Can an injury to the brain, either from an accident or loss of oxygen, lead to autism, even mild autism?
Though autism spectrum disorder is classified as a neurodevelopmental condition, there are many who wonder if it’s at all possible for a traumatic brain injury (TBI) to lead to this condition.
Autism researchers believe that ASD originates during early brain development, long before most people are diagnosed.
It was already there, very early on in brain development, even in those who are diagnosed later in adulthood – such as myself.
Research consistently shows that the neurological differences associated with autism are present in infancy or early childhood, even if signs are subtle at first (commonly mistaken, especially decades ago, as just “oddness,” “weirdness,” social awkwardness or even ADHD).
Autism is not considered an acquired condition that suddenly appears after injury.
Can a TBI ever cause autism?
A traumatic brain injury does not cause autism in the clinical sense.
Though a TBI can cause a permanent situation that resembles a feature that’s found in ASD, this doesn’t mean that a head injury, brain bleed or brain tissue death from lack of oxygen could outright cause someone to go from neurotypical to autistic.
An example of a disability that brain trauma can cause, that’s found in some autistic people, is difficulty forming spoken language.
A perfect example of this is an ischemic stroke that damages the Broca’s area of the brain.
This area is responsible for language expression.
But just because this patient will always have speech difficulty doesn’t mean they’ve become autistic.
Autism is understood to arise chiefly from genetic factors, possibly combined with early developmental influences (though that second scenario remains hotly debated among researchers, especially since ASD tends to run in families).
Though there’s yet to be an established, definitive, clear flow chart on just how autism happens, researchers do know for certain that brain trauma (motor vehicle crash, gunshot wound, fall, hemorrhagic or ischemic stroke, hypoxia) can’t make you autistic.
Autism is a different kind of brain wiring, not brain damage.
Autism is a different kind of brain wiring, not brain damage.
Brain injuries that occur later in early childhood, adolescence or adulthood do not create autism, even if behavior changes look similar to autistic traits.
Medical reviews emphasize that autism is developmental, while TBI is an injury based condition with different origins.
Why TBI and Autism Get Confused
The confusion happens because TBI and autism can look alike on the surface.
After a brain injury, a person may have trouble with communication, emotional regulation, sensitivity to loud noise, expressed attention or social interaction. And in some cases, speech output.
These overlaps can make it seem like autism appeared after the injury – even though in TBI cases, the new presentation usually excludes the strengths of autism such as high attention to detail, heightened sense of justice, thinking outside the box, great problem solving skills, hyperfocus and resistance to peer pressure.
Shared symptoms (especially only the troublesome ones) don’t mean the same underlying condition.
Post-injury neurological changes can mimic autism without being autism.
Depending on the TBI patient’s medical history and available resources, therapy can eliminate or nearly eliminate some of the conditions caused by the injury.
In autism, similar presentations can’t be eliminated because that’s just how the brain is wired.
Elimination is not to be confused with masking, which is when an autistic person willfully conceals behaviors to appear neurotypical to others.
Another form of masking is that of acting neurotypical such as by consciously inducing rehearsed body language, facial expressions or vocal intonation to appear “normal.”
But the autistic wiring is still there. Being good at masking has nothing to do with eliminating a feature of ASD.
What Research Says About Early Childhood Brain Injury
Some research has focused specifically on brain injuries that occur very early in life, when the brain is still developing – still malleable.
A large nationwide longitudinal study led by Mu-Hong Chen, published in The Journal of Clinical Psychiatry (2018), examined kids who experienced TBI before age three.
The study found higher rates of later autism spectrum diagnoses compared to kids without early TBI.
Importantly, the authors did not conclude that TBI caused their autism.
They described the relationship as an association, not proof of causation.
The risk was higher with more severe or repeated injuries.
Why did kids under three have a higher rate of later ASD diagnosis?
Because autism itself is a neurodevelopmental condition that typically begins showing in early childhood (though not always diagnosed at that point), brain injury during this period might interact with underlying developmental processes.
The researchers referenced existing literature suggesting that injury to specific brain areas (such as the cerebellum or regions involved in social processing) can contribute to autism-like features.
This doesn’t prove causation but suggests a mechanistic overlap where TBI might lead to features that resemble autism or unveil subtle developmental differences.
We can also certainly wonder if the TBI’s in these cases led to behavior or cognitive issues that were misdiagnosed as autism.
A review paper led by Rahul Singh, published in Behavioural Neurology (2017), examined similarities between pediatric TBI and autism.
The authors discussed shared biological pathways and overlapping symptoms, but explicitly noted that TBI does not equal autism and should not be treated as such.
Wrapping It All Up
Traumatic brain injury is not a cause of autism in people who were previously neurotypical.
We can also put it this way: I’m autistic. If I were to suffer a TBI from a baseball striking my head at a ballgame – there’s no way this is going to amplify the way autism overall manifests in myself.
Depending on where in my brain the injury occurs, I may end up with a speech deficit.
But it’s not going to cause me to overthink more than I already do; rehearse conversations more than I already do; show empathy less; be worse at reading social cues; stim more; think more literally; become more obsessed with my special interests; suddenly find many food textures intolerable; or find eye contact unbearable – or score higher on the Autism Quotient Test.
Autism is rooted in early brain development, not acquired later through trauma.
In very young children, early TBI may be associated with a higher likelihood of an autism diagnosis, but current research fails to show a causation.
