Effect of the Environment on Neurodevelopment

Aditi Nair

Founder & Executive Director

Imagine not being able to properly communicate with others, and what if your brain processes information differently, making it difficult to understand things the same way as everyone else?

As the second blog post on the I’mPossible website, I decided to delve into a disorder that I feel is quite commonly associated with learning disabilities–autism. According to the CDC, “Autism Spectrum Disorder (ASD) is a developmental disability caused by differences in the brain.” [1] The causes of ASD are still not yet defined, but many have come to the conclusion that a “wide range of potential environmental challenges” are, sometimes, associated with autism. [2] 

Studies are continuing to suggest that the environment affects brain development in children. But, does the environment or genetics alone affect cognitive-behavioral growth, or is it a combination of both? 

As I was researching, to get more answers, I came across the twin study conducted by Folstein and Rutter in 1977, the first ever to indicate a genetic influence and eventually, clear the dogma that autism is caused by poor parenting. [2] At first, I didn’t think to further look into the study, as I consistently found newly published work that either proves or disavows the relevance of the study. I, then, decided to break down published work in the field to the nitty-gritty details in order to dissect whether autism, as a matter of fact, is genetically passed. 

Let’s start with the results from the twin study conducted by Folstein and Rutter. The study was conducted on a group of 21 pairs of same-gender twins, 11 MZ and 10 DZ (MZ and DZ determine if the pair of twins arose from one zygote or two zygotes–identical or fraternal) and concluded with results stating that “here were important hereditary influences concerning a cognitive deficit which included but was not restricted to autism.” [3] In simple terms, heredity does influence one’s cognitive ability, but it doesn’t necessarily result in autism. However, the authors stated that autism could arise from “brain injury in the infancy period or in combination with genetic predisposition.” [4] This suggests the influence of other factors that may result in the disorder.  So, if the Folstein and Rutter study was the first to identify the genetic influence on autism, does the fetal environment have a role to play in shaping a child while in its mother's womb?

The results of the study directed me into the blog’s main question: Does the environment play a role in neurodevelopmental disorder-related learning difficulties? 

Well, I have one study to back up my answer, but I needed another just to prove my point. According to another study, exposure to harmful contaminants during pregnancy may trigger genetic mutations in the fetus leading to autism. [6] These “harmful contaminants” could enter a woman’s body and genetically mutate her unborn child. To understand mutations, let’s first go into how genes are formed. A gene is a section of DNA used to make a protein. [7] The gene goes through transcription, which is when a gene is copied into an mRNA molecule. From there, the mRNA translates each codon in the copied gene into a protein. If everything moves smoothly, the proper proteins are made, but in the case of a genetic mutation that may arise from a missing codon sequence or sequence frameshift, a mutated protein is made that may interfere with the normal functioning of the native tissue. Now, going back to the main question, an article in the Duke Magazine stated, “Environmental factors such as food, drugs, or exposure to toxins can cause epigenetic changes by altering the way molecules bind to DNA or changing the structure of proteins that DNA wraps around.” [8] When the “structure of protein” changes, that can affect the body in a multitude of ways. 

In essence, the environment does play a significant role in influencing the genetics responsible for causing autism. 

I hope this blog addressed some questions relating to the role of the environment during neurodevelopment in children. Nonetheless, I still have so many questions. For example, how does ASD, specifically, affect the brain that could cause learning disabilities? In addition, does the extent of the disability depend on where the student is on the autism spectrum? The questions keep coming, so look out for my next blog post, as I try to answer these questions.

​Until then, keep reading and exploring the many possibilities in life…..

Sources:
[1] "What is Autism Spectrum Disorder?" Centers for Disease Control and Prevention,
     31 Mar. 2022, www.cdc.gov/ncbddd/autism/facts.html. Accessed 21 June 2022.
[2] Amaral, David G. "Examining the Causes of Autism." Cerebrum: The Dana Forum on
     Brain Science, 1 Jan. 2017. National Library of Medicine,
     www.ncbi.nlm.nih.gov/pmc/articles/PMC5501015/. Accessed 21 June 2022.
[3] Folstein, Susan, and Michael Rutter. "INFANTILE AUTISM: A GENETIC STUDY of 21
     TWIN PAIRS." Journal of Child Psychology and Psychiatry, vol. 18, no. 4,
     Sept. 1977, pp. 297-321, https://doi.org/10.1111/
     j.1469-7610.1977.tb00443.x. Accessed 21 June 2022.
[4] ---. "INFANTILE AUTISM: A GENETIC STUDY of 21 TWIN PAIRS." Journal of Child
     Psychology and Psychiatry, vol. 18, no. 4, Sept. 1977, pp. 297-321,
     https://doi.org/10.1111/j.1469-7610.1977.tb00443.x.
[5] "How Do Genes Direct the Production of Proteins?" Open Oregon Educational
     Resources, openoregon.pressbooks.pub/mhccbiology102/chapter/
     how-do-genes-direct-the-production-of-proteins/
     #:~:text=A%20gene%20is%20the%20section,make%20functional%20molecules%20called%20p
     roteins. Accessed 21 June 2022.
[6] Duke Magazine Staff. "Big Question: Can your environment change your DNA?"
     Duke Magazine, nos. Jul-Aug 2012, 8 Aug. 2012, alumni.duke.edu/magazine/
     articles/big-question-can-your-environment-change-your-dna. Accessed 21
     June 2022.