29. Understanding PTSD: Diagnosis, Neurobiology and Treatment

Why does a sound, a smell or a flash of light have the power to pull someone back into the worst moment of their life, years after it happened?

In this episode, we explore post-traumatic stress disorder (PTSD) in depth. We cover the ICD-11 diagnostic criteria, the three core symptom clusters, and the neurobiology that explains why PTSD symptoms are so persistent and so difficult to simply talk yourself out of.

Topics include re-experiencing, avoidance and hyperarousal, the role of the amygdala, hippocampus and prefrontal cortex, the paradox of cortisol in PTSD, and evidence-based treatments including trauma focused-CBT, EMDR and pharmacological options.

Ideal for MRCPsych Part A revision, psychiatry trainees and anyone working with patients who have experienced trauma.

Aligned with the Royal College of Psychiatrists MRCPsych Part A syllabus, paragraph 1.1.9, 3.5.1.13 and 3.9.5.

Transcript

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Welcome to MRC Psycho. Revision is a child. I miss the chin. I spend a lot of time for you too. So I started this podcast to help you revisit the goal. Each episode breaks down one healed topic mapped to the syllabus. This is then followed by five questions to help reinforce your learning. So grab your headphones, turn travel time into revision time, and let's get started. In episode 28, we introduce trauma and the three types of motivational conflict described by Kurt Lewin. In this episode, we turn our full attention to post traumatic stress disorder or PTSD. PTSD is common but frequently missed. The ICD 11 made two significant changes. It streamlined the diagnosis and introduced complex PTSD as a distinct category, which we will cover in detail in the next episode. Post traumatic stress disorder requires exposure to an event or series of events of an extremely threatening or horrific nature. This may be a single event, such as an assault or road traffic accident, or prolonged exposure, such as combat, torture or childhood abuse. Following exposure in the ICD 11, PTSD is defined by three core symptom clusters. The first is re-experiencing the traumatic event in the present. This is not simply remembering what happened. The person relives the event as though it is happening now, through intrusive memories, vivid flashbacks, or recurrent nightmares. From the person's perspective, a sound, a smell, or a particular quality of light can transport them instantly back into the trauma with the same terror they felt at the time. The second cluster is avoidance. People actively avoid thoughts, feelings, people or places that remind them of the trauma. From the outside, this can look like disengagement or emotional flatness. From the inside, it is an exhausting effort to keep the trauma at arm's length. The third cluster is a persistent sense of current threat. This manifests as hypervigilance, an exaggerated startle response, sleep disturbance and difficulty concentrating. The person's nervous system remains on high alert, as though the danger has never passed. Remember, CD eleven PTSD requires exposure to an extremely threatening event, followed by three symptom clusters, re-experiencing avoidance, and a persistent sense of current threat. A useful mnemonic is RAT or rat re experiencing avoidance and threat. We turn now to the neurobiology of PTSD, which explains why symptoms are so persistent and why simply telling someone they are safe is rarely enough. During a traumatic event, the amygdala, the brain's threat detection center, becomes highly activated and encodes the emotional memory with exceptional intensity. Normally, the prefrontal cortex regulates the amygdala, dampening the threat response once danger has passed. The prefrontal cortex is the brain's rational control center, responsible for decision making, emotional regulation, and putting the brakes on impulsive or fearful responses. In PTSD, this regulation breaks down. The amygdala remains hyper responsive to anything resembling the original threat. This is why a car backfiring can trigger a full fear response in a combat veteran. The brain is not malfunctioning. It simply cannot update its threat assessment. The hippocampus normally contextualizes memories in time and place, stamping them as past events. In PTSD, the hippocampus is reduced in volume, impairing this contextualization. The relationship between cortisol and PTSD is more complex than it first appears. Unlike chronic stress, where cortisol remains persistently elevated, people with PTSD often show paradoxically low baseline cortisol levels. However, when triggered, cortisol spikes intensely and then crashes rapidly. This dysregulated pattern means the stress response cannot be properly shut down after a trigger, leaving the body in a prolonged state of alarm. Over time, this repeated dysregulation contributes to hippocampal atrophy and impairs the brain's ability to file traumatic memories as belonging in the past. This is the neurobiological basis of flashbacks. The person is not being dramatic. Their brain is genuinely unable to locate the memory in the past. Remember, post-traumatic stress disorder involves amygdala hyperresponsivity, impaired prefrontal regulation, and reduced hippocampal volume. People with PTSD often show paradoxically low baseline cortisol levels, with intense spikes and rapid crashes following a trigger. We turn now to treatment. Post traumatic stress disorder is highly treatable, and many people make substantial and lasting recovery with the right intervention. The two first line psychological treatments are trauma focused cognitive behavioral therapy and eye movement desensitization and reprocessing, or EMDR therapy. Trauma focused cognitive behavioral therapy helps people process the traumatic memory in a structured and safe way. It addresses distorted cognitions