A Brief History of the Science of Autism Spectrum Disorder

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In 1943, Leo Kanner, a child psychiatrist at Johns Hopkins University, identified autism as a separate disorder from schizophrenia in young children. Kanner called his newly identified disorder early infantile autism. The sample of children he studied was entirely male. Kanner described early infantile autism as being characterized by symptoms that included obsessiveness, deficits in social behavior and social communication, and a need for sameness.

In 1944, a German pediatrician at the University of Vienna named Hans Asperger studied a similar group of children that he described as having autistic psychopathy. The sample Asperger studied consisted of boys who had slightly higher cognitive functioning and were better at interacting with the world than Kanner’s sample. They had the same symptoms and were described as having deficits in social behavior and communication and obsessiveness, but they were more “high functioning” than the group Kanner studied.

Thus, early diagnostics divided these children with the same symptoms into two groups that were defined by their ability to function in society and cognitive abilities. Autistic children had more disabilities than the group with higher cognitive functioning, who were described as having Asperger’s syndrome.

In 1967, Kanner hypothesized that autism was caused by inferior parenting on the part of the mother. He described these mothers who created autistic children as “refrigerator mothers” because they were cold and aloof. In 1977, Folstein and Rutter conducted several identical twin studies and found that in most cases, both identical twins would have autism whether they were raised in the same household or in separate households. Studies found that non-genetically identical siblings of autistic children do not show the same patterns.

Autism was first seen in the Diagnostic and Statistical Manual of Mental Disorders (DSM) as its own diagnosis in 1980. Previously, it had been diagnosed as a form of schizophrenia. Autism was divided into subcategories: infantile autism, residual autism, childhood-onset pervasive developmental disorder, and atypical form. It wasn’t until 1994 with the DSM-IV that Asperger’s Disorder first emerged as a separate diagnosis and defined people with all the symptoms of autism who had higher cognitive functioning and were able to blend in more with normative society.

In 1998, the famous Wakefield study was published in The Lancet. In this study, Andrew Wakefield and his colleagues released a report in The Lancet journal suggesting that the measles, mumps, and rubella (MMR) vaccine may predispose children to autism. The study involved only 12 subjects and did not have scientific controls, but it received widespread media attention. This resulted in a decline in MMR vaccination rates.

In 2001, the use of thimerosal, a mercury-based preservative used in vaccines, was discontinued in childhood vaccines. This was due to the speculation regarding the association between thimerosal and autism. All scientific studies have reported that there is no association between thimerosal and autism.

Wakefield’s study has since been entirely discredited, and Wakefield has admitted to falsifying his data. The Lancet has apologized for its part in the spread of this misinformation and has published numerous studies repudiating Wakefield’s work, but to this day, politicians and many autism agencies publicly claim this research shows that autism is caused by “chemicals” and say vaccines cause autism. A large antivaccine movement still cites this entirely discredited and singular study as evidence of the link between autism and vaccines.

In 2013, the DSM-5 was released, which combined all the subcategories of autism into a single diagnostic entity called the “autism spectrum disorder.” This was done to address inconsistencies in the criteria used in diagnosis. Prior to the DSM-5, the prevalence rate of autism was that 1 in 68 children had autism. Currently, the prevalence rate is that 1 in 36 children has autism. This is not because of an epidemic of autism. This is because prior to the DSM-5, autism, Asperger’s Syndrome, Pervasive Developmental Disorder NOS, and other pervasive developmental disorders were diagnosed separately, but after the DSM-5, all of these diagnoses are now included under the autism spectrum disorder diagnosis.

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Since the release of the DSM-5 and with the growing autism advocacy movement, more and more people are getting diagnosed with autism spectrum disorder, and more autistic adults are speaking out. Previously, almost all the research into the area of autism was done on children who couldn’t explain what their experience as autistic people was like. Now, research into autism and data on the subject has exploded. Gathering data from autistic adults has given us a more detailed and accurate depiction of autism, and understanding neurology and completing the human genome project has also given us a window into autism that was never present before.

Similar to other neuropsychiatric disorders, the risk factors for ASD involve a substantial genetic component, which is profoundly complex and multifactorial, involving hundreds of risk genes (Gandall et al, 2022). Surprisingly, the most profound gene-expression changes in ASD were observed in the primary visual cortex (BA17). It is interesting to speculate that the substantial changes observed in primary sensory regions may be related to the widespread sensory processing differences in ASD, which are so pervasive that they have been included in the DSM-5 diagnostic criteria³¹ (Gandall et al., 2022).

Data from genome screens of families suggest that there are at least 10 genes associated with autism that can be identified. There are consistent differences found at chromosome 15 (Muhle, 2004). Every autism researcher concludes the same thing in all of these studies. While we are discovering the genetic roots of autism, more research needs to be done to understand the depth of the genetic complexity.

As we look at the history of autism, it is easy to see that the research, treatments, and study of the disorder have been colored by the drive of many autism parents and families to find a cure for autism. Raising an autistic child can be difficult, and many parents and families want to believe there is an easy cure. So, even though as early as 1977, twin studies showed that autism was genetic and ran in families, we have ignored the real research and embraced discredited and fraudulent research like the Wakefield study because these studies offer a solution to what many people view as a horrible problem plaguing families.

Refrigerator mothers, vaccines, and food additives are easier villains than the unstoppable drive of genetic drift. However, the research shows that autism is multivariant, complex, and primarily genetic. I hope as we move forward, we can learn to see the beauty in autism, learn to love our autistic children instead of trying to cure them of who they are, and embrace the beauty of truth and the beautiful minds of our neurodiverse nation.