Thursday, April 11, 2024

What Causes Autism Exploring The Environmental Contribution

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Are There Important Vaccine Safety Issues

The opportunity to prevent serious childhood illnesses through the use of effective vaccination regimes is a critical public health measure. In general, vaccine safety is quite exceptional when compared with overall safety of pharmaceutical agents and medical procedures as recently reviewed by House . However, the lack of association with MMR vaccination and risk of autism does not mean that improved vaccine safety testing is not important in future strategies to reduce environmental health risks. There are some issues particularly in the timing of vaccinations for the developing immune system ) where some protocols may be more beneficial than others for certain health risks . Additionally, immune dysfunction is a prominent feature in autistic children and has led to discussion of possible immunological links with autism .

What Challenges Do Students With Asd Experience In School

While teachers often ask if autism is a learning disability, the answer isnt as straightforward as youd think. Autism itself isnt a learning disability, but there are some learning difficulties associated with autism. For example, students diagnosed with autism are more likely to develop attention-deficit hyperactivity disorder and . When teaching students with ASD, its helpful to watch for symptoms of learning disorders and refer them to a specialist if needed.

Children with autism are also more likely to develop emotional disorders due to the unique challenges they face. Without support in the classroom, these students are more likely to feel isolated or misunderstood. At least one in three people with autism with develop mental health issues like depression or anxiety in their lives. And since the risk of self-harm behaviors is 28 times more likely for children with autism, making sure your students receive the emotional support they need is essential.

Another issue many students with autism face is bullying. Around 34% of children with autism report being picked on at school to the point that it distresses them. Because these kids may think or act differently from others, other students may tease them or leave them out of their friend circles. Thats why its important to educate all children in your school about autism, not just the student with ASD.

Do Vaccines Cause Autism

We want to be clear here: there is no scientific evidence that vaccines cause autism. Both the American Academy of Pediatrics and the CDC have compiled dozens of studies that show no connection between vaccines and autism. Heres the short storyfor many families, autism diagnosis corresponds with the timing of their childs vaccinations, hence the theory that vaccinations were at fault. Scientists have conducted extensive research over the last 20 years and the research is clear: vaccines do not cause autism.

Children With Autism Will Never Achieve As Much As Their Peers

Students with autism have so much potential, and some of the brightest minds in the world have been people with autism spectrum disorder, including:

  • Charles Darwin
  • Temple Grandin
  • Wolfgang Amadeus Mozart

Beloved poets, talented musicians and artists, and scientists who shaped how we see the world today have been included on lists of famous people with autism. Our communities would not be the same without people on the autism spectrum. While students with autism may have different weaknesses than their classmates, they often have plenty of strengths, too.

Limitations Of Current Research

What Causes Autism

Compared to genetic studies of ASD, studies of environmental risk factors are in their infancy. Many previous studies of environmental risk factors have been limited by small sample size, retrospective or cross-sectional design, indirect measurement of exposure, and inability to ascertain exact timing of exposure with relation to a critical neurodevelopmental period. Moreover, for various reasons, most previous studies have not investigated important factors that might explain the heterogeneity of ASD such as differences in risk between males and females, differences between subtypes, and relation of symptom severity to risk factors. Importantly, the definition of ASD is very broad and encompasses multiple subtypes of the disorder, mirroring the etiological heterogeneity of the condition.

Current Research On Genes

Other avenues of research on autism include investigations into gene variants that could play a role in the development of ASD.

A recent study analyzed the DNA of more than 35,584 people worldwide, including 11,986 autistic individuals. The scientists identified variants in 102 genes linked with an increased probability of developing ASD.

The researchers also discovered that 53 of the genes identified were mostly associated with autism and not other developmental conditions.

Expanding the research further, the team found that autistic people who carried the ASD-specific gene variants showed increased intellectual function compared with autistic individuals who did not have the variants.

The gene variants the scientists identified mainly reside in the cerebral cortex, which is responsible for complex behaviors.

These variants may play a role in how the brain neurons connect and also help turn other genes on or off a possible factor that may contribute to autism.

Fun Classroom Activities For Teaching Students With Autism

Sometimes, educational strategies for autism may differ from the lesson plans you make for the rest of your class. But thankfully, autism activities can be as simple as stocking sensory toys in your classroom or reading picture books about social skills. Use these four activities for students with autism to help these students learn academic concepts.

What Is Niehs Doing

2018 Spirit Lecture

Watch Temple Grandin, Colorado State University, deliver a lecture at NIEHS, “Developing Individuals Who Have Different Kinds of Minds, 3rd Edition.” Also read about the lecture in this newsletter article.

