Everything You Need To Know About Autism Spectrum Disorder (ASD)

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What to Know About Autism Spectrum Disorder (ASD)

Medically reviewed by Dannell Roberts, PhD, BCBA-D — Written by Kristeen Cherney and Jill Seladi-Schulman, Ph.D. — Updated on December 24, 2024

Symptoms
The autism spectrum
Causes
Autism tests
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Takeaway

ASD describes a group of neurodevelopmental conditions that become evident during early childhood. Certain genetic and environmental factors can contribute to its development.

Autism spectrum disorder (ASD), or autism, is a broad term used to describe a group of neurodevelopmental conditions.

Differences in communication and social interaction characterize these conditions. People with ASD often demonstrate restricted and repetitive interests or patterns of behavior.

What are the symptoms of autism?

Symptoms of ASD typically become clearly evident during early childhood, between ages 12 and 24 months. However, symptoms may also appear earlier or later.

Early symptoms may include a marked delay in language or social development.

The Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR), used by clinicians to diagnose various psychiatric disorders, divides symptoms of ASD into two categories:

problems with communication and social interaction
restricted or repetitive patterns of behavior or activities

To be diagnosed with autism, a person must experience symptoms in both of these categories.

Problems with communication and social interaction

ASD can involve a range of issues with communication, many of which appear before age 5.

Here’s a what this might look like over time:

From birth: trouble maintaining eye contact
By 9 months: not responding to their name; not displaying facial expressions reflective of their emotions (like surprise or anger)
By 12 months: not engaging in basic interactive games; not calling a parent a special name, like “mama” or “dada”; using few or no gestures, like waving
By 15 months: not sharing their interests with others (by showing someone a favorite toy, for example)
By 18 months: not pointing or looking where others point; not pointing to show you something
By 24 months: not noticing when others appear sad or hurt; not saying more than one of two words
By 36 months: not noticing other children or joining them in play
By 48 months: not engaging in “pretend play,” like like pretending to be a doctor or treacher
By 60 months of age: not singing, acting, or dancing

Additionally, autistic children might have trouble expressing their feelings or understanding those of others starting at 36 months.

As they age, they might have difficulty talking or very limited speaking skills. Other autistic children might develop language skills at an uneven pace. If a particular topic interests them, for example, they might develop a very strong vocabulary for talking about that one topic, but they might have difficulty communicating about other things.

As autistic children begin talking, they might also talk in an unusual tone ranging from high-pitched and “sing-songy” to robotic or flat.

They might also show signs of hyperlexia, which involves reading beyond what’s expected of their age. Children on the autism spectrum might learn to read earlier than their neurotypical peers, sometimes as early as age 2. But they tend not to comprehend what they’re reading.

While hyperlexia does not always accompany autism, a 2017 review suggests anywhere from 6% to 20% of autistic children demonstrate early signs of hyperlexia, depending on how narrowly hyperlexia is defined.

As they interact with others, autistic children might have difficulty sharing their emotions and interests with others or find it hard to maintain back-and-forth conversations. Nonverbal communication, like maintaining eye contact or body language, might also remain difficult.

These challenges with communication can persist throughout adulthood.

»MORE:Symptoms of autism in babies

Restricted or repetitive patterns of behavior or activities

In addition to the communication and social issues mentioned above, autism includes symptoms related to body movements and behaviors.

These can include:

repetitive movements, like rocking, flapping their arms, spinning, or running back and forth
lining objects, like toys, up in strict order and getting upset when that order is disturbed
attachment to strict routines, like those around bedtime or getting to school
repeating words or phrases they hear someone say over and over again
getting upset over minor changes
focusing intently on parts of objects, like the wheel of a toy truck or the hair of a doll
unusual reactions to sensory input, like sounds, smells, and tastes
obsessive interests
exceptional abilities, like musical talent or memory capabilities

Other characteristics

Some autistic people might experience additional symptoms, including:

delayed movement, language, or cognitive skills
seizures
gastrointestinal symptoms, like constipation or diarrhea
excessive worry or stress
unusual levels of fear (either higher or lower than expected)
hyperactive, inattentive, or impulsive behaviors
unexpected emotional reactions
unusual eating habits or preferences
unusual sleep patterns
self-stimulating behaviors, known as “stimming“

What are the different types of autism?

