Autism

• What are the symptoms of autism?
• When is autism diagnosed?
• How is autism diagnosed?
• Who is at risk for autism?
• What causes autism?
• Do childhood vaccines contribute to autism?
• How is autism treated?
• For more information
• References

Autism is a general term for a group of disorders that affect how a child functions in several areas, including speech, social skills and behavior. Children who have problems in these areas are sometimes said to have an autistic spectrum disorder because the severity and breadth of symptoms varies greatly.

Autism affects about 1 in 150 children in the United States (1, 2). More children than ever are being diagnosed with autism. The current rates of autism are about 10 times higher than in the 1980s, though much or all of this increase may be due to improved awareness and changes in how autism is diagnosed (1).

The American Academy of Pediatrics (AAP) recommends that all children be screened for autism during well-child visits at ages 18 months and 24 months (3). Early diagnosis and treatment can greatly improve the outlook for children with autism.

What are the symptoms of autism?
Each child with autism is unique. Some common characteristics and behaviors include (2, 4):

• Does not speak (about 40 percent of children with autism do not speak at all)

• Repeats words

• Performs repetitive movements, such as hand-flapping

• Doesn't play “pretend” games

• Is overly active

• Has frequent temper tantrums

• Avoids eye contact

• Has difficulty starting and maintaining conversation and making friends

• Does not respond to being called by name

• Insists on same routine

• Repeats actions again and again

• Focuses on single subject or activity

• Wants to be alone

• Is overly sensitive to the way things feel, sound, taste or smell

• Dislikes being held or cuddled

• Has sleep disturbances

• Lacks fear in risky situations

• Has some degree of mental retardation or learning disabilities (in many, but not all, affected children)

• Is aggressive

• Hurts himself

• Loses skills (for example, stops saying words he used to say)

Children with a mild autistic spectrum disorder called Asperger syndrome have some of the features of autism. However, children with Asperger syndrome generally have normal intelligence and learn to speak at the expected age.

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When is autism diagnosed?
A child with autism usually does not look different from other children. She may appear to develop normally for the first year or so of life. But during the second year, some children with autism begin to fall behind in social skills, fail to develop speech or even lose skills that they had previously acquired. Autism is often diagnosed around age 3; however, subtle signs of the disorder may appear before 18 months (3). These signs may include (3):

• Not turning when the parent says the baby's name
• A lack of back-and-forth babbling with parents starting around 6 months of age
• Late smiling
• Does not look when a parent points and says, “Look at…”

Toddlers with these signs do not necessarily have autism, as each child develops at a different rate. However, parents should not hesitate to discuss these possible signs and other developmental concerns with their baby's health care provider.

Speech delays also can be early signs of autism. The American Academy of Pediatrics recommends an immediate evaluation for autism if the child (3):

• Does not babble, point or use other gestures by 12 months

• Does not say any single words by 16 months

• Does not say any two-word phrases by 24 months

• Loses language or social skills at any age

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How is autism diagnosed?
There is no specific medical test to diagnose autism. Health care providers generally diagnose autism by observing a child's behavior and by using screening tests that measure a number of characteristics and behaviors associated with autism. If a screening test suggests a possible problem, the provider may do additional tests or recommend evaluation by a specialist.

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Who is at risk for autism?
Autism occurs in all racial, social and educational groups. Boys are about 4 times as likely as girls to be affected (2). Siblings of an affected child may be at increased risk for autism, though the risk appears fairly low: 2 to 8 percent (2, 3). Two recent studies also suggest that premature (born before 37 completed weeks of pregnancy) babies may be at increased risk of symptoms associated with autism (5, 6).

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What causes autism?
While the causes of autism are poorly understood, scientists do know that autism is not caused by poor parenting or other social factors. It is a biological disorder that appears to be associated with subtle abnormalities in specific structures or functions in the brain.

Both genetic and environmental factors appear to play a role in the disorder. Scientists believe that at least a dozen genes on different chromosomes may contribute (4). A consortium of autism researchers recently found that abnormalities in a small region of chromosome 16 appear to increase a child's risk for autism by up to 100-fold (7). These abnormalities appear to cause about 1 percent of cases of autism (7).

In a minority of cases, other genetic diseases, such as fragile X syndrome (mental retardation and behavioral problems) and tuberous sclerosis (non-cancerous tumors affecting the brain and other organs), also may play a role (2, 3). Certain infections that occur before birth (such as rubella and cytomegalovirus) have been associated with autism (2).    

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Do childhood vaccines contribute to autism?
Childhood vaccines, including the measles/mumps/rubella (MMR) vaccine, do not cause autism. Some parents of children with autism suspect that this vaccine, given around 12 to 15 months of age, contributes to autism because children sometimes begin to display symptoms of autism around the time they are vaccinated. However, most likely, this is because symptoms of the disorder commonly begin at this time, even if a child is not vaccinated.

Another reason that childhood vaccines have been suspected of playing a role in autism is that, until recently, they contained a preservative called thimerosal that contains mercury. Since 2002, all routine childhood vaccines have been free of thimerosal. The exception is the flu shot, and thimerosal-free versions are available (8). While higher doses of certain forms of mercury may affect brain development, studies suggest that thimerosal does not.

In 2004, an Institute of Medicine panel concluded, after reviewing many studies, that neither the MMR vaccine nor thimerosal-containing vaccines are associated with autism (9). A 2008 study found that the rate of autism in California continued to increase after thimerosal was removed from childhood vaccines, also suggesting a lack of association between thimerosal and autism (10).

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How is autism treated?
Children often show great improvement in symptoms with intensive behavioral treatment beginning during the preschool years (2, 8). An individualized treatment program should begin as soon as the diagnosis of autism is seriously considered and should continue through the school years (11).

There is no cure for autism. However, some children benefit from medications that help improve their behavioral symptoms so that they are better able to learn. Some commonly used medications include antidepressants, anti-psychotics and stimulants. One such medication is Ritalin, which is commonly prescribed for attention deficit hyperactivity disorder (ADHD). A new anti-psychotic called risperidone (Risperdal) is the only drug that is approved by the Food and Drug Administration (FDA) specifically for autistic behaviors, such as aggression, self-injury and temper tantrums (4).

Some children with autism also are treated with various alternative therapies, such as dietary restrictions, vitamins and detoxification therapies (such as chelation to reduce the amounts of mercury and other metals in the body). To date, there is not enough evidence to show whether or not these treatments may be helpful or harmful (11). Parents who are interested in alternative treatments should discuss the possible risks and benefits with their child's health care provider.

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For more information
Autism Information Center
Centers for Disease Control and Prevention (CDC)
National Center on Birth Defects and
Developmental Disabilities (NCBDDD)
(800) 311-3435

Autism Fact Sheet
National Institute of Neurological Disorders and Stroke (NINDS)

Autism Spectrum Disorders
National Institute of Mental Health

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References

1. Centers for Disease Control and Prevention (CDC). Prevalence of Autism Spectrum Disorders, Autism and Developmental Disabilities Monitoring Network, Six Sites, United States, 2000; 14 Sites, 2002. Morbidity and Mortality Weekly Report, February 9, 2007, volume 56, No. SS-1.
2. Centers for Disease Control and Prevention (CDC). Autism Information Center. Updated 2/7/07.
3. Johnson, C.P., Myers, S.M., and the Council on Children with Disabilities. Identification and Evaluation of Children with Autism Spectrum Disorders. Pediatrics, volume 120, number 5, November 2007, pages 1183-1215.
4. National Institute of Child Health & Human Development. Autism Research at the NICHD. May 2005.
5. Limperopoulos, C., et al. Positive Screening for Autism in Ex-Preterm Infants: Prevalence and Risk Factors. Pediatrics, volume 121, number 4, April 2008, pages 758-765.
6. Schendel, D. and Bhasin, T.K. Birth Weight and Gestational Age Characteristics of Children with Autism, Including a Comparison with Other Developmental Disabilities. Pediatrics, volume 121, number 6, June 2008, pages 1155-1164.  
7. Weiss, L.A., et al. Association Between Microdeletion and Microduplication at 16p11.2 and Autism. New England Journal of Medicine, volume 358, number 7, February 14, 2008, pages 667-675.
8. National Institute of Mental Health. Autism Spectrum Disorders (with Addendum January 2007). NIH Publication Number 5511, National Institute of Mental Health, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, MD, April 2004.
9. Institute of Medicine. Immunization Safety Review: Vaccines and Autism. National Academies Press, 2004.
10. Schechter, R. and Grether, J. Continuing Increases in Autism Reported to California's Developmental Services System. Archives of General Psychiatry, volume 65, number 1, January 2008, pages 19-24.   
11. Myers, S.M., Johnson, C.P., and the Council on Children with Disabilities. Management of Children with Autism Spectrum Disorders. Pediatrics, volume 120, number 5, November 2007, pages 1162-1182.

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November 2008