cortex (MTC) (P50.002). (e) Beta-3 frequency band (26 Hz): increased power
in the bilateral CBL, right fusiform, left parahippocampal, left MTC (P50.04).
Copyright © 2019 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The American College of Gastroenterology The American Journal of GASTROENTEROLOGY
FUNCTIONAL GI DISORDERS
Bifidobacterium longum 1714ÔStrain Modulates Brain Activity 5
MEG power in each frequency band showed brain regions that
had signicantly dierent activities during the exclusion
compared with the inclusion condition (Figure 3). The global
NTS (t
37
513.39, P,001) and SEP (t
38
59.99, P,001)
scores were signicantly higher, and the MQ scores (t
39
5
29.42, P,001) were lower in the exclusion condition com-
pared with inclusion condition (Table 1). At baseline, there
were no signicant dierences in SF36 scores or CBG sub-
jective scores (NTS, MQ, and SEP) after the social stress be-
tween groups (Table 1).
B. longum 1714altered resting-state brain activity measured
by MEG
After a 4-week intervention, comparison between probiotic and
placebo group showed that B. longum 1714feeding increased
theta band (6 Hz) power (P,0.05; Figure 4a) in the bilateral
inferior, middle, and superior frontal cortex (IFC, MFC, and SFC)
as well as in the bilateral anterior and middle cingulate cortex
(ACC and MCC). Furthermore, feeding B. longum 1714reduced
beta-2 band (26 Hz) power (P,0.05; Figure 4b) in the bilateral
fusiform gyrus, the bilateral hippocampus, the left inferior and
superior temporal and bilateral middle temporal cortex, and the
left cerebellum.
B. longum 1714induced change in neural activity correlated
with increased vitality
No signicant dierence was found in changes of SF36 scores
after intervention between groups. To investigate the re-
lationship between changes in neural activity during resting
state and quality of life, the changes in averaged theta and beta-
2 band power with changes in SF36 scores were correlated. In
both groups, a signicant positive correlation was obtained
between changes of the SF36 subscale Energy/Vitalitywith
changes of theta band power (r50.33, P50.04; Figure 5a).
Group-specic correlations revealed that only in the B. longum
1714group, changes in SF36 score for Energy/Vitality
positively correlated with changes in averaged theta band
power (r50.61, P50.007), and negatively correlated with
changes in beta-3 band power during the resting state (r52
0.50, P50.04; Figure 5b).
Figure 4. Difference of neural activity change during resting state comparing
B. longum 1714vs placebo. (a) After the intervention, an increased theta
band (6 Hz) power was obtained in a cluster including regions of bilateral
inferior frontal cortex, middle frontal cortex, and the bilateral anterior cingu-
late cortex and middle cingulate cortex, comparing B. longum 1714with
the placebo group (P,0.05). (b) After the intervention, reduced beta-2
band (26 Hz) power was obtained in a cluster, consisting of the bilateral
fusiform gyrus and hippocampus, left inferior temporal cortex and superior
temporal cortex, bilateral middle temporal cortex and left cerebellum, com-
paring B. longum 1714with the placebo group (P,0.05).
Figure 5. Correlation between neural activity change during resting state and SF36 change. (a) In all groups, a positive correlation was obtained between
changes of SF36 item Energy/vitalitywith changes of theta band power in the cluster (r50.33, P50.04). (b) In only B. longum 1714group, changes of
SF36 item Energy/vitalitypositively correlated with change of averaged theta band power (r50.61, P50.007), and negatively correlated with change of
beta-3 band power in the activated clusters during the resting state, respectively (r520.50, P50.04). SF36, 36-item short-form health survey.
The American Journal of GASTROENTEROLOGY VOLUME 00 | MONTH 2019 www.amjgastro.com
FUNCTIONAL GI DISORDERS
Wang et al.6
All groups reported enhanced social stress measured by
subjective ratings after a 4-week intervention
Analysis of changes in NTS, MQ, and SEP scores showed signicant
main eects of condition on NTS (F(1, 33) 55.91, P50.02) and on
SEP (F(1, 36) 55.61, P50.02) as determined by ANOVA
(Intervention 3Condition). Participants in all groups reported in-
creased scores of NTS (exclusion: M 55.20 62.37; inclusion:
M524.32 61.85) and SEP (exclusion: M 50.94 60.42; inclusion:
M520.30 60.16) in the exclusion compared with inclusion
condition, after 4 weeks of intervention. The changes in MQ scores
(exclusion: M 521.87 61.08;inclusion:M50.30 60.86) showed
no dierence after intervention (F(1, 34) 51.72, P50.20)
(Figure6).Therewerenoeects of intervention on the subjective
scores of these questionnaires (Table 2).
B. longum 1714altered brain activity during social stress
measured by MEG
After a 4-week intervention, B. longum 1714induced changes in
source power in theta (6 Hz) band and alpha band (11 Hz) in
response to the CBG, compared with placebo. B. longum 1714
increased theta band power in 1 cluster, consisting of the right IFC
and the bilateral MFC and SFC, the left ACC, the bilateral MCC, and
the right supramarginal gyrus in both conditionsinclusion and
exclusion (P50.03; Figure 7a). Furthermore, B. longum 1714also
increased the alpha band power in the cluster, including regions of
the right IFC, the bilateral MFC and SFC, the bilateral ACC and
MCC, and the right supramarginal gyrus in both conditions (P5
0.04; Figure 7b). No main eects of condition or interaction of
intervention and condition were observed.
B. longum 1714induced change in neural activity in social
stress correlated with changes in distress levels
Correlation analysis between changes in neural activities and changes
in subjective ratings during the CBG revealed that only with B. lon-
gum 1714and only during the exclusion condition, NTS changes
positively, correlated with changes in the theta band power (r50.62,
P50.008) and alpha band power (r50.54, P50.03; Figure 8).
Summaries of frequency bands and neuroanatomical areas
found to be related to B. longum 1714intervention, and asso-
ciations of changes in neural activity and subjective eects are
provided in Tables 3 and 4, respectively.
Figure 6. Main effects of condition on NTS and SEP. Participants in all groups
reported increased scores of NTS and SEP in the exclusion condition com-
pared with inclusion condition, after a 4-week intervention. MQ, mood ques-
tionnaire; NTS, Need Threat Scale; SEP, subjective exclusion perception.
