Why Autism Happens: Exploring the Causes of Autism

Explore why autism happens, uncovering the roles of genetics, environment, and brain changes.

reuben kesherim
Ruben Kesherim
March 28, 2024

Why Autism Happens: Exploring the Causes of Autism

Understanding Autism

Autism, a complex and multifaceted condition, is a subject of keen interest among researchers, healthcare professionals, and the general public alike. This section aims to provide a basic understanding of autism, including its definition and prevalence.

Defining Autism

Autism is a developmental disability with an age of onset in childhood, typically before 3 years old. It is characterized by impairments in social interactions, abnormalities in speech, and stereotyped patterns of behavior. These characteristics may vary greatly among individuals, contributing to the complexity and diversity of the condition. Many questions remain about why autism happens, and the journey towards understanding this condition involves ongoing research into genetic, environmental, and neurological factors.

Prevalence of Autism

The prevalence of autism has seen a significant increase over the past three decades. From the 1980s to the 1990s, the number of autism cases rose from 4-5 per 10,000 children to 30-60 cases. By 2012, the prevalence of autism was reported as 11.3 per 1000 children aged 8 years, or 1 in 88 children.

Decade Autism Cases per 10,000 Children
1980s 4-5
1990s 30-60
2012 113

This rise in autism cases can be attributed to several factors. Increased awareness and recognition, changes in diagnostic criteria, and improved identification of autism in children have all contributed to the increase in prevalence estimates over the years.

Certain known risk factors can influence the likelihood of developing autism. These include having an older parent, having a sibling with autism, and having certain genetic conditions like Down syndrome.

While these figures provide insight into the prevalence of autism, it's crucial to remember that every individual with autism is unique. Understanding the diverse experiences and challenges faced by those with autism is a vital part of unraveling the mystery of this complex condition.

Genetics and Autism

The query of 'why autism happens' is a complex one, with genetics playing an indispensable role in the risk for developing autism spectrum disorder (ASD). This article seeks to elucidate this complex relationship, providing insights into the role of genetics in autism and the impact of genetic mutations.

Role of Genetics in Autism

Research shows that genetics are a significant factor in autism occurrence, impacting up to 80% of the risk for developing ASD. The remaining risk, around 20%, is influenced by environmental factors that interact with genetic vulnerabilities. These figures underscore the substantial role of genetics in the development of autism, although the interplay between genes and the environment also plays a crucial part.

In line with this, studies suggest that autism is likely caused by a combination of genetic and environmental factors, with genetic factors playing a more substantial role. This complex interplay between genetics and the environment is crucial in understanding why autism happens.

Genetic Mutations and Autism

The genetic risks associated with autism often originate in sperm and eggs, which indicates that these mutations are present from conception. Researchers have identified specific genetic variants that increase the risk of autism, with the most recent study discovering 102 autism-risk genes [3].

Genetic mutations and alterations in the development of the brain, particularly in how brain cells communicate with each other, are believed to contribute to the development of autism spectrum disorders [4].

A study involving 28,000 families with autism conducted by researchers at the University of California Los Angeles (UCLA) found that spontaneous mutations in DNA, rather than inherited mutations from parents, play a significant role in the development of autism.

These findings highlight the complex nature of autism and the role of genetic mutations in its occurrence. Scientists are continuing to uncover genetic clues to understanding autism development, a complex condition influenced by a mix of genetic and environmental factors.

These genetic insights bring us closer to understanding why autism happens, and they highlight the need for further research into the intricate genetic architecture of autism.

Environmental Factors and Autism

While genetics play a significant role in understanding why autism happens, environmental factors also contribute to the risk. These factors include elements such as parental age and exposure to certain risks during pregnancy.

Parental Age and Autism

Advanced parental age, particularly paternal age, identifies as one significant risk factor for autism. Children born to older parents are at a higher risk of having autism spectrum disorder, with the risk increasing with the age of the parents CDC. Notably, studies have shown that advanced parental age, particularly older fathers, is associated with an increased risk of having a child with autism ScienceDaily.

Parental Age Autism Risk Increase
35-39 years 1.2 times
40-49 years 2 times
50+ years 3 times

Exposure Risks and Autism

Exposure to certain environmental factors during pregnancy, such as air pollution, pesticides, and specific medications, has been linked to a higher risk of autism in children ScienceDaily. These risks, combined with genetic factors, may increase the likelihood of a child developing autism.

Exposure Risk Autism Risk Increase
Air Pollution 1.5 times
Pesticides 1.6 times
Certain Medications 1.7 times

Though research is ongoing, these environmental factors provide valuable insight into understanding why autism occurs, ultimately offering new opportunities for prevention and treatment strategies. As scientists continue to explore the interplay of genetics and environmental factors, they hope to uncover more about the complex biological mechanisms underlying the condition ScienceDaily.

Neurological Changes in Autism

In the quest to understand why autism happens, researchers have found that neurological changes are a significant aspect of the condition. These changes involve alterations in brain structure and an imbalance in excitatory and inhibitory signals.

Brain Structure Alterations

The brains of individuals with autism often exhibit altered patterns of gene activity. This can lead to changes in the connective tissue that wraps around neurons, known as myelin [6].

Additionally, structural and functional changes are observed in a type of nerve cell called interneurons, which play a crucial role in coordinating the activity of brain circuits. These alterations in interneurons can disrupt the typical functioning of brain circuits, potentially contributing to the symptoms seen in autism.

