What is autism?
What are some common signs of autism?
What are the symptoms of autism?
How is autism diagnosed?
What causes autism?
What role does inheritance play?

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What is autism?

Autism (sometimes called “classical autism”) is the most common condition in a group of developmental disorders known as the autism spectrum disorders (ASDs). Autism is characterized by impaired social interaction, problems with verbal and nonverbal communication, and unusual, repetitive, or severely limited activities and interests.

Autistic disorder is the most commonly known type of ASD, but there are others, including pervasive developmental disorder-not otherwise specified (PDD-NOS) and Asperger syndrome. These three conditions all have some of the same symptoms, but they differ in terms of when the symptoms start, how fast they appear, how severe they are, and their exact nature. These three conditions, along with Rett syndrome and childhood disintegrative disorder, make up the broad diagnosis category of pervasive developmental disorders.
Date: June27, 2006 Content source: National Center on Birth Defects and Developmental Disabilities

Experts estimate that three to six children out of every 1,000 will have autism. Males are four times more likely to have autism than females.

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What are some common signs of autism?

There are three distinctive behaviors that characterize autism. Autistic children have difficulties with social interaction, problems with verbal and nonverbal communication, and repetitive behaviors or narrow, obsessive interests. These behaviors can range in impact from mild to disabling. The hallmark feature of autism is impaired social interaction. Parents are usually the first to notice symptoms of autism in their child. As early as infancy, a baby with autism may be unresponsive to people or focus intently on one item to the exclusion of others for long periods of time. A child with autism may appear to develop normally and then withdraw and become indifferent to social engagement.

Children with autism may fail to respond to their name and often avoid eye contact with other people. They have difficulty interpreting what others are thinking or feeling because they can’t understand social cues, such as tone of voice or facial expressions, and don’t watch other people’s faces for clues about appropriate behavior. They often lack empathy and 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 autism don’t know how to play interactively with other children. Some 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. Many children with autism have a reduced sensitivity to pain, but are abnormally sensitive to sound, touch, or other sensory stimulation. These unusual reactions may contribute to behavioral symptoms such as a resistance to being cuddled or hugged.

Children with autism appear to have a higher than normal risk for certain co-existing 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. For reasons that are still unclear, about 20 to 30 percent of children with autism develop epilepsy by the time they reach adulthood. While people with schizophrenia may show some autistic-like behavior, their symptoms usually do not appear until the late teens or early adulthood. Most people with schizophrenia also have hallucinations and delusions, which are not found in autism.

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What are the symptoms of autism?

As the name “autism spectrum disorder” implies, ASDs cover a wide range of behaviors and abilities. People who have ASDs, like all people, differ greatly in the way they act and what they can do. No two people with ASDs will have the same symptoms. A symptom might be mild in one person and severe in another person. Types of problems and behaviors a child or adult with an ASD might have include the following:

• Social skills: People with ASDs might not interact with others the way most people do, or they might not be interested in other people at all. People with ASD might not make eye contact and may just want to be alone. They might have trouble understanding other people’s feelings or talking about their own feelings. Children with ASD might not like to be held or cuddled, or might cuddle only when they want to. Some people with ASD might not seem to notice when other people try to talk to them. Others might be very interested in people, but not know how to talk, play, or relate to them.

• Speech, language, and communication: About 40% of children with ASD do not talk at all. Others have echolalia, which is when they repeat back something that was said to them. The repeated words might be said right away or at a later time. For example, if you ask someone with ASD, “Do you want some juice?” he or she will repeat “Do you want some juice?” instead of answering your question. Or a person might repeat a television ad heard sometime in the past. People with ASD might not understand gestures such as waving goodbye. They might say “I” when they mean “you”, or vice versa. Their voices might sound flat and it might seem like they cannot control how loudly or softly they talk. People with ASD might stand too close to the people they are talking to, or might stick with one topic of conversation for too long. Some people with ASD can speak well and know a lot of words, but have a hard time listening to what other people say. They might talk a lot about something they really like, rather than have a back-and-forth conversation with someone.

• Repeated behaviors and routines: People with ASD might repeat actions over and over again. They might want to have routines where things stay the same so they know what to expect. They might have trouble if family routines change. For example, if a child is used to washing his or her face before dressing for bed, he or she might become very upset if asked to change the order and dress first and then wash.

Children with ASD develop differently from other children. Children without ASD develop at about the same rate in areas of development such as motor, language, cognitive, and social skills. Children with ASD develop at different rates in different areas of growth. They might have large delays in language, social, and cognitive skills, while their motor skills might be about the same as other children their age. They might be very good at things like putting puzzles together or solving computer problems, but not very good at some things most people think are easy, like talking or making friends. Children with ASD might also learn a hard skill before they learn an easy one. For example, a child might be able to read long words, but not be able to tell you what sound a “b” makes. A child might also learn a skill and then lose it. For example, a child may be able to say many words, but later stop talking altogether.

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Sources: 
Mauk J.E., Reber M., Batshaw M.L. Autism and other pervasive developmental disorders (4th edition). In: ML Batshaw, editor. Children with disabilities. Baltimore: Paul H. Brookes; 1997.
Powers MD. What is autism? In: MD Powers, editor. Children with autism: a parents’ guide, 2nd edition. Bethesda, MD: Woodbine House; 2000. pp. 1-44.