Autism Spectrum Disorder (ASD)

Autism is a group of developmental brain disorders, collectively called autism spectrum disorder (ASD). The term "spectrum" refers to the wide range of symptoms, skills, and levels of impairment, or disability, that children with ASD can have. Some children are mildly impaired by their symptoms, but others are severely disabled.

ASD is diagnosed according to guidelines listed in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition - Text Revision (DSM-IV-TR).¹ The manual currently defines five disorders, sometimes called pervasive developmental disorders (PDDs), as ASD:

• Autistic disorder (classic autism)


• Asperger's disorder (Asperger syndrome)


• Pervasive developmental disorder not otherwise specified (PDD-NOS)


• Rett's disorder (Rett syndrome)


• Childhood disintegrative disorder (CDD).

What are the symptoms of ASD?

Symptoms of autism spectrum disorder (ASD) vary from one child to the next, but in general, they fall into three areas:

• Social impairment


• Communication difficulties


• Repetitive and stereotyped behaviors.

Children with ASD do not follow typical patterns when developing social and communication skills. Parents are usually the first to notice unusual behaviors in their child. Often, certain behaviors become more noticeable when comparing children of the same age.

In some cases, babies with ASD may seem different very early in their development. Even before their first birthday, some babies become overly focused on certain objects, rarely make eye contact, and fail to engage in typical back-and-forth play and babbling with their parents. Other children may develop normally until the second or even third year of life, but then start to lose interest in others and become silent, withdrawn, or indifferent to social signals. Loss or reversal of normal development is called regression and occurs in some children with ASD.²

Social impairment

Most children with ASD have trouble engaging in everyday social interactions. According to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition - Text Revision, some children with ASD may:

• Make little eye contact


• Tend to look and listen less to people in their environment or fail to respond to other people


• Do not readily seek to share their enjoyment of toys or activities by pointing or showing things to others


• Respond unusually when others show anger, distress, or affection.

Recent research suggests that children with ASD do not respond to emotional cues in human social interactions because they may not pay attention to the social cues that others typically notice. For example, one study found that children with ASD focus on the mouth of the person speaking to them instead of on the eyes, which is where children with typical development tend to focus.³ A related study showed that children with ASD appear to be drawn to repetitive movements linked to a sound, such as hand-clapping during a game of pat-a-cake.⁴ More research is needed to confirm these findings, but such studies suggest that children with ASD may misread or not notice subtle social cues—a smile, a wink, or a grimace—that could help them understand social relationships and interactions. For these children, a question such as, "Can you wait a minute?" always means the same thing, whether the speaker is joking, asking a real question, or issuing a firm request. Without the ability to interpret another person's tone of voice as well as gestures, facial expressions, and other nonverbal communications, children with ASD may not properly respond.

Likewise, it can be hard for others to understand the body language of children with ASD. Their facial expressions, movements, and gestures are often vague or do not match what they are saying. Their tone of voice may not reflect their actual feelings either. Many older children with ASD speak with an unusual tone of voice and may sound sing-song or flat and robotlike.¹

Children with ASD also may have trouble understanding another person's point of view. For example, by school age, most children understand that other people have different information, feelings, and goals than they have. Children with ASD may lack this understanding, leaving them unable to predict or understand other people's actions.

Communication issues

According to the American Academy of Pediatrics' developmental milestones, by the first birthday, typical toddlers can say one or two words, turn when they hear their name, and point when they want a toy. When offered something they do not want, toddlers make it clear with words, gestures, or facial expressions that the answer is "no."

For children with ASD, reaching such milestones may not be so straightforward. For example, some children with autism may:

• Fail or be slow to respond to their name or other verbal attempts to gain their attention


• Fail or be slow to develop gestures, such as pointing and showing things to others


• Coo and babble in the first year of life, but then stop doing so


• Develop language at a delayed pace


• Learn to communicate using pictures or their own sign language


• Speak only in single words or repeat certain phrases over and over, seeming unable to combine words into meaningful sentences


• Repeat words or phrases that they hear, a condition called echolalia


• Use words that seem odd, out of place, or have a special meaning known only to those familiar with the child's way of communicating.

Even children with ASD who have relatively good language skills often have difficulties with the back and forth of conversations. For example, because they find it difficult to understand and react to social cues, children with Asperger syndrome often talk at length about a favorite subject, but they won't allow anyone else a chance to respond or notice when others react indifferently.¹

Children with ASD who have not yet developed meaningful gestures or language may simply scream or grab or otherwise act out until they are taught better ways to express their needs. As these children grow up, they can become aware of their difficulty in understanding others and in being understood. This awareness may cause them to become anxious or depressed. For more information on mental health issues in children with ASD, see the section: What are some other conditions that children with ASD may have?

Repetitive and stereotyped behaviors

Children with ASD often have repetitive motions or unusual behaviors. These behaviors may be extreme and very noticeable, or they can be mild and discreet. For example, some children may repeatedly flap their arms or walk in specific patterns, while others may subtly move their fingers by their eyes in what looks to be a gesture. These repetitive actions are sometimes called "stereotypy" or "stereotyped behaviors."

Children with ASD also tend to have overly focused interests. Children with ASD may become fascinated with moving objects or parts of objects, like the wheels on a moving car. They might spend a long time lining up toys in a certain way, rather than playing with them. They may also become very upset if someone accidentally moves one of the toys. Repetitive behavior can also take the form of a persistent, intense preoccupation.¹ For example, they might be obsessed with learning all about vacuum cleaners, train schedules, or lighthouses. Children with ASD often have great interest in numbers, symbols, or science topics.

While children with ASD often do best with routine in their daily activities and surroundings, inflexibility may often be extreme and cause serious difficulties. They may insist on eating the same exact meals every day or taking the same exact route to school. A slight change in a specific routine can be extremely upsetting.¹ Some children may even have emotional outbursts, especially when feeling angry or frustrated or when placed in a new or stimulating environment.

No two children express exactly the same types and severity of symptoms. In fact, many typically developing children occasionally display some of the behaviors common to children with ASD. However, if you notice your child has several ASD-related symptoms, have your child screened and evaluated by a health professional experienced with ASD.