Some children show signs of autism spectrum disorder in early infancy, such as reduced eye contact, lack of response to their name or indifference to caregivers. Other children may develop normally for the first few months or years of life, but then suddenly become withdrawn or aggressive or lose language skills they've already acquired. Signs usually are seen by age 2 years.

Each child with autism spectrum disorder is likely to have a unique pattern of behavior and level of severity — from low functioning to high functioning.

Some children with autism spectrum disorder have difficulty learning, and some have signs of lower than normal intelligence. Other children with the disorder have normal to high intelligence — they learn quickly, yet have trouble communicating and applying what they know in everyday life and adjusting to social situations.

Because of the unique mixture of symptoms in each child, severity can sometimes be difficult to determine. It's generally based on the level of impairments and how they impact the ability to function.

Below are some common signs shown by people who have autism spectrum disorder.

Social communication and interaction

A child or adult with autism spectrum disorder may have problems with social interaction and communication skills, including any of these signs:

• Fails to respond to his or her name or appears not to hear you at times
• Resists cuddling and holding, and seems to prefer playing alone, retreating into his or her own world
• Has poor eye contact and lacks facial expression
• Doesn't speak or has delayed speech, or loses previous ability to say words or sentences
• Can't start a conversation or keep one going, or only starts one to make requests or label items
• Speaks with an abnormal tone or rhythm and may use a singsong voice or robot-like speech
• Repeats words or phrases verbatim, but doesn't understand how to use them
• Doesn't appear to understand simple questions or directions
• Doesn't express emotions or feelings and appears unaware of others' feelings
• Doesn't point at or bring objects to share interest
• Inappropriately approaches a social interaction by being passive, aggressive or disruptive
• Has difficulty recognizing nonverbal cues, such as interpreting other people's facial expressions, body postures or tone of voice

Patterns of behavior

A child or adult with autism spectrum disorder may have limited, repetitive patterns of behavior, interests or activities, including any of these signs:

• Performs repetitive movements, such as rocking, spinning or hand flapping
• Performs activities that could cause self-harm, such as biting or head-banging
• Develops specific routines or rituals and becomes disturbed at the slightest change
• Has problems with coordination or has odd movement patterns, such as clumsiness or walking on toes, and has odd, stiff or exaggerated body language
• Is fascinated by details of an object, such as the spinning wheels of a toy car, but doesn't understand the overall purpose or function of the object
• Is unusually sensitive to light, sound or touch, yet may be indifferent to pain or temperature
• Doesn't engage in imitative or make-believe play
• Fixates on an object or activity with abnormal intensity or focus
• Has specific food preferences, such as eating only a few foods, or refusing foods with a certain texture

As they mature, some children with autism spectrum disorder become more engaged with others and show fewer disturbances in behavior. Some, usually those with the least severe problems, eventually may lead normal or near-normal lives. Others, however, continue to have difficulty with language or social skills, and the teen years can bring worse behavioral and emotional problems.

When to see a doctor

Babies develop at their own pace, and many don't follow exact timelines found in some parenting books. But children with autism spectrum disorder usually show some signs of delayed development before age 2 years.

If you're concerned about your child's development or you suspect that your child may have autism spectrum disorder, discuss your concerns with your doctor. The symptoms associated with the disorder can also be linked with other developmental disorders.

Signs of autism spectrum disorder often appear early in development when there are obvious delays in language skills and social interactions. Your doctor may recommend developmental tests to identify if your child has delays in cognitive, language and social skills, if your child:

• Doesn't respond with a smile or happy expression by 6 months
• Doesn't mimic sounds or facial expressions by 9 months
• Doesn't babble or coo by 12 months
• Doesn't gesture — such as point or wave — by 14 months
• Doesn't say single words by 16 months
• Doesn't play "make-believe" or pretend by 18 months
• Doesn't say two-word phrases by 24 months
• Loses language skills or social skills at any age

Autism spectrum disorder has no single known cause. Given the complexity of the disorder, and the fact that symptoms and severity vary, there are probably many causes. Both genetics and environment may play a role.

• Genetics. Several different genes appear to be involved in autism spectrum disorder. For some children, autism spectrum disorder can be associated with a genetic disorder, such as Rett syndrome or fragile X syndrome. For other children, genetic changes (mutations) may increase the risk of autism spectrum disorder. Still other genes may affect brain development or the way that brain cells communicate, or they may determine the severity of symptoms. Some genetic mutations seem to be inherited, while others occur spontaneously.
• Environmental factors. Researchers are currently exploring whether factors such as viral infections, medications or complications during pregnancy, or air pollutants play a role in triggering autism spectrum disorder.

