After trauma, some people develop post-traumatic stress disorder ( PTSD ), a mental health condition that can involve intrusive nightmares, flashbacks and physical reactions when reminded of the traumatic event, such as a racing heart or difficulty breathing.
Some people with PTSD also develop profoundly negative beliefs about themselves - intense shame, guilt and even feeling responsible for what happened.
For example, someone who experienced a violent assault may believe they somehow deserved to be attacked. Such beliefs can cause significant distress and drive persistent PTSD symptoms.
There are multiple evidence-based forms of cognitive therapy, also called "talk therapy", that can effectively treat PTSD by helping to reframe these negative self-beliefs.
However, some people don't respond to these kinds of therapy much - or at all.
In our research , we scanned the brains of 136 people - half who had PTSD, and half who didn't - while they used cognitive therapy techniques to challenge negative beliefs. We found the reason some people don't respond to treatment may lie in the way PTSD has restructured their brains.
First, how does talk therapy work for PTSD?
Research shows talk therapies targeting negative beliefs - including cognitive processing therapy (CPT) and trauma-informed cognitive behavioural therapy (TF-CBT) - are broadly effective for PTSD. Most people show meaningful improvement in their symptoms.
Talk therapy for PTSD usually aims to equip patients with skills to challenge distorted negative beliefs through a structured dialogue, known as cognitive restructuring.
During therapy, a therapist might guide the person to counter the rationale underlying beliefs (for example, "who made the decision to commit the assault?"), or consider alternative perspectives ("is there another way of understanding what happened, which doesn't put the blame on you?").
Another therapy, prolonged exposure (PE) gradually increases how much someone is exposed to reminders of the trauma, usually alongside reframing techniques. This can be done during therapy (for example, repeatedly describing what happened) or between sessions (for example, revisiting the scene of the trauma).
But it doesn't work for everyone
Clinical studies show, after these kinds of cognitive therapy for PTSD, about one-third of people will still have diagnosable PTSD symptoms.
While zero improvement is rare, it means a significant proportion of people still aren't achieving ideal outcomes from therapy. The factors underpinning this are complex and poorly understood.
But we know some people with PTSD are more likely to show no or little improvement after talk therapy. They include those with:
- the most severe symptoms
- persistent exposure to trauma (particularly during childhood)
- other psychiatric diagnoses, such as depression or substance use disorders.
Some studies also suggest older people, men, those from racial minorities and military veterans show less benefit on average from cognitive PTSD therapies.
This may because these groups are more likely to report other factors which affect how well treatment works. For example, men with PTSD typically have more symptoms of anger problems than women, and less social support.
What we did and what we found
Our recent study showed there may be a neurobiological explanation for why talk therapies work for some people and not others.
We asked 70 people with PTSD, and 66 people who'd been exposed to trauma but without PTSD, to challenge negative self-beliefs via cognitive restructuring while inside an MRI brain scanner.
In people with PTSD, we found their prefrontal cortex (the brain's "control centre") was worse at regulating activation in the thalamus - a small structure that works as a relay hub, allowing different parts of the brain to communicate.
These regions work together to let us represent abstract information - such as self-beliefs - in the brain, and to update our beliefs and their associated emotions with new information .
Among people with PTSD in our study, those with more severe negative beliefs showed weaker connectivity in this pathway when using restructuring techniques to challenge negative self-beliefs.
Weaker connection between these regions might hinder people's ability to update negative self-beliefs with new information, resulting in less benefit from therapy.
So, why might this be?
We know that self-beliefs in people with PTSD are more often heavily influenced by negative information and events - that is, being criticised might make you feel worse about yourself, but being praised won't make you feel that much better.
The way PTSD changes brain pathways points to why some people's self-beliefs are harder to counter with positive reframing techniques, meaning these beliefs become "stuck".
These trauma survivors may understand, on an intellectual level, that they weren't to blame for what happened. But that understanding never quite shifts the part of them that still feels responsible, and they have little emotional relief.
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What might work instead?
Some people may need treatments that first address the brain's wiring needed to engage with talk therapy. For example, certain evidence-based approaches aim to build people's emotion regulation skills before talk therapy.
A therapist will help someone improve their ability to deal with negative emotions, for example by learning effective strategies to tolerate and manage distress. They will unpack how these emotions influence their interactions with other people, so they are better able to take on the challenges of cognitive restructuring in therapy.
Other emerging evidence suggests therapy using MDMA or ketamine for PTSD may help those who haven't responded to other treatments, by directly influencing brain pathways. Research is exploring how these can be delivered safely.
For some people, simply trying different treatments can yield better outcomes. What works can depend on a person's symptoms or preferences. This won't always be the first treatment someone tries.
However, we know people whose symptoms don't improve after one first-line intervention (the "best-practice" treatments with the strongest evidence base) are less likely to engage in further treatment.
By refining our understanding of the brain mechanisms underpinning cognitive restructuring, we're hopeful our work can inform more precise and targeted approaches to treating PTSD.
But there are other limitations
People with ongoing or repeated exposure to trauma, such as first responders, are also at risk of re-traumatisation . This is where past trauma causes heightened reactions to new trauma. Ongoing trauma can also amplify symptoms and make therapy less effective.
Cultural factors may also shape how well standard therapy formats fit. There is growing evidence that culturally adapted or group-based approaches (especially for interpersonal trauma, such as abuse) better serve some communities than the standard model of one-on-one talk therapy.
Trevor Steward receives funding from the National Health and Medical Research Council.
Andrea Putica and James Agathos do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.
