Among
the many reasons that some parents refuse to vaccinate their children, the most
prevalent is the mistaken connection with autism.
The
subject of Autism Spectrum Disorder (ASD) is a complex one. Many questions have
arisen in recent years:
- is
autism truly on the rise, or is there simply a growing awareness of the
condition?
- if
it is actually on the rise, is that due to the definition of autism being
expanded?
and
obviously, what is causing it?
An
Overview
WebMD
recently published a comprehensive report written by KathleenDoheny and reviewed by Louise Chang,MD, which attempted to answer these questions.
“The number of children diagnosed with autism or related
disorders has grown at what many call an alarming rate. In the 1970s and 1980s,
about one out of every 2,000 children had autism. Today, the CDC estimates
that one in 150 8-year-olds in the U.S. has an autism spectrum disorder, or
ASD. This expanded definition refers not only to autism but also to a
collection of brain development disorders such as Asperger's syndrome and a
condition known as pervasive developmental disorder -- not otherwise specified
(PDD-NOS). Though all the disorders share some symptoms, they are different in
other ways, including the timeline of symptoms and the severity, according to
the CDC.
“‘The debate about whether the reported increase in autism is
affected by factors such as more awareness misses the point’, says Isaac
Pessah, PhD, a professor of toxicology, director of the Center for Children's
Environmental Health Sciences, and a member of the MIND Institute at the
University of California Davis. Rather than argue about whether the increase is
because of some children being reclassified or other factors, he says, ‘We need
to understand why it's one in 150.’”
“'There won't be one single explanation,’' says Marvin Natowicz,
MD, PhD, a medical geneticist and vice chairman of the Genomic Medicine Institute
at the Cleveland Clinic. ‘There's been a lot of progress in the last few
years in terms of understanding the causes of autism, We know a lot more than
we did.’ Still, he says, research has a long way to go. ‘One number you see
often is that about 10% of those with autism have a definitive diagnosis, a
causative condition.’ The other 90% of cases are still a puzzle to the experts.
“Often, a child with autism will have a co-existing problem,
such as a seizure disorder, depression, anxiety, or gastrointestinal or other
health problems. At least 60 different disorders -- genetic, metabolic, and
neurologic -- have been associated with autism, according to a report published
in The New England Journal of Medicine. On one point most
agree: A combination of genetics and environmental factors may play a role.
Scientists are looking at both areas.
“A variety of environmental triggers is under investigation as a
cause or contributing factor to the development of ASD, especially in a
genetically vulnerable child. Exposure to pesticides during pregnancy may
boost risk. In a study published in Environmental Health Perspectives,researchers
compared 465 children diagnosed with ASD with nearly 7,000 children without the
diagnosis, noting whether the mothers lived near agricultural areas using
pesticides. The risk of having ASD increased with the poundage of pesticides
applied and with the proximity of the women's homes to the fields.
“Another
toxin to the brain is mercury in its organic form. But according to a report
published in Pediatrics, there is no evidence that children
with autism in the U.S. have increased mercury concentrations or environmental
exposures. Though many parents of children with ASD believe their child's
condition was caused by vaccines that used to contain thimerosal (a
mercury-containing preservative), the Institute of Medicine concludes there is
no causal association.
“Pessah
and other researchers are focusing on how the interaction of genes and the
environment play a role in autism. Among the findings so far, he says, is that
the immune system functioning of the mother may play a role in the child's
later development of autism.
“In
another study, the UC Davis team found that levels of leptin, a hormone that
plays a role in metabolism and weight, was much higher in children with autism
than in normally developing children, especially if their autism was early in
onset.
“Even if some environmental exposures or other findings do stand
out, he says, we are going to have to resist the temptation to say, 'This is
it’, Newschaffer says. Natowitz of Cleveland Clinic agrees. ‘There won't be one
single explanation.’"
The Importance of “Good” Gut Bacteria
The gastrointestinal connection to autism appears over and over
in the literature. The importance of a proper balance and quantity of “good”
gut bacteria in the intestines of children is thought to be an important
factor.
In
an article in Autism Speaks in July of 2013, an important study was discussed:
“The
study appears today in the journal PLOS ONE. Rosa Krajmalnik-Brown and Jin
Gyoon Park, of Arizona State University’s Biodesign Institute, led the
investigation.
Researchers
using high-tech DNA analysis found that children with autism have fewer kinds
of intestinal bacteria than do children without autism. However, this reduced
“biodiversity” did not relate to the severity of gastrointestinal problems.
