Introduction

Autism is the fastest-growing developmental disability in the U.S. today. The number of children diagnosed with autism or related disorders has grown at what many call an alarming rate. In the 1970s and 1980s, about one out of every 2,000 children had autism.

Autism Spectrum Disorders (ASDs)

ASDs are developmental disabilities and are defined by considerable impairments in social interaction and communication and the presence of unusual behaviors and interests. They can be diagnosed as early as 18 months and last throughout a person's life. ASDs include autistic disorder, pervasive developmental disorder - not otherwise specified (PDD-NOS, including atypical autism), and Asperger syndrome. The causes of ASDs are not known but if they are identified in children early, they can begin receiving appropriate interventions sooner. 

Latest Autism Statistics (source,  Talk About Curing Autism (TACA)

• One in every 150 children born in the US has autism (read CDC report). It is estimated approximately 1 million in the US have this disorder.
• A new case of autism is diagnosed nearly every 20 minutes.
• There are 24,000 new cases diagnosed in the U.S. per year.
• The economic impact of autism is more than $90 billion and expected to more than double in the next decade.
• Autism receives less than 5% of the research funding of many less prevalent childhood diseases.
• There is no medical detection treatment, or cure for autism.
• MORE THAN TWO new cases each day – 7 days a week in California alone!
• From 1987-1998 there was a 633% increase in Autism (DSM-IV) in the State of California. (Note: In 1998 mandatory immunizations programs and the MMR vaccine were introduced.)
• From 1998-2002 there was an additional 96% increase in Autism (DSM IV) in the State of California.

Autism Studies  

The Centers for Disease Control and Prevention (CDC) most recent report issues 2/7/08 showed an average of 6.7 children out of 1,000 had an autism spectrum disorder (ASD). For decades, the best estimate for the prevalence of autism was four to five per 10,000 children. More recent studies from multiple countries using current diagnostic criteria conducted with different methods have indicated that there is a range of ASD prevalence between 1 in 500 children and 1 in 166 children. A 2000 study found ASD rates ranged from one in 222 children to one in 101 eight-year old children in the six communities studied. The 2000 study included approximately 4.5 percent of U.S. eight-year-old children born in 1992 from six states - Arizona, Georgia, Maryland, New Jersey, South Carolina and West Virginia. A total of 1,252 eight-year olds were identified as having an ASD.

The 2002 study found ASD rates ranging from one in 303 to one in 94 among eight-year old children. The average finding of 6.6 and 6.7 per 1,000 eight-year-olds translates to approximately one in 150 children in these communities. This is consistent with the upper end of prevalence estimates from previously published studies, with some of the communities having an estimate higher than those previously reported in U.S. studies. The 2002 study included approximately 10 percent of U.S. eight-year-old children born in 1994 from 14 states - Alabama, Arizona, Arkansas, Colorado, Georgia, Maryland, Missouri, New Jersey, North Carolina, Pennsylvania, South Carolina, Utah, West Virginia and Wisconsin. A total of 2,685 eight-year-olds were identified as having an ASD.  

Autism Rise, Fact or Fiction?

The jump in autism cases has spawned not only alarm but also debate about whether the number of children with autism could have increased that much in a relatively brief time. The apparent rise in cases triggers two important questions: 

• Is autism truly on the rise, or do the new statistics simply reflect the growing awareness of the condition, the expanded definition, and other factors?
• If autism is on the rise, as most experts believe, what is causing the increase? 

Many experts believe that autism is on the rise, but noit at such a rate that would be considered alarming.  Some of the increase in reported cases is because of "diagnostic substitution," says Paul Shattuck, PhD, assistant professor of social work at Washington University in St. Louis and an autism researcher."A kid labeled autistic today could have been labeled mentally retarded 10 years ago in the same school system," Shattuck says. It wasn't until 1992 that schools began to include autism as a special education classification. 

Getting to the Causes of Autism

There's been a lot of progress in the last few years in terms of understanding the causes of autism, however there are still many roadblocks that prevent a full understanding. Identifying the causes is difficult than unraveling the causes of many other diseases because in many other diseases you can see it on an X-ray or with another diagnostic tool. The problem at this juncture for scientist in finding the cause is that there isn't a biomarker, image, blood test or pathology for autism. 

Additionally, often children with autism have a co-existing problems, such as a seizure disorder, anxiety , depression  or gastrointestinal or other health problems. At least 60 different disorders — genetic, metabolic, and neurologic — have been associated with autism, according to a report published in The New EnglandJournal of Medicine.

On one point most agree: A combination of genetics and environmental factors may play a role. Scientists are looking at both areas.

Genetics and Autism

Some evidence that genetics plays a role in autism and ASD is provided by research on twins:  

• If one identical twin has autism, there's a 75% chance the other twin will be affected, too. If a fraternal twin is affected, the other twin has a 3% chance of having autism.
• Parents who give birth to a child with ASD have up to an 8% chance of having another child who is also affected, the CDC estimates.
• Many U.S. couples have delayed childbearing, and the older ages of both the mother and the father have been linked with a higher risk of having children with ASD, according to a report in the journal Pediatrics. With age could come increased risk for genetic mutations or other genetic problems.
• Major chromosomal abnormalities are identified in about 5% of ASD.
• Fragile X Syndrome is responsible for about 3%. Fragile X syndrome, a family of genetic conditions, is the most common cause of inherited mental impairment, and also the most common known cause of autism or autism-like behaviors.
• Aa team of researchers reported in The New England Journal of Medicine that duplications and deletions on a specific chromosome seem to be associated with some cases of autism.  
  

Experts genetics is not the whole story, that there also are otheer factors not related to genetics.

Environmental Triggers

A variety of environmental triggers is under investigation as a cause or contributing factor to the development of ASD, especially in a genetically vulnerable child. 

• Exposure to pesticides during pregnancy may boost risk. In a study published in Environmental Health Perspectives, researchers compared 465 children diagnosed with ASD with nearly 7,000 children without the diagnosis, noting whether the mothers lived near agricultural areas using pesticides.The risk of having ASD increased with the poundage of pesticides applied and with the proximity of the women's homes to the fields.
• Exposure to organic pollutants that have built up in the environment are another area of concern. Biopersistant pollutants such as polychlorinated biphenyls (PCBs), substances previously found in electrical equipment, fluorescent lighting, ballasts, and other productsare a concern because they can be developmental neurotoxins. Another toxin to the brain is mercury in its organic form. Mercury is alo biopersistant and can build up in the environment. According to a report published in Pediatrics, there is no evidence that children with autism in the U.S. have increased mercury concentrations or environmental exposures. 

Vaccine Link?

The Institute of Medicine concludes there is no causal association betweeen vaccines and autism. However, the vaccine-autism debate reignited in early March 2008, after federal officials conceded to award compensation to the family of a 9-year-old Georgia girl who developed autism-like symptoms as a toddler after getting routine childhood vaccinations before thimerosal was phased out. Thimerosal is a mercury-containing preservative) that was used in vaccines. 

Current Studies May Shed More Light on Causes

The CHARGE Study (Childhood Autism Risks from Genetics and the Environment),is an ongoing study of 2,000 children. The researchers are focusing on how the interaction of genes and the environment play a role in autism. Preliminary findings suggest  that the immune system functioning of the mother may play a role in the child's later development of autism.  In another study, researchers found that levels of leptin, a hormone that plays a role in metabolism and weight, was much higher in children with autism than in normally developing children, especially if their autism was early in onset.