No link between vaccines and autism spectrum disorder

One of the greatest controversies in autism spectrum disorder centers on whether a link exists between the disorder and childhood vaccines. Despite extensive research, no reliable study has shown a link between autism spectrum disorder and any vaccines. In fact, the original study that ignited the debate years ago has been retracted due to poor design and questionable research methods.

Avoiding childhood vaccinations can place your child and others in danger of catching and spreading serious diseases, including whooping cough (pertussis), measles or mumps.

The number of children diagnosed with autism spectrum disorder is rising. It's not clear whether this is due to better detection and reporting or a real increase in the number of cases, or both.

Autism spectrum disorder affects children of all races and nationalities, but certain factors increase a child's risk. These may include:

• Your child's sex. Boys are about four times more likely to develop autism spectrum disorder than girls are.
• Family history. Families who have one child with autism spectrum disorder have an increased risk of having another child with the disorder. It's also not uncommon for parents or relatives of a child with autism spectrum disorder to have minor problems with social or communication skills themselves or to engage in certain behaviors typical of the disorder.
• Other disorders. Children with certain medical conditions have a higher than normal risk of autism spectrum disorder or autism-like symptoms. Examples include fragile X syndrome, an inherited disorder that causes intellectual problems; tuberous sclerosis, a condition in which benign tumors develop in the brain; and Rett syndrome, a genetic condition occurring almost exclusively in girls, which causes slowing of head growth, intellectual disability and loss of purposeful hand use.
• Extremely preterm babies. Babies born before 26 weeks of gestation may have a greater risk of autism spectrum disorder.
• Parents' ages. There may be a connection between children born to older parents and autism spectrum disorder, but more research is necessary to establish this link.

Problems with social interactions, communication and behavior can lead to:

• Problems in school and with successful learning
• Employment problems
• Inability to live independently
• Social isolation
• Stress within the family
• Victimization and being bullied

There's no way to prevent autism spectrum disorder, but there are treatment options. Early diagnosis and intervention is most helpful and can improve behavior, skills and language development. However, intervention is helpful at any age. Though children usually don't outgrow autism spectrum disorder symptoms, they may learn to function well.

Your child's doctor will look for signs of developmental delays at regular checkups. If your child shows any symptoms of autism spectrum disorder, you'll likely be referred to a specialist who treats children with autism spectrum disorder, such as a child psychiatrist or psychologist, pediatric neurologist, or developmental pediatrician, for an evaluation.

Because autism spectrum disorder varies widely in symptoms and severity, making a diagnosis may be difficult. There isn't a specific medical test to determine the disorder. Instead, a specialist may:

• Observe your child and ask how your child's social interactions, communication skills and behavior have developed and changed over time
• Give your child tests covering hearing, speech, language, developmental level, and social and behavioral issues
• Present structured social and communication interactions to your child and score the performance
• Use the criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), published by the American Psychiatric Association
• Include other specialists in determining a diagnosis
• Recommend genetic testing to identify whether your child has a genetic disorder such as Rett syndrome or fragile X syndrome

No cure exists for autism spectrum disorder, and there is no one-size-fits-all treatment. The goal of treatment is to maximize your child's ability to function by reducing autism spectrum disorder symptoms and supporting development and learning. Early intervention during the preschool years can help your child learn critical social, communication, functional and behavioral skills.

The range of home-based and school-based treatments and interventions for autism spectrum disorder can be overwhelming, and your child's needs may change over time. Your health care provider can recommend options and help identify resources in your area.

If your child is diagnosed with autism spectrum disorder, talk to experts about creating a treatment strategy and build a team of professionals to meet your child's needs.

