Increasing incidence rates of Autism Spectrum Disorder: CDC data. 2014


Centers for Disease Control and Prevention’s (CDC)  latest report show that autism spectrum disorders in USA has gone up by 30%. Surveillance programs in 14 states began in 2000.  incidence rates among 8-year-old children were recorded every two years . Incidence rate  in 2010 was  14.7 per 1000 i.e. one in every 68  eight yr old child has ASD. This was one in 150 children in 2000.

Largest increases have been reported among Hispanic children, black children, and children without a co-occurring intellectual disability. Condition remains nearly 5 times more common among boys than girls and white children are more likely to be diagnosed with autism spectrum disorder than black or Hispanic children.

Better awareness and diagnosis  are likely to play some role in this increase. The CDC do highlight that  improved the ability of the monitoring network to identify children with ASD as a factor. Surveillance areas selected are not representative of the States, suggesting limitations in generalisability of these findings.

UK saw an increase in autism in 1990s, then it stabilised. along with UK, USA and Denmark also  recorded dramatic increase during that period.  Few children were diagnosed as autistic in either Uk or USA prior to 1990.

The annual prevalence of autistic spectrum disorders in UK  was estimated at 3.8 per 1,000 boys and 0.8 per 1,000 girls. That figure was stable between 2004 and 2010. Annual incidence estimates is about 1.2/1000 boys over the years in UK. UK data is from the GP database, i.e.individuals diagnosed with autism and under the GP’s care. This is different from CDC method of surveillance by data collection from schools/medical records i.e. they review these data and evaluate them to determine presence of ASD. They do not see these children or do any screening/ confirmatory assessments.

The estimated prevalence rates of autism in the UK population is  about 4 per 1000 in 8-year-old boys (2008). This is far lower than 11 per 1000 in 8-year-old boys reported by the CDC (USA- 2008). This large difference is closely similar to differences in rates reported for chil- dren diagnosed and treated for ADHD between the two countries.

What explain  this huge increase?

. CDC data do not address these questions. It is possible factors mentioned elsewhere like that aging of parents,environmental factors, broadening of diagnosis and increased awareness are possible factors.

Ref: prevalence of ASD among children aged 8 years: ADDMN, 2010,March 28,2014/63)SS02.

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