The DSM-5-TR currently recognizes five ASD subtypes or specifiers:

with or without accompanying intellectual impairment
with or without accompanying language impairment
associated with a known medical or genetic condition or environmental factor
associated with another neurodevelopmental, mental, or behavioral disorder
with catatonia

Someone can receive a diagnosis of one or more specifiers.

Before the DSM-5-TR, autistic people may have received a diagnosis of:

autistic disorder
Asperger’s syndrome
pervasive development disorder-not otherwise specified (PDD-NOS)
childhood disintegrative disorder

It’s important to note that a person who received one of these earlier diagnoses has not lost their diagnosis and will not need to be reevaluated.

»MORE:Asperger's syndrome and the other older classifications for autism

What causes autism?

The exact cause of ASD is unknown.

Some suspected risk factors for ASD include:

having an immediate family member who’s autistic
certain genetic mutations
fragile X syndrome and other genetic disorders
being born to older parents
low birth weight
metabolic imbalances
exposure to heavy metals and environmental toxins
a maternal history of viral infections
fetal exposure to the medications valproic acid or thalidomide (Thalomid)

Vaccines and autism

A controversial 1998 study proposed a link between autism and the measles, mumps, and rubella (MMR) vaccine. However, that study was debunked and eventually retracted in 2010.

»MORE:Austism risk factors

What tests are used to diagnose autism?

An ASD diagnosis involves:

several screenings
genetic tests
evaluations

Developmental screenings

The American Academy of Pediatrics (AAP) recommends that all children undergo ASD screening at ages 18 and 24 months.

Screening can help identify ASD in children earlier than later. They may benefit from early diagnosis and support.

The Modified Checklist for Autism in Toddlers (M-CHAT) is a common screening tool many pediatric offices use.

It’s important to note that screening is not a diagnosis. Children who screen positively for ASD do not necessarily have it. Additionally, screenings do not always identify every child who’s autistic.

Other screenings and tests

Your child’s physician may recommend a combination of tests for autism, including:

DNA testing for genetic diseases
behavioral evaluation
visual and audio tests to rule out any issues with vision and hearing that aren’t related to ASD
occupational therapy screening
developmental questionnaires

Determining the diagnosis

A team of specialists typically makes the diagnosis. This team may include:

child psychologists
occupational therapists
speech and language pathologists

»MORE:Tests used to diagnose ASD

What treatments are available for autism?

There are no “cures” for ASD. Rather, for some autistic people, supportive therapies and other considerations can help them feel better or alleviate certain symptoms.

Many approaches involve therapies such as:

behavioral therapy
play therapy
occupational therapy
physical therapy
speech therapy

Massages, weighted clothing and blankets, and meditation techniques may also help some autistic people manage symptoms. However, results will vary. Some people may respond well to certain approaches, while others may not.

Alternative remedies

Research on alternative remedies is mixed, and some remedies can have negative health impacts.

Before investing in any alternative therapy, parents and caregivers should weigh the research and financial costs against any possible benefits.

When in doubt, talk with a healthcare professional.

»MORE:Alternative approaches for autism

The bottom line

ASD is a complex condition with symptoms that can vary greatly from person to person. There’s no cure for autism, but several approaches can help with managing symptoms, building social skills, and improving quality of life.

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How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

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https://www.aap.org/en/patient-care/autism/
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Medically reviewed by Dannell Roberts, PhD, BCBA-D — Written by Kristeen Cherney and Jill Seladi-Schulman, Ph.D. — Updated on December 24, 2024

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