When we hear the word trauma, many of us think of major life-threatening events, like accidents, natural disasters, violence, or war. But trauma is more than just what happens to us. It’s about what happens inside us as a result.
What Is Trauma?
The World Health Organization (WHO, 2021) define traumatic events as ‘experiences involving actual or threatened death or serious injury or sexual violence or events that are extremely threatening or horrific in nature’ (APA, 2024).
Common examples of traumatic events can include one-off (aka single incident) events, such as:
- Car accidents
- Physical or sexual assault
- Witnessing violence
- Sudden loss of a loved one
- Invasive medical procedures
- Natural disasters or fires
Studies worldwide have shown that at least two of every three persons worldwide will experience at least one traumatic event over their lifetime, with many experiencing multiple events (APA, Benjet et al., 2016).
But trauma is not just what happened (the event) but it’s the response to an event (or series of events) that is deeply distressing, overwhelming, or threatening. This response occurs when something happens that is too much, too fast, too soon, or conversely, when there is not enough safety, support, or protection.
The Neuropsychology of Trauma
Our trauma responses are linked to how the nervous system experiences the trauma. What may seem like “no big deal” to one person might be deeply destabilising to another. It’s personal, relational, and physiological.
Let’s start with ‘stress’, because that’s where it all starts. As Gabor Mate noted, “all trauma is stressful, but not all stress is trauma”.
Any stressor leads to our nervous system activating a cascade of responses to either fight or flee the stressor or somehow get back to safety and equilibrium (kind of like, returning to baseline, the way the systems were before the stressor).
But when it comes to trauma, where stressors were too much, too often, too overwhelming, or when there was not enough safety, support, or protection, our natural stress responses get kind of ‘stuck’.
Trauma alters the brain’s stress response systems, reshaping how we perceive and react to the world. When we experience overwhelming threat, the brain’s amygdala (our alarm system) becomes hyperactive, constantly scanning for danger. Meanwhile, the prefrontal cortex (responsible for reasoning and regulation) can become underactive, making it harder to think clearly, make decisions, or feel safe, even when there’s no immediate threat.
Another important area of the brain in this context is the hippocampus, which helps process memory and context. When the hippocampus is affected, trauma survivors often report fragmented or intrusive memories. And it’s these changes that can keep the body in a prolonged state of fight, flight, freeze, or fawn, long after the trauma has passed.
Over time, it is then these patterns that can contribute to anxiety, dissociation, emotional dysregulation, and difficulty trusting others. But the brain is adaptable: with trauma-informed support, healing is possible through practices that restore safety, connection, and regulation.
What Is PTSD?
In some cases, trauma may result in a person developing post-traumatic stress disorder (PTSD), but not always. Several factors make it more likely for people to develop PTSD, such as experiencing a multitude of traumatic events. Also, interpersonal trauma (such as assault, violence, and trauma perpetrated by those in position of authority) rather than events such as natural disasters where there are often a lot people affected, and thereby a shared experience, have been found to increase the risk of PTSD.
PTSD is a condition in which a person re-experiences traumatic memories intrusively, for example through nightmares, flashbacks, or thinking of the event when they don’t mean to. People with PTSD avoid places, situations, and activities that might remind them of the trauma, and they tend to experience negative thoughts and emotions, and hyperarousal (APA, 2022).
It’s important to realise though that even without a diagnosis of PTSD (or other mental health disorders), trauma can leave lasting imprints on our sense of safety, self-worth, and ability to regulate emotions.
What Is Complex Trauma?
While trauma can stem from a single event, complex trauma refers to repeated or ongoing trauma, often starting in early life and happening within relationships that were meant to be safe, such as with caregivers, family members, or authority figures.
Complex PTSD (CPTSD) is a condition involving the same criteria to PTSD (per ICD-11 criteria, which is the European diagnostic system), coupled with additional problems labelled as ‘Difficulties with Self Organization (DSO)’, such as problems with emotion regulation, negative self-concept, and relational disturbance (WHO, 2021).
Also known as developmental or relational trauma, complex trauma can include:
- Childhood emotional, physical, or sexual abuse
- Chronic neglect or abandonment
- Growing up in a household with domestic violence, addiction, or mental illness
- Being shamed, silenced, or not allowed to express needs or emotions
- Living in situations of ongoing threat, chaos, or instability
Because these experiences happen during the years when our brains, bodies, and identities are still forming, the impact can be profound and long-lasting.
Trauma vs. Complex Trauma: What’s the Difference?
| Factor | Trauma | Complex Trauma |
| Type of Experience | Often a single or short-term event | Ongoing, repeated, or chronic experiences |
| Timing | Can happen at any age | Often begins in childhood |
| Relational Aspect | May or may not involve betrayal | Often occurs in relationships with caregivers or trusted adults |
| Impact | May lead to PTSD or anxiety | Can affect sense of self, relationships, body, and worldview |
How Complex Trauma Affects Us
The effects of complex trauma tend to show up in more diffuse, long-term ways. They can be hard to trace back to a single cause and are often misdiagnosed or misunderstood.
Common signs of complex trauma may include:
- Chronic anxiety or depression
- Emotional numbness or emotional overwhelm
- Persistent shame or self-blame
- Difficulty trusting others or forming close relationships
- People-pleasing, fawning, or avoiding conflict
- Feeling “not good enough” or disconnected from your true self
- Physical symptoms like fatigue, headaches, or digestive issues
These responses aren’t character flaws; they are survival strategies the nervous system developed to adapt to a lack of safety.
So, to sum it up: Trauma affects every facet of one’s being. The good news is that there are a range of evidence-based interventions and therapy modalities that have been shown to be effective in treating PTSD, CPTSD and the effects of trauma more broadly.
References:
Professional Practice Guideline for Working with Adults with Complex Trauma Histories, published jointly by the American Psychological Association (APA, Division 56, Trauma Psychology) and the International Society for the Study of Trauma and Dissociation (ISSTD) (APA, 2024). https://www.apa.org/practice/guidelines/adults-complex-trauma-histories.pdf
American Psychiatric Association (2022). Diagnostic And Statistical Manual Of Mental Disorders 5-TR. (5th Ed.TR).
Benjet, C. et al. (2016). The epidemiology of traumatic event exposure worldwide: Results from the World Mental Health Survey Consortium. Psychological Medicine, 46(2), 327–343. https://doi. org/10.1017/S0033291715001981
World Health Organization (2021). International statistical classification of diseases and related health problems (11th) https://icd.who.int/en/.