Table 2. Changes in subjective scores of SF36, NTS, MQ, and SEP
B. longum 1714Placebo Pvalue
SF36
Physical functioning 1.11 60.95 0.53 60.36 0.94
Role limitations due to physical health 0.00 60.00 0.00 60.00 1.00
Role limitations due to emotion problems 0.00 60.00 0.00 60.00 1.00
Energy/vitality 23.42 62.02 23.00 62.03 0.71
Emotional well-being 0.00 61.82 20.84 61.72 0.59
Social functioning 23.13 61.63 4.17 62.34 0.83
Pain 4.88 62.27 5.00 62.11 0.83
General health 20.26 62.31 20.79 61.68 0.95
CBG
NTS
Inclusion 4.11 63.24 4.53 61.79
Exclusion 24.82 63.82 25.58 63.02 P
intervention
50.98
MQ
Inclusion 0.63 61.34 20.03 61.11
Exclusion 20.61 61.74 23.00 61.30 P
intervention
50.60
SEP
Inclusion 20.25 60.24 20.34 60.22
Exclusion 0.53 60.58 1.35 60.60 P
intervention
50.63
CBG, Cyberball Game; MQ, mood questionnaire; NTS, Need Threat Scale; SEP, subjective exclusion perception; SF36, 36-item short-form health survey.
Copyright © 2019 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The American College of Gastroenterology The American Journal of GASTROENTEROLOGY
FUNCTIONAL GI DISORDERS
Bifidobacterium longum 1714ÔStrain Modulates Brain Activity 7
DISCUSSION
B. longum 1714has been shown to reduce stress-related
behaviors in preclinical studies (4,5) and improve stress respon-
ses and cognitive function in healthy volunteers (6). The current
functional neuroimaging study showed that B. longum 1714
signicantly altered neural activities in the resting state and in
response to a social stressor in healthy participants after a 4-week
intervention. The alteration in the resting brain activity by B.
longum 1714was associated with the SF36 scale Energy/Vi-
tality.In response to the social stress, the changed neural ac-
tivities occurred only in the probiotic group. These data suggest
that B. longum 1714may play a role in managing stress
responses by modulating the relevant neural processes.
During the resting state, B. longum 1714induced an increase
in theta band power in the frontal and cingulate cortex and
a decrease in beta-3 band power in the fusiform cortex, hippo-
campus, temporal cortex, and cerebellum. Although no signi-
cant change of SF36 was noted after the 4-week probiotic intake,
the increase in theta band and decrease in beta-3 band power
found in the resting state was associated with increase in per-
ceived energy/vitality levels, as assessed by the SF36. Energy/
vitality in the SF36 measures subjective reception of participants
how full of pep and energetic they felt. Other studieshave shown an
association between increased power in theta band (whole brain,
especially prominent in the frontal regions) on a resting-state EEG
with improved attention and arousal after consumption of glucose
(24,25) whereas decreased theta band power measured by MEG in
cingulate cortex has been correlated with subjective level of fatigue
(26). Of interest, an increase in beta band power has been linked to
mental fatigue (27), andinversely, reduced beta power could index
increased alertness and arousal, accompanied with decreased
anxiety and stress (28,29). These data suggest that B. longum 1714
altered neural activities in a manner associated with enhanced vi-
tality and reduced mental fatigue.
From an evolutionary perspective, humans are programmed
to be highly sensitive to social exclusion and have developed
monitoring systems to detect cues (30,31). This is necessary for
human survival as social isolation is often a fatal threat (32,33). As
expected, the CBG induced a social stress eect at baseline across
all participants. Social exclusion produced dierential neural
oscillations in all frequency bands in various areas, such as frontal,
temporal, and fusiform cortex. These results were similar to
previous EEG and MEG studies, showing modulation of neural
oscillations by social exclusion (14,15,17,21). Previously reported
ACC activations were related to processing of negative emotions
and event appraisal due to the social stress/exclusion, and PFC
activation was related to emotional regulation (13,3436). Theta
band oscillations in ACC and insula were described as a marker of
social pain in the context of the CBG and was also found during
a cold pressor test and physical pain (37,38). The participants
reported enlarged subjective distress and decreased mood level
during the exclusion condition compared with the inclusion
Figure 8. Correlation between neural activity change during the Cyberball
game and subjective score changes. Only in B. longum 1714group and
only during the exclusion condition, NTS changes positively correlated with
changes of the theta band power (r50.62, P50.008) and alpha band
power (r50.54, P50.03). NTS, Need Threat Scale.
Figure 7. Difference in neural activity change during the Cyberball game com-
paring B. longum 1714vs placebo. (a) Theta band showed an increased
power in a cluster, consisting of the right inferior frontal cortex (IFC) and the
bilateral middle frontal cortex (MFC) and superior frontal cortex (SFC), the left
anterior cingulate cortex (ACC), the bilateral middle cingulate cortex (MCC), and
the right supramarginal gyrus (SMG), comparing B. longum 1714 group and the
placebo group in both conditions (P50.03). (b) Alpha band power also showed
an increased power in cluster, including regions of the right IFC, the bilateral MFC
and SFC, the bilateral ACC and MCC, and the right SMG, comparing B. longum
1714group and the placebo group in both conditions (P50.04). No main
effects of condition or interaction of intervention and condition were observed.
The American Journal of GASTROENTEROLOGY VOLUME 00 | MONTH 2019 www.amjgastro.com
FUNCTIONAL GI DISORDERS
Wang et al.8
condition, consistent to previous studies (12,14,15,17). After the
intervention, as expected, all participants reported higher distress
level during the exclusion condition compared with the inclusion
condition after 4 weeks, regardless of the type of intervention
(probiotic, placebo). However, a clinical eect of B. longum 1714
on reducing stress was not observedthe study was not powered
to detect dierences in subjective stress. Furthermore, as with
other stress paradigms, the repetition of stress may reinforce the
feeling of being excluded and consolidated the memory of the
stressful event making it dicult to detect dierences with small
numbers.
Although both placebo and probiotic groups reported
higher subjective distress, changes in neural processing of
social stress were observed only after B. longum 1714con-
sumption and not placebo. In addition, the correlation be-
tween changes in subjective distress and neural activities was
seen only with B. longum 1714. Therefore, these data support
the notion that B. longum 1714may play a role in managing
stress responses by modulating the relevant neural processes;
B. longum 1714aecting individualsneurophysiology is
anovelnding and was previously only reported for behavioral
data in animals and humans (46).
