The causes and science of PTSD and C-PTSD: Info for Healthcare Professionals

The causes and science of PTSD and C-PTSD: Info for Healthcare Professionals

The human body is an incredible system, but it is also complex, and full of feedback loops between body parts and brain. If you interfere with any of these loops dramatically (as in the case of experiencing a trauma), you can affect the whole system.

Post-Traumatic Stress Disorder (PTSD and C-PTSD) are conditions that some people develop after experiencing or witnessing a traumatic life-threatening event or serious injury – put simply, PTSD and C-PTSD are essentially memory filing errors caused by the brain ‘suspending’ normal function during a traumatic situation.

It causes a huge variety of life-altering and intrusive symptoms and so can cause substantial distress and disruption of social and occupational functioning, and cause major problems in relationships and jobs.

It’s estimated that 50% of people will experience a trauma at some point in their life and although the majority of people exposed to traumatic events only experience some short-term distress, around 20% of people who experience a trauma go on to develop PTSD or C-PTSD. It’s estimated that in any given week, 4 in 100 people in England have PTSD or C-PTSD.

Despite it’s prevalence across the world, PTSD and C-PTSD are still very misunderstood conditions and many people have pre-conceived ideas of what PTSD or C-PTSD is, and particularly what can cause them.

There is a widespread misunderstanding that PTSD or C-PTSD only affects veterans, or those in the armed forces – likely due to it’s previous name of shell-shock – but it can affect anyone, of any age. It’s vital that healthcare providers are aware if they (or a patient or even loved one) have suffered any trauma, they should be mindful of trauma symptoms, and the possibility of PTSD or C-PTSD.

What can cause PTSD?

PTSD and C-PTSD are as ancient as humankind and can occur in all people, of any ethnicity, nationality, gender, occupation or culture, and at any age and from any trauma (perceived or actual).  The defining characteristic of a traumatic event is its capacity to cause fear, helplessness, or horror as a response to the threat of injury or death. Some examples of traumatic events include:

  • Road traffic incidents
  • Being told you have a life-threatening illness
  • Bereavement
  • Violent personal assault, such as a physical attack, robbery, or mugging
  • Military combat and service
  • Any form of abuse, including Childhood Abuse and Domestic Abuse
  • Burglary
  • Events experienced in employment where you repeatedly see distressing images or hear details of traumatic events
  • Caring for a child with a complex medical condition or disability
  • Witnessing a suicide or attempted suicide
  • Natural disasters such as flooding or an earthquake
  • Terrorist attack
  • Being kidnapped or held hostage
  • Being bullied (as a child or adult)
  • Traumatic childbirth (in people who give birth and birth partners)
  • Refugee and asylum seekers
  • Early pregnancy Loss (including miscarriage and ectopic pregnancy)
  • Sexual Assault or rape
  • Admission to an Intensive Care Unit

Causes of Complex PTSD

There is also a second, subtype of PTSD, called Complex PTSD, or C-PTSD. This is usually a result of repeated, or sustained traumas, and presents in a similar way to PTSD, but with some additional symptoms too. Any of the causes noted above (and many others) can cause C-PTSD if someone has experienced repeated, sustained or a number of different traumas.  

The science of how PTSD is caused

PTSD and C-PTSD isn’t ‘all in the mind‘ or something you can just ‘get over’ or ‘move on’ from. No matter how much reasoning and coaxing you do, someone with PTSD or C-PTSD may find it impossible to achieve sustainable recovery without professional treatment.

That’s because PTSD and C-PTSD is a form of injury to the brain. Brain scans show that symptoms and behaviours are caused by biological changes in the brain, NOT by some personal failure.

Modern science has enabled us to get a far clearer picture of the brain and in fact the whole neurological system’s structure and activities. It has become possible to map and measure the different development paths that each human brain follows.

This form of investigation has clearly shown PTSD’s impact on the way we think, feel and behave has a physical imprint: markers that you can see on brain scans such as through SPECT (single photon emission computed tomography), a nuclear medicine study that evaluates blood flow and activity in the brain.

The extreme stress and reactions from PTSD and C-PTSD result in acute and chronic changes in neurochemical systems and specific brain regions, which result in long-term changes in brain “circuits,” involved in the stress response. This is why replacing negative connections and cycles, or finding a way to bypass them, can take a heavy investment of time and therapy.


The amygdala is the part of the brain that formulates a response to stress. It takes this ‘alert’ from sensory input – such as something you see or hear – and connects it to something from the memory.

In response to perceived danger, it sends out an ‘alarm’ to warn the rest of the body that various psychological actions are needed. For instance, that to defend yourself you need to activate flight, fight or freeze.

Once the danger or perceived danger has passed, new signals are transmitted to calm everything back down.

Someone who has PTSD or C-PTSD often has excessive activity in their amygdala, which can be picked up on brain scans.

