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:

Other characteristics

Some autistic people might experience additional symptoms, including: