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Autism is a developmental disorder that appears in the first 3 years of life, and affects the brain's normal development of social and communication skills.

Pervasive developmental disorder - autism

Autism is a physical condition linked to abnormal biology and chemistry in the brain. The exact causes of these abnormalities remain unknown, but this is a very active area of research. There are probably a combination of factors that lead to autism.

Genetic factors seem to be important. For example, identical twins are much more likely than fraternal twins or siblings to both have autism. Similarly, language abnormalities are more common in relatives of autistic children. Chromosomal abnormalities and other nervous system (neurological) problems are also more common in families with autism.

A number of other possible causes have been suspected, but not proven. They involve:

• Diet
• Digestive tract changes
• Mercury poisoning
• The body's inability to properly use vitamins and minerals
• Vaccine sensitivity

The exact number of children with autism is not known. A report released by the U.S. Centers for Disease Control and Prevention (CDC) suggests that autism and related disorders are more common than previously thought. It is unclear whether this is due to an increasing rate of the illness or an increased ability to diagnose the illness.

Autism affects boys 3 - 4 times more often than girls. Family income, education, and lifestyle do not seem to affect the risk of autism.

Some parents have heard that the MMR vaccine children receive may cause autism. This theory was based, in part, on two facts. First, the incidence of autism has increased steadily since around the same time the MMR vaccine was introduced. Second, children with the regressive form of autism (a type of autism that develops after a period of normal development) tend to start to show symptoms around the time the MMR vaccine is given. This is likely a coincidence due to the age of children at the time they receive this vaccine.

Several major studies have found NO connection between the vaccine and autism. The American Academy of Pediatrics and the Center for Disease Control and Prevention report that there is no proven link between autism and the MMR vaccine, or any other vaccine.

Some doctors believe the increased incidence in autism is due to newer definitions of autism. The term "autism" now includes a wider spectrum of children. For example, a child who is diagnosed with high-functioning autism today may have been thought to simply be odd or strange 30 years ago.

Other pervasive developmental disorders include:

• Asperger syndrome (like autism, but with normal language development)
• Rett syndrome (very different from autism, and only occurs in females)
• Childhood disintegrative disorder (rare condition where a child learns skills, then loses them by age 10)
• Pervasive developmental disorder - not otherwise specified (PDD-NOS), also called atypical autism.

Most parents of autistic children suspect that something is wrong by the time the child is 18 months old and seek help by the time the child is age 2. Children with autism typically have difficulties in:

• Pretend play
• Social interactions
• Verbal and nonverbal communication

Some children with autism appear normal before age 1 or 2 and then suddenly "regress" and lose language or social skills they had previously gained. This is called the regressive type of autism.

People with autism may:

• Be overly sensitive in sight, hearing, touch, smell, or taste (for example, they may refuse to wear "itchy" clothes and become distressed if they are forced to wear the clothes)
• Have unusual distress when routines are changed
• Perform repeated body movements
• Show unusual attachments to objects

The symptoms may vary from moderate to severe.

Communication problems may include:

• Cannot start or maintain a social conversation
• Communicates with gestures instead of words
• Develops language slowly or not at all
• Does not adjust gaze to look at objects that others are looking at
• Does not refer to self correctly (for example, says "you want water" when the child means "I want water")
• Does not point to direct others' attention to objects (occurs in the first 14 months of life)
• Repeats words or memorized passages, such as commercials
• Uses nonsense rhyming

Social interaction:

• Does not make friends
• Does not play interactive games
• Is withdrawn
• May not respond to eye contact or smiles, or may avoid eye contact
• May treat others as if they are objects
• Prefers to spend time alone, rather than with others
• Shows a lack of empathy

Response to sensory information:

• Does not startle at loud noises
• Has heightened or low senses of sight, hearing, touch, smell, or taste
• May find normal noises painful and hold hands over ears
• May withdraw from physical contact because it is overstimulating or overwhelming
• Rubs surfaces, mouths or licks objects
• Seems to have a heightened or low response to pain

Play:

• Doesn't imitate the actions of others
• Prefers solitary or ritualistic play
• Shows little pretend or imaginative play

Behaviors:

• "Acts up" with intense tantrums
• Gets stuck on a single topic or task (perseveration)
• Has a short attention span
• Has very narrow interests
• Is overactive or very passive
• Shows aggression to others or self
• Shows a strong need for sameness
• Uses repetitive body movements

All children should have routine developmental exams done by their pediatrician. Further testing may be needed if the doctor or parents are concerned. This is particularly true if a child fails to meet any of the following language milestones:

• Babbling by 12 months
• Gesturing (pointing, waving bye-bye) by 12 months
• Saying single words by 16 months
• Saying two-word spontaneous phrases by 24 months (not just echoing)
• Losing any language or social skills at any age

These children might receive a hearing evaluation, blood lead test, and screening test for autism (such as the Checklist for Autism in Toddlers [CHAT] or the Autism Screening Questionnaire).

A health care provider experienced in diagnosing and treating autism is usually needed to make the actual diagnosis. Because there is no biological test for autism, the diagnosis will often be based on very specific criteria from a book called the Diagnostic and Statistical Manual IV.

An evaluation of autism will often include a complete physical and nervous system (neurologic) examination. It may also include a specific screening tool, such as:

• Autism Diagnostic Interview - Revised (ADI-R)
• Autism Diagnostic Observation Schedule (ADOS)
• Childhood Autism rating Scale (CARS)
• Gilliam Autism Rating Scale
• Pervasive Developmental Disorders Screening Test - Stage 3

Children with known or suspected autism will often have genetic testing (looking for chromosome abnormalities) and may have metabolic testing.

Autism includes a broad spectrum of symptoms. Therefore, a single, brief evaluation cannot predict a child's true abilities. Ideally, a team of different specialists will evaluate the child. They might evaluate:

• Communication
• Language
• Motor skills
• Speech
• Success at school
• Thinking abilities

Sometimes people are reluctant to have a child diagnosed because of concerns about labeling the child. However, without a diagnosis the child may not get the necessary treatment and services.

For organizations that can provide additional information and help on autism, see autism resources.

Autism remains a challenging condition for children and their families, but the outlook today is much better than it was a generation ago. At that time, most people with autism were placed in institutions.

Today, with the right therapy, many of the symptoms of autism can be improved, though most people will have some symptoms throughout their lives. Most people with autism are able to live with their families or in the community.

The outlook depends on the severity of the autism and the level of therapy the person receives.

Autism can be associated with other disorders that affect the brain, such as:

• Fragile X syndrome
• Mental retardation
• Tuberous sclerosis

Some people with autism will develop seizures.

The stresses of dealing with autism can lead to social and emotional complications for family and caregivers, as well as the person with autism.

Parents usually suspect that there is a developmental problem long before a diagnosis is made. Call your health care provider with any concerns about autism or if you think that your child is not developing normally.

Autism and Developmental Disabilities Monitoring Network Surveillance Year 2002 Principal Investigators; Centers for Disease Control and Prevention. Prevalence of autism spectrum disorders--autism and developmental disabilities monitoring network, 14 sites, United States, 2002. MMWR Surveill Summ. 2007 Feb 9;56(1):12-28.

Johnson CP, Myers SM; American Academy of Pediatrics Council on Children with Disabilities. Identification and evaluation of children with autism spectrum disorders. Pediatrics. 2007;120:1183-1215.

Dover CJ, Le Couteur A. How to diagnose autism. Arch Dis Child. 2007;92:540-545.

Shah PE, Dalton R, Boris NW. Pervasive developmental disorders and childhood psychosis. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 29.

Bertoglio K, Hendren RL. New developments in autism. Psychiatr Clin North Am. 2009;32:1-14.