What Is Autism Spectrum Disorder?

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). 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).

 

Signs & Symptoms

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normally until the second or even third year of life, but then start to lose interest in others and become silent, withdrawn, or indifferent to social signals.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.

 

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. 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. 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 robot-like.

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.

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.

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. 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.

Signs and symptoms of autism spectrum disorders: Social skills

Basic social interaction can be difficult for children with autism spectrum disorders. Symptoms may include:

Unusual or inappropriate body language, gestures, and facial expressions (e.g. avoiding eye contact or using facial expressions that don’t match what he or she is saying).

Lack of interest in other people or in sharing interests or achievements (e.g. showing you a drawing, pointing to a bird).

Unlikely to approach others or to pursue social interaction; comes across as aloof and detached; prefers to be alone.

Difficulty understanding other people’s feelings, reactions, and nonverbal cues.

Resistance to being touched.

Difficulty or failure to make friends with children the same age.

 

Signs and symptoms of autism spectrum disorders: Speech and language

Problems with speech and language comprehension are a telltale sign of the autism spectrum disorders. Symptoms may include:

Delay in learning how to speak (after the age of 2) or doesn’t talk at all.

Speaking in an abnormal tone of voice, or with an odd rhythm or pitch.

Repeating words or phrases over and over without communicative intent.

Trouble starting a conversation or keeping it going.

Difficulty communicating needs or desires.

Doesn’t understand simple statements or questions.

Taking what is said too literally, missing humor, irony, and sarcasm.

 

Signs and symptoms of autism spectrum disorders: Restricted behavior and play

Children with autism spectrum disorders are often restricted, rigid, and even obsessive in their behaviors, activities, and interests. Symptoms may include:

Repetitive body movements (hand flapping, rocking, spinning); moving constantly.

Obsessive attachment to unusual objects (rubber bands, keys, light switches).

Preoccupation with a specific topic of interest, often involving numbers or symbols (maps, license plates, sports statistics).

A strong need for sameness, order, and routines (e.g. lines up toys, follows a rigid schedule). Gets upset by change in their routine or environment.

Clumsiness, abnormal posture, or odd ways of moving.

Fascinated by spinning objects, moving pieces, or parts of toys (e.g. spinning the wheels on a race car, instead of playing with the whole car).

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. 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.

Rett syndrome and childhood disintegrative disorder (CDD) are two very rare forms of ASD that include a regression in development. Only 1 of every 10,000 to 22,000 girls has Rett syndrome. Even rarer, only 1 or 2 out of 100,000 children with ASD have CDD.

Unlike other forms of ASD, Rett syndrome mostly affects girls. In general, children with Rett syndrome develop normally for 6–18 months before regression and autism-like symptoms begin to appear. Children with Rett syndrome may also have difficulties with coordination, movement, and speech. Physical, occupational, and speech therapy can help, but no specific treatment for Rett syndrome is available yet.

CDD affects very few children, which makes it hard for researchers to learn about the disease. Symptoms of CDD may appear by age 2, but the average age of onset is between age 3 and 4. Until this time, children with CDD usually have age-appropriate communication and social skills. The long period of normal development before regression helps to set CDD apart from Rett syndrome. CDD may affect boys more often than girls.

Children with CDD experience severe, wide-ranging and obvious loss of previously-obtained motor, language, and social skills. The loss of such skills as vocabulary is more dramatic in CDD than in classic autism. Other symptoms of CDD include loss of bowel and bladder control.

 

What are some other conditions that children with ASD may have?

Sensory problems

Many children with autism spectrum disorder (ASD) either overreact or underreact to certain sights, sounds, smells, textures, and tastes. For example, some may:

            Dislike or show discomfort from a light touch or the feel of clothes on their skin

            Experience pain from certain sounds, like a vacuum cleaner, a ringing telephone, or a sudden storm; sometimes they will cover their            

            ears and scream

            Have no reaction to intense cold or pain.

 

At times they may ignore people speaking to them, even to the point of appearing deaf. However, at other times they may be disturbed by even the softest sounds. Sudden noises such as a ringing telephone can be upsetting, and they may respond by covering their ears and making repetitive noises to drown out the offending sound. Children on the autism spectrum also tend to be highly sensitive to touch and to texture. They may cringe at a pat on the back or the feel of certain fabric against their skin.

Researchers are trying to determine if these unusual reactions are related to differences in integrating multiple types of information from the senses.

Emotional difficulties

Children with autism spectrum disorders may have difficulty regulating their emotions or expressing them appropriately. For instance, your child may start to yell, cry, or laugh hysterically for no apparent reason. When stressed, he or she may exhibit disruptive or even aggressive behavior (breaking things, hitting others, or harming him or herself). The National Dissemination Center for Children with Disabilities also notes that autistic kids may be unfazed by real dangers like moving vehicles or heights, yet be terrified of harmless objects such as a stuffed animal.

Sleep problems

Children with ASD tend to have problems falling asleep or staying asleep, or have other sleep problems. These problems make it harder for them to pay attention, reduce their ability to function, and lead to poor behavior. In addition, parents of children with ASD and sleep problems tend to report greater family stress and poorer overall health among themselves.