“Among children with autism, GI problems such as constipation
and gut pain are common. Some have suspected that imbalances in intestinal
bacterial are to blame. Other research has suggested that problematic gut
bacteria might contribute to autism symptoms by triggering inflammation that
reaches the brain. Considerable research has shown that intestinal bacteria
play important roles in both digestion and regulation of the immune system in
all persons.
“The researchers found significantly decreased microbial
diversity (fewer types of bacteria) in the children with autism. However, they
were surprised to find no link between this lowered diversity and the
severity of GI symptoms. Nor did they find links to differences in the
children’s diets. Among the types of bacteria reduced in those with
autism, Prevotella was the most conspicuous. It occurred only in very
low levels in the children with autism. By contrast, it was common in those not
affected by autism – who altogether had more diverse and robust communities of
intestinal bacteria.”
Then, on Oct 22, 2014, Autism Speaks announced that they had
“selected two major research projects – one focused on intestinal bacteria, the
other on chronic constipation – to advance understanding of autism’s gut-brain
connection. Funding for the studies, each spanning three years, will total more
than $2.3 million.
“‘Listening to our parents, we hear how often autism and GI
problems can go hand in hand,’ says Autism Speaks Chief Science Officer
Rob Ring. ‘While we now know that autism and gastrointestinal problems
frequently co-occur, improving our understanding of the underlying biology
becomes essential for developing needed treatments.’”
Are Antibiotics Altering Gut Bacteria?
Might the indiscriminate use of antibiotics be a reason for the
lack of quantity and diversity of the gut bacteria? James B. Adams of Arizona
State University was part of a team of researchers that addressed this and
other issues. The study was published in BioMed Central in March of 2011.
Excerpts from the report:
“… a study by our group of 51 children with ASD compared to 40
typical controls ages 3-15 found that 63% of children with autism were reported
to have moderate or severe chronic diarrhea and/or constipation, vs. 2% of the
control children. In summary, these studies demonstrate that GI symptoms are
common in autism.
“The
cause of these GI problems is unclear, but it appears to partly relate to
abnormal gut flora and possibly to the excessive use of oral antibiotics which
can alter gut flora. Several studies by our group and others have reported
significantly higher oral antibiotic use in children with autism vs. typical
children.
“Oral
antibiotics were primarily used for treating otitis media (ear infections),
which may suggest an impaired immune system. Commonly used oral antibiotics
eliminate almost all of the normal gut microbiota, which play an important role
in the breakdown of plant polysaccharides, promoting gastrointestinal motility,
maintaining water balance, producing some vitamins, and competing against
pathogenic bacteria. Loss of normal gut flora can result in the overgrowth of
pathogenic flora, which can in turn cause constipation and other
problems.”
The Role of Glyphosate (Roundup) in Altering Gut Bacteria
If the gut bacteria/autism link can be accepted as at least
likely, then any agent, including antibiotics, that alters gut bacteria should
be examined more closely.
The subject of genetically modified organisms (GMO) warrants an
extensive commentary of its own. But due to their potential for adversely
affecting the balance of gut bacteria, I believe that an overview is in
order.
The active ingredient in Roundup, a Monsanto herbicide, is
glyphosate. In brief, glyphosate kills plants by interfering with the shikimate
pathway in plants, by inhibiting the enzyme EPSP. Genetically
modified crops are designed to overcome that inhibition.
The
shikimate pathway is a seven step metabolic route used by
bacteria, fungi, algae, parasites, and plants for the
biosynthesis of aromatic amino acids (phenylalanine,
tyrosine, and tryptophan). This pathway is not found in animals;
therefore, phenylalanine and tryptophan represent essential
amino acids that must be obtained from the animal's diet.
Monsanto’s basis for its safety claims for Roundup is that the
shikimate pathway does not exist in animals and humans. But since it does exist
in bacteria, it matters if their various forms are affected differently.
Unfortunately the beneficial ones such as the forms of enterococcus,
bifidobacterium and lactobacillus are susceptible to glyphosate. Pathogenic
bacteria such as the various forms of salmonella and clostridium are highly
resistant. This leads to an inevitable imbalance of gut bacteria, thereby
contributing to the GI problems suspected of being a cause of autism.
Experts in the field of ASD research are clear that there are
many possible causes for autism, but one of them is not
vaccinations. Vaccines have not contained mercury since 1999, and many
such as MMR, Polio, and HPV (Gardasil) never contained it. They also
realize that there is probably not one clear answer, and much more research
needs to be done.
Concerned parents, whether or not they have children with
autism, need to beware of the effects of antibiotics. They would do well to
research the subject of gut bacteria. Probiotics show promise, and may
eventually prove to be a viable option for treatment.
D.
Norman