Unraveling the Mysteries: What Causes Autism?

Autism spectrum disorder, commonly referred to as just autism, is one of the most complex conditions affecting people today. As a neurodevelopmental disorder, autism affects how people interact with the world, as well as how they learn, communicate, and behave. As a spectrum disorder, autism can affect each person differently, and there is significant variation in the type and severity of the symptoms.

Autism is extraordinarily difficult to research. It affects people of all genders, ethnicities, races, and economic backgrounds. It lacks clear physical markers and can often be subtle enough that a person goes their entire life without a diagnosis. Even now, experts argue about how to classify and study autism.

Autism research has accelerated in recent years and given us a far better understanding of the condition, its mechanisms, and symptoms. In a mere century, we have moved from identifying autism as a symptom of schizophrenia to recognizing it as the complex spectrum of symptoms that it truly is. However, the recency of these discoveries has led to many people misunderstanding autism as a condition, making myths and misinformation prevalent.

The truth is that researchers have identified many potential genetic, environmental, and biological causes of autism. However, none of these findings fill in the gaps in our knowledge about how people inherit autism. Many of its genetic interactions also remain a mystery.

It is likely that there is no single cause of autism but instead stems from a complex web of factors. Understanding these topics and how they interact is the key to unraveling the mysteries behind autism.


Genetic factors in autism

Genes play an extremely important role in autism. Experts believe that the heritability of autism sits somewhere between 80 and 90 percent. In cases of identical twins, on the off-chance that one twin has autism, and the other does not, the one without the condition often has other learning or social disabilities. Over the years, scientists have found dozens of genes with strong links to autism and hundreds more that could be connected. Though some cases of autism are inherited through parental DNA, the vast majority of cases occur sporadically—despite the high heritability of the condition. For this reason, many experts refer to these genes as "risk factors" and believe that it is environmental factors that then influence whether or not a person will develop autism.

Autism 3d word in dna strand genes for hereditary cause of the learning disorder or brain condition

Environmental influences: what we know

Studies show that several environmental factors could increase the risk of autism. Many of these involve the pregnancy or the very early stages of infancy. Premature birth and low birth weight also increase the risk. A few research efforts have pointed to air pollution exposure during pregnancy or early infancy leading to autism, but this requires more study. Similarly, diesel exhaust, microplastics, alcohol, smoking, illicit drugs, pesticides, and heavy metals have all also appeared in lists as potential culprits. Ultimately, it is nearly impossible to identify every environmental factor because there are so many variables.

Vector illustration on the theme of National Autism awareness month of April. world autism day background. 2 April world autism awareness day background. world autism day background design

The role of brain structure and function

Scientists have frequently indicated brain structure differences as influences in the development of autism. The specifics of this are complex, and the mechanisms often vary. For example, some experts think that autism is a form of autoimmune disease where antibodies attack the brain during development. Others believe that thyroid issues during pregnancy impact the infant's brain. The areas of the brain that are most often related to autism include:

  • Amygdala - responsible for emotional responses
  • Basal ganglia - help regulate automatic movement
  • Brain stem - helps transfer messages between the brain and body
  • Cerebellum - assists with balance, body movements, speaking muscles, and motor activity
  • Cerebral cortex - responsible for higher mental functions, movement, behavioral reactions, and perception
  • Corpus callosum - allows the hemispheres of the brain to communicate
  • Hippocampus - responsible for retaining information and memories

Brain shaped white jigsaw puzzle on yellow background, a missing piece of the brain puzzle, mental health and problems with memory

Prenatal factors and risks

During pregnancy, many different factors could influence the chance of the infant developing autism. Infection, high blood pressure, or diabetes are all common issues during pregnancy, and each may be a risk factor. Even prenatal stress could be a factor. Experts realized that many prenatal issues involve inflammation of some kind, potentially revealing that inflammation is truly responsible.

Happy pregnant woman visit gynecologist doctor at hospital or medical clinic for pregnancy consultant. Doctor examine pregnant belly for baby and mother healthcare check up. Gynecology concept.

