By December
2020 7.3% of the Swedish cohort born in 1997-9 had been diagnosed with a
Neurodevelopmental Disorder (ND). This can be predicted by samples previously collected.
Today’s post
is all about the microbiome and covers three different areas covered recently
in the research. Eight years after I wrote a post about our informal trial of Biogaia
probiotics for autism, we now have a published paper.
Aggression
and self injurious behavior (SIB) affects at least half of those diagnosed with
level 3 autism at some point in their lives. SIB can become the overriding concern
for care givers.
Our first paper
looks at the role of the microbiome in aggression.
Gut-brain axis appears to play
a critical role in aggression
A series of experiments on mice has found that they become
more aggressive when their gut microbiome is depleted. Additionally,
transplanting gut microbiota from human infants exposed to antibiotics led to
heightened aggression in mice compared to those receiving microbiome
transplants from non-exposed infants. The research was published in Brain,
Behavior, and Immunity.
In the past decade, scientists have discovered a complex
communication pathway linking gut microbiota—the trillions of microorganisms
living in the human gut—with the brain. This pathway is called the
microbiota-gut-brain axis. It regulates various physiological functions,
including digestion and immunity, but also affects mood and behavior. The gut
microbiota produces neurotransmitters and other metabolites that can influence
brain function through neural, immune, and endocrine pathways.
Recent studies have demonstrated that symptoms of various
disorders, once considered primarily psychological or neurological, can be
transferred to rodents by transplanting gut microbiota from humans with these
disorders. For example, researchers have shown that transplanting gut
microorganisms from people with Alzheimer’s disease into mice (whose gut
microbiota had been depleted to enhance transplant effectiveness) resulted in
cognitive impairments in the mice. Similarly, symptoms of anxiety have been induced
in mice by transplanting gut microbiota from humans with social anxiety.
For the humanized mice, the researchers obtained fecal
samples from infants who had been exposed to antibiotics shortly after birth,
as well as from unexposed infants. These samples were transplanted into
five-week-old germ-free mice. The researchers then waited for four weeks before
testing the mice for aggression.
To measure aggression, the researchers employed the
resident-intruder test, a well-established behavioral assay in which a male
mouse (the “resident”) is introduced to another unfamiliar male mouse (the
“intruder”) in its home cage. Aggression was quantified based on the latency to
the first attack (how quickly the resident mouse attacked the intruder) and the
total number of attacks during a 10-minute period.
The results showed
that mice raised without gut bacteria (germ-free) and those treated with
antibiotics exhibited higher levels of aggression compared to the control
group. These mice
attacked more frequently and were quicker to initiate aggressive behavior in
the resident-intruder test.
The researchers found that humanized mice receiving fecal microbiota from
antibiotic-exposed infants were significantly more aggressive than those
receiving transplants from non-exposed infants. Even though the infants’
microbiomes had a month to recover after antibiotic exposure, the aggressive
behavior was still evident in the recipient mice.
Biochemical analyses revealed that aggressive mice (both
germ-free and antibiotic-treated) had distinct metabolite profiles compared to
control mice. Specifically, levels of tryptophan—a precursor to serotonin, a
neurotransmitter associated with mood and behavior—were elevated in these mice.
Additionally, the levels of certain metabolites associated with microbial
activity, such as indole-3-lactic acid, were reduced in the aggressive mice,
suggesting that the absence of a healthy microbiome might alter key biochemical
pathways involved in aggression.
