Autistic brains more vulnerable to PTSD, new study shows

Researchers at the Australian National University (ANU) and the University of Queensland (UQ) have found that not only are autism and post-traumatic stress disorder (PTSD) vulnerably linked, but that recontextualisation can help improve the resulting implication of autistic symptoms.

The study, by Dr Shaam Al Abed and Dr Nathalie Dehorter of the John Curtin School of Medical Research at The Australian National University and Queensland Brain Institute at University of Queensland, investigated the molecular mechanisms underlying the development and adaptation of neurons in the brain, focusing on autism and traumatic memory.

The study found that autism and PTSD were vulnerably linked, which means that the conditions affect, and amplify, each other.

It found that not only are autistic brains more susceptible to developing PTSD than allistic (non-autistic) brains, but that traumatic memory (PTSD) can be caused by far less “significant” traumatic incidents than is currently officially understood.

“The most surprising finding was that the formation of traumatic memory in the autistic condition has negative impact on the autistic traits themselves,” said Dr Dehorter.

Studying the autistic brain

Dr Dehorter and Dr Al Abed said the purpose of the study was to create a better understanding of the neurobiology of autism.

“The cognitive deficits in autism spectrum disorder are still poorly understood as compared to other core traits of the condition. Social impairments, communication, and repetitive movement — there’s a lot of research on that. But not as much regarding specific cognitive aspects,” said Dr Dehorter.

Dr Al Abed and Dr Dehorter used mouse models, including several genetic models of autism, to build on models that Dr Al Abed had used previously in her work regarding PTSD.

“We studied prefrontal interneurons (cells providing inhibition in the brain) because they present with altered activity in both animal models and humans with autism. They represent a key target in research,” she said.

Dr Al Abed said that the level of stress necessary to create PTSD was interesting.

“The most important finding was that PTSD was being triggered for levels of stress that would leave intact the control population (without autism), and really showed that there’s a lower threshold of stress for that susceptibility,” said Dr Al Abed.

“Some events that would be trivial for the neurotypical population might be disastrous for the neurodivergent population,” said Dr Al Abed.

“Because PTSD is difficult to detect, people on the spectrum who might have meltdowns, for example – it might not only be a core trait presentation, but PTSD. Because of the amnesia involved with PTSD, it can be difficult to tease that out. But it might allow health professionals to think about the presentation as a whole,” said Dr Al Abed.

Lived experience important in interpreting data

“One limitation that we don’t want to shy away from is that, in the context of autism, PTSD could come from small, repeated bullying or microaggressions,” said Dr Al Abed.

Dr Al Abed said that these minor triggers for PTSD are not currently recognised in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM5).

“The problem that we could have for patients would be to identify those events. But that’s from a clinical perspective. Talking to people on the spectrum, I feel that autistic people often know what the traumatic events were. Sometimes, I think that if we listen to that community, maybe they will be perfectly able to identify the problem and deconstruct it,” said Dr Al Abed.

Treating PTSD to reverse its effect on autistic traits

Following the initial findings, the researchers wanted to test whether current treatments for traumatic memory could work to reverse the impact on autistic traits.

“Recontextualisation is a type of behavioural rehabilitation that is already being used in the clinics to treat PTSD patients,” said Dr Al Abed.

“We tried a model of that in mice to see whether it would apply in the context of autism. So, it basically involves trying to recall as much as possible the traumatic events, and try and make that memory safe again,” she said.

The study found that traumatic memory “can be treated by recontextualisation, reducing the… effects on the core symptoms of ASD [autism spectrum disorder].” The study provides a neurobiological and psychological framework for future examination of the impact of PTSD-like memory in autism.

“The good news is that [there are] ways of alleviating those traumatic memories [and therefore their effect], just as for [the] neurotypical population with PTSD. There’s always hope to manage it,” said Dr Al Abed.

Implications for the health care community

The researchers have been buoyed by a positive response from the neurodivergent community.

“That was the part where we felt we did something really good, when we first posted the study on social media. Some people said, ‘I’ve been feeling this my entire life. You’ve put words on something I couldn’t see,’” said Dr Dehorter.

“If we create an awareness that PTSD is more likely in the neurodivergent population, GPs and specialists may be able to take this into consideration when talking to patients, and will be able to better tailor approaches,” said Dr Dehorter.

The researchers are hopeful that changes might be reflected in future updates to the DSM5.

“The psychiatry association might take this into account. Because now, what we have demonstrated is outside of a PTSD diagnosis, because a PTSD diagnosis requires ‘objectively’ traumatic events,” said Dr Dehorter.

“For people on the spectrum, it’s not surprising. We want to reach experts, and improve communication between neurodivergent people, organisations, professionals and scientists,” said Dr Al Abed.

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