This is when the amygdala is too sensitive, triggers too easily or stays on high alert for longer than it should. The symptoms would be hypervigilance and an extreme reaction to perceived threats, including being easily startled and often in a state of anxiety.

Having an overactive amygdala creates other physical effects too, including poor sleep patterns.


This part of the brain works in tandem with the amygdala. It is where we store memories, and also the brain tissue that sorts and retrieves memories. PTSD and C-PTSD can make this link ‘unstable’.

For example, when someone without the condition hears a loud bang, though it makes them jump, in a split second they make a connection with fireworks and realise one has gone off nearby. The message is relayed to the amygdala that all is well, and it’s appropriate to stay calm.

Someone who has experienced trauma may make the connection to an extremely traumatic incident instead. For example, a firework sends them into a state of anxiety and fear, possibly creating flashbacks and extreme behaviours – their mind thinking it’s someone breaking into their house, a gun shot, a terrorist attack etc. 

In this situation, the hippocampus does not supply the amygdala with the message to calm everything down.

It’s believed that this sort of constant activity can reduce the size of the hippocampus, so again the physical effect of PTSD or C-PTSD can be seen on scans.

Also, re-experiencing the trauma can create other physiological symptoms, such as sweating, insomnia and severe headaches.

Medial prefrontal cortex

The prefrontal cortex – situated around the forehead – deals with emotions and impulses, and therefore has a substantial role to play in someone’s actions.

Under normal circumstances, it would act in tandem with the hippocampus, sending signals to the amygdala to ‘switch off the alarm system’ when a situation calms down. It is like a ‘brake’ system for physical responses to stress, reassuring the body and mind that all is well.

When someone has PTSD or C-PTSD, this part of the brain is often underactive. It is ‘dampened down’ by the trauma. This can manifest as someone being withdrawn, irritable and appearing ‘cold’ or showing avoidance behaviours.

It’s an involuntary defence mechanism, creating emotional numbness so they don’t have to relive the intense feelings created by your trauma.

Low activity in the prefrontal cortex means it doesn’t interact efficiently with the hippocampus and its store of memories and interferes with the amygdala alarm system’s ‘off switch’.

Alternatively, a malfunctioning medial prefrontal cortex could make fear the dominant emotion. This too keeps the amygdala on high alert.

Importantly, the frontal lobe is also the part of the brain that deals with language skills. PTSD and C-PTSD can therefore result in the individual struggling to articulate their emotions and thoughts.

‘Deranged’ cortisol levels

Cortisol is a stress warning to your body, and therefore it heightens alertness and creates fear.

When the brain ‘decides’ to put the body on full alert, the amount of cortisol produced increases. It can alter or even shut down certain functions, to keep the body ready for ‘fight or flight’ for example

When the perceived danger is gone, the brain again adjusts the production of cortisol, calming it down and so allowing the rest of the body to ‘reset’ back to normal.

What happens if this ‘calm down’ message is never issued? The alarm system is switched on around the clock and the body is continuously in stress mode.

This then impacts on the core bodily functions like digestion, skin repair and sleep.

Someone with PTSD may also have problems with moods, memory and concentration. As well as anxiety, or depression.

The perfect storm in your brain

These changes in the brain as a result of trauma really create a ‘perfect storm’. The amygdala is over-active – but the system to calm it down is not effective – leaving someone continuously or repeatedly in ‘danger’ mode which leads to extreme reactions and actions, that to someone else, looks out of proportion to the situation.

Therapies such a EMDR (Eye movement Desensitisation Reprocessing) for PTSD and C-PTSD will often focus on ‘rewiring’ the connection between memories, emotions and behaviours to give someone new associations and coping strategies, to dismantle negative cycles and create healthier brain function.

There is evidence from a variety of studies that successful treatment of PTSD and C-PTSD with therapies such as EMDR and CBT do produce measurable structural changes in brain regions associated with fear conditioning.

These studies show why it’s possible to reverse the effects and heal from PTSD and C-PTSD. 

If you or your workplace would be willing to have a stand with/hand out leaflets and booklets about PTSD – please do drop us an email with your name, address and some information about what you need.

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You’ll find up-to-date news, research and information here along with some great tips to ease your PTSD in our blog.

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Treatments for PTSD

It is possible for PTSD to be successfully treated many years after the traumatic event occurred, which means it is never too late to seek help. For some, the first step may be watchful waiting, then exploring therapeutic options such as individual or group therapy – but the main treatment options in the UK are psychological treatments such as Eye Movement Desensitisation Reprogramming (EMDR) and Cognitive Behavioural Therapy (CBT).

Traumatic events can be very difficult to come to terms with, but confronting and understanding your feelings and seeking professional help is often the only way of effectively treating PTSD. You can find out more in the links below, or here.