REPORTED RATES OF AUTISM ARE INCREASING OVER TIME
A new (2014) report from the Centers for Disease Control and Prevention and the National Center for Health Statistics, USAfound that 1- in- 45 children or 2.24% of children aged 3 through 17, met the diagnosis of autism spectrum disorder (ASD). This figure is a dramatic jump from earlier surveys, also conducted by the Centers for Disease Control (CDC); 1-in-68 in 2013 and 1-in-88 in 2010.
Changes in the format of the questionnaire may be an important reason for the notable increase.
In previous surveys, the presence of a developmental disability was asked first, rather than the presence of ASD. The new questionnaire flipped the two categories. Not surprisingly, the prevalence of developmental disabilities decreased.
Other findings from the surveys
– High rates of co-occurring conditions – Learning disabilities were the most common (62.6 %); next highest was ADHD (42.8%).
– As previously seen, ASD is almost five times more common among boys than girls: 1 in 42 boys versus 1 in 189 girls. White children are more likely to be identified as having ASD than are black or Hispanic children.
– ASD can be diagnosed as early as age 2 but most children with ASD are diagnosed after age 4.
The new survey was based on responses of parents whose children had received medical or special education services. Thus, children who were not receiving those services might have been missed.
This new prevalence figure does not replace the CDC’s 1-in-68 figure seen in a 2011-2013 survey as the official estimate of autism prevalence in the United States.
Survey statistics are estimates and are subject to limitations of sample characteristics. Since ASD can be diagnosed at ages later than 17 years (the upper limit of the recent survey), it is possible this recent estimate could still be an underestimate.
Thus, surveys limited to children younger than age three are likely to produce underestimates. Note that the previous CDC surveys sampled children up to 8 years of age and the most recent (2014) survey which yielded a 1/45 figure was based on children up to 17 years of age.