Autism Basics

The number of autism cases in the United States continues to rise.

Some children seem to live in a world all their own. They appear distant and closed-in, avoiding eye contact and shying away from their parents' hugs. They may exhibit unusual behaviors, like flapping their arms or obsessively lining up their toys. They are among the approximately 1.5 million children in America who have autism -- a condition that interferes with a child's ability to communicate and interact socially.

Autism has up to now been very difficult to decipher. Scientists still don't fully understand the mystery that lies deep in the brains of children with autism. Although researchers have uncovered clues to what causes the condition, they have not yet discovered a way to prevent or cure autism.


­What is concerning to many scientists is that autism appears to be on the rise. Today, one out of every 110 American children has the condition, according to the Centers for Disease Control and Prevention (CDC). Since the 1980s and early 1990s, the rate of autism has increased by approximately 10 to 17 percent annually. Doctors don't know whether this apparent increase is the result of some environmental factor -- such as greater exposure to toxic chemicals -- or simply that children are being diagnosed more effectively than they were two decades ago.  On the next page, we'll take a closer look at the definition and characteristics of autism.



What is autism?

Autism is part of a cluster of conditions called autism spectrum disorders (ASDs), or known by the broader term, pervasive developmental disorders (PDDs). All of these conditions share similar symptoms. Although autism can affect children of any race and ethnicity, it is four times more common in boys than in girls.

Autism can range from mild to severe, but most children with the condition have difficulty in these three areas:


Communication - Children with autism have trouble with both verbal and nonverbal communication. They may avoid making eye contact or smiling, and may not understand the meaning of a smile, wink or wave. About 40 percent of children with autism don't speak at all. Another 25 percent start talking at between 12 and 18 months, but then rapidly lose their language ability. Some children with autism have difficulty forming words into sentences, or repeat exactly what they hear -- a condition called echolalia. Because they can't communicate what they want, sometimes autistic children scream or cry out of frustration.

Social interaction - Children with autism have difficulty relating to other people, in part because they can't understand other people's feelings and social cues. As a result, they can appear distant or aloof. They may shy away from physical or emotional contact, avoiding hugs and eye contact. Because autism affects the senses, some everyday sounds or smells may be unbearable to autistic children. They may cover their ears and scream when the phone rings, or gag from the smell of a peach. Or they may be less sensitive to pain than other children, and not feel a thing when they get a cut or bruise.

­Repetitive behaviors - Autistic children often repeat the same behaviors (called stereotyped behaviors, or stereotypy) over and over, including waving their arms, banging their head against a wall, repeating the same words, or obsessively lining up toys, books or other objects. Repetition is a theme throughout an autistic child's life. Any change to their daily routine -- even something as simple as cutting a sandwich straight across rather than on a diagonal -- can lead to a meltdown.

The symptoms of autism can vary dramatically from child to child. While one child may be entirely unable to communicate, another may be able to recite entire plays by Shakespeare. One child may be unable to add 3 + 4, another may be able to perform advanced calculus functions.

In addition to autism, four other conditions fall under the header of ASDs:

  • Asperger syndrome - Children with this condition have some symptoms of autism, including poor social skills and a lack of empathy, but they have age-appropriate language skills and a normal or high IQ.
  • Rett syndrome - This condition affects 1 out of every 10,000 to 15,000 children, the vast majority of them girls. Those with Rett syndrome shy away from social contact. They may wring their hands and be unable to control the movement of their feet.
  • Childhood Disintegrative Disorder (CDD) - This rare disorder affects only about two out of every 100,000 children with ASDs, most of them male. Children with CDD will develop normally until about age 3 or 4, then will suddenly and dramatically lose their motor, language and social skills.
  • Pervasive Developmental Disorder - Not Otherwise Specified (PDD-NOS) - This condition shares some of the same symptoms with autism (communication and social delays), but does not meet the full criteria for diagnosis.

