Zeeshan Haider Introduction
Rise in autism diagnoses since the 1990s has been a consistent and significant trend, prompting researchers to delve into the reasons and timelines associated with this rise. While there isn’t a singular cause, several factors are likely contributing to this notable increase.
One major factor is increased awareness of autism. As understanding of the spectrum broadens and more information becomes available, there’s a heightened recognition of the diverse ways autism can manifest. This improved awareness leads to more accurate identification and diagnosis of individuals on the spectrum.
Changes in reporting practices also play a role in the observed rise. Diagnostic criteria and guidelines have evolved over the years, potentially capturing a broader range of cases. The expansion of the autism spectrum, encompassing a spectrum of severity and traits, may lead to more individuals meeting the criteria for an autism diagnosis.
Environmental factors are also under scrutiny. Advanced parental age, particularly for mothers, has been associated with an increased risk of autism in their offspring. Maternal health, exposure to certain environmental toxins, and other prenatal factors may contribute to the rise in autism diagnoses.
According to the Centers for Disease Control and Prevention (CDC), the prevalence of autism in the United States was approximately 1 in 150 children in 2000. By 2020, this figure had risen to approximately 1 in 36 children aged 8. This significant shift over two decades underscores the complexity of the issue and the need for ongoing research to better understand the multifaceted factors influencing the prevalence of ASD.
Diagnostic Criteria Evolution
The conceptualization of autism traces back to the 1940s when it was initially characterized by pronounced traits, now akin to what is classified as “level 3” autism spectrum disorder, necessitating substantial support. A pivotal shift occurred in 1994 with the release of the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) by the American Psychiatric Association. This edition acknowledged autism as a spectrum disorder, accommodating a spectrum from mild to profound traits.
This transformation led to the introduction of additional diagnoses like Asperger’s syndrome and Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS), terms that have since fallen out of usage. The evolution continued with the DSM-5 in 2013, consolidating Asperger’s and related diagnoses into a unified category known as Autism Spectrum Disorder (ASD). This alteration potentially expanded the criteria, contributing to an uptick in reported autism cases.
The growing awareness of autism has prompted pediatricians to incorporate routine screening into their practices, becoming another influential factor in the increased incidence of reported cases. The American Academy of Pediatrics recommends screening for ASD at 18 and 24 months, coupled with regular developmental surveillance to foster early detection and intervention.
Shifting Reporting Practices
The CDC’s analysis of autism statistics relies on health and school records from 8-year-old children residing in specific counties across the United States. Researchers, affiliated with the Autism and Developmental Disabilities Monitoring Network established by the CDC in 2000, work to estimate autism prevalence. Clinicians scrutinize school records for indications of autism traits, such as social challenges or repetitive behaviors. The focus on 8-year-olds stems from the fact that most children are enrolled in school and have undergone routine health assessments by that age. Notably, the data does not hinge on whether children have received an official ASD diagnosis.
Prior to 1990, autism lacked inclusion in legislation aimed at securing education for individuals with disabilities. The Individuals with Disabilities Education Act rectified this by incorporating autism into its covered conditions in 1990. This legislative update also introduced transition services and assistive technologies as requirements. Autism had not been monitored as an educational statistic before 1990, and since that year, there has been a substantial surge in autism incidence within school settings.
A separate set of prevalence estimates disclosed in a 2019 Pediatrics publication revealed a notable increase in autism cases in the United States, from 1 in 91 children in 2009 to 1 in 40 in 2017. These results derived from telephone or in-person interviews with parents of 88,530 children aged 3 to 17, collected by the CDC as part of its National Health Interview Survey.
External Factors at Play
The exact cause of autism remains elusive, but extensive research suggests a complex interplay between genetic and environmental factors. Notably, having an autistic sibling increases a child’s susceptibility to autism, pointing towards a genetic component.
Environmental factors, particularly those occurring before or during birth, have also been implicated in autism risk. These factors encompass advanced parental age, prenatal exposure to air pollution or certain pesticides, maternal obesity, diabetes, or immune system disorders, extreme prematurity, very low birth weight, and birth difficulties leading to periods of oxygen deprivation to the baby’s brain. Some of these factors may be on the rise, potentially contributing to an increase in autism rates. For instance, about 20% of women in the United States now give birth to their first child after the age of 35.
It’s essential to distinguish between supported evidence and debunked theories regarding environmental causes of autism. Contrary to earlier misinformation, credible research has refuted theories linking autism to vaccines, poor nutrition, so-called “bad” parenting, and cell phone use, among others. It underscores the importance of relying on scientifically validated information when exploring the intricate factors influencing autism spectrum disorders.
The Future of Autism Diagnoses
The trajectory of autism rates remains uncertain, influenced by the dynamic interplay of evolving diagnostic criteria and shifting environmental factors. Changes in diagnostic guidelines may result in fluctuations in the number of children qualifying for an autism diagnosis. Additionally, alterations in environmental elements, such as delayed parenthood, can impact the prevalence of autism and conditions associated with advanced parental age.
The elimination of Asperger’s syndrome and PDD-NOS as catch-all options led to diverse expectations among experts. Some anticipated a decline in autism diagnoses, while others foresaw an increase due to heightened awareness and improved services. Currently, the trend indicates a persistent rise in both the number and rate of children diagnosed with autism.
The intricacies of these factors underscore the need for ongoing research, monitoring, and a nuanced understanding of the multifaceted elements influencing autism prevalence. As diagnostic methodologies and awareness evolve, so too does our comprehension of the complex landscape surrounding autism spectrum disorders.
Conclusion
In conclusion, the surge in documented autism cases since the 1990s is a multifaceted phenomenon. Factors such as evolving diagnostic criteria, altered reporting practices, and heightened awareness collectively contribute to the observed increase. The amalgamation of previously distinct conditions under the ASD umbrella further complicates the statistical landscape. As of now, the trajectory suggests that diagnoses of autism are likely to continue rising.
Source
- Centers for Disease Control and Prevention (CDC). (2020). Data and Statistics on Autism Spectrum Disorder.
- American Psychiatric Association. (1994). Diagnostic and Statistical Manual of Mental Disorders (4th ed.). Washington, DC: American Psychiatric Association.
- American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.). Washington, DC: American Psychiatric Association.
- Mandell, D. S., Novak, M. M., & Zubritsky, C. D. (2005). Factors Associated With the Age of Diagnosis Among Children With Autism Spectrum Disorders. Pediatrics, 116(6), 1480-1486.
- Newschaffer, C. J., Croen, L. A., Daniels, J., Giarelli, E., Grether, J. K., Levy, S. E., … & Windham, G. C. (2007). The epidemiology of autism spectrum disorders. Annual Review of Public Health, 28, 235-258.
