Autism is a pervasive developmental disorder that affects 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 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 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).
What are the symptoms of autism?
Children with autism have a number of symptoms, ranging from mild to severe. Symptoms include:
- Difficulty interacting with others and making friends.
- Communication problems, both with spoken language and nonverbal gestures. About 40 percent of affected children do not talk at all (2).
- Insistence on the same routine.
- Repetitive movements, such as hand flapping.
- Some degree of mental retardation or learning disabilities (in many but not all affected children).
Each child with autism is unique, but some common characteristics and behaviors may include (2, 3):
- Repeats words
- Doesn't play “pretend” games
- Doesn't point at objects or wave “bye-bye”
- Is overly active
- Has frequent temper tantrums
- Avoids eye contact
- Has difficulty starting or maintaining conversation
- Does not respond to being called by name
- 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
- 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 share some of the features of autism. However, children with Asperger syndrome have normal intelligence and learn to speak at the expected age.
When is autism diagnosed?
A child with autism usually does not look different from other children. The child may appear to develop normally for the first year or so of life.
But during the second year of life, 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, though it can sometimes be diagnosed as early as 18 months (2).
How is autism diagnosed?
There is no 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.
The Centers for Disease Control and Prevention (CDC) recommends that all children be screened for autism at their 18-, 24- and 30-month well-child visits (2). If a screening test suggests a possible problem, the provider may do additional tests or recommend evaluation by a specialist.
Who is at risk of 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).
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 (3). 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), may play a role (2). Certain infections that occur before birth (such as rubella and cytomegalovirus) have been associated with autism (2).
Do childhood vaccines contribute to autism?
Childhood vaccines, including the measles/mumps/rubella (MMR) vaccine, do not cause autism. Some 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. Most likely, this is the age when symptoms of the disorder commonly begin, even if a child is not vaccinated.
Another reason that childhood vaccines were suspected of playing a role in autism is that, until recently, they included a preservative called thimerosol that contains mercury. Since 2002, all routine childhood vaccines have been free of thimerosol. The exception is the flu shot, and thimerosol-free versions are available (4).
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 that neither the MMR vaccine nor thimerosol-containing vaccines are associated with autism (5).
How is autism treated?
Children often show great improvement in symptoms with intensive behavioral treatment beginning during the preschool years (2, 4). An individualized treatment program can begin as early as age 2 or 3 and continue through the school years.
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, antipsychotics 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).
For more information
Autism Society of America
(800) 3AUTISM (328-8476)
Autism Information Center
Centers for Disease Control and Prevention (CDC)
Nation Center on Birth Defects and
Developmental Disabilities (NCBDDD)
(800) 311-3435
References
- 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.
- Centers for Disease Control and Prevention (CDC). Autism Information Center. Updated 2/7/07.
- National Institute of Child Health & Human Development. Autism Research at the NICHD. May 2005.
- 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.
- Institute of Medicine. Immunization Safety Review: Vaccines and Autism. National Academies Press, 2004.
April 2007
