Why Is Autism Rising?

Autism cases are rising. But there is a lot of controversy as to why. In this article, we analyse the data to tell you what is really going on.

What Is Autism? 

Autism Spectrum Disorder (ASD) is a lifelong neurodevelopmental condition ⁽¹⁾. This means that from pregnancy, the brain of a person with autism develops in a different way to the brain of typically developing people.  

Autism very often goes hand in hand with other conditions such as intellectual disabilities, ADHD, apraxia, dyspraxia, epilepsy, or anxiety-based disorders. It is estimated that around 70% of people with autism have another condition.  

What Causes Autism? 

We all want to a simple explanation ⁽²⁾ for autism, but the reality is that autism is a very complex condition, and its causes are also very complex.  

For the most part, autism is genetic. But this does not mean that there is one single gene responsible in everyone who has it. It seems that there are hundreds or thousands of genes involved.  

However, there are factors that, when interacting with a genetic predisposition to develop autism, make it more likely that the child will develop autism. But these factors alone are unlikely to cause autism.  

What Are These factors? 

• Infections during pregnancy, like rubella  

• The use of some epilepsy drugs, early in pregnancy. 

• Preterm birth 

• Very low birth weight 

• Maternal obesity, diabetes, or immune system disorders 

• Older fathers 

• Air pollution 

There are also some factors that have been ruled out: 

• Emotionally distant parenting 

• Narcissistic parents 

• Prenatal exposure to antidepressants 

• Ultrasounds 

• Vaccines: vaccines DO NOT cause autism. There is a very strong body of literature supporting this finding.   

Is Autism Really Rising? 

If we simply look at the data, it does seem that autism in on the rise. A new report ⁽³⁾ by the Centre for Disease Control and Prevention (CDC) suggests that autism is more common than ever before. As of 2022, 1 in 31 children in the U.S were diagnosed with autism by the time they were 8. This contrasts with 1 in 36 in 2020 and 1 in 50 in 2000. The U.S. is not the only country reporting more cases of autism. The UK ⁽⁴⁾, for example, is also finding an increase in cases.  

From this data, we could conclude that there are more people with autism than ever before, but if we look at the data carefully, we realize that quite likely this is not the case. Cases of autism are not really rising, what is happening is that we are getting better at screening and diagnosing the condition. So, it is not that autism cases are increasing but that diagnoses are increasing.  

In a way, this is good news because it means that as a society, we are becoming more aware and better understanding what autism is. The lessening of stigma around people with autism also means that more adults are getting evaluated, whereas before they wouldn’t have been diagnosed. It also means that more children and adults are getting the support the need. 

How Do We Know that We Are Better at Diagnosing It? 

It is true that we cannot be a 100% sure that the reason why there are more cases of autism is that we are getting better at diagnosing it, but it seems quite likely because of two reasons.  

First, the latest CDC report shows that the prevalence of autism is different across U.S. states. For example, there are twice as many cases in California than in Maryland. There is there no reason why there should be more cases in one state over another. So, these differences seem to indicate that some states are better at monitoring and screening autism than others. 

Second, the fact that more and more adults are getting diagnosed means that many adults with autism have been living with an undiagnosed condition.  

Both these reasons mean that rather than cases of autism being on the up, it is the diagnosis that is improving.  However, it is true that we cannot be 100% sure.  

What Other Possible Factors Are There? 

The two factors that could be driving the change are: 

• Preterm birth: more babies ⁽⁵⁾ born early are surviving than ever before. Babies born between 22 and 27 weeks are about six times more likely to have autism than children born full time. This could be causing the rise, but it is unlikely that it explains the entire rise because the number of preterm babies is too small to be an important part of the trend.  

• Older fathers: older fathers ⁽⁶⁾ are more likely to have children with autism. Fathers over 50 are slightly more likely to have children with autism. It is true that the age of fathers has risen over the last few years but again, this factor alone doesn’t seem to be relevant enough to explain the rise of autism cases.  

Finally…. 

It seems that the rise of autism really is an improvement in our ability to diagnose it. What we don’t know yet is this fact explains a 100% of the rise or there are other factors 

playing a part. In the meantime, there are many people using this uncertainty, to create fear and spread misinformation amongst parents. What we need is more research to settle this debate and better support for people with autism and their families.  

I hope this information helps. If you have questions about autism or any other issues, get in touch with me. 

Love, 

Ana 

Dr Ana Aznar 

References 

⁽¹⁾ Muhle, R., Trentacoste, S. V., & Rapin, I. (2004). The genetics of autism. Pediatrics, 113(5), e472-e486. https://doi.org/10.1542/peds.113.5.e472 

⁽²⁾ Landrigan, P. J., Lambertini, L., & Birnbaum, L. S. (2012). A research strategy to discover the environmental causes of autism and neurodevelopmental disabilities. Environmental health perspectives, 120(7), 258-260. doi:10.1289/ehp.1104285 

⁽³⁾ Shaw KA, Williams S, Patrick ME, et al. Prevalence and Early Identification of Autism Spectrum Disorder Among Children Aged 4 and 8 Years — Autism and Developmental Disabilities Monitoring Network, 16 Sites, United States, 2022. MMWR Surveill Summ 2025;74(No. SS-2):1–22. DOI: http://dx.doi.org/10.15585/mmwr.ss7402a1 

⁽⁴⁾ Russell, G., Stapley, S., Newlove-Delgado, T., Salmon, A., White, R., Warren, F., Pearson, A., & Ford, T. (2021). Time trends in autism diagnosis over 20 years: a UK population-based cohort study. The Journal of Child Psychology and Psychiatry, 63(6), 674-682.  

⁽⁵⁾ Chen, L. W., Wang, S. T., Wang, L. W., Kao, Y. C., Chu, C. L., Wu, C. C., … & Huang, C. C. (2019). Behavioral characteristics of autism spectrum disorder in very preterm birth children. Molecular Autism, 10, 1-9. https://doi.org/10.1186/s13229-019-0282-4 

⁽⁶⁾ Parner, E. T., Baron-Cohen, S., Lauritsen, M. B., Jørgensen, M., Schieve, L. A., Yeargin-Allsopp, M., & Obel, C. (2012). Parental age and autism spectrum disorders. Annals of epidemiology, 22(3), 143-150. https://doi.org/10.1016/j.annepidem.2011.12.006