However, in comparison to other neurophysiological
studies with the CBG (22,23), our study involved repeated
exposure to the social stress 4 weeks apart. Indeed, similar
changes in theta band activity induced by B. longum 1714
were observed in the resting-state data (before playing the
CBG) of the current study, which correlated with increased
vitality. These data suggest that the increase in theta and alpha
band power by B. longum 1714before the stressor may be to
some degree a priming for the stressor and may represent an
upregulation of appraisal processes and coping mechanisms in
the expectation of being exposed to a similar stressful situation
again. Furthermore, lower frontal alpha power has been as-
sociated with anxiety (39,40). The increased alpha oscillation
activity in our study may indicate the inhibition of limbic ac-
tivity and thereby counter-regulate negative emotions and
stress. Taking this argument further, we suggest that in con-
trast to placebo, B. longum 1714reduced participantsstress
response and enabled them to manage the increased distress
level by upregulating processes appraising stressful events and
downregulating negative emotions.
Other studies, in line with our data, showed neural modu-
lation by dierent psychobiotic strains, and provided some
clues of the potential mechanisms involved. Preclinical studies
have reported an increase in serotonin and dopamine level, 2
crucial neurotransmitters regulating mood and emotions, in
brain regions of mice such as PFC after interventions with
Lactobacillus plantaraum and Lactobacillus helveticus (4143).
Another study showed Lactobacillus rhamnosus JB-1 modulated
GABAergic system and reduced stress-related psychiatry-like
behaviors in mice, and some of the eects were mediated by the
vagus nerve (44). However, eects of the L. rhamnosus JB-1 were
not found in a clinical study in healthy volunteers, indicating
possibly the challenge of translating preclinical studies into
clinical relevance (3). The lack of evidence of translating pre-
clinical to clinical studies was also addressed by a recent meta-
analysis on the anxiolytic eect of probiotics (45), suggesting
a need to investigate strain specicity and use functional imag-
ing techniques in clinical studies in alternative to subjective
questionnaires.
In our recent study, antistress eects of rifaximin on social
stress were associated with a reduction of frontal and cingulate
beta band power in the insula, frontal and cingulate gyrus,
after 1-week intervention (21). Although causing a stress re-
duction like B. longum 1714, rifaximin may act through dif-
ferent pathwaysdierent neural oscillations and brain
regions. Because the peripheral and central mechanisms by
which rifaximin aects stress management are not well un-
derstood, one may speculate on an eubioticeect of this
antibiotic promoting benecial bacteria such as Bidobacteria
and Lactobacilli (46,47). Therefore, although eects of probiotics
Table 3. Summarized neuroanatomical areas and frequency
bands of changed neural activities influenced by effect of
condition, intervention and/or interaction of condition and
intervention
Comparison
Frequency
band
Brain
region Hemisphere
P
value
Intervention effect on resting
state: B. longum group vs
placebo group
Theta IFC B ,0.05
MFC B
SFC B
ACC B
MCC B
Beta-3 FFG B ,0.05
HIPP B
ITC L
MTC B
STC L
CBL L
Intervention effect on the CBG
for all conditions: B. longum
group vs placebo group
Theta IFC R 0.03
MFC B
SFC B
ACC L
MCC B
SMG R
Alpha IFC R 0.04
MFC B
SFC B
ACC B
MCC B
SMG R
ACC, anterior cingulate cortex; B, bilateral; CBG, Cyberball Game; CBL, cerebellum;
FFG, fusiform gyrus; HIPP, hippocampus; IFC, inferior frontal cortex; ITC, inferior
temporal cortex; L, left; MCC, middle cingulate cortex; MFC, middle frontal cortex;
MTC, middle temporal cortex; R, right; SFC, superior frontal cortex; SMG,
supramarginal gyrus; STC, superior temporal cortex.
Copyright © 2019 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The American College of Gastroenterology The American Journal of GASTROENTEROLOGY
FUNCTIONAL GI DISORDERS
Bifidobacterium longum 1714ÔStrain Modulates Brain Activity 9
on CNS functions appear to be strain-specic (4), results of
existing studies help to understand the possible pathways of the
strain we used in the current trial. More studies are required to
investigate the eects of dierent strains on diverse brain activi-
ties in response to stress in order to obtain a detailed picture of the
eects of probiotics on brain functioning.
CONCLUSION
B. longum 1714inuenced resting neural activities associated
with enhanced vitality and stress-related neural responses,
which may be involved in the counter-regulation of negative
emotions. Our results further support the role of B. longum
1714in reducing stress responses and provides new evidence
that this probiotic aects brain function through modulating
neural oscillations in certain brain regions. The understanding
of neural oscillations induced by stress and their modulation
by probiotics is still at its beginning. Studies that examine the
mechanisms by which probiotics modulate the gut-brain axis
and compare their eects on other CNS functions with other
interventions are warranted. To fully understand the eects of
B. longum 1714on brain function and human behavior, it is
necessary to consider the eects of the strain on other CNS
functions such as pain sensitivity, mood, and memory in both
healthy controls and in patients with psychiatric (depression,
anxiety), neurologic (neurodegenerative), and gastrointestinal
disorders such as IBS.
ACKNOWLEDGMENTS
We thank Dr. Gerald Clarke, Prof. John Cryan, and Prof. Ted
Dinan at the APC Microbiome Institute, University College Cork,
Ireland for support on training and advice on the probiotic
selection.
1714, 1714-Serenitas, and Zenoreare trademarks of Alimentary
Health.
CONFLICTS OF INTEREST
Guarantor of the article: Paul Enck, PhD.
Specic author contributions: P.E.: inception of the study and
publication of the work. H.W.: contributed to the design of the study,
data collection and analysis, drafting of the manuscript, and critical
revisions of the manuscript. C.B., E.M., and P.E.: contributed to the
design of the study, data analysis, and critical revisions of the
manuscript. All authors approved the nal version of the manuscript.
1714, 1714-serenitas and Zenore are trademarks of Alimentary
Health.
Financial support: The research leading to these results has received
funding from the People Programme of the European Unions
Seventh Framework Programme under REA grant agreement no.
607652 (NeuroGut).
Potential competing interests: E.M. is the Technical Director at
Alimentary Health Group. Alimentary Health provided the
placebo and probiotic containing the B. longum 1714strain (also
known as 1714-Serenitas), but had no further inuence on data
collection and data evaluation. P.E. is a consultant for Alimentary
Health. The other authors declare no potential conicts of
interest.
