
Autism Spectrum Disorder or ASD impacts an individual's ability to communicate, socially interact, behave, and learn. ASD is considered to be a spectrum disorder. That means ASD affects each person in different ways and can range from very mild to severe. Some children and adults with ASD are fully able to perform all activities of daily living while others require substantial support to perform basic activities. Every individual with ASD is unique in their abilities and challenges.
ASD is the fastest-growing developmental disability. The number of people who are receiving a diagnosis of ASD is increasing. Recent reports estimate that, on average, as many as one in every 59 children in the United States has an Autism Spectrum Disorder. No single factor can explain why more children are being identified with ASD. It is not clear whether this is due to the creation of a broader definition of ASDs or better diagnosis. It affects individuals from all racial, ethnic, and socioeconomic backgrounds. ASD is four times more common in boys. The first signs usually appear in early childhood but may not be recognized until later in life.
ASD is considered to be a lifelong neurological developmental disorder for which there is no known etiology or cure.

The Diagnostic and Statistical Manual of Mental Disorders (DSM), published by the American Psychiatric Association (APA), is used by clinicians and researchers to diagnose and classify disorders, including ASD. To be diagnosed with ASD, a person must have difficulty with social communication and interaction and display restricted, repetitive patterns of behavior, interests, or activities. At this time, there is no medical test to diagnose autism.

For many individuals with ASD, symptoms improve with age and behavioral therapies. Many individuals with ASD are also affected by other disabilities and disorders such as depression or anxiety. People with ASD may continue to need services and supports throughout life, but with support can work successfully and live independently.

Social Communication
Individuals with ASD typically have some differences in the way that they communicate and socialize. Some may have difficulty understanding the feelings, thoughts and intentions of others and difficulty identifying and communicating their own feelings, thoughts and intentions to others.
While many young people with ASD speak fluently, the mutual give-and-take nature of typical communication and interaction is often particularly challenging. Many experience problems using language appropriately in social situations. This might mean they find it difficult to hold two-way conversations. A tendency for making literal interpretations can mean figures of speech and sarcasm are misunderstood or misused. Problems with pragmatic language might also lead to people having trouble using the right language for a social situation – their language might be very formal, and their vocabulary might be very rich. Some individuals might prefer to be alone or seem uninterested in others. Difficulties in reading social cues or situations, expressing empathy and understanding others, mean that they might need help to interact with others. They also might have difficulty with eye contact, facial expressions, body language, and forming or maintaining social relationships.
Behavior and Interests
Many individuals with ASD engage in repetitive movements or unusual behaviors. Sometimes one or more senses are either over- or under-reactive to stimulation, resulting in behaviors such as rocking, spinning, and hand-flapping. Some people with ASD develop special interests that are unusual in their intensity and focus. Public transportation, maps, physics and computers are all examples of the wide and varied special interests of people with ASD. Individuals with ASD prefer situations to be consistent and thrive on routine and consistency. Changes to the daily patterns of life and transitions can be very difficult.
Thinking
Autism consists of perceptual and thinking differences; a different way of perceiving and experiencing the world. Many with ASD are often logical thinkers and can be good with facts, figures and details. This logical thinking may mean that they can have difficulty understanding non-concrete ideas and filtering irrelevant details.

The Centers for Disease Control and Prevention (CDC) have identified possible red flags for autism spectrum disorder in young children, including:
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Not responding to his/her name by 12 months of age
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Not pointing at objects to show interest by 14 months
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Not playing "pretend" games by 18 months
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Avoiding eye contact or preferring to be alone
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Getting upset by minor changes
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Flapping their hands, rocking their body, or spinning in circles
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Having unusual and sometimes intense reactions to the way things smell, taste, feel, and/or look
If there is a strong concern that your child is showing possible signs of autism, then a diagnostic evaluation should be performed. This typically involves an interview and play-based testing with your child done by a psychologist, developmental-behavioral pediatrician, child psychiatrist or other providers.

While children are not typically cured nor do they outgrow autism, studies have shown that symptoms can improve with early diagnosis and treatment. There is no single treatment for autism. Treatments can include intensive skill-building and teaching educational sessions, known as applied behavior analysis (ABA). Additionally, there are many evidence-based interventions that are effective.

In 2013, a revised version of the Diagnostic and Statistical Manual of Mental Disorders (DSM) was released. This revision changed the way autism is classified and diagnosed. Using the previous version of the DSM, people could be diagnosed with one of several separate conditions:
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Autistic disorder
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Asperger’s syndrome
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Pervasive developmental disorder not otherwise specified (PDD-NOS)
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Rett's disorder
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Childhood Disintegrative Disorder
In the current revised version of the DSM (the DSM-5), these separate conditions have been combined into one diagnosis called “autism spectrum disorder.” Using the DSM-5, people who were previously diagnosed with Asperger’s syndrome would now be diagnosed with autism spectrum disorder. Although the “official” diagnosis of ASD has changed, there is nothing wrong with continuing to use terms such as Asperger’s syndrome to describe oneself or to identify with a peer group. Rett's disorder was removed from the DSM since recent research identified that mutations in the MeCP2 gene cause the disorder. Children with Rett syndrome are no longer automatically considered to be on the autism spectrum. Instead, the individual will have to meet the diagnostic criteria for autism spectrum disorder outlined in the DSM-5.