Here is the
link to the original paper:
A gut reaction? The role of
the microbiome in aggression
Recent research has unveiled conflicting evidence regarding
the link between aggression and the gut microbiome. Here, we compared behavior
profiles of control, germ-free (GF), and antibiotic-treated mice, as well as
re-colonized GF mice to understand the impact of the gut microbiome on
aggression using the resident-intruder paradigm. Our findings revealed a link
between gut microbiome depletion and higher aggression, accompanied by notable
changes in urine metabolite profiles and brain gene expression. This study
extends beyond classical murine models to humanized mice to reveal the clinical
relevance of early-life antibiotic use on aggression. Fecal microbiome
transplant from infants exposed to antibiotics in early life (and sampled one
month later) into mice led to increased aggression compared to mice receiving
transplants from unexposed infants. This study sheds light on the role of the
gut microbiome in modulating aggression and highlights its potential avenues of
action, offering insights for development of therapeutic strategies for
aggression-related disorders
Note the ABX means antibiotics
We include a study of humanized mice using unique fecal
samples of 1-month-old infants, collected nearly a month after
early-life ABX administration. In previous work (Uzan-Yulzari et al. 2021,
Nat Comm), we have demonstrated that ABX in this critical period of life can
have lasting effects of childhood growth. Here, we extend these findings
using samples from the same cohort. Using fecal samples collected weeks after
ABX administration also reduces the direct chemical effects of ABX on the host,
highlighting the causative role of the dysbiotic host microbiome and associated
metabolome in driving aggressive behavior. We demonstrate that infant microbiota, perturbed
within the first 48 h of life, has a lasting signature through
1 month of age that, when transplanted into GF mice, results in increased
aggression (3–5 weeks after transplant) when compared to effects of stools
of infants not exposed to any early-life antibiotics. The findings are
revolutionary as they show how ABX-altered microbiota during a
critical development window can lead to persisting behavioral deficits.
Gut
microbe imbalances could predict a child’s risk for autism, ADHD and speech
disorders years before symptoms appear.
Study Identifies Gut Microbe
Imbalances That Predict Autism And ADHD
We are researchers
who study the role
the microbiome plays in a variety of conditions, such as mental illness,
autoimmunity, obesity, preterm birth and others. In our recently published
research on Swedish children, we found that microbes and the metabolites they
produce in the guts of infants – both found in poop and cord blood – could help
screen for a child’s risk of neurodevelopmental
conditions such as autism. And these differences can be detected as early as
birth or within the first year of life. These markers were evident, on average,
over a decade before the children were diagnosed.
The imbalance in microbial composition – what microbiologists
call dysbiosis –
we observed suggests that incomplete recovery from repeated antibiotic use may
greatly affect children during this vulnerable period. Similarly, we saw that
repeated ear infections were linked to a twofold increased likelihood of developing autism.
Children who both repeatedly used antibiotics and had
microbial imbalances were significantly more likely to develop autism. More
specifically, children with an absence of Coprococcus comes, a bacterium linked to mental health
and quality of life, and increased prevalence of Citrobacter, a bacterium known for antimicrobial
resistance, along with repeated antibiotic use were two to four times more
likely to develop a neurodevelopmental disorder.
Antibiotics are necessary for treating certain bacterial infections in children,
and we emphasize that our findings do not suggest avoiding their use altogether.
Parents should use antibiotics if they are prescribed and deemed necessary by
their pediatrician. Rather, our study suggests that repeated antibiotic use
during early childhood may signal underlying immune dysfunction or disrupted
brain development, which can be influenced by the gut microbiome. In any case,
it is important to consider whether children could benefit from treatments to
restore their gut microbes after taking antibiotics, an area we are actively
studying.
Another microbial imbalance in children who later were
diagnosed with neurodevelopmental disorders was a decrease in Akkermansia
muciniphila, a bacterium that reinforces the lining of
the gut and is linked to neurotransmitters important to neurological health.
Even after we accounted for factors that could influence gut
microbe composition, such as how the baby was delivered and breastfeeding, the
relationship between imbalanced bacteria and future diagnosis persisted. And these imbalances preceded
diagnosis of autism, ADHD or intellectual disability by 13 to 14 years on
average, refuting the assumption that gut microbe imbalances arise from diet.
We found that lipids and bile acids were depleted in the cord
blood of newborns with future autism. These compounds provide nutrients for
beneficial bacteria, help maintain immune balance and influence neurotransmitter
systems and signaling pathways in the brain.
The full
paper is here:
Infant microbes and
metabolites point to childhood neurodevelopmental disorders
Highlights
• Infant
microbes and metabolites differentiate controls and future NDs
• Early-life
otitis lowers Coprococcus and increases Citrobacter in
future NDs
• Preterm
birth, infection, stress, parental smoking, and HLA DR4-DQ8 increase ND risk
• Linolenic
acid is lower and PFDA toxins higher in the cord serum of future ASD
Summary
This study has followed a birth cohort for over 20 years to
find factors associated with neurodevelopmental disorder (ND) diagnosis.