Table 4. Summarized correlations of changes of averaged power in activated areas with changes of subjective results
Groups Subjective item
Resting-state MEG Functional MEG during CBG
Theta band
power change
Beta-3 band
power change
Theta band
power change
Alpha band
power change
Both groups SF36-energy/vitality r50.33
P50.04
———
B. longum group SF36-energy/vitality r50.61
P50.007
r520.50
P50.04
——
NTS r50.62
P50.008
r50.54
P50.03
The changes in neural activity during resting state was correlated with changes of SF36, and the changes in the neural activity during CBG was correlated with changes of
the NTS, respectively, for each of the 2 conditions of exclusion and inclusion.
CBG, Cyberball Game; MEG, magnetoencephalography; NTS, Need Threat Scale; SF36, 36-item short-form health survey.
Study Highlights
WHAT IS KNOWN
3Accumulating evidence indicates that the gut microbiota
communicates with the CNS, possibly through neural,
endocrine, and immune pathways, and influences brain
function.
3Effects of probiotics on the CNS functions are strain specific.
3B. longum 1714has been shown to reduce stress-related
behaviors in preclinical studies and improve stress responses
and cognitive function in healthy volunteers.
WHAT IS NEW HERE
3B. longum 1714altered brain activity of healthy
volunteers during social stress as measured by
neuroimaging method MEG with high temporal resolution
and fine spatial resolution.
3B. longum 1714influenced resting neural activities
associated with enhanced vitality and stress-related neural
responses, which may be involved in the counter-regulation of
negative emotions.
3Our results further support the role of B. longum 1714in
reducing stress responses in humans and provides new
evidence that this probiotic strain affects brain function
through modulating neural oscillations in brain regions
involved in emotional regulation.
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FUNCTIONAL GI DISORDERS
Wang et al.10
REFERENCES
1. Cryan JF, Dinan TG. Mind-altering microorganisms: The impact of the gut
microbiota on brain and behaviour. Nat Rev Neurosci 2012;13(10):70112.
2. Wang H, Lee IS, Braun C, et al. Eect of probiotics on central nervous
system functions in animals and humans: A systematic review.
J Neurogastroenterol Motil 2016;22(4):589605.
3. Kelly JR, Allen AP, Temko A, et al. Lost in translation? The potential
psychobiotic Lactobacillus rhamnosus (JB-1)failstomodulatestressorcognitive
performance in healthy male subjects. Brain Behav Immun 2017;61:509.
4. Savignac HM, Kiely B, Dinan TG, et al. Bidobacteria exert strain-specic
eects on stress-related behavior and physiology in BALB/c mice.
Neurogastroenterol Motil 2014;26(11):161527.
5. Savignac HM,Tramullas M, KielyB, et al. Bidobacteriamodulate cognitive
processes in an anxious mouse strain. Behav Brain Res 2015;287:5972.
6. Allen AP, Hutch W, Borre YE, et al. Bidobacterium longum 1714 as
a translational psychobiotic: Modulation of stress, electrophysiology and
neurocognition in healthy volunteers. Transl Psychiatry 2016;6(11):e939.
7. Tillisch K, Labus J, Kilpatrick L, et al. Consumption of fermented milk
product with probiotic modulates brain activity. Gastroenterology. 2013;
144(7):1394401, 401.e14.
8. Bagga D, Reichert JL, Koschutnig K, et al. Probiotics drive gut microbiome
triggering emotional brain signatures. Gut Microbes 2018;9(6):48696.
9. Bagga D, Aigner CS, Reichert JL, et al. Inuence of 4-week multi-strain
probiotic administration on resting-state functional connectivity in
healthy volunteers. Eur J Nutr 2018. [Epub ahead of print May 30, 2018.]
10. Pinto-Sanchez MI, Hall GB, Ghajar K, et al. Probiotic Bidobacterium
longum NCC3001 reduces depression scores and alters brain activity: A
pilot study in patients with irritable bowel syndrome. Gastroenterology
2017;153(2):44859.e8.
11. Krieger N. Theories for social epidemiology in the 21st century: An
ecosocial perspective. Int J Epidemiol 2001;30(4):66877.
12. Williams KD, Jarvis B. Cyberball: A program for use in research on
interpersonal ostracism and acceptance. Behav Res Methods 2006;38(1):
17480.
13. Wang H, Braun C, Enck P. How the brain reacts to social stress
(exclusion): A scoping review. Neurosci Biobehav Rev 2017;80:808.
14. Cristofori I, Harquel S, Isnard J, et al. Monetary reward suppresses
anterior insula activity during social pain. Soc Cogn Aect Neurosci 2015;
10(12):166876.
15. Cristofori I, Moretti L, Harquel S, et al. Theta signal as the neural signature
of social exclusion. Cereb Cortex 2013;23(10):243747.
16. Kawamoto T, Nittono H, Ura M. Cognitive, aective, and motivational
changes during ostracism: An ERP, EMG, and EEG study using
a computerized cyberball task. Neurosci J 2013;2013:304674.
17. van Noordt SJ, White LO, Wu J, et al. Social exclusion modulates event-
related frontal theta and tracks ostracism distress in children. Neuroimage
2015;118:24855.
18. Longstreth GF, Thompson WG, Chey WD, et al. Functional bowel
disorders. Gastroenterology 2006;130(5):148091.
19. Kroenke K, Spitzer RL, Williams JB, et al. The Patient Health
Questionnaire Somatic, Anxiety, and Depressive Symptom Scales: A
systematic review. Gen Hosp Psychiatry 2010;32(4):34559.
20. Ware JE Jr, Sherbourne CD. The MOS 36-item short-form health survey
(SF-36). I. Conceptual framework and item selection. Med Care 1992;
30(6):47383.
21. Wang H, Braun C, Enck P. Eects of Rifaximin on central responses to
social stress-a pilot experiment. Neurotherapeutics 2018;15(3):80718.
22. Sebastian C, Viding E, Williams KD, et al. Social brain development and
the aective consequences of ostracism in adolescence. Brain Cogn 2010;
72(1):13445.
23. Oostenveld R, Fries P, Maris E, et al. FieldTrip: Open source software for
advanced analysis of MEG, EEG, and invasive electrophysiological data.
Comput Intell Neurosci 2011;2011:156869.
