Is autism prevalance increasing?

Autism spectrum disorder (ASD) is one of neurodevelopmental disorders; and it is characterised by persistent deficits in social interaction and communication skills and also by atypical patterns of activities and behaviours. ASD can be diagnosed in early childhood by a child psychiatrist. In terms of etiology of ASD, studies suggest that there are probably many factor for a child to be predisposed to autism, including environmental and genetic factors (1).
 
Many prevalence studies have been performed worldwide since 1966. Prevalence varies substantially across studies mainly because of the methodological differences. The analysis of the literature on ASD prevalence studies published since 2014 confirms a high variability of prevalence estimates worldwide. According to Centers for Disease Control and Prevention (CDC), in 2000, prevalance rate was about 1 in 150 children. In 2008, it was 1 in 88 children. With years, prevalance rates were tended to increase. In 2014, rate was 1 in 59 children and since 2018, these rates have risen up to 1 in 44 children (2).  Many attribute this increase in prevalence to many factors… Changes in diagnostic criteria over time is among these factors. Formal diagnostic criteria for ASD did not emerge until the publication of the Diagnostic and Statistic Manual of Mental Disorders (DSM), Third Edition. After that ASD criteria were also modified throughout the versions of the DSM. That’s why, diagnosis were not made according to the exact same criteria. In addition to this, the increase in the members of the occupational group who have the competence to diagnose also facilitates access to the physician, so, it makes the diagnosis process more widespread.
 
Increases in autism awareness and acceptance is another factor in terms of increasing rates. ASD is discussed in the media, every year on April 2, World Autism Awareness Day is celebrated with the motive to spread awareness among the people about autism. Raising awareness will help people understand and accept people who are suffering from ASD and support them. Increased awareness lead families to have their children assessed  by a child psychiatrist earlier. It made possible to diagnose children at lower age. Besides these factors, cultural differences, environmental factors, using new assessment instruments, different research methodologies to identify prevalence rates (i.e. focusing on populations that are more likely to include autistic children, that is, children with developmental delays) would result in differences in prevalence rates. Cultural differences can explain differences seen across countries (3). Additionally, major improvements in perinatal and neonatal care have resulted in greater survival rates for premature infants. These babies are more likely to be affected  by neurodevelopmental disorders, including autism, at much higher rates than the general population (4).
 
Overall, etiology of ASD is multifactorial, therefore, multiple factors effect the increased prevalance rates. It is not possible to blame one reason for this increase. However, the change in diagnostic criteria and increased awareness appear to be at the core of the increasing prevalence of ASD. But still there is a need to carry out more research on this subject.
 
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