Fortunately, sleep problems can often be treated with changes in behavior, such as following a sleep schedule or creating a bedtime routine. Some children may sleep better using medications such as melatonin, which is a hormone that helps regulate the body's sleep-wake cycle. Like any medication, melatonin can have unwanted side effects. Talk to your child's doctor about possible risks and benefits before giving your child melatonin. Treating sleep problems in children with ASD may improve the child's overall behavior and functioning, as well as relieve family stress.

Intellectual disability

Many children with ASD have some degree of intellectual disability. When tested, some areas of ability may be normal, while others—especially cognitive (thinking) and language abilities—may be relatively weak. For example, a child with ASD may do well on tasks related to sight (such as putting a puzzle together) but may not do as well on language-based problem-solving tasks. Children with a form of ASD like Asperger syndrome often have average or above-average language skills and do not show delays in cognitive ability or speech.

The autism spectrum disorders occur at all intelligence levels. However, even kids with normal to high intelligence often have unevenly developed cognitive skills. Not surprisingly, verbal skills tend to be weaker than nonverbal skills. In addition, children with Autism spectrum disorders typically do well on tasks involving immediate memory or visual skills, while tasks involving symbolic or abstract thinking are more difficult.

Seizures

One in four children with ASD has seizures, often starting either in early childhood or during the teen years. Seizures, caused by abnormal electrical activity in the brain, can result in

            A short-term loss of consciousness, or a blackout

            Convulsions, which are uncontrollable shaking of the whole body, or unusual movements

            Staring spells.

Sometimes lack of sleep or a high fever can trigger a seizure. An electroencephalogram (EEG), a nonsurgical test that records electrical activity in the brain, can help confirm whether a child is having seizures. However, some children with ASD have abnormal EEGs even if they are not having seizures.

Seizures can be treated with medicines called anticonvulsants. Some seizure medicines affect behavior; changes in behavior should be closely watched in children with ASD. In most cases, a doctor will use the lowest dose of medicine that works for the child. Anticonvulsants usually reduce the number of seizures but may not prevent all of them.

Fragile X syndrome

Fragile X syndrome is a genetic disorder and is the most common form of inherited intellectual disability, causing symptoms similar to ASD. The name refers to one part of the X chromosome that has a defective piece that appears pinched and fragile when viewed with a microscope. Fragile X syndrome results from a change, called a mutation, on a single gene. This mutation, in effect, turns off the gene. Some people may have only a small mutation and not show any symptoms, while others have a larger mutation and more severe symptoms.

Around 1 in 3 children who have Fragile X syndrome also meet the diagnostic criteria for ASD, and about 1 in 25 children diagnosed with ASD have the mutation that causes Fragile X syndrome.  Because this disorder is inherited, children with ASD should be checked for Fragile X, especially if the parents want to have more children. Other family members who are planning to have children may also want to be checked for Fragile X syndrome.

Tuberous sclerosis

Tuberous sclerosis is a rare genetic disorder that causes noncancerous tumors to grow in the brain and other vital organs. Tuberous sclerosis occurs in 1 to 4 percent of people with ASD. A genetic mutation causes the disorder, which has also been linked to mental retardation, epilepsy, and many other physical and mental health problems. There is no cure for tuberous sclerosis, but many symptoms can be treated.

Gastrointestinal problems

Some parents of children with ASD report that their child has frequent gastrointestinal (GI) or digestion problems, including stomach pain, diarrhea, constipation, acid reflux, vomiting, or bloating. Food allergies may also cause problems for children with ASD. It's unclear whether children with ASD are more likely to have GI problems than typically developing children. If your child has GI problems, a doctor who specializes in GI problems, called a gastroenterologist, can help find the cause and suggest appropriate treatment.

Some studies have reported that children with ASD seem to have more GI symptoms, but these findings may not apply to all children with ASD. For example, a recent study found that children with ASD in Minnesota were more likely to have physical and behavioral difficulties related to diet (for example, lactose intolerance or insisting on certain foods), as well as constipation, than children without ASD. The researchers suggested that children with ASD may not have underlying GI problems, but that their behavior may create GI symptoms—for example, a child who insists on eating only certain foods may not get enough fiber or fluids in his or her diet, which leads to constipation.

Some parents may try to put their child on a special diet to control ASD or GI symptoms. While some children may benefit from limiting certain foods, there is no strong evidence that these special diets reduce ASD symptoms. If you want to try a special diet, first talk with a doctor or a nutrition expert to make sure your child's nutritional needs are being met.

Co-occurring mental disorders

Children with ASD can also develop mental disorders such as anxiety disorders, attention deficit hyperactivity disorder (ADHD), or depression. Research shows that people with ASD are at higher risk for some mental disorders than people without ASD. Managing these co-occurring conditions with medications or behavioral therapy, which teaches children how to control their behavior, can reduce symptoms that appear to worsen a child's ASD symptoms. Controlling these conditions will allow children with ASD to focus more on managing the ASD.