Autism is much more common in people with certain genetic, chromosomal, and metabolic disorders, such as fragile X syndrome (an inherited form of mental retardation whose name refers to a damaged and fragile-looking X chromosome), phenylketonuria (an inherited condition in which the body lacks the enzyme needed to process the amino acid phenylalanine, leading to mental retardation) and tuberous sclerosis (a rare genetic disorder that causes benign tumors to grow throughout the body and brain). Epileptic seizures, mental retardation and vision and/or hearing loss are also common in children who have autism.

Next, we'll look at some of the potential causes of autism.


Causes of Autism

Some have put forth the theory that certain childhood vaccines and vaccine preservatives may lead to autism, although current research indicates that there is no link.
Image courtesy Dreamstime

Scientists believe that autism stems from a combination of genetic and environmental factors. Research done with twins reveals a strong family connection. If one identical twin has autism, the other twin has a 60 to 90 percent chance of also having the condition (in non-identical twins, the rate is about 3 percent). In families with one autistic child, the chance of having a second child with the condition is about 2 to 8 percent -- 75 times greater than among the general population. Also, members of families with autistic children are more likely to have language delays and social difficulties, as well as mental disorders.

Scientists believe that not just one, but a combination of as many as a dozen genes is to blame for autism. Mutations in these genes can make a child more susceptible to autism, or can lead to specific symptoms of the condition. Some of the genes scientists have isolated are HOXA1 (involved in brain structures and nerves), RELN (involved in connections between nerve cells), and GABA pathway genes (involved in helping nerve cells communicate with one another).


These genes likely set the stage for autism, but it's possible that environmental factors actually trigger the condition. A number of environmental factors have been linked to autism, from viral infections to exposure to chemicals such as mercury, lead or polychlorinated biphenyls (PCBs -- a group of chemicals that were once used as lubricants and coolants). Some research has suggested that prenatal exposure to substances such as thalidomide (a drug used in the 1950s and '60s to treat morning sickness, used to treat cancer) or valproic acid (a drug used to treat epileptic seizures) can cause a child to develop autism.

In 1998, a British study by Dr. Andrew Wakefield cast international attention on one potential environmental culprit: childhood vaccines. His small study suggested that the measles-mumps-rubella (MMR) vaccine caused an infection in the intestines, which led to the developmental and gastrointestinal disorders seen in autism. Because children are vaccinated at around the same age as autism is diagnosed, the theory that vaccinations were to blame gained popularity. In the years following the study, however, many of Dr. Wakefield's co-authors disavowed the results, and it was revealed that Dr. Wakefield had a financial motive for linking vaccines to autism. Finally, in 2011, the study was deemed fraudulent by the medical community after it was discovered that Dr. Wakefield falsified data about the children in the report.

Adding to the questions surrounding vaccines was other research indicating that exposure to thimerosal, a mercury-based substance that was once used as a vaccine preservative (specifically in the diphtheria, tetanus, pertussis, Haemophilus influenzae type b (Hib) and Hepatitis B vaccines), could affect brain development and trigger autism. However, thimerosal is no longer present in vaccines, and autism rates haven't dropped.

In 2004, the Institute of Medicine completed a thorough review of all the evidence related to vaccines and autism, and concluded that there was no apparent link between thimerosal or the MMR vaccine and autism. Several other large studies have echoed those conclusions. 

We'll look at the brain and autism next.


The Autistic Brain

The brain of a child with autism has an abnormal corpus callosum, amygdala and cerebellum.

Much like a computer, the brain relies on intricate wiring to process and transmit information. Scientists have discovered that in people with autism, this wiring is faulty, leading to misfiring in communications between brain cells.

In the brain, nerve cells transmit important messages that regulate body functions -- everything from social behavior to movement. Imaging studies have revealed that autistic children have too many nerve fibers, but that they're not working well enough to facilitate communication between the various parts of the brain. Scientists think that all of this extra circuitry may affect brain size. Although autistic children are born with normal or smaller-than-normal brains, they undergo a period of rapid growth between ages 6 and 14 months, so that by about age four, their brains tends to be unusually large for their age. Genetic defects in brain growth factors may lead to this abnormal brain development.


