Autism Spectrum Disorder (ASD) occurs in all racial, ethnic and socioeconomic groups. Notably, ASD is almost 5 times more common among boys (1 in 42) than among girls (1 in 189).
The number of children diagnosed with autism has increased significantly over the last few decades. In 1992, only one in every 150 children was identified as having autism. By 2008, the rate had increased to one in 88.
Experts are currently unable to agree on the cause or the significance of the increasing rate of autism. Some of the increase could be explained by increased awareness of ASD, improvements in monitoring and accuracy of diagnosis, changes in environment, or a combination of any of these factors.