such as it was my fault or I am permanently damaged. It uses gradual controlled in vivo exposure techniques to reduce the fear response to trauma related cues. EMDR involves recalling traumatic memories while engaging in bilateral sensory stimulation. This is most commonly tracking a moving light or the therapist's finger movements with the eyes using alternating sounds or taps. The proposed mechanism is that bilateral stimulation activates memory consolidation processes similar to those occurring during REM sleep. This allows the brain to process and integrate the traumatic memory. Many people find it produces rapid and significant reductions in distress. Pharmacological treatment is considered where psychological therapy is not immediately accessible, or symptoms are severe. First line medications are the selective serotonin reuptake inhibitors, or SSRI. The two SSRI with the strongest evidence base are Certraline and peroxetine. Venlofaxine, a serotonin and noradrenaline reuptake inhibitor, or SNRI, is also recommended as an alternative. For PTSD related nightmares specifically, prazosin, an alpha one blocker, is sometimes used off label in clinical practice. The massive 2018 Prazocin and Combat Trauma PTSD trial, called PAC trial, found that Prazosin was no better than a placebo at reducing combat related nightmares. Because of these mixed results, NICE guidelines remain hesitant to recommend it routinely, though you may encounter it being used in certain settings, particularly where nightmares are the predominant and most distressing symptom. Medication does not process the traumatic memory, but can reduce symptom intensity enough to allow engagement with therapy. Remember, first line psychological treatments are trauma focused CBT and EMDR. First line medications are sertraline and peroxetine. Prazosin may be used off label for nightmares, though NICE does not recommend it. A final clinical note. People with PTSD may present as hostile, avoidant, or somatically focused. They may struggle to trust clinicians, particularly if their trauma involved authority figures. Trauma informed care means holding this context in mind throughout the encounter. Asking about trauma history sensitively and routinely is one of the most important things a clinician can do. If there is one book I would recommend to any trainee working with trauma, it is The Body Keeps the Score by Bessel van der Kolk. Reading it fundamentally changed how I understood trauma, not just as a set of symptoms to diagnose, but as something that reshapes how a person thinks, feels and moves through the world. It is accessible, evidence-based, and gives an invaluable sense of what trauma actually feels like from the inside. And if reading feels like one more thing on an already impossible list, there's also an audiobook version available on Spotify. I would encourage every trainee to read it. Now, let's test your recall. I will read out five exam style questions. After each one, I will pause for 10 seconds so you can attempt them before hearing the answer. Question one. Question two. A person presents with severe PTSD but strongly prefers medication over psychological therapy. According to clinical guidelines, what is the primary role of pharmacotherapy in PTSD? And what are the preferred first line choices? Medication does not process the traumatic memory, but it can reduce symptom intensity. First line choices are SSRI, specifically sertraline or peroxetine, or the SNRI, venlifaxin. Question three A person asks why he cannot simply remind himself he is safe, given that his trauma happened ten years ago. How would you explain the neurobiology of his flashbacks? During a flashback, the hyperactive amygdala triggers a survival response to present-day cues, completely overpowering the regulatory control of the prefrontal cortex, because a smaller hippocampal volume impairs the brain's ability to contextualize the memory in time and place. The brain cannot register the trauma as a past event, perceiving the threat as happening right now. Question four. A person with PTSD declines trauma focused CBT as they do not want to talk about what happened. What alternative first line psychological treatment should be offered? It does not require detailed verbal narration of the trauma. Instead, the person recalls the memory while engaging in bilateral sensory stimulation. What can be used for nightmares in PTSD? Prazosin may be used off label for nightmares, though NICE does not recommend it. Let's summarize what we have learned today. Post traumatic stress disorder requires exposure to an extremely threatening event, followed by three core symptom clusters re-experiencing, avoidance, and a persistent sense of current threat. Remember RAT. The neurobiology involves amygdala hyperresponsivity, impaired prefrontal regulation, and reduced hippocampal volume, alongside a dysregulated cortisol response that leaves the brain unable to file traumatic memories as belonging in the past. First line psychological treatments are trauma focused CBT and eye movement desensitization and reprocessing. First line medications, if needed for symptom control, are SSRI or SNRI. PTSD is manageable and trauma-informed care, including sensitive and routine inquiry about trauma history is central to good clinical practice. In the next episode, we turn to complex PTSD, exploring how prolonged and repeated interpersonal trauma produces a distinct clinical picture, and why a phased approach to treatment is so important. Thank you very much for listening to this episode of MRT Type on the Go. Provision essential. I hope this episode helped to move your provision forward. If you have any questions or just want to continue the discussion, you can find me a link to MRT Type on the Go. MRC is about making provision accessible. If you find it useful, let's always keep replacing on the goal.