24. An YJ, Jung KY, Kim SM, et al. Eects of blood glucose levels on resting-
state EEG and attention in healthy volunteers. J Clin Neurophysiol 2015;
32(1):516.
25. Wang C, Szabo JS, Dykman RA. Eects of a carbohydrate supplement
upon resting brain activity. Integr Physiol Behav Sci 2004;39(2):12638.
26. Ishii A, Tanaka M, Watanabe Y. The neural mechanisms underlying the
decision to rest in the presence of fatigue: A magnetoencephalography
study. PLoS One 2014;9(10):e109740.
27. Tanaka M, Ishii A, Watanabe Y. Neural eects of mental fatigue caused by
continuous attention load: A magnetoencephalography study. Brain Res
2014;1561:606.
28. Diego MA, Field T, Sanders C, et al. Massage therapy of moderate and
light pressure and vibrator eects on EEG and heart rate. Int J Neurosci
2004;114(1):3144.
29. Field T, Ironson G, Scadi F, et al. Massage therapy reduces anxiety and
enhances EEG pattern of alertness and math computations. Int J Neurosci
1996;86(3-4):197205.
30. Macdonald G, Leary MR. Why does social exclusion hurt? The relationship
between social and physical pain. Psychol Bull 2005;131(2):20223.
31. Williams KD. Chapter 6 ostracism: A temporal needthreat model. In:
Advances in Experimental Social Psychology, Vol 41. Academic Press:
San Diego, CA, 2009, pp. 275314.
32. Kling A, Lancaster J, Benitone J. Amygdalectomy in the free-ranging
vervet (Cercopithecus aethiops). J Psychiatr Res 1970;7(3):1919.
33. Silk JB, Alberts SC, Altmann J. Social bonds of female baboons enhance
infant survival. Science 2003;302(5648):12314.
34. Bolling DZ, Pelphrey KA, Vander Wyk BC. Unlike adults, children
and adolescents show predominantly increased neural activation to
social exclusion by members of theoppositegender.SocNeurosci
2016;11(5):47586.
35. Luo S, Yu D, Han S. Genetic and neural correlates of romantic
relationship satisfaction. Soc Cogn Aect Neurosci 2016;11(2):33748.
36. Preller KH, Pokorny T, Hock A, et al. Eects of serotonin 2A/1A receptor
stimulation on social exclusion processing. Proc Natl Acad Sci USA 2016;
113(18):511924.
37. Chang PF, Arendt-Nielsen L, Chen AC. Dynamic changes and spatial
correlation of EEG activities during cold pressor test in man. Brain Res
Bull 2002;57(5):66775.
38. Chen AC, Dworkin SF, Haug J, et al. Topographic brain measures of
human pain and pain responsivity. Pain 1989;37(2):12941.
39. Luijcks R, Vossen CJ, Hermens HJ, et al. The inuence of perceived stress
on cortical reactivity: A proof-of-principle study. PLoS One 2015;10(6):
e0129220.
40. Roozendaal B, McEwen BS, Chattarji S. Stress, memory and the amygdala.
Nat Rev Neurosci 2009;10(6):42333.
41. Liang S, Wang T, Hu X, et al. Administration of Lactobacillus helveticus
NS8 improves behavioral, cognitive, and biochemical aberrations caused
by chronic restraint stress. Neuroscience 2015;310:56177.
42. Liu WH, Chuang HL, Huang YT, et al. Alteration of behavior and
monoamine levels attributable to Lactobacillus plantarum PS128 in germ-
free mice. Behav Brain Res 2016;298(Pt B):2029.
43. Liu YW, Liu WH, Wu CC, et al. Psychotropic eects of Lactobacillus
plantarum PS128 in early life-stressed and na¨
ıve adult mice. Brain Res
2016;1631:112.
44. Bravo JA, Forsythe P, Chew MV, et al. Ingestion of Lactobacillus strain
regulates emotional behavior and central GABA receptor expression in
a mouse via the vagus nerve. Proc Natl Acad Sci USA 2011;108(38):
160505.
45. Reis DJ, Ilardi SS, Punt SEW. The anxiolytic eect of probiotics: A
systematic review and meta-analysis of the clinical and preclinical
literature. PLoS One 2018;13(6):e0199041.
46. Ponziani FR, Scaldaferri F, Petito V, et al. The role of antibiotics in gut
microbiota modulation: The eubiotic eects of Rifaximin. Dig Dis 2016;
34(3):26978.
47. Xu D, Gao J, Gillilland M III, et al. Rifaximin alters intestinal bacteria and
prevents stress-induced gut inammation and visceral hyperalgesia in
rats. Gastroenterology 2014;146(2):48496.e4.
48. Schulz F, Altman DG, Moher D. CONSORT 2010 Statement: Updated
guidelines for reporting parallel group randomised trials. BMJ 2010;340:
c332.
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FUNCTIONAL GI DISORDERS
Bifidobacterium longum 1714ÔStrain Modulates Brain Activity 11
... A germ-free mouse model study showed that stress activated a hyperactive HPA axis, including elevated adrenocorticotropic hormone (ACTH) and corticosterone levels, and normal nervous system function was restored after fecal microbiota transplantation from healthy mice (Cenit et al., 2017). Additionally, numerous studies on the consumption of probiotic supplements have shown improvements in stress and emotional responses through changes in the gut microbiota (Allen et al., 2016;Boehme et al., 2023;Culpepper et al., 2016;Wang et al., 2019;Zhang et al., 2020). Importantly, the addition of probiotic feed containing Bifidobacterium may counteract the adverse effects of overcrowding stress, potentially enhancing gut health and improving the quality of livestock food products. ...
... These results are consistent with prior investigations, which postulated that probiotics, such as Lactobacillus, can exert regulatory effects on the intricate composition of the gut microbiota, thereby potentially enhancing sleep quality. 50,51 In addition to differences in the relative abundance of gut microbes, alterations in microbial metabolites play a crucial role in the regulation of sleep quality by probiotics. In our study, the low-dose group exhibited greater changes in acetic acid, propionic acid, butyric acid, and valeric acid levels than the placebo group. ...
... Similarly, it has been shown that B. longum improved mental flexibility and reduced stress in the elderly, suggesting a positive impact on their mental well-being [194] . Furthermore, another study described that supplementation with B. longum significantly reduces perceived stress and improves sleep quality, highlighting the role of this probiotic bacteria in enhancing stress management and overall mental health [195] . Additional research efforts have been made to explore the physiological and behavioral effects of B. longum, revealing that this probiotic microorganism modifies neural oscillations in response to social stress, suggesting an impact on brain functions associated with stress management [196] . ...