NIEHS-funded researchers are primarily interested in risk factors related to gene and environment interaction. Key findings are grouped by topic below.

Air pollution Researchers found early-life exposure to air pollution may be a risk factor for autism.

  • Children of mothers living near a freeway, and traffic-related pollution, during the third trimester of pregnancy were twice as likely to develop ASD. A distance of 1,014 feet, or a little less than 3.5 football fields, was considered near a freeway.
  • Children with a mutation in a gene called MET, combined with high levels of exposure to air pollution, may have increased risk.

Prenatal conditions and maternal factors Problems with a mothers immune system, certain metabolic conditions, or inflammation during pregnancy may be linked with higher autism risk for her children.

  • Some mothers of autistic children have antibodies, or proteins in the body that fight infection, that may interfere with their childrens brain development, possibly leading to autism.
  • Maternal diabetes or obesity are linked to increased likelihood of having a child with autism or other developmental disability.
  • Fever during pregnancy was associated with increased risk of autism for children.

Federal Collaboration

Progress Toward The Aspirational Goal

Investments in the past 5 years have led to identification of new genetic and environmental factors contributing to ASD risk and identified the importance of the conception and gestational periods for the development of ASD. The new gene findings hold promise for a better understanding of the neurobiology of ASD and the development of novel pharmacotherapies. Rare genetic variants, as they are discovered, create both clinical and research opportunities. Genetic tests are now being routinely carried out in individuals who experience unexplained developmental delays. Chromosome microarray is already recommended by the American Academy of Pediatrics   and the American College of Medical Genetics , and can inform some families about some ASD causes, rare but potentially serious comorbid medical conditions, and, in certain cases, the risk of ASD recurrence in future offspring.

Finally, additional efforts are needed to address barriers to enrollment and retention of racially and ethnically diverse populations in order to ensure their representation in both epidemiologic and clinical studies. This information is critical for identifying vulnerable subgroups and informing public health prevention efforts.  Enhancing the overall diversity of study populations should also prove helpful in detecting environment-ASD associations, as groups underrepresented in clinical studies are often those with disproportionate exposures.

Offspring Of Mothers With The Ptenwt/m3m4 Genotype Show Increased Asd

To interrogate the impact of maternal genetics on the incidence and severity of an ASD-like phenotype in the offspring, PtenWT/m3m4 females were bred to PtenWT/WT males or PtenWT/WT females were bred to PtenWT/m3m4 males to compare pups of a heterozygous mutant mother vs. pups of a homozygous wildtype mother . Average litter sizes from PtenWT/WT females X PtenWT/m3m4 males and PtenWT/m3m4 females X PtenWT/WT males were similar. In contrast, a significant decrease in litter size was observed when PtenWT/m3m4 females X PtenWT/m3m4 males, most likely due to 100% loss of Ptenm3m4/m3m4 homozygous mutant fetuses in-utero around E15.5. For this reason, PtenWT/m3m4 female X PtenWT/m3m4 male crosses were not compared further in the study for the maternal inflammatory state, due to additional inflammatory insults from resorption of homozygous mutant fetuses in-utero. The number of PtenWT/WT and PtenWT/m3m4 pups born were as expected per Mendelian ratios indicating no genotype preference or in-utero mortality differences between the two maternal or offspring genotypes . However, postnatally, PtenWT/m3m4 mothers lost more pups between P0 and P8. Litters of Momsm3m4 had postnatal mortality of 2024% of their pups in 5667% of all litters compared to only 4% pup death in 29% of litters from MomWT .

Fig. 1: Pups of PtenWT/m3m4 mothers have higher postnatal mortality, macrocephaly, and ASD-like behavior compared to PtenWT/WT mothers.

Viruses & Bacteria In Autism

Caruso JM et al. Persistent preceding focal neurologic deficits in children with chronic Epstein-Barr virus encephalitis. J Child Neurol. 2000 Dec;15:791-6.

Chess S, Fernandez P, Korn S. Behavioral consequences of congenital rubella. J Pediatr. 1978 Oct;93:699-703.

DeLong GR, et al. Acquired reversible autistic syndrome in acute encephalopathic illness in children. Arch Neurol. 1981 Mar;38:191-4.

Dyken PR. Neuroprogressive disease of post-infectious origin: a review of a resurging subacute sclerosing panencephalitis . Ment Retard Dev Disabil Res Rev. 2001;7:217-25.

