What are the common signs of autism?

Dr. Jeanne Morrison, PhD
Family Practitioner

The hallmark feature of autism spectrum disorder (ASD) is impaired social interaction. A child's primary caregivers are usually the first to notice signs of ASD. As early as infancy, a baby with ASD may be unresponsive to people or focus intently on one item to the exclusion of others for long periods. A child with ASD may appear to develop normally and then withdraw and become indifferent to social engagement.

Children with ASD may fail to respond to their names and often avoid eye contact with other people. They have difficulty interpreting what others are thinking or feeling because they cannot understand social cues, such as tone of voice or facial expressions, and do not watch other people's faces for clues about appropriate behavior. They lack empathy.

Many children with ASD engage in repetitive movements, such as rocking and twirling, or in self-abusive behavior, such as biting or head-banging. They also tend to start speaking later than other children, and may refer to themselves by name instead of "I" or "me." Children with ASD do not know how to play interactively with other children. Some of them speak in a sing-song voice about a narrow range of favorite topics, with little regard for the interests of the person to whom they are speaking.

Children with ASD appear to have a higher than normal risk for certain co-occurring conditions, including Fragile X syndrome (which causes mental retardation), tuberous sclerosis (in which tumors grow on the brain), epileptic seizures, Tourette syndrome, learning disabilities, and attention deficit disorder. Almost twenty to thirty percent of children with ASD develop epilepsy by the time they reach adulthood.

This answer is based on source information from the National Institute of Neurological Disorders and Stroke.

People with autism have one or more symptoms in each of the areas listed below. While many of these symptoms show up in childhood, autism warning signs can be seen in babies. Remember that autism symptoms happen along a spectrum. They may be present in different combinations and with different degrees of severity.

Problems with social interactions. People with autism:

  • Don't use or respond to social cues like eye-to-eye contact, facial expressions, or body postures.
  • Have trouble making friends and mixing with others.
  • Appear aloof and seem to prefer to spend time alone.
  • Lack interest in sharing ideas, fun activities, or achievements with others.
  • May not want to cuddle or be cuddled.
  • Don't engage in imaginative or symbolic play.

Trouble communicating. People with autism:

  • Have delayed language development.
  • Have trouble starting or maintaining conversation, talk at -- not with -- others in one-sided conversations.
  • May repeat words or phrases.
  • Have difficulty expressing needs -- may gesture or point instead of using words.
  • Are not responsive to verbal cues -- may appear deaf.

Repeating patterns of behavior, interests, and activities. People with autism:

  • Have intense preoccupations with certain topics.
  • May have unusual attachments to particular objects.
  • Insist on schedules, routines, and rituals.
  • Display sustained odd play or gestures (for example, spinning objects, hand or finger flapping, or rocking).
  • May hurt themselves (for example, bite their own arms) or physically attack others.
  • Are noticeably overactive or underactive.
  • May have uneven development of motor skills (for example, can stack blocks but not kick a ball).

Other. People with autism:

  • May be overly sensitive to sounds, sights, sensations, and smells. For example, particular smells might cause a child to gag. Bright lights or even a hug may cause the child to draw back.
  • May be overly sensitive to pain -- or may be noticeably under-sensitive to pain.
  • Show little or no fear of danger.


Some signs of autism include:
  • trouble understanding other people's feelings or talking about his or her own feelings
  • delayed speech and language skills 
  • repeating words or phrases over and over 
  • getting upset by minor changes 
  • having obsessive interests 
  • unusual body movements like flapping his or her hands, rocking, or spinning 
  • having unusual reactions to the way things sound, smell, taste, look, or feel.
It is very important that you talk to your pediatrician about these concerns so that he or she can refer your child to the appropriate specialist for an evaluation. Getting help early on is very important!

In toddlers, more obvious markers of ASD may not be present and it is often the absence of normal behavior that provides cues about aberrant development. There are three core symptom domains (social relatedness, communication difficulties, and repetitive behaviors/restricted interests). However, the symptom presentation varies across individuals. Some common symptoms include fleeting eye contact, limited gesturing (pointing, waving good-bye), limited pretend play, difficulty reading nonverbal cues, difficulty taking others’ perspectives, odd language (scripted speech, echolalia) repetitive motor and object play, difficulties with changes in environment/routine. 

Autism is a disorder characterized by impaired social and communicative disorders with repetitive behavior or restricted interests seen before the age of three. Impairments in social development may include poor eye contact, awkward social interactions, and predominant nonverbal communication. Communication problems can include delayed babbling and the inability to hold a conversation. Finally, repetitive behavior can include lining objects up, repetitive movement including head bobbing or hand flapping or resistance to change.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.