Vaccines and autism: debunking myths

One of the most persistent myths about autism is that vaccines can cause autism. This is completely false. The brain development consistent with autism is visible in scans even while the child is in the womb, before the administration of any vaccines. Some people believe that giving too many vaccines in too short a time is responsible for autism. This thought has no scientific basis and is biologically implausible. In the few studies indicating a link between vaccines and autism, the vast majority of authors have rescinded their interpretations, and the journals often retract the papers. Investigations of these studies have consistently found issues of data manipulation or outright fraud to assert the link between vaccines and autism. High-quality, peer-reviewed studies consistently find no causal relationship between the two. Finally, the preservative thiomersal has been the focus of misinformation. Since 2002, this ingredient has appeared in only a single childhood vaccine, and rates of autism have not diminished. International scientific and medical bodies have overwhelmingly rejected the idea that thiomersal causes autism.

Asian child getting vaccine shot in clinic.Ill preschooler holding sensory toy to distract attention.Autism and autistic toys.Vaccination during pandemic Covid19.Doctor injecting in arm of little girl

Family history and autism

Because of its high heritability and genetic linkage, many people assume that autism runs in families. However, the truth is a bit more complicated than that. A family history of autism does indicate a greater chance of a child developing it, as well. The same is true, though, of depression, schizophrenia, and obsessive-compulsive disorder. Some researchers have proposed the theory that there are two methods of autism development: inheritance and spontaneous development. The spontaneous form seems to be more common in the general populace.

Family autism history concept icon. Autism risk factor abstract idea thin line illustration. Intellectual disability cause. Affect development. Vector isolated outline color drawing. Editable stroke

Early developmental indicators

Children can start to show signs of autism at an extremely early age—usually within the first year. That being said, it is worth pointing out that many children show some of these signs, and parents should not use them to diagnose their child. By 12 months old, a child with autism might not babble, respond to verbal cues, react to waving or peekaboo, or look at objects that someone else points to. Within the next few months, the child might not say a single word or participate in pretend play. In general, slow language development is one of the major signs of autism.

baby girl playing peek-a-boo - isolated on white

The impact of parental age

Parental age is potentially a major risk factor for autism. As the parents age, the risk for genetic mutations increases dramatically. This is particularly true for sperm, as genetic mutations in sperm gradually accumulate over years. Several studies showed that paternal mutations were the primary drivers of autism development rather than the maternal mutations. Additionally, the relationship between mutations and age was more direct in the male figure.

 Happy Old parents Having Fun With children In Park

The interplay of multiple factors

From the health and age of the parents to the environment during pregnancy, there are far too many considerations to point to a single cause for autism. Instead, the condition stems from a deep and complex web of interconnecting factors. With more time and research efforts, scientists will allow for a better understanding of this web. This will allow more accurate predictions of autism development and enable earlier, more accurate diagnoses.

Autism, autism spectrum disorder, disease name composed with colored stones over black sand

Misconceptions about the causes of autism

As with any complex medical topic, misconceptions about autism will continue to exist, and new ones will appear. People worry for their children and wish for them to be healthy. A simple answer that a specific factor causes autism is far easier to comprehend than the complex truth. Though many individuals feel concerned that the rates of autism are increasing, this is due to a better understanding of the condition and more accurate diagnostic measures.

Hands and puzzle ribbon for World Autism Awareness Day.
Charlie, Heywise Staff

Article WriterCharlie, Heywise Staff

Charlie took to the written word like a fish takes to water. That is to say; they found themselves immersed in literature from before they were born. They've been known to tell their friends how they can still remember the passages their parents read to them when they were in utero - Emily Dickinson, Jane Austen, and a bit of Hunter S. Thompson thrown in to balance it out. Charlie keeps their feet wet, whether they're whipping up pithy one-liners to tease your brain or busy working on their second novel (the first one is available on Amazon under a pen name they refuse to disclose). You’re sure to get a kick out of giggle-worthy explanations and outrageous hints, and still come away feeling like you’ve just expanded your knowledge base.

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