Gillberg IC. Autistic syndrome with onset at age 31 years: herpes encephalitis as a possible model for childhood autism. Dev Med Child Neurol. 1991 Oct;33:920-4.

Hornig M, Weissenbock H, Horscroft N, Lipkin WI. An infection-based model of neurodevelopmental damage. Proc Natl Acad Sci USA 1999 Oct 12; 96:12102-7.

Hornig M, Lipkin WI. Infectious and immune factors in the pathogenesis of neurodevelopmental disorders: Epidemiology, hypotheses, and animal models. Ment Retard Dev Disabil Res Rev 2001; 7:200-10.

Ivarsson SA et al. Autism as one of several disabilities in two children with congenital cytomegalovirus infection. Neuropediatrics. 1990 May;21:102-3.

Libbey JE, Sweeten TL, McMahon WM, Fujinami RS. Autistic disorder and viral infections. J Neurovirol. 2005 Feb;11:1-10.

Lintas C, et al. Association of autism with polyomavirus infection in postmortem brains. J Neurovirol. 2010 Apr;16:141-9.

Whats Next In Treatment

The better we get at diagnosing autism spectrum disorders, the more we need medicine to keep pace. Researchers have historically struggled to create good medications to treat autismand the one that may be the most effective is still under a cloud of cultural hurdles and legal obstacles. But not all governments are the same. Israel is leading the charge with medical cannabis research, with both the public and private sector working in concert. Will we catch up? Lets hope so, because for people with autism, this may be one of the best options for treatment.

Autism stats: Centers for Disease Control and Prevention . Community report on autism.

Vaccines & Smoking As Factors

Autism spectrum disorders

Similarly, childhood vaccinations also do not cause autism. The research that claimed to show a causal link between the two was fraudulent and later retracted. Despite many claims to the contrary over social media and from dubious channels, there is no credible research that supports a connection.

Smoking during pregnancy was once thought to contribute to the risk of autism. While smoking is itself generally unhealthy , the Pediatric and Perinatal Epidemiology journal writes on the topic of smoking during pregnancy, that no associations were observed for childhood autism and Aspergers syndrome.

What should parents, prospective parents and caregivers do about environmental factors that can lead to autism? When a high risk for autism has been established, families should consult with a doctor, a pediatrician, or even a genetic counselor for recommendations.

In most cases, following general recommendations of staying healthy and getting vaccinations will be helpful to control that risk.

What Are The Warning Signs Of Autism Spectrum Disorder

Keep in mind that the diagnosis of autism spectrum disorder is applied based on analysis of all behaviors and their severity, but here are the top behaviors that may signal autism.

  • Doesnt speak, or has delayed speech
  • Trouble understanding other peoples feelings or expressing their own
  • Performs repetitive movements like rocking, spinning, hand-flapping
  • Resists cuddling or holding
  • Lack of spontaneous or make-believe play
  • Sensory sensitivities to light, sound or touch, but possible indifference to pain or temperature
  • Persistent fixation on objects or parts of objects like the wheels on a toy
  • New Horizon Of Diagnostics And Testing

    Autism can be challenging to detect, especially in very young children. has shown early diagnosis and treatment interventions can lead to better long-term outcomes for autistic people.

    Because of this, the scientific community is working toward finding innovative diagnostic methods that can help detect this neurotype much earlier.

    Hearing tests may be one such diagnostic tool. Researchers from Harvard Medical School in Boston, MA, and the University of Miami analyzed data from auditory brainstem response hearing tests routinely given to infants shortly after birth in the state of Florida.

    The team then matched the data to the Florida Department of Education records of those children who later received a diagnosis of a developmental condition.

    Results showed that infants who later received an ASD diagnosis had slower brain responses to sounds during their ABR tests conducted at birth.

    This study appears in the journal Autism Research .

    The investigators hope to conduct more studies to determine whether the ABR test could help recognize autism at an early age.

    Further advancements in recognizing autism include new research into biomarkers.

    found metabotypes associated with autism in 357 children aged 1848 months.

    After optimizing these and previously discovered metabotypes into screening tests, the research team detected autism in of the participants in the CAMP study.