Detailed, early-life longitudinal questionnaires captured infection and
antibiotic events, stress, prenatal factors, family history, and more.
Biomarkers including cord serum metabolome and lipidome, human leukocyte
antigen (HLA) genotype, infant microbiota, and stool metabolome were assessed.
Among the 16,440 Swedish children followed across time, 1,197 developed an ND.
Significant associations emerged for future ND diagnosis in general and for
specific ND subtypes, spanning intellectual disability, speech disorder,
attention-deficit/hyperactivity disorder, and autism. This investigation
revealed microbiome connections to future diagnosis as well as early emerging
mood and gastrointestinal problems. The findings suggest links to immune-dysregulation
and metabolism, compounded by stress, early-life infection, and antibiotics.
The convergence of infant biomarkers and risk factors in this prospective,
longitudinal study on a large-scale population establishes a foundation for
early-life prediction and intervention in neurodevelopment.
ABIS = All Babies in Southeast Sweden cohort
NDs = Neurodevelopmental disorders
Young children later diagnosed with ASD or exhibiting
significant autistic traits tend to experience more ear and upper respiratory
symptoms. In ABIS, infants who had otitis in their first year were found
to be more prone to acquiring NDs if they lacked detectable levels of Coprococcus or
harbored Citrobacter. The absence of Coprococcus,
despite comparable levels in controls irrespective of otitis, raises
questions about microbial community recovery. This potential failure of the
microbiome to recover following such events may serve as a mechanism connecting
otitis media to ND risk. Moreover, antibiotic-resistant Citrobacter was
more prevalent in these infants. The presence of strains related to Salmonella and Citrobacter,
labeled in this investigation as SREB, was significantly higher in infants who
later developed comorbid ASD/ADHD (21%), compared to controls (3%). This
disruption may have consequences on neurodevelopment during a critical
period. Salmonella and Citrobacter have shown
the ability to upregulate the Wingless (Wnt) signaling. The Wnt pathway is vital for immune dysregulation
and brain development, and its disruption has been implicated in ASD
pathogenesis.
Two fatty acid differences were notable in the stool of
future ASD versus controls: omega-7 monounsaturated palmitoleic acid,
(9Z)-hexadec-9-enoic acid (below the level of detection in 87.0% of future ASD
but present in 43.5% of controls), and palmitic acid (elevated in future ASD).
Palmitoleic acid has been associated with a decreased risk of islet and primary
insulin autoimmunity. Conversely, palmitic acid, a saturated fatty acid,
has been linked to neuronal homeostasis interference. Its effects are
partially protected by oleic acid, which although approaching
significance, was lower in the cord serum of future ASD.
Few metabolites were higher in stool of infants with future
ASD, but there are a few notable examples: α-d-glucose, pyruvate, and
3-isopropylmalate. Coprococcus inversely correlated with
3-isopropylmalate, suggesting gut-brain connections and a possible
imbalance in branched-chain amino acid (BCAA) pathways given the role of
3-isopropylmalate dehydrogenase in leucine and isoleucine biosynthesis. An
increase in dehydroascorbate suggests potential disruptions in vitamin C
metabolism, crucial for neurotransmitter synthesis and antioxidant defense,
while elevated pyruvate suggests disturbance of neurotransmitter synthesis or
energy production early in life. Pimelic acid elevation, found in disorders of fatty acid oxidation, suggests
disruption of mitochondrial pathways for fatty acid oxidation.
Akkermansia and Coprococcus,
absent or reduced in infants with future NDs, positively correlated with
signals in stool representing neurotransmitter precursors and essential
vitamins in stool.