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The prevalence of brain disorders, including stress-related neuropsychiatric disorders and conditions with cognitive dysfunction, is rising. Poor dietary habits contribute substantially to this accelerating trend. Conversely, healthy dietary intake supports mood and cognitive performance. Recently, the communication between the microorganisms within the gastrointestinal tract and the brain along the gut-brain axis has gained prominence as a potential tractable target to modulate brain health. The composition and function of the gut microbiota is robustly influenced by dietary factors to alter gut-brain signalling. To reflect this interconnection between diet, gut microbiota and brain functioning, we propose that a diet-microbiota-gut-brain axis exists that underpins health and well-being. In this Review, we provide a comprehensive overview of the interplay between diet and gut microbiota composition and function and the implications for cognition and emotional functioning. Important diet-induced effects on the gut microbiota for the development, prevention and maintenance of neuropsychiatric disorders are described. The diet-microbiota-gut-brain axis represents an uncharted frontier for brain health diagnostics and therapeutics across the lifespan.
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Background Recent advances have significantly expanded our understanding of the gut microbiome's influence on host physiology and metabolism. However, the specific role of certain microorganisms in gestational health and fetal development remains underexplored. Objective This study investigates the impact of Bifidobacterium breve UCC2003 on fetal brain metabolism when colonized in the maternal gut during pregnancy. Methods Germ-free pregnant mice were colonized with or without B. breve UCC2003 during pregnancy. The metabolic profiles of fetal brains were analyzed, focusing on the presence of key metabolites and the expression of critical metabolic and cellular pathways. Results Maternal colonization with B. breve resulted in significant metabolic changes in the fetal brain. Specifically, ten metabolites, including citrate, 3-hydroxyisobutyrate, and carnitine, were reduced in the fetal brain. These alterations were accompanied by increased abundance of transporters involved in glucose and branched-chain amino acid uptake. Furthermore, supplementation with this bacterium was associated with elevated expression of critical metabolic pathways such as PI3K-AKT, AMPK, STAT5, and Wnt-β-catenin signaling, including its receptor Frizzled-7. Additionally, there was stabilization of HIF-2 protein and modifications in genes and proteins related to cellular growth, axogenesis, and mitochondrial function. Conclusions The presence of maternal B. breve during pregnancy plays a crucial role in modulating fetal brain metabolism and growth. These findings suggest that Bifidobacterium could modify fetal brain development, potentially offering new avenues for enhancing gestational health and fetal development through microbiota-targeted interventions.
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In a previous study, we reported the in vitro potential probiotic and gamma-aminobutyric acid (GABA) production, of several strains from a collection of Lactiplantibacillus (Lpb) strains within the community of natural whey starters from the artisanal cheese industry. GABA is a non-protein amino acid widely distributed in nature and produced in animals, plants, and microorganisms. However, the best known role of GABA is its function as the major inhibitory neurotransmitter of the central nervous system. Preclinical and clinical evidence suggests that the GABAergic system has a relevant role in mental health disorders, such as anxiety and major depression. The modulation of the GABAergic system has been suggested as a potential strategy for treatment, one such mechanism of modulation is the influence of the microbiota-gut-brain axis through probiotic treatments. The present study was designed to investigate the in vivo probiotic potential of LPB145, a Lactiplantibacillus strain previously characterised as a GABA-producing potentially probiotic strain. Therefore, we evaluated the behavioural effects of chronic oral administration of LPB145 on rats’ anxiety- and depression-like behaviours, using the elevated plus maze, open field, and the forced swimming test. The impact of LPB145 strain treatment on the gut microbiota structure and diversity was assessed to discern a possible mechanism of action of the LPB145 treatment through the microbiota-gut-brain axis. Our results showed that LPB145 administration induced an antidepressive-like behaviour without changes in locomotor activity. In contrast, the treatment did not modify the experimental anxiety. The structure and diversity of the intestinal microbiota remained unaffected by the treatment when compared to the control. However, specific clades that could be implicated in the behavioural changes did show differences in their relative abundance. These findings provide evidence regarding the potential of probiotic strains isolated from alimentary sources, to modulate the microbiota-gut-brain axis and positively impact mental health.
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Background Probiotics have generated intensive research interest in recent years as a novel mode of treatment for physical and mental illness. Nevertheless, the anxiolytic potential of probiotics remains unclear. The present systematic review and meta-analysis aimed to evaluate the clinical and preclinical (animal model) evidence regarding the effect of probiotic administration on anxiety. Methods The PubMed, PsycINFO, and Web of Science databases were reviewed for preclinical and clinical studies that met the defined inclusion and exclusion criteria. The effects of probiotics on anxiety-like behavior and symptoms of anxiety were analyzed by meta-analyses. Separate subgroup analyses were conducted on diseased versus healthy animals, specific preclinical probiotic species, and clinical versus healthy human samples. Results Data were extracted from 22 preclinical studies (743 animals) and 14 clinical studies (1527 individuals). Overall, probiotics reduced anxiety-like behavior in animals (Hedges’ g = -0.47, 95% CI -0.77 –-0.16, p = 0.004). Subgroup analyses revealed a significant reduction only among diseased animals. Probiotic species-level analyses identified only Lactobacillus (L.) rhamnosus as an anxiolytic species, but these analyses were broadly under-powered. Probiotics did not significantly reduce symptoms of anxiety in humans (Hedges’ g = -0.12, 95% CI -0.29–0.05, p = 0.151), and did not differentially affect clinical and healthy human samples. Conclusions While preclinical (animal) studies suggest that probiotics may help reduce anxiety, such findings have not yet translated to clinical research in humans, perhaps due to the dearth of extant research with clinically anxious populations. Further investigation of probiotic treatment for clinically relevant anxiety is warranted, particularly with respect to the probiotic species L. rhamnosus.