Scientists also have discovered irregularities in the brain structures themselves, such as in the corpus callosum (which facilitates communication between the two hemispheres of the brain), amygdala (which affects emotion and social behavior), and cerebellum (which is involved with motor activity, balance, and coordination). They believe these abnormalities occur during prenatal development.

In addition, scientists have noted imbalances in neurotransmitters -- chemicals that help nerve cells communicate with one another. Two of the neurotransmitters that appear to be affected are serotonin (which affects emotion and behavior) and glutamate (which plays a role in neuron activity). Together, these brain differences may account for autistic behaviors.

Scientists continue to look for clues to the origins of autism. By studying the genetic and environmental factors that may cause the condition, they hope to develop tests to identify autism earlier, as well as new treatment methods.

Several research studies are looking at the link between genes and autism. The largest of these is the National Alliance for Autism Research (NAAR) Autism Genome Project. This collaborative effort, conducted at approximately 50 research institutions in 19 countries, is poring through the 30,000 genes that make up the human genome in a search for the genes that trigger autism.

Other autism studies include:

  • Using animal brain models to study how neurotransmitters are impaired in children with autism
  • Testing a computer-based program that would help autistic children interpret facial expressions
  • Examining brain images to discover which areas are active during the obsessive and repetitive behaviors of autism
  • Continuing to investigate the link between thimerosal and autism

In the next section, we'll look at how autism is typically identified in children.


Autism Symptoms

Psychologists and other professionals often use the Autism Diagnostic Observation Schedule to identify delayed social and communication behaviors in children.
Image courtesy Western Psychological Services

Within the first few months of their baby's life, the parents of an autistic child may begin to feel that something is not quite right. They may notice that their child, who once seemed normal in every way, is acting strangely, refusing to make eye contact, point to toys or speak.

Even though the signs may appear before age 2, most children aren't diagnosed with autism until age 4 or 5, according to the Centers for Disease Control and Prevention. Part of the reason for this delay is that the symptoms of autism can look much like those of other conditions, which is why autism screening is a multistep process involving several different health and mental health professionals.


The first step to diagnosing autism begins with a developmental test administered by the child's pediatrician. If this test suggests an ASD, the next step is to bring in a team of experts, which may include a psychologist, neurologist, child psychiatrist, speech therapist, occupational therapist, physical therapist, and possibly other professionals. These doctors will evaluate the child for neurologic or genetic problems, as well as for cognitive and language skills. Evaluation may include observations, parent interviews, patient histories, speech and language assessments and psychological tests.

Screening tests for autism include:

  • The Autism Diagnostic Observation Schedule (ADOS-G): An observational test used to identify delayed social and communication behaviors.
  • The Autism Diagnosis Interview-Revised (ADI-R): An interview that assesses the child's communication and social skills.
  • Childhood Autism Rating Scale (CARS): An observational test to determine autism severity that uses a 15-point scale to evaluate a child's verbal communication abilities, listening skills, body use, and social relationships.
  • The Autism Screening Questionnaire: A 40-question scale used in children 4 and older to evaluate social and communication abilities

According to the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), children with autism meet at least six of the following criteria:

  • Social impairments: Does not properly use nonverbal behaviors such as gestures and facial expressions Fails to develop age-appropriate peer relationships Does not spontaneously share objects or interests with others Lacks social or emotional reciprocity
  • Communication impairments: Is slow to speak Has difficulty sustaining a conversation Repeatedly uses the same language Does not engage in age-appropriate make-believe or socially imitative play
  • Repetitive behaviors: Is intensely preoccupied with one or more interests Is inflexible and unwilling to change set routines Repeats motions or mannerisms (such as waving arms, flapping, or twisting) Is preoccupied with parts of objects

Next, we'll look at conventional treatments for autism.


Autism Treatments

There is no cure for autism, but with treatment, people with the condition can live fuller lives. Behavioral therapy (also called behavioral intervention) is the most commonly used treatment. Teachers, parents and counselors work together to help the child improve his or her communication, physical and social skills.

