Most of our knowledge about the prevalence of ASD in the U.S. comes from studies that are published by the Centers for Disease Control (CDC) every 4 years. These studies examine the rate of ASD diagnoses in a specific “slice” of the population: 8-year-olds living in 11 communities across the U.S. A new study, based on data collected by the CDC, provides information about how ASD diagnoses may change over time.
This study surveyed parents of 6- to 17-year-olds who reported in 2009-2010 that their child had “ever been diagnosed with” an ASD. The authors found that approximately 13% of children who had been diagnosed previously with ASD had “lost” their diagnosis by the time of the present study. The children who no longer had an ASD diagnosis had higher current levels of adaptive functioning and lower levels of ASD symptoms compared to those who retained the diagnosis. However, there were no early differences between the groups in the age of first concerns (about 2 ½ years), age of first service (about 4 ½ years), or age of initial diagnosis (about 5 ½ years). Parents reported several reasons for the changes in diagnosis: because “new information” became available (73.5%), because the initial diagnosis was made to help the child obtain services (24.2%), due to treatment or maturation (21%), or due to an initial misdiagnosis (15.5%). The vast majority of the children whose ASD diagnosis was removed (96%) had received a “replacement” diagnosis, the most common being ADHD.
The authors conclude that these changes in ASD diagnoses over time have implications for the current methods used to assess the prevalence of ASD, the characteristics of ASD, and the adequacy of services.