Characterized by significant impairments in communication, social skills, and behavior, autism is a devastating and mysterious disorder that affects people of all ages and in all cultures. According to Autism Speaks, a national advocacy group, tens of millions of individuals around the globe have been diagnosed with autism. Unfortunately, such statistics are vague and don't offer the full picture of the prevalence of the disorder. In order to understand the number of people affected by autism worldwide, it's essential to take a closer look at the numbers for each country that has been studied, as well as social and cultural factors that may apply.
Autism Prevalence Around the World
There's is no official count of the number of people who have been diagnosed with autism worldwide. Some countries don't have well-established health and education systems, so those on the higher functioning end of the spectrum can slip through the cracks. According to the Simmons Foundation Autism Research Initiative, a number of factors can affect the accuracy of autism surveys worldwide. In addition to the heath and education resources available, these include the way that the society views autism and an autism diagnosis and the methods used to gather the data.
Although there are many countries that simply don't have enough official data about autism, several countries have conducted reputable studies. They can offer a few clues about the prevalence of autism around the globe.
In a study conducted by the Yale University School of Medicine, researchers found that about 2.64% of South Korean children between the ages of seven and 12 have some level of autism. This study was unique because it examined children in regular classrooms, rather than the population that was already identified as having special needs. This resulted in a much higher prevalence than previous studies, but the New York Times reports that many experts feel this may be a more accurate measurement of the number of children on the autism spectrum.
A study published in the Journal of Child Neurology was the first large-scale examination of the prevalence of autism in China. The study found that 1.61% of children under the age of 15 years were receiving some level of services for an autism spectrum disorder. The data for this study came from a national registry, so unlike the South Korean study, it does not include children with high functioning autism who may be undiagnosed.
According to a study published in the Journal of Pediatrics and Child Health, 1.21% to 3.57% of Australian children aged six to 12 have been diagnosed with autism. The study examined whether this method of assessing prevalence was accurate, and it found that there was a great deal of variation in the numbers based on the area of the country and the reporting agency. This suggests that the rate of autism in Australia may be under-reported.
The Journal of European Child and Adolescent Psychology published a study examining the prevalence of autism in Finland. For children aged five to seven years, the study found that the autism rate was 2.07%. The rate was lower for older children, who had been tested when the diagnostic criteria were stricter.
A review of autism prevalence studies published in Acta Psychiatrica Scandanavia in 1999 found that the overall rate of autism diagnosis in all countries in Africa between 1970 and 1997 was 0.1%. The researchers speculated that this low rate might be due to a strict interpretation of the diagnostic criteria. Additionally, in the years since this review was published, the worldwide rate of autism has gone up. More research is needed to determine the actual rate of autism in Africa.
According to a study published in the British Journal of Psychiatry, 1.57% of British five- to nine-year-olds have autism. The study examined children who had already received an autism diagnosis or were receiving special education services, as well as children in the regular classroom. While previous estimates had placed the prevalence at 0.99%, the study found that including previously undiagnosed children increased the prevalence rate significantly.
The Center for Disease Control and Prevention (CDC) estimates that 1.14% of eight-year-olds in the United States have an autism spectrum disorder. This translates to one in 88 children. Statistics for other age groups are not as comprehensive. The CDC reports that this rate is similar to the prevalence reported in Europe, North Africa, and Asia.
Caution About Extrapolating Worldwide
It may seem that it would be possible to better estimate the worldwide prevalence of autism by multiplying the percentages for each country by the population of that country. However, there are a few problems with this approach:
- The statistics for each country represent a specific age group. Although they may apply to seven-year-olds, they don't necessarily apply to adults or older children. Diagnostic criteria have changed over time, and some experts also feel that environmental factors may be contributing to an increase in the incidence of the disorder.
- Data may not be gathered the same way for all studies. Some studies simply examine the number of children already diagnosed with the disorder, while others look at the general population. The results can vary ignorantly.
- Cultural factors can also affect the number of children diagnosed. Some cultures prize many of the characteristics of high functioning autism, leading to children being under diagnosed. Others may have a social stigma attached to the disorder, and parents may hesitate to answer surveys truthfully.
- In countries with limited medical and educational resources, it's very likely that the number of autism diagnoses is dramatically lower than the actual prevalence.
Larger-scale studies will have to be conducted to determine the real worldwide prevalence of the disorder. The Autism Speaks estimate of "tens of millions" may be the most accurate worldwide prevalence rate possible at this time.
Who Is Affected by Autism?
Although tens of millions of people worldwide carry the diagnosis of autism, this disorder affects more than just those individuals who have it. Parents, siblings, grandparents, teachers, community workers, and friends are also affected. In addition, public education and health systems are paying billions of dollars to care for children on the autism spectrum, and they receive their funds from individual taxpayers. No matter what the official worldwide prevalence rate is, nearly everyone in the world is at least indirectly affected by this devastating disorder.