What are the main causes of Autism?

- By Somaiyya Jawaid Posted On - 23/04/2021

The article elucidates information on the main causes of autism.

Around 1 in 100 children in India below the age of 10 years have been diagnosed with autism. (Katsneleson, 2018).

In a recent survey by the “Centers for Disease Control and Prevention (CDC)”, Autism now impacts 1 child in every 59 children and in that 1 in 37 among boys. Several other researchers have suggested that the current prevalence may be even more. Distinctively, 1 in 150 children were impacted by the year 2000 and these prevalence rate urges to take into account what actually have been potential factors behind it. There is no quick and easy understanding to understand what causes autism but there are many theories and explanations with respect to the causes of Autism but the most accepted theory proposes that “there is no single cause for ASD, but rather a combination of factors that create complex neurological disorders.”

Does Genes play the role?

On the basis of twin concordance rate, heritability guesstimate that autism have “ranged from 37% to higher than 90%.”

Evidently, more than 15% of the diagnosed cases of autism indicate an association with a perceived “genetic mutation”, with different “de novo copy number variants or de novo mutations” in explicit genes affiliated with the disorder in different families. Even though, when autism is found to be associated with an explicit genetic mutation, it does not give any indication to be wholly penetrant. The Endangerment for the leftover cases signals to be “polygenic”, and may be along with hundreds of “genetic loci” responsible for relatively small contributions. (American Psychiatric Association, 2013) Reviews on studies on parents with Autism or a family member with Autism, indicated that children born are far more likely to have autism. On a similar note, if parents with one child, and the child diagnosed with Autism, the chance of having another child with Autism from the same parents increases dramatically. (Special Leaning, INC, 2009)

Does the environment affect too?

Not all the cases of Autism accounts for genetics, so it is considered that the environment will eventually be held responsible for the remaining ones and the most prominent one is the prenatal environment, “which may affect a pregnancy during the critical first eight weeks of conception.”

One meta analysis, with respect to environmental toxicants found “92% of 37 studies showed a relationship between autism and environmental exposures such as phthalates, pesticides, solvents, ,PCBs, air pollutants, toxic waste sites and heavy metals.” The most prominent association with autism was found in studies to be with air pollution and pesticides.

Age of Parents: Studies have found there is a heightened possibility for being diagnosed with Autism in children being born to maternal age over 35 and paternal age over 40 years of age.(Ellis, 2018)

Pesticides- On various occasions, it has been found that autism in children being born near farm fields that employed “organochlorine pesticides” namely dicofol and endosulfan. Although there have been very few cases where children with Autism can be directly linked to be conceived with autism under these conditions and relatively small controlled samples to evaluate against this link makes further studies connecting pesticides with autism very challenging. However these pesticides “have been found to be related to problems in memory, motor coordination, cognitive development, and visuospatial performance.”

Teratogens- Environmental agents such as valproic acid, rubella or misoprostol thalidomide are known to cause infection to the mother and responsible for birth defects.

Ultrasound - A research conducted in 2006 indicated that the sustainable amount of exposure to “mouse embryos” to ultrasound waves impacted a small but empirically significant number of neurons to fail to acquire their proper position during neuronal migration.

Folic Acid - Empirically not proven but a hypothesis states that Folic Acid might be responsible for diagnosis with autism due to its “modulation of gene expression through epigenetic mechanism.”

Fetal Testosterone - A study suggested that heightened levels of “fetal testosterone” could be responsible for behaviors in relevance to observed in autism. Although this remains a controversial theory. (Special Leaning, INC, 2009)

The Perinatal Environment Leaky Gut Syndrome - A research published in 2007 on the review of risk factors found associations in obstetric conditions that included closer spacing of pregnancies, prematurity, low birth weight and gestation duration, being a first-born child.and hypoxia during childbirth.

Mercury - This theory hypothesizes that autism is associated with mercury poisoning, based on some similarity of symptoms.

Viral Infection - Viruses have long been suspected as triggers for immune-mediated diseases such as multiple sclerosis but showing a direct role for viral causation is difficult in those diseases, and mechanisms whereby viral infections could lead to autism are speculative.

Oxidative Stress - This theory hypothesizes that toxicity and oxidative stress may cause autism in some cases by damaging Purkinje cells in the cerebellum after birth. It has been suggested that glutathione is involved.

Amygdala Neurons - It is theorized that the amygdala’s involvement in social knowledge and social cognition and the deficits in this network are instrumental in causing autism.

Lead - Lead poisoning has been suggested as a possible risk factor for autism, as the lead blood levels of autistic children has been reported to be significantly higher than normal.

Vitamin D - This theory is not backed by scientific study. It is hypothesized that autism is caused by vitamin D deficiency, and that recent increases in diagnosed cases of autism are due to medical advice to avoid the sun. (Special Leaning, INC, 2009)