Defining complex trauma
According to the World Health Organisation (WHO), complex trauma involves exposure to prolonged or repeated trauma where escape is difficult or impossible, especially when trust, safety, or identity are affected — often in close relationships or power dynamics (e.g., childhood abuse, domestic violence, captivity).
While these multiple traumatic events can often occur in the context of childhood, complex trauma may also arise from a series of ongoing events experienced in adulthood, such as those experienced by first responders, or through disempowering relationship dynamics in the workplace.
Complex trauma is interpersonal, ongoing, and can involve being or feeling trapped; and it may sometimes also be premeditated and extreme. This can include experiences such as ongoing abuse, neglect, domestic violence, or living in chronically unsafe environments.
Complex trauma is surprisingly common yet it is often not recognised as a major contributing factor in someone’s difficulties with life. Estimated to affect 1 in 4 Australian adults, it is substantially different from single-incident trauma such as natural disasters, motor vehicle accidents, or physical assault.
Complex trauma and developmental impact
Complex trauma often arises from repeated experiences of physical, sexual, or emotional abuse, as well as neglect, particularly during childhood. When such trauma occurs during critical periods of brain development, it can profoundly alter the structural growth of neural networks and disrupt the biochemistry of neuroendocrine systems. These changes can significantly impact emotional regulation, cognitive function, and overall mental health.
Prolonged effects of complex trauma
The long-term consequences of complex trauma include a strong and often co-occurring relationship with numerous physical health and mental health problems, as well as economic, social, and behavioral issues throughout people’s lives. These issues are not usually thought of as related to earlier abuse or neglect, and people do not grow out of it. Links between complex trauma and conditions such as heart disease, cancer, chronic pain, and more are now