    Study author Elizabeth L. R. Donley of Stemina Biomarker Discovery in Madison, WI, told MNT:

    Risk Identification And Reduction: Research And Safety Testing

    Research is an important component in the ultimate prevention of autism. However, research is most often after the fact and is reactive to emerging health threats that have already taken a heavy societal toll. In contrast, well-conceived safety testing of chemicals and drugs is far more likely to be proactive in the prevention of developmental conditions affecting the neurological and other systems. In the case of autism, increased prevalence that has emerged over the past 3040 years and the targeted research that has followed to date, have yet to produce a definite list of causative environmental factors. Still, safety testing today is not designed to detect the types of developmental disruptions that are likely to result in autism . Why is the primary response to this emerging health threat only to be found in research and not reflected in purposeful and effective changes to regulations that determine the safety of our drugs and chemicals? Recently, investigators focused on the developmental origins of chronic disease called for a more forceful role of public health officials to reduce the burden of disease established early in life . We concur with this appeal, which will require a different level of engagement on issues in developmental toxicity such as the prevention of autism.

    Dr Philip J Landrigan Calls For Expanded Research Into Environmental Causes Of Autism

    What causes autism? Exploring the environmental contribution“Expanded research is needed into environmental causation of autism. Children today are surrounded by thousands of synthetic chemicals. Two hundred of them are neurotoxic in adult humans, and 1000 more in laboratory models. Yet fewer than 20% of high-volume chemicals have been tested for neurodevelopmental toxicity. I propose a targeted discovery strategy focused on suspect chemicals, which combines expanded toxicological screening, neurobiological research and prospective epidemiological studies.”“studies demonstrating the sensitivity of the developing brain to external exposures such as lead, ethyl alcohol and methyl mercury”“studies specifically linking autism to exposures in early pregnancy thalidomide, misoprostol, and valproic acid; maternal rubella infection; and the organophosphate insecticide, chlorpyrifos.” Autism and Human Exposure to Environmental Chemicals: Time to Put a Stake Through the Heart of the “It’s Gotta Be Genetic” Model of Autism ResearchCDC Fourth National Report on Human Exposure to Environmental Chemicals“measured 212 chemicals in people’s blood or urine75 of which have never before been measured in the U.S. population. The new chemicals include acrylamide, arsenic, environmental phenols, including bisphenol A and triclosan, and perchlorate”Environmental Health Perspectives

    Medication Treatment For Autism

    Currently, there is no medication that can cure autism spectrum disorder or all of its symptoms. But some medications can help treat certain symptoms associated with ASD, especially certain behaviors.

    NICHD does not endorse or support the use of any medications not approved by the U.S. Food and Drug Administration for treating symptoms of autism or other conditions.

    Healthcare providers often use medications to deal with a specific behavior, such as to reduce self-injury or aggression. Minimizing a symptom allows the person with autism to focus on other things, including learning and communication. Research shows that medication is most effective when used in combination with behavioral therapies.

    The FDA has approved the use of some antipsychotic drugs, such as risperidone and aripripazole, for treating irritability associated with ASD in children between certain ages. Parents should talk with their child’s healthcare providers about any medications for children with ASD.

    Other drugs are often used to help improve symptoms of autism, but they are not approved by the FDA for this specific purpose. Some medications on this list are not approved for those younger than 18 years of age. Please consult the FDA for complete information on the following listed medications.

    All medications carry risks, some of them serious. Families should work closely with their children’s healthcare providers to ensure safe use of any medication.

    Close Citations

    Are Environmental Factors A Significant Cause Of Autism

    Environmental influences may be risk factors for autism, but research into this area is ongoing, and no true consensus exists.

    There is no known cause of autism. Researchers believe that there is a significant genetic component to the disorder, but many other factors, such as environmental exposure, have been shown in studies to contribute to autism spectrum disorder.

    Autism Research Activities And Advances

    NICHD’s autism spectrum disorder research portfolio is spread throughout the Institute and includes extramural components that support research on ASD and other intellectual and developmental disabilities . NICHD also conducts some autism-related research projects through its intramural program.

    In addition, several extramural and intramural entities within NICHD sponsor or conduct research that is not autism-focused but that can inform our understanding of the developmental and molecular processes involved in autism pathophysiology. Some of these efforts are described below.

    Autism Causes & Risk Factors

    Disability power point

    It is extremely difficult to study and classify autism because it is hard to find two people with exactly the same set and degree of symptoms. Due to the varied spectrum and the possible combination of factors contributing to autism, pinning autism down to one cause is impossible.Causes

    Risk FactorsSome of the most significant risk factors include:

    • Age of ParentsOlder parents have been shown to have a greater risk of having a child with autism.  
    • Family historyChildren are more likely to be born with the disorder when the elder sibling has autism. In cases where the parents are not in the autistic spectrum, it may be possible to notice a minor symptom such as communication or social skill problems.  
    • GenderMales have a greater chance of developing autism than females. The risk for boys is about four times higher than for girls. 
    • Preterm BabiesChildren are at greater risk of developing autism if they are born before 26 weeks of pregnancy.