One of the most popular behavioral therapies is called Treatment and Education of Autistic and Communication Handicapped Children (TEACCH), which was developed in the 1970s. With this method, parents and professionals (teachers, therapists, etc.) work closely together to improve the child's adaptive skills through structured cognitive and behavioral therapy. The program is individualized to the child, and takes place in several environments-from clinics to classrooms. Other educational programs include the Higashi School, which teaches positive behaviors through art, academics and physical education; and Bright Start, which helps improve children's communication, attention and cognitive skills.


Children also may need occupational therapy (to learn everyday tasks), sensory integration therapy (to help process stimuli), physical therapy (to improve motor skills) and speech therapy. Treatment should be tailored to the individual child.

Although they can't treat autism specifically, medications can help manage the symptoms of autism. Most drugs prescribed for autism are used off-label, which means they are not approved by the U.S. Food & Drug Administration specifically for autism, but they have been approved to treat the same symptoms in other conditions. These medications include:

Antidepressants - Researchers have found that people with autism have a higher-than-normal level of the neurotransmitter serotonin. Drugs called selective serotonin reuptake inhibitors (SSRIs), which include Prozac and Zoloft, help regulate serotonin levels and control anxiety, depression and obsessive-compulsive behaviors. (There is concern that these drugs may be associated with suicidal thoughts and behaviors in children, however; so they are used with caution.)

Antipsychotic medications - These drugs, which were originally designed to treat schizophrenia, may be helpful for aggression and other severe behavioral problems associated with autism. Antipsychotic medications work by reducing the amount of the neurotransmitter, dopamine, in the brain. The older antipsychotic medications (such as Haldol) may be effective for autism, but they can have side effects, including sedation and unusual movements (called dyskinesias). In 2006, the FDA approved a newer antipsychotic medication, Risperdal, for irritability in autistic children and adolescents ages 5 to 16. It is the first drug to be approved specifically for autism-related behaviors, such as aggression, hostility, self-injury, and agitation, and it tends to have fewer side effects than the older antipsychotics.

Stimulant medications - Medications used to treat attention-deficit hyperactivity disorder (ADHD), such as Ritalin or Adderall, may be effective for the symptoms of hyperactivity and impulsivity in children with autism. These drugs, too, can have behavioral side effects and children taking them need to be carefully monitored.

We'll examine some complementary and alternative therapies for autism in the next section.


Helping Children with Autism

There are a lot of gluten- and casein-free foods available for children with autism who are on these special types of diets.
Image courtesy Amazon

Because there are no real cures for autism, parents often turn to complementary and alternative therapies for their children. Although some parents have had success with these methods, none is scientifically proven to treat autism.

Vitamin and mineral supplements - Dietary interventions stem from the belief that food allergies or vitamin and mineral deficiencies can trigger autism. Some parents give their children B vitamin supplements (B vitamins create enzymes needed by the brain) or magnesium, although research has not proven their effectiveness.


Special diets - Some research suggests that children with autism may have trouble digesting proteins such as gluten-- found in the seeds of wheat, oat, rye, and barley plants, and casein -- found in dairy products. Many children with autism are on gluten- or casein-free diets.

Secretin - Some research found that this hormone, which aids in digestion, improved communication and social skills in autistic children. However, research by the National Institute of Child Health and Human Development found no real improvements with this treatment compared to placebo.

Chelation therapy - Following the school of thought that autism may be caused by exposure to environmental toxins, such as mercury and other heavy metals, chelation uses a chemical agent to bind to and remove these metals from the body. Although a number of parents have claimed that this treatment has improved their children's symptoms, chelation hasn't been scientifically proven, and the substances used in the treatment can themselves be toxic and cause allergic reactions in some children.

In facilitated communication, a facilitator may hold the arm of an autistic child and helps him type on a computer keyboard to assist in communication.