Specifically, Akkermansia correlated with tyrosine and
tryptophan (i.e., catecholamine and serotonin precursors, respectively)
and Coprococcus with riboflavin. Disruption of BCAA metabolism
in ASD has been documented, involving coding variants in large amino acid
transporters (LATs) and reduced utilization of trypotphan and large aromatic
amino acids along with increased glutamate and decreases in tyrosine,
isoleucine, phenylalanine, and tryptophan in children with ASD. Oxidative
stress, a diminished capacity for efficient energy transport, and
deficiencies in vitamins (like vitamin B2) essential for neurotransmitter
synthesis and nerve cell maintenance have been implicated. Riboflavin
as an antioxidant reduces oxidative stress and inflammation, demonstrating
neuroprotective benefits in neurological disorders, possibly through
maintenance of vitamin B6, which is necessary for glutamate conversion to
glutamine and 5-hydroxytryptophan to serotonin.
Together, these
findings support a hypothesis of early-life origins of NDs, mediated by gut
microbiota. This provides a foundation for research and for developing early
interventions for NDs.
Today’s final
paper was highlighted recently in a comment on a post I wrote eight years ago,
when we were trialing Biogaia probiotics. This original interest was prompted
by a reader sharing her successful experiences of treating her son with severe
autism. Perhaps she left the recent comment?
The two
bacteria involved are both types of L. reuteri.
L. reuteri 6475
is sold as Biogaia Osfortis
L. reuteri
17938 is sold Biogaia Protectis
The
combination of L. reuteri 17938 and L. reuteri 6475 is sold as
Biogaia Gastrus.
My old post
from 2016:-
Epiphany:
Biogaia Trial for Inflammatory Autism Subtypes
The recently
published trial:
Precision microbial
intervention improves social behavior but not autism severity: A pilot
double-blind randomized placebo-controlled trial -
Highlights
• L. reuteri (6475 + 17938) improves
social functioning in children with autism
• L. reuteri does not improve overall autism
severity or repetitive behaviors
• L. reuteri does not significantly
alter microbiome composition or immune profile
• Only the 6475 strain
reverses the social deficits in a mouse model for autism
we performed a double-blind, randomized,
placebo-controlled, parallel-design pilot trial in children with ASD.
Importantly, we found that L. reuteri, compared with placebo,
significantly improved social functioning, both in terms of reducing social
deficits, as measured by the social responsiveness scale (SRS31,32),
and increasing adaptive social functioning, as measured by the social adaptive
composite score of the Adaptive Behavior Assessment System, Second Edition
(ABAS-233). L. reuteri did not improve overall
autism severity, restricted and repetitive behaviors, and co-occurring
psychiatric and behavioral problems, nor did it significantly modulate the
microbiome or immune response. Thus, this safe microbial manipulation has the potential
for improving social deficits associated with ASD in children.
I had to
amend my old post with a warning long ago.
UPDATE: A
significant minority of parents report negative reaction to Bio Gaia, this
seems to relate to histamine; but more than 50% report very positive effects
without any side effects; so best to try a very small dose initially to see if
it is not well tolerated.
Histamine
Reaction to BioGaia gastrus
Conclusion
The gut
microbiota does indeed play a key role in how your brain functions, but the
gut-brain axis works in both directions. What goes on in your brain can affect
your gut and not just the other way around. It is called bidirectional
signaling.
Antibiotics taken
during pregnancy, or during early childhood, will have unintended consequences.
Often there is no choice, like for those readers whose baby experienced sepsis
at birth (bacterial blood stream infection); you have to give antibiotics to
avoid death.
In today’s
second paper we see that the researchers are thinking about therapeutical implications.
Perhaps the newborn’s gut flora should be repopulated during the weeks after
the antibiotic treatment?
I receive
many questions about how to treat self injurious behavior that does not respond
to anything the doctor has prescribed. Rifaximin, an antibiotic used to treat
irritable bowel syndrome with diarrhea, is one therapy that does help some
types of SIB (and SIBO, small intestinal bacterial overgrowth, of course). This
probably would not surprise the authors of today’s first paper.
Biogaia
Gastrus (L. reuteri 6475 + 17938) from today’s third paper worked
wonders for the SIB of one reader’s child.
Not
surprisingly fecal microbiota transplantation (FMT) can improve SIB in some people.
The Swedish
data shows interesting insights such as that lipids and bile acids were
depleted in the cord blood of newborns with future autism. The researchers
think they can predict the diagnosis of autism or ADHD. The question is and
then what? Even when there is a diagnosis of autism, not much changes for most children.
