There is not a cure for autism, and not for want of trying—entire careers and many millions of dollars have been spent on the search for a cure that has not appeared. This article is my view on why, despite a great deal of effort, scientists have not come anywhere close to finding a cure.
We don’t know what autism is
The diagnostic criteria are vague and behavior-based. The current Diagnostic and Statistical Manual (DSM) requires only two symptoms to diagnose autism: restricted/repetitive behavior or interests, and difficulties in social communication, both of which must have been present since early childhood. There is no biomarker for autism. There is only the individual clinician’s opinion based on an interview with the autistic person and possibly their parents or other family.
This means that the autism spectrum is incredibly heterogenous and likely biased by sex, race, and other demographics (for example, compared to the DSM IV, the DSM V tends to miss females and people with high IQs). This is a problem because recruitment of autistic people into studies relies on their diagnosis.
We don’t know whether autism has one fundamental feature/cause or is a myriad of conditions and comorbids—from anxiety to intellectual disability to gut problems—all grouped together by two common symptoms. This does not mean that the diagnostic criteria should be changed; this concept of autism may be the one that most closely carves nature at its joints. It does, however, make autism difficult to study scientifically.
Autism is genetic—but the genetics are highly complex
Autism is a genetic condition: about 80-90% of the variance in autism development can be explained by genetics rather than environmental influences (Bai et al., 2019, Sandin et al., 2017). Some genetic conditions can be treated with restrictive diets, supplements, or experimental treatments like gene therapy. However, autism is much more complicated.
Hundreds of autism “risk” genes have been identified; combined, they explain 10-20% of cases. Genes that affect the likelihood of developing autism interact with each other affect the epigenetic landscape of the genome and are often duplicated or deleted. Some are common, while some are de novo—occurring only in the autistic person rather than being inherited.
Autistics tend to have higher mutational loads in the form of point mutations that substitute one DNA base for another, or copy number variants (duplications or deletions)—these are usually scattered around the genome, so there is no single gene that is responsible.
There are several autism-associated syndromes that have known genetic causes, including Fragile X syndrome, Rett syndrome, 22q13 deletion syndrome, cortical dysplasia-focal epilepsy, Angelman syndrome, and tuberous sclerosis. Gene therapy treatments for those are much more feasible—but syndromes caused by a single gene make up only 5% of autism cases combined. Even within that 5%, when you consider the extraordinary cost of gene therapy, it may not be economically feasible to develop one for each known cause.
Thus, going after autism at the root causes (genetic variants) is unlikely to work. It is possible that among the hundreds of different genes that are associated with autism, similarities could be found between them that point to a common process. Despite the many people who have tried to find such a process, there has been no simple answer.
Autism is difficult to model
Biomedical scientists often use animal models to study diseases, understand causes, and test out potential treatments. Autism is not suitable to being studied this way (though researchers certainly still try: animal research made up 44% of all autism research funding in the UK in 2016, according to Autistica).
Autism is hard to model due to its genetic heterogeneity; each model would have to uniquely match its human counterpart. Also, autism is fundamentally about emergent functions of the mind that are uniquely human.
Animals that have been used to model autism include mice, rats, songbirds, rhesus monkeys, and nematode worms, among others. These animals are made “autistic” by mutating part of their genomes to some variant we know causes or increases the likelihood of some cases of autism, by removing oxytocin or opioid receptors, or by inflicting them or their pregnant mothers with environmental injuries with thalidomide. Animal studies of autism often focus on one associated trait, such as repetitive activities like marble burying or self-grooming.
Autism is a very human condition, characterized by differences in socialization and language as well as repetitive behaviors. Other animals have different cognitive capacities compared to humans, which is how researchers justify using them in the first place.
They also have very different social behaviors; for example, mice are highly territorial, so their behavior in a test of sociability may actually be a test of confrontation. Some researchers are using primate models instead to avoid that issue, but even apart from ethics, there are many traits that non-human animals simply cannot replicate—in autism, those are the traits that matter.
The animal observations actually bear little relevance to the traits of actual human autistics. Mice do not face environments similar to those relevant for autistic humans, like getting through school and the workplace. The outcomes studied, such as marble-burying (repetitive behaviors) or pheromone emissions or ultrasonic vocalizations (social interaction), may be unrelated to the effects people actually want in a cure for autism.
They also fail to represent the workarounds real autistics use in their daily lives, e.g. an autistic person using scripts to navigate conversations instead of relying solely on their instincts and spontaneous conversation.
We don’t know what a cure for autism would look like in a person
What is a cure for autism? A person could be diagnosed with autism for being in a high percentile for each of the two diagnostic traits — would a cure mean bringing those traits below the 95th percentile? The 70th? All the way to the median? You could perhaps say it means changing the person’s brain so that they are permanently no longer negatively affected by their autistic traits, no matter their environment.
I would define a cure for autism as some medical intervention given to an autistic person that permanently changes their brain so that they no longer possess the underlying inclinations that led to diagnosable behaviours. For example, a ‘previously autistic’ individual would no longer feel the desire to stim, rather than simply forcing themselves to suppress it (masking).
It is difficult to imagine how the adult brain could be changed so drastically, so the cure would have to be administered in early childhood or potentially in utero as a prevention. Other preventions may include selectively aborting or choosing not to implant embryos with genetics indicating likely autism (and remember, a vast majority of the genetic variants are unknown).
Autism researchers are missing out on a huge source of information
That source is, of course, autistic people. There is a chasm between autistic people and autism professionals, with perhaps the most notorious example being the identity language used: most autistic adults prefer “autistic people,” and autism professionals mostly call them “person with autism,” regardless of preference.
Autistic people’s knowledge of autism has been found to be more scientifically-based, which is not surprising considering that many autistic people’s special interest is autism. If you’re looking to understand autistic minds—which, if you’re trying to understand autism, you should be—autistic people also have blogs all over the internet offering insights into their life experiences and things that help them. You probably need them more than you think: neurotypical people tend to struggle to read autistics.
Of course, autism professionals should, as a matter of ethics, be listening to autistic people anyway, but that’s not my point here—my point is that they are missing out on genuinely valuable information that will push the field of study forward.
All in your head: on a cure for autism as a human condition
Autism is defined by behavior—a difference in brain wiring. Brains are difficult to target for drug delivery, gene therapy, and finding blood biomarkers. Brains are difficult to reduce to individual components, and in the fields of language and sociality, human brains are unique.
Autism is about the complex behaviors involved in navigating the modern world, about all the interactions within the brain and within society. With that in mind, it’s not surprising that autism is hard to pin down.
The good news is that it does not need to be pinned down. Instead of trying to eradicate autistic people and replace them with neurotypicals inside previously-autistic bodies, we can focus our efforts on improving the quality of life for actual autistic people right now.
The failure of research to find a cure for autism may turn out to be a blessing in disguise.