Facilitated communication - In this type of therapy, a facilitator holds the hand, arm or shoulder of a autistic child and helps him type on a computer keyboard to assist in communication. This technique is not considered a valid treatment for autism, and it is very controversial, because some people claim that the facilitator is doing the communicating rather than the child.

In the next section, we'll examine some common myths about autism.


Autism Awareness

Kim Peek is a well-known savant and was the inspiration for the title character of "Rain Man."
Image courtesy Kim Peek, Darold A. Treffert, M.D. and Wisconsin Medical Society

From the 1950s until the 1980s, a prevailing theory about the cause of autism was that it stemmed from bad parenting -- the so-called "refrigerator mother theory" (meaning the mother is emotionally cold) put forth by child psychologist Bruno Bettelheim. Today, we know this is untrue. Autistic children aren't poorly raised -- they are born with an inherited susceptibility to the condition.

Autistic children also are not badly behaved -- their temper tantrums and other unusual behaviors stem from their frustration in being unable to effectively communicate and interact socially. They are not dumb, either; in fact, some autistic children are extremely gifted in one or more areas.


A common misconception is that people with autism are slow or mentally retarded. In fact, a small percentage of people with ASDs are remarkably gifted. Consider Kim Peek, the inspiration for Dustin Hoffman's character, Raymond Babbitt, in the 1988 film, "Rain Man." Peek has read more than 7,000 books, and can recall with photographic accuracy more than 80 percent of their contents. Given a person's date of birth, he can immediately produce the day of the week on which the person was born. London-born author and math whiz Daniel Tammet can recite the number pi to more than 20,000 digits, and fluently speaks 10 languages. He's even invented his own language, Manti.

There are also people who were diagnosed with autism as a child but may actually have Pervasive Developmental Disorder - Not Otherwise Specified (PDD-NOS). Dr. Temple Grandin, a professor of Animal Science at Colorado State University, is a famous example of a person who overcame autism and became highly successful. Dr. Grandin has designed livestock handling facilities used throughout the world, written four books -- including a New York Times bestseller -- and appeared on numerous TV and radio shows.

For lots more information about autism, autism spectrum disorders and related topics, check out the links on the next page.


Lots More Information

Related Articles
More Great Links

  • "Are Autism Cases on the Rise in the U.S.?" HealthDay, Feb. 16, 2007.
  • Associated Press via New York Times. "Study Linking Vaccine to Autism is Called Fraud." Jan. 6, 2011. (March 14, 2011)
  • "Autism and Genes." National Institute of Child Health and Human Development.
  • Autism Fact Sheet. National Institute of Neurological Disorders and Stroke.
  • Autism Information Center: Centers for Disease Control and Prevention
  • Autism Society of America
  • "Autism Spectrum Disorders." National Institute of Mental Health.
  • "Biomedical and Dietary Approaches." Autism Society of America. pagename=about_treatment_biomedical
  • Blakemore, Bill. "Study Suggests Autism Causes are Genetic."
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  • CNN. "Retracted autism study an 'elaborate fraud,' British journal finds." Jan. 5, 2011. (March 14, 2011)
  • Edelson, Stephen M., Ph.D., "Theory of Mind." Center for the Study of Autism.
  • Hertz-Picciotto, Irva, et al. "The CHARGE Study: An Epidemiologic Investigation of Genetic and Environmental Factors Contributing to Autism." Environmental Health Perspectives, Volume 114, Number 7, July 2006, page 1119.
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  • "Largest-Ever Search for Autism Genes Reveals New Clues." National Institutes of Health, Feb. 18, 2007.
  • Lyall, Sarah. "Brainman, At Rest in his Oasis." The New York Times, Feb. 15, 2007.
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  • The Medical/Psychiatric Diagnosis of Autism: The DSM-IV Criteria
  • MMR Vaccine and Autism Fact Sheet. Centers for Disease Control and Prevention.
  • NAAR Autism Genome Project: Fact Sheet
  • "Prevalence of the Autism Spectrum Disorders in Multiple Areas of the United States, Surveillance Years 2000 and 2002." Centers for Disease Control and Prevention.
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