Treatment options may include:

• Behavior and communication therapies. Many programs address the range of social, language and behavioral difficulties associated with autism spectrum disorder. Some programs focus on reducing problem behaviors and teaching new skills. Other programs focus on teaching children how to act in social situations or communicate better with others. Applied behavior analysis (ABA) can help children learn new skills and generalize these skills to multiple situations through a reward-based motivation system.
• Educational therapies. Children with autism spectrum disorder often respond well to highly structured educational programs. Successful programs typically include a team of specialists and a variety of activities to improve social skills, communication and behavior. Preschool children who receive intensive, individualized behavioral interventions often show good progress.
• Family therapies. Parents and other family members can learn how to play and interact with their children in ways that promote social interaction skills, manage problem behaviors, and teach daily living skills and communication.
• Other therapies. Depending on your child's needs, speech therapy to improve communication skills, occupational therapy to teach activities of daily living, and physical therapy to improve movement and balance may be beneficial. A psychologist can recommend ways to address problem behavior.
• Medications. No medication can improve the core signs of autism spectrum disorder, but specific medications can help control symptoms. For example, certain medications may be prescribed if your child is hyperactive; antipsychotic drugs are sometimes used to treat severe behavioral problems; and antidepressants may be prescribed for anxiety. Keep all health care providers updated on any medications or supplements your child is taking. Some medications and supplements can interact, causing dangerous side effects.

Managing other medical and mental health conditions

In addition to autism spectrum disorder, children, teens and adults can also experience:

• Medical health issues. Children with autism spectrum disorder may also have medical issues, such as epilepsy, sleep disorders, limited food preferences or stomach problems. Ask your child's doctor how to best manage these conditions together.
• Problems with transition to adulthood. Teens and young adults with autism spectrum disorder may have difficulty understanding body changes. Also, social situations become increasingly complex in adolescence, and there may be less tolerance for individual differences. Behavior problems may be challenging during the teen years.
• Other mental health disorders. Teens and adults with autism spectrum disorder often experience other mental health disorders, such as anxiety and depression. Your doctor, mental health professional, and community advocacy and service organizations can offer help.

Planning for the future

Children with autism spectrum disorder typically continue to learn and compensate for problems throughout life, but most will continue to require some level of support. Planning for your child's future opportunities, such as employment, college, living situation, independence and the services required for support can make this process smoother.

Because autism spectrum disorder can't be cured, many parents seek alternative or complementary therapies, but these treatments have little or no research to show that they're effective. You could, unintentionally, reinforce negative behaviors. And some alternative treatments are potentially dangerous.

Talk with your child's doctor about the scientific evidence of any therapy that you're considering for your child.

Examples of complementary and alternative therapies that may offer some benefit when used in combination with evidence-based treatments include:

• Creative therapies. Some parents choose to supplement educational and medical intervention with art therapy or music therapy, which focuses on reducing a child's sensitivity to touch or sound. These therapies may offer some benefit when used along with other treatments.
• Sensory-based therapies. These therapies are based on the unproven theory that people with autism spectrum disorder have a sensory processing disorder that causes problems tolerating or processing sensory information, such as touch, balance and hearing. Therapists use brushes, squeeze toys, trampolines and other materials to stimulate these senses. Research has not shown these therapies to be effective, but it's possible they may offer some benefit when used along with other treatments.
• Massage. While massage may be relaxing, there isn't enough evidence to determine if it improves symptoms of autism spectrum disorder.
• Pet or horse therapy. Pets can provide companionship and recreation, but more research is needed to determine whether interaction with animals improves symptoms of autism spectrum disorder.

Some complementary and alternative therapies may not be harmful, but there's no evidence that they're helpful. Some may also include significant financial cost and be difficult to implement. Examples of these therapies include:

• Special diets. There's no evidence that special diets are an effective treatment for autism spectrum disorder. And for growing children, restrictive diets can lead to nutritional deficiencies. If you decide to pursue a restrictive diet, work with a registered dietitian to create an appropriate meal plan for your child.
• Vitamin supplements and probiotics. Although not harmful when used in normal amounts, there is no evidence they are beneficial for autism spectrum disorder symptoms, and supplements can be expensive. Talk to your doctor about vitamins and other supplements and the appropriate dosage for your child.
• Acupuncture. This therapy has been used with the goal of improving autism spectrum disorder symptoms, but the effectiveness of acupuncture is not supported by research.

Some complementary and alternative treatments do not have evidence that they are beneficial and they're potentially dangerous. Examples of complementary and alternative treatments that are not recommended for autism spectrum disorder include:

• Chelation therapy. This treatment is said to remove mercury and other heavy metals from the body, but there's no known link with autism spectrum disorder. Chelation therapy for autism spectrum disorder is not supported by research evidence and can be very dangerous. In some cases, children treated with chelation therapy have died.
• Hyperbaric oxygen treatments. Hyperbaric oxygen is a treatment that involves breathing oxygen inside a pressurized chamber. This treatment has not been shown to be effective in treating autism spectrum disorder symptoms and is not approved by the Food and Drug Administration (FDA) for this use.
• Intravenous immunoglobulin (IVIG) infusions. There is no evidence that using IVIG infusions improves autism spectrum disorder, and the FDA has not approved immunoglobulin products for this use.