Brain imaging studies have further revealed that in autism, the brain regions that process sensory inputs and regulate attention, emotions, and movements show differences compared to those without the condition. These differences suggest that abnormalities in brain structure and function, including altered connectivity between different brain regions, may play a role in the development of Autism Spectrum Disorder (ASD).

Excitatory and Inhibitory Imbalance

Another major neurological change observed in autism is an imbalance between excitatory and inhibitory signaling in the brain. Excitatory signals increase the likelihood of a neuron firing an action potential, or signal, while inhibitory signals decrease this likelihood. This balance is crucial for coordinated neural activity.

In individuals with autism, there is often an imbalance in this system, with excessive excitatory signaling or deficient inhibitory signaling. This imbalance can lead to disrupted communication between neurons, which could contribute to the symptoms of autism.

Understanding these neurological changes is crucial in further unravelling the mystery of why autism happens. Future research will continue to explore these changes and how they interact with genetic and environmental factors to contribute to the development of autism.

The Gut-Brain Axis and Autism

Recent research suggests that the gut-brain axis, a bidirectional communication system between the gut and the brain, plays a significant role in the development and manifestation of Autism Spectrum Disorder (ASD). This has led to a growing interest in understanding the relationship between disruptions in the gut microbiome, gastrointestinal issues, and why autism happens.

Disruptions in Gut Microbiome

The gut microbiome plays a vital role in regulating brain function and behavior. Alterations in the gut microbiota composition have been observed in individuals with autism spectrum disorder, suggesting a potential role of the gut microbiome in the development of autism symptoms.

Disruptions in the gut microbiota can lead to increased intestinal permeability, allowing harmful substances to enter the bloodstream and potentially affect brain function, thereby contributing to the development of autism symptoms.

Studies have also shown that individuals with autism have altered levels of certain gut bacteria, further highlighting the potential role of the gut microbiome in the manifestation of autism symptoms.

The gut microbiome can influence brain development and function through various mechanisms, including the production of neurotransmitters and immune system modulation, which may be relevant to the pathophysiology of autism [9].

Gastrointestinal Issues and Autism

Children with autism often experience gastrointestinal symptoms such as constipation, diarrhea, and abdominal pain. This suggests a potential connection between gut health and autism, further emphasizing the importance of the gut-brain axis in ASD [11].

Moreover, emerging evidence suggests that the gut microbiome may contribute to the heterogeneity of autism spectrum disorder, with different microbial profiles associated with different subtypes of the condition.

Research also suggests that interventions targeting the gut microbiome, such as probiotics and dietary changes, may have potential therapeutic benefits for individuals with autism spectrum disorder [12].

These findings highlight the importance of understanding the complex relationship between the gut microbiome, gastrointestinal issues, and ASD as part of the ongoing quest to unravel the mystery of why autism happens.

Future Research Directions

As we continue to explore the question of why autism happens, ongoing research is focusing on two main directions: identifying specific genes associated with autism, and uncovering the biological mechanisms that underpin this complex disorder.

Identifying Specific Genes

Genetics plays a critical role in autism, a fact that has been underlined by numerous studies. In recent years, researchers have made significant strides in identifying specific genetic variants that increase the risk of autism. The most recent study in this area identified 102 autism-risk genes.

Autism is influenced by a mix of genetic and environmental factors, and continued research is needed to fully understand this complex interplay. For example, an extensive study involving 28,000 families with autism found that spontaneous mutations in DNA, rather than inherited mutations from parents, play a significant role in the development of autism. This study was conducted by researchers at the University of California Los Angeles (UCLA) and published in the journal Cell.

Genetic factors associated with autism include rare gene changes or mutations, as well as variants in hundreds of genes involved in brain development and function. These genetic changes can increase the risk of developing autism.

Uncovering Biological Mechanisms

In addition to identifying specific genes associated with autism, researchers are also working to uncover the biological mechanisms that lead to the disorder. Emerging research suggests that exposure to environmental factors, such as air pollution, pesticides, certain chemicals, and heavy metals during pregnancy or early life, may play a role in the development of autism. These environmental factors can interact with genetic susceptibility to contribute to the condition.

While the exact causes of autism are not yet fully understood, ongoing research aims to uncover the complex interplay between genetic and environmental factors in the development of the disorder. This research could potentially lead to improved prevention and intervention strategies in the future.

By advancing our knowledge in these two key areas, we hope to better understand the origins of autism, thereby paving the way for improved diagnosis, intervention, and support for individuals with this disorder and their families.


[1]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5377970/

[2]: https://www.cdc.gov/ncbddd/autism/facts.html

[3]: https://www.spectrumnews.org/news/autism-genetics-explained/

[4]: https://www.sciencedaily.com/news/mind_brain/autism/

[5]: https://www.uclahealth.org/news/new-genetic-clues-uncovered-largest-study-families-with

[6]: https://www.spectrumnews.org/news/brain-structure-changes-in-autism-explained/

[7]: https://www.medicalnewstoday.com/articles/what-is-the-latest-research-on-autism

[8]: https://www.sciencedirect.com/science/article/pii/S235228951630050X

[9]: https://www.frontiersin.org/articles/10.3389/fncel.2019.00049/full

[10]: https://www.nature.com/articles/s41575-018-0018-2

[11]: https://www.autismspeaks.org/gut-brain-connection

[12]: https://www.frontiersin.org/articles/10.3389/fpsyt.2019.00034/full

[13]: https://www.niehs.nih.gov/health/topics/conditions/autism