By Jayne Leonard

Reviewed by Timothy J. Legg, PhD, CRNP

  1. What is autism?
  2. Signs and symptoms in a 3-year-old
  3. Signs of autism in older children
  4. Autism in girls vs. boys
  5. Diagnosis
  6. Management
  7. Summary

Parents and caregivers who notice particular changes or challenges in a 3-year-old may wonder if these could indicate autism.

Autism spectrum disorder (ASD) affects approximately 1 in 59 children. ASD covers a range of conditions that doctors used to believe were different, including autism and Asperger's syndrome.

Behavioral symptoms often develop in early childhood, with research suggesting that parents and caregivers tend to notice some of these behaviors before a child's first birthday.

Despite this, the Centers for Disease Control and Prevention (CDC) report that most autistic children do not receive a diagnosis until after 4 years of age.

In this article, we discuss the possible signs and symptoms of autism in 3-year old children.

What is autism?

signs of autism in 3 year old lonely


Autistic people may have difficulty developing friendships and understanding other people's feelings.

Autism is one of the more common neurodevelopmental disorders. It is characterized by challenges with social interaction, communication, and flexibility in thinking and behavior.

Autistic people may have difficulty relating to those around them, developing friendships, and understanding other people's feelings. They may also have repetitive thoughts and perform repetitive behaviors.

Autistic people often have higher rates of co-occurring, or comorbid, conditions than the general population. Some of these conditions include:

According to some research, 70% of autistic children have one co-occurring condition, while 41% have two or more, including attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder, or social anxiety.

There is no "cure" for autism, and many autistic people feel that ASD is an integral part of their identity. Doctors and therapists can help people manage their symptoms and maintain a happy, healthy life.

Signs and symptoms in a 3-year-old

Some signs of autism in a 3-year-old might include:

Social detachment

Autistic children may not play with others. They may:

  • play alone
  • have no interest in socializing
  • avoid sharing toys
  • not understand turn-taking play
  • not respond to their name
  • not understand make-believe or "pretend" play

Differences in emotional expression

Autistic people experience a full range of emotions, but they typically read and express them differently from others.

An autistic 3-year old may:

  • have difficulty discussing or expressing their feelings
  • have trouble understanding the feelings of others
  • struggle to be soothed or comforted
  • make facial expressions that may not match internal feelings
  • avoid physical contact with others
  • become rigid when hugged
  • show no emotion when a parent leaves the room

Communication difficulties

Autism is characterized by difficulty communicating. At 3 years of age, an autistic child may:

  • demonstrate delays or regression in speech and language skills
  • speak in a flat or sing-song manner
  • not speak at all
  • avoid eye contact
  • appear expressionless
  • not answer questions appropriately
  • repeat the words of others
  • use words, phrases, or sounds repeatedly, which doctors call echolalia
  • use the wrong pronouns, for example, "you" instead of "I"
  • not use gestures, such as pointing or waving
  • not respond to pointing
  • not understand age-appropriate humor


Autistic children often display seemingly unusual or repetitive behaviors. They may:

  • flap their hands repeatedly
  • spin around
  • rock back and forth
  • appear fascinated with a particular toy or activity
  • have obsessive behaviors
  • line up toys in an ordered fashion
  • be hyperactive in certain situations
  • have a short attention span
  • insist on specific routines or rituals
  • display agitation, anger, or frustration when someone disturbs their routine or ritual

Other signs

Additional potential signs of autism in children include:

  • aggression
  • impulsivity
  • self-injuring
  • intense reactions to sounds, smells, textures, colors, or tastes
  • temper tantrums
  • unusual eating habits

Not all autistic children show all these signs, and many neurotypical children occasionally demonstrate some of them. For this reason, a professional diagnosis is essential.


Signs of autism as children get older

signs of autism in 3 year old toys


Autistic children may have a preference for being alone as they get older.

Autistic children may experience more or different challenges with communication, socialization, and behavior as they age. This is partly due to increasing social demands at school and in the community.

School-age children and teenagers may display some of the following:

  • a need for routine
  • a preference for being alone
  • a lack of friendships
  • aggression
  • agitation or frustration when routines are disturbed
  • anxiety
  • difficulty making conversation and taking turns in a conversation
  • heightened or lowered sense of smell, taste, touch, vision, and hearing
  • obsession with specific topics or activities
  • problems interpreting nonverbal and social cues
  • rigidity when following rules in school and sports
  • unusual posture or movements, such as biting or flicking of the fingers
  • unusual speech patterns and tone

What is the difference between autism and ADHD?

What is the difference between autism and ADHD?

Learn about the key differences between autism and ADHD here.

Read now

Autism in girls vs. boys

ASD is 4 times more common in boys than in girls.

Studies suggest that autistic girls may display different and more subtle symptoms. This may lead to underdiagnosis or misdiagnosis and subsequent difficulties accessing effective treatment.

The authors of a study involving more than 800 autistic children reported that girls and boys showed differences in both brain structure and behavior. Girls tended to show less repetitive and restrictive behaviors.

Recent research also suggests that autistic girls and autistic boys tell stories differently. Girls may use more "cognitive process" words, such as "think" and "know," while previous studies suggested that all autistic children use fewer of these words.

Other theories about why ASD is considered to be less prevalent in females include:

  • Genetic differences between the sexes mean that females are less likely to inherit autism.
  • Teachers, parents, and caregivers underreport behaviors that suggest autism in girls.
  • Girls may be better able to "mask" their social challenges.
  • Diagnostic tools are based on how symptoms present in males, leading to underdiagnosis in females.


Parents and caregivers who think that a child may be autistic should consult a doctor for a diagnosis or a referral to a specialist.

In order to know when to seek help, it is important to be aware of the milestones that a child should reach at each age. The CDC provide a comprehensive list of milestones for 3-year old children.

A specialist — such as a developmental pediatrician or a child psychologist — can provide a formal diagnosis. These professionals will observe a child's behavior and track their development.

They will also test the child's hearing and vision and may perform additional tests to rule out other underlying conditions that could be causing symptoms.

For example, a child with hearing problems may also demonstrate social difficulties or not respond when spoken to.

A doctor may diagnose a specific level of autism. Each level requires a different type and amount of support. Learn more about levels of autism in this article.


signs of autism in 3 year old child therapy Communication and behavioral therapies may be helpful for autistic children.

Early intervention is key for improving outcomes for autistic children. When they are young, children can learn helpful social, communication, and behavioral skills.

There are many options for autistic children, and these vary, depending on the child's symptoms. The best place to seek information is from the child's doctor.

The local school district should also be able to provide information about nearby resources, including early intervention programs.

Therapies and other forms of support that may be helpful for autistic children include:

  • behavioral therapies
  • communication skills training
  • educational programs
  • family therapy and parent education
  • occupational therapy
  • physical therapy
  • psychological interventions
  • speech therapy
  • medications
  • lifestyle changes, such as creating and sticking to a particular routine

It is essential to manage any other conditions that occur in children, teenagers, and adults with autism. These can include:

  • ADHD
  • depression
  • anxiety
  • seizures


Autistic 3-year-olds will display noticeable signs and symptoms of the condition, particularly related to communication, social interaction, and behavior.

The earlier a child receives an accurate diagnosis and support, the better the outcome. A variety of therapies are available for autistic children and their families.

Parents and caregivers should speak to a doctor if they think that they are noticing signs of autism.

A doctor can evaluate the child and refer them to a specialist. They can also provide information about treatments and local and national resources.