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Purpose: Experimental investigations in rodents have contributed significantly to our current understanding of the potential importance of the gut microbiome and brain interactions for neurotransmitter expression, neurodevelopment, and behaviour. However, clinical evidence to support such interactions is still scarce. The present study used a double-blind, randomized, pre- and post-intervention assessment design to investigate the effects of a 4-week multi-strain probiotic administration on whole-brain functional and structural connectivity in healthy volunteers. Methods: Forty-five healthy volunteers were recruited for this study and were divided equally into three groups (PRP: probiotic, PLP: placebo, and CON: control). All the participants underwent resting-state functional MRI and diffusion MRI brain scans twice during the course of study, at the beginning (time point 1) and after 4 weeks (time point 2). MRI data were acquired using a 3T whole-body MR system (Magnetom Skyra, Siemens, Germany). Results: Functional connectivity (FC) changes were observed in the default mode network (DMN), salience network (SN), and middle and superior frontal gyrus network (MFGN) in the PRP group as compared to the PLP and CON groups. PRP group showed a significant decrease in FC in MFGN (in frontal pole and frontal medial cortex) and in DMN (in frontal lobe) as compared to CON and PLP groups, respectively. Further, significant increase in FC in SN (in cingulate gyrus and precuneus cortex) was also observed in PRP group as compared to CON group. The significance threshold was set to p < 0.05 FWE corrected. No significant structural differences were observed between the three groups. Conclusions: This work provides new insights into the role of a multi-strain probiotic administration in modulating the behaviour, which is reflected as changes in the FC in healthy volunteers. This study motivates future investigations into the role of probiotics in context of major depression and stress disorders.
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Experimental manipulation of the gut microbiome was found to modify emotional and cognitive behavior, neurotransmitter expression and brain function in rodents, but corresponding human data remain scarce. The present double-blind, placebo-controlled randomised study aimed at investigating the effects of 4 weeks’ probiotic administration on behavior, brain function and gut microbial composition in healthy volunteers. Forty-five healthy participants divided equally into three groups (probiotic, placebo and no intervention) underwent functional MRI (emotional decision-making and emotional recognition memory tasks). In addition, stool samples were collected to investigate the gut microbial composition. Probiotic administration for 4 weeks was associated with changes in brain activation patterns in response to emotional memory and emotional decision-making tasks, which were also accompanied by subtle shifts in gut microbiome profile. Microbiome composition mirrored self-reported behavioral measures and memory performance. This is the first study reporting a distinct influence of probiotic administration at behavioral, neural, and microbiome levels at the same time in healthy volunteers. The findings provide a basis for future investigations into the role of the gut microbiota and potential therapeutic application of probiotics.
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Probiotics that promote the gut microbiota have been reported to reduce stress responses, and improve memory and mood. Whether and how antibiotics that eliminate or inhibit pathogenic and commensal gut bacteria also affect central nervous system functions in humans is so far unknown. In a double-blinded randomized study, 16 healthy volunteers (27.00 ± 1.60 years; 9 males) received either rifaximin (600 mg/day) (a poorly absorbable antibiotic) or placebo for 7 days. Before and after the drug intervention, brain activities during rest and during a social stressor inducing feelings of exclusion (Cyberball game) were measured using magnetoencephalography. Social exclusion significantly affected (p < 0.001) mood and increased exclusion perception. Magnetoencephalography showed brain regions with higher activations during exclusion as compared to inclusion, in different frequency bands. Seven days of rifaximin increased prefrontal and right cingulate alpha power during resting state. Low beta power showed an interaction of intervention (rifaximin, placebo) × condition (inclusion, exclusion) during the Cyberball game in the bilateral prefrontal and left anterior cingulate cortex. Only in the rifaximin group, a decrease (p = 0.004) in power was seen comparing exclusion to inclusion; the reduced beta-1 power was negatively correlated with a change in the subjective exclusion perception score. Social stress affecting brain functioning in a specific manner is modulated by rifaximin. Contrary to our hypothesis that antibiotics have advert effects on mood, the antibiotic exhibited stress-reducing effects similar to reported effects of probiotics (supported by NeuroGUT, a EU 7th Framework Programme ITN no. 607652; ClinicalTrials.gov identifier number NCT02793193).
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Probiotics that promote the gut microbiota have been reported to reduce stress responses, and improve memory and mood. Whether and how antibiotics that eliminate or inhibit pathogenic and commensal gut bacteria also affect central nervous system functions in humans is so far unknown. In a double-blinded randomized study, 16 healthy volunteers (27.00 ± 1.60 years; 9 males) received either rifaximin (600 mg/day) (a poorly absorbable antibiotic) or placebo for 7 days. Before and after the drug intervention, brain activities during rest and during a social stressor inducing feelings of exclusion (Cyberball game) were measured using magnetoencephalography. Social exclusion significantly affected (p < 0.001) mood and increased exclusion perception. Magnetoencephalography showed brain regions with higher activations during exclusion as compared to inclusion, in different frequency bands. Seven days of rifaximin increased prefrontal and right cingulate alpha power during resting state. Low beta power showed an interaction of intervention (rifaximin, placebo) × condition (inclusion, exclusion) during the Cyberball game in the bilateral prefrontal and left anterior cingulate cortex. Only in the rifaximin group, a decrease (p = 0.004) in power was seen comparing exclusion to inclusion; the reduced beta-1 power was negatively correlated with a change in the subjective exclusion perception score. Social stress affecting brain functioning in a specific manner is modulated by rifaximin. Contrary to our hypothesis that antibiotics have advert effects on mood, the antibiotic exhibited stress-reducing effects similar to reported effects of probiotics (supported by NeuroGUT, a EU 7th Framework Programme ITN no. 607652; ClinicalTrials.gov identifier number NCT02793193).
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The emerging concept of psychobiotics - live microorganisms with a potential mental health benefit - represents a novel approach for the management of stress-related conditions. The majority of studies have focused on animal models. Recent preclinical studies have identified the B. longum 1714 strain as a putative psychobiotic with an impact on stress-related behaviors, physiology and cognitive performance. Whether such preclinical effects could be translated to healthy human volunteers remains unknown. We tested whether psychobiotic consumption could affect the stress response, cognition and brain activity patterns. In a within-participants design, healthy volunteers (N=22) completed cognitive assessments, resting electroencephalography and were exposed to a socially evaluated cold pressor test at baseline, post-placebo and post-psychobiotic. Increases in cortisol output and subjective anxiety in response to the socially evaluated cold pressor test were attenuated. Furthermore, daily reported stress was reduced by psychobiotic consumption. We also observed subtle improvements in hippocampus-dependent visuospatial memory performance, as well as enhanced frontal midline electroencephalographic mobility following psychobiotic consumption. These subtle but clear benefits are in line with the predicted impact from preclinical screening platforms. Our results indicate that consumption of B. longum 1714 is associated with reduced stress and improved memory. Further studies are warranted to evaluate the benefits of this putative psychobiotic in relevant stress-related conditions and to unravel the mechanisms underlying such effects.
