What are the Types of Autism and Their Symptoms?

Autism, or autism spectrum disorder (ASD), is a developmental and neurological disorder that affects more than 5.4 million adults in the United States. And the condition is individual to every one of those people—manifesting itself in a wide range of symptoms and capabilities.

ASD typically presents itself in childhood, often before a person reaches the age of 3. Diagnosing ASD, however, can be difficult. No genetic test, medical exam or blood test can indicate autism. Because of that difficulty, as well as misunderstandings about the condition, many people go undiagnosed well into adulthood.

Autistic adults may find they have difficulty making friends, dating or engaging in romantic relationships. Or they may not. All people with autism have a unique experience.

"Autism is a spectrum, so there are more severe cases and more high-functioning cases," said Julian Lagoy, M.D., a psychiatrist with Mindpath Health in San Jose, California. "With all cases, there is an appropriate treatment which can help with social life functioning."

Autism can affect social development, but it doesn't stop autistic individuals from developing sexually. Autistic young adults reported similar socio-sexual interests to their non-autistic peers, according to a 2021 study published in Front Psychology. Autistic young people reported less sexual experience even though their levels of desire were similar.

The Front Psychology study also suggested that autistic adolescents received less sexual education than their peers, with students reporting they needed more guidance on applying what they learned to real-life situations.

Understanding ASD and its relation to other parts of health—such as sexual or mental health—is crucial in breaking down stigmas for autistic individuals and increasing awareness of the broad spectrum that is autism.

Breaking down ASD

Autism is considered a spectrum disorder, which means each person with autism has an individual set of strengths and challenges. For some people with ASD, social interactions may come easily but sensory sensitivities can be overwhelming, and vice versa. This distinct level of individuality makes autism a difficult condition to fully understand.

Common symptoms of ASD include the following:

• Difficulty communicating or interacting socially
• Repetitive behaviors or interests
• Delayed language, cognitive or movement skills
• Unusual moods or reactions
• Hyperactive or inattentive behavior

This is only a short list of potential autism symptoms. The range is as diverse as the individuals with ASD are.

Autism can affect people of all genders and ages. Symptoms of ASD are usually present in young children, and unfortunately, there is no "growing out" of autism. However, people can learn to adjust behaviors and adopt different learning styles and communication styles to better manage their condition.

Experts previously categorized ASD into five types:

1. Asperger's syndrome, or Type 1 ASD: This type categorized people with above-average intelligence and normal language development but difficulties with social communication.
2. Kanner's syndrome: This was the diagnosis for "classic" autism, describing people who experienced differences in social interaction and more overt symptoms of ASD.
3. Childhood disintegrative disorder: This type was used to classify children who developed "normally" until ages 3 or 4 when they would stop hitting developmental milestones.
4. Rett syndrome: This syndrome most often affected girls, describing children who developed as expected for a time but then had trouble walking and experienced decreased head growth and difficulty speaking.
5. Pervasive developmental disorder: This describes individuals who exhibited symptoms of autism but did not fit into the other categories.

Medical experts no longer use these delineations, instead acknowledging autism as a continuous spectrum. Rett syndrome is now considered its own genetic condition, unassociated with ASD.

ASD can affect everyone, but the condition is more than four times more common in men than women, according to the Centers for Disease Control and Prevention (CDC). The reasons behind this disparity are unclear.

It could be that ASD presents differently in women than it does in men, causing additional difficulties with diagnosis. It could be genetic, with some researchers theorizing that spontaneous genetic mutations more common in males could be contributing to the disparity.

What causes autism?

Speaking of genes, there is a genetic factor in autism. Genes are estimated to contribute to 40 percent to 80 percent of ASD risk, according to MedlinePlus.

"There seems to be multiple factors associated with the development of autism and its severity," said pediatrician David Berger, M.D., the founder of Wholistic Pediatrics & Family Care in Tampa, Florida. "There are genes that are associated with an increased risk, and we know there is a much higher risk of having a child with autism if a family has a child with autism already.

"Additionally, I look for genes that are related to how the body metabolizes certain B vitamins and is able to properly control toxins and inflammation."

Mutations in more than 1,000 genes are thought to be potential causes of ASD, and many of the genes associated with autism contribute to brain development.

Other than genetic predisposition, risk factors of autism include advanced maternal age (above 35), environmental factors like toxic exposures and prenatal infections, according to Lagoy.

Environmental factors refer to those that are outside of genetic changes. For autism, these factors also include parental age, maternal nutrition and health, premature birth, and exposure to chemicals.

"We know that there is an environmental factor as well," Berger said. "There is an association for people exposed to heavy metals such as lead and pesticides and autism."

Autism across cultures

ASD is found across countries and cultures, but the way we experience autism and look at individuals with autism varies. Certain behaviors may present similarly but be interpreted differently.

For example, an inability to hold eye contact is a common symptom of ASD. In Western culture, a lack of eye contact is noticeable in its deviation from the norm. However, in some Asian cultures, minimal eye contact is considered polite and may be less obvious as a symptom of ASD.

Symptoms are defined by a deviation from the control group, and when that control group's behavior differs (as it does across cultures), the understanding of the symptoms or atypical behavior differs, too.

Beyond symptoms, diagnosis varies significantly between socioeconomic groups. Children with educated mothers had twice the diagnosis rate of children of mothers with lower education levels, according to a 2019 study in the United Kingdom. Similar results have been found in the U.S. These results indicate that higher education levels for parents often mean greater access to screening programs and a higher level of awareness of ASD.

Awareness of ASD within the medical community also varies. Delays in access to information, education and treatment can cause further issues for autistic individuals.

Key facts about autism

The understanding of ASD is growing, but we do know a lot about the spectrum disorder. Some important facts about autism include:

• One child in 44 is diagnosed with ASD.
• ASD is more common in boys than girls.
• Autism can look different in every autistic person.
• Autism does not discriminate by race, but certain socioeconomic factors can influence diagnosis rates.
• Vaccines do not cause autism.
• An estimated 40 percent of autistic individuals are nonverbal.

Autism is a complicated condition. It's difficult to diagnose and presents itself differently in every person. Understanding a little more about this common disorder can help build awareness, as well as encourage education and empathy toward people with autism.

"Remember once you've met one autistic person, you've met one autistic person," said Hester Grainger, a co-founder of Perfectly Autistic, a neurodiversity consultancy in the U.K. "Everyone is different, whether they are autistic or not."

Follow-up stories about autism will examine how the condition is diagnosed and how it affects patients' lives in general, including their physical and mental health and their dating life.