    Progress In The Field Of Environmental Risk Factors

    In 2008, little was known about environmental risk factors for ASD.  Given what had been revealed about ASD’s genetic complexity at that time, it was suspected that environmental exposures and gene-environment interaction would likely be important to fully understanding ASD risk.  The California Autism Twin Study  published in 2011 demonstrated that the environmental component of ASD etiology is probably quite substantial. Recent analysis of non-twin family data , , , also supports the idea that mechanisms beyond inherited gene mutations and de novo, or spontaneous, mutations or copy number variants will be necessary for understanding the complex causes of ASD.  The time around conception and during pregnancy are likely the most important time windows of heightened vulnerability for the development of the brain with supporting evidence from early reports linking autism symptoms to maternal ingestion of drugs such as thalidomide, and valproic acid,, and infection with congenital rubella,, as well as more recent reports showing that maternal intake of prenatal vitamins has a “protective” effect, reducing risk for ASD, and that many genes that have been identified as linked to autism are expressed in the brain during fetal development.,

    How Is Autism Diagnosed

    Heres the deal: theres no blood test, brain scan, or other objective test that can definitively diagnose autism, though researchers are actively trying to develop such a test. Diagnosing an autism spectrum disorder involves two steps: developmental screening and a comprehensive diagnostic evaluation. Even though ASD can be diagnosed as early as age 2 years, most children are not diagnosed with ASD until after age 4 years.

    Developmental screening looks to see if children are learning basic skills when they should, or if they may have developmental delays. The next step for diagnosis is a comprehensive evaluation, which is an in-depth review that looks at a childs behavior and overall development, and generally includes an interview with the parents. There is often accompanying hearing and vision screening, along with neurological and genetic testing.

    Baylor College Of Medicine Blog Network

    Ana RodríguezAsperger SyndromeAutism Spectrum Disorderbrain growthGlobal Burden of Disease Studyvaccines and autism

    New information gained from major scientific papers over the last two years has shed light on the causes and progression of autism spectrum disorder.  Estimates from the Global Burden of Disease Study indicate that globally 62.2 million people are currently on the autism spectrum and are affected by autism spectrum disorder.  Such numbers have not changed significantly over the last decade.

    Autism spectrum disorder is typically diagnosed between 1 and 2 years of age, a time which has been noted to coincide with marked brain volume overgrowth.  Now, additional and new evidence from magnetic resonance imaging studies indicates that the changes in the brains of children with autism spectrum disorder leading to brain overgrowth can be detected by 6 to 12 months of age.  However, from autopsy studies it appears that the dysregulation of the prefrontal and temporal lobes of the brains in children with autism spectrum disorder actually occurs much earlier and during pregnancy.  Such prenatal changes are set in motion due to genetic and/or epigenetic alterations happening around the time of conception or shortly thereafter.  Approximately 65 new genes have been identified in this role.

    The Global Burden of Disease Study

    The Causes of Autism

    Natural History of Autism

    Synthesizing the Information

    Peter Hotez, M.D., Ph.D.


    Exploring The Environmental Causes Of Autism And Learning Disabilities Part 1

    Dr. Landrigan has been a member of the faculty of Mount Sinai School of Medicine in New York City since 1985, and Chair of the Department of Preventive Medicine since 1990. He was named Dean for Global Health in 2010. Dr. Landrigan is also the director of the Childrens Environmental Health Center.

    Each year, biologically based disorders of brain developmentautism, attention deficient/hyperactivity disorder , mental retardation, dyslexia, and subclinical neurodevelopmental disabilitiesaffect between 200,000 and 400,000 of the 4 million babies born in the United States. Thats between 5 and 10 percent of all American children.

    There is great concern about the rising rates of autism spectrum disorder . The Centers for Disease Control and Prevention report that the prevalence of ASD increased by 57 percent between 2002 and 2006, and is now affecting one of every 110 babies born in the U.S.


    Beyond Genetic Research


    Until recently, most research into the causes of ASD had focused on genetic factors. This elegant research has linked a series of genetic factors to autismincluding specific gene mutations, recurrent chromosomal microduplications, microdeletions, and copy number variations.

    The Case for an Environmental Contribution

    Exploring the Environmental Causes of Autism and Learning Disabilities

  • Thalidomide: A medication taken by women in early pregnancy during the 1950s.
  • Valproic acid: A medication used to control epilepsy.

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