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To systematically review the effects of probiotics on central nervous system function in animals and humans, to summarize effective interventions (species of probiotic, dose, duration), and to analyze the possibility of translating preclinical studies. Literature searches were conducted in Pubmed, Medline, Embase, and the Cochrane Library. Only randomized controlled trials were included. In total, 38 studies were included: 25 in animals and 15 in humans (2 study was conducted in both). Most studies used Bifidobacterium (eg, B. longum, B. breve, and B. infantis) and Lactobacillus (eg, L. helveticus, and L. rhamnosus), with doses between 10(9) and 10(10) colony-forming units for 2 weeks in animals and 4 weeks in humans. These probiotics showed efficacy in improving psychiatric disorder-related behaviors including anxiety, depression, autism spectrum disorder (ASD), obsessive-compulsive disorder, and memory abilities, including spatial and non-spatial memory. Because many of the basic science studies showed some efficacy of probiotics on central nervous system function, this background may guide and promote further preclinical and clinical studies. Translating animal studies to human studies has obvious limitations but also suggests possibilities. Here, we provide several suggestions for the translation of animal studies. More experimental designs with both behavioral and neuroimaging measures in healthy volunteers and patients are needed in the future.
Article
Objectives: The Cyberball paradigm is often used to study social stress by exclusion/rejection. We aimed to review the existing neuroimaging literatures in order to provide an overview of the neurophysiological mechanisms of social exclusion. Method: Literature search was conducted to identify neurophysiological studies that investigated effects of social exclusion on neural activity using the Cyberball game and the relevant influential factors on these effects. Results: In total, 42 studies using different neuroimaging methods were considered. Regions of the insula, anterior cingulate cortex, temporal and prefrontal cortex were activated to social exclusion. These neural activities were pronounced at latencies ranging from 200 to 400ms, and between 400 and 900ms. Influential factors were identified and categorized as intrinsic and extrinsic factors. Conclusion: An integrated framework describing neural activities under social exclusion in terms of both, temporal and spatial processes is provided. Furthermore, the summary of influential intrinsic and extrinsic factors may help us to understand the diversity of the processes and may guide clinical therapy of stress related disorders.
Article
Background & aims: Probiotics can reduce symptoms of irritable bowel syndrome (IBS), but little is known about their effects on psychiatric comorbidities. We performed a prospective study to evaluate the effects of Bifidobacterium longum NCC3001 (BL) on anxiety and depression in patients with IBS. Methods: We performed a randomized, double-blind, placebo-controlled study of 44 adults with IBS and diarrhea or a mixed-stool pattern (based on Rome III criteria) and mild to moderate anxiety and/or depression (based on the Hospital Anxiety and Depression scale) at McMaster University in Canada, from March 2011 to May 2014. At the screening visit, clinical history and symptoms were assessed and blood samples were collected. Patients were then randomly assigned to groups and given daily BL (n=22) or placebo (n=22) for 6 weeks. At week 0, 6 and 10, we determined patients' levels of anxiety and depression, IBS symptoms, quality of life, and somatization using validated questionnaires. At week 0 and 6, stool, urine and blood samples were collected, and functional magnetic resonance imaging (fMRI) test was performed. We assessed brain activation patterns, fecal microbiota, urine metabolome profiles, serum markers of inflammation, neurotransmitters and neurotrophin levels. Results: At week 6, 14/22 patients in the BL group had reduction in depression scores of 2 points or more on the Hospital Anxiety and Depression scale, vs 7/22 patients in the placebo group (P=.04). BL had no significant effect on anxiety or IBS symptoms. Patients in the BL group had a mean increase in quality of life score compared with the placebo group. The fMRI analysis showed that BL reduced responses to negative emotional stimuli in multiple brain areas, including amygdala and fronto-limbic regions, compared with placebo. The groups had similar fecal microbiota profiles, serum markers of inflammation, and levels of neurotrophins and neurotransmitters, but the BL group had reduced urine levels of methylamines and aromatic amino acids metabolites. At week 10, depression scores were reduced in patients given BL vs placebo. Conclusion: In a placebo-controlled trial, we found that the probiotic BL reduces depression but not anxiety scores and increases quality of life in patients with IBS. These improvements were associated with changes in brain activation patterns that indicate that this probiotic reduces limbic reactivity. ClinicalTrials.gov no. NCT01276626.
Article
Background: Preclinical studies have identified certain probiotics as psychobiotics - live microorganisms with a potential mental health benefit. Lactobacillus rhamnosus (JB-1) has been shown to reduce stress-related behaviour, corticosterone release and alter central expression of GABA receptors in an anxious mouse strain. However, it is unclear if this single putative psychobiotic strain has psychotropic activity in humans. Consequently, we aimed to examine if these promising preclinical findings could be translated to healthy human volunteers. Objectives: To determine the impact of L. rhamnosus on stress-related behaviours, physiology, inflammatory response, cognitive performance and brain activity patterns in healthy male participants. Methods: An 8week, randomized, placebo-controlled, cross-over design was employed. Twenty-nine healthy male volunteers participated. Participants completed self-report stress measures, cognitive assessments and resting electroencephalography (EEG). Plasma IL10, IL1β, IL6, IL8 and TNFα levels and whole blood Toll-like 4 (TLR-4) agonist-induced cytokine release were determined by multiplex ELISA. Salivary cortisol was determined by ELISA and subjective stress measures were assessed before, during and after a socially evaluated cold pressor test (SECPT). Results: There was no overall effect of probiotic treatment on measures of mood, anxiety, stress or sleep quality and no significant effect of probiotic over placebo on subjective stress measures, or the HPA response to the SECPT. Visuospatial memory performance, attention switching, rapid visual information processing, emotion recognition and associated EEG measures did not show improvement over placebo. No significant anti-inflammatory effects were seen as assessed by basal and stimulated cytokine levels. Conclusions: L. rhamnosus was not superior to placebo in modifying stress-related measures, HPA response, inflammation or cognitive performance in healthy male participants. These findings highlight the challenges associated with moving promising preclinical studies, conducted in an anxious mouse strain, to healthy human participants. Future interventional studies investigating the effect of this psychobiotic in populations with stress-related disorders are required.