Raising a child with autism spectrum disorder can be physically exhausting and emotionally draining. These suggestions may help:

• Find a team of trusted professionals. A team, coordinated by your doctor, may include social workers, teachers, therapists, and a case manager or service coordinator. These professionals can help identify and evaluate the resources in your area and explain financial services and state and federal programs for children and adults with disabilities.
• Keep records of visits with service providers. Your child may have visits, evaluations and meetings with many people involved in his or her care. Keep an organized file of these meetings and reports to help you decide about treatment options and monitor progress.
• Learn about the disorder. There are many myths and misconceptions about autism spectrum disorder. Learning the truth can help you better understand your child and his or her attempts to communicate.
• Take time for yourself and other family members. Caring for a child with autism spectrum disorder can put stress on your personal relationships and your family. To avoid burnout, take time out to relax, exercise or enjoy your favorite activities. Try to schedule one-on-one time with your other children and plan date nights with your spouse or partner — even if it's just watching a movie together after the children go to bed.
• Seek out other families of children with autism spectrum disorder. Other families struggling with the challenges of autism spectrum disorder may have useful advice. Some communities have support groups for parents and siblings of children with the disorder.
• Ask your doctor about new technologies and therapies. Researchers continue to explore new approaches to help children with autism spectrum disorder. See the Centers for Disease Control and Prevention website on autism spectrum disorders for helpful materials and links to resources.

Your child's health care provider will look for developmental problems at regular checkups. Mention any concerns you have during your appointment. If your child shows any signs of autism spectrum disorder, you'll likely be referred to a specialist who treats children with the disorder for an evaluation.

Bring a family member or friend with you to the appointment, if possible, to help you remember information and for emotional support.

Here's some information to help you prepare for your appointment.

What you can do

Before your child's appointment, make a list of:

• Any medications, including vitamins, herbs and over-the-counter medicines that your child is taking, and their dosages.
• Any concerns you have about your child's development and behavior.
• When your child began talking and reaching developmental milestones. If your child has siblings, also share information about when they reached their milestones.
• A description of how your child plays and interacts with other children, siblings and parents.
• Questions to ask your child's doctor to make the most of your time.

In addition, it may be helpful to bring:

• Notes of any observations from other adults and caregivers, such as babysitters, relatives and teachers. If your child has been evaluated by other health care professionals or an early intervention or school program, bring this assessment.
• A record of developmental milestones for your child, such as a baby book or baby calendar, if you have one.
• A video of your child's unusual behaviors or movements, if you have one.

Questions to ask your child's doctor may include:

• Why do you think my child does (or doesn't) have autism spectrum disorder?
• Is there a way to confirm the diagnosis?
• If my child does have autism spectrum disorder, is there a way to tell how severe it is?
• What changes can I expect to see in my child over time?
• What kind of special therapies or care do children with autism spectrum disorder need?
• How much and what kinds of regular medical care will my child need?
• What kind of support is available to families of children with autism spectrum disorder?
• How can I learn more about autism spectrum disorder?

Don't hesitate to ask other questions during your appointment.

What to expect from your child's doctor

Your child's doctor is likely to ask you a number of questions. Be ready to answer them to reserve time to go over any points you want to focus on. Your doctor may ask:

• What specific behaviors prompted your visit today?
• When did you first notice these signs in your child? Have others noticed signs?
• Have these behaviors been continuous or occasional?
• Does your child have any other symptoms that might seem unrelated to autism spectrum disorder, such as stomach problems?
• Does anything seem to improve your child's symptoms?
• What, if anything, appears to worsen symptoms?
• When did your child first crawl? Walk? Say his or her first word?
• What are some of your child's favorite activities?
• How does your child interact with you, siblings and other children? Does your child show interest in others, make eye contact, smile or want to play with others?
• Does your child have a family history of autism spectrum disorder, language delay, Rett syndrome, obsessive-compulsive disorder, or anxiety or other mood disorders?
• What is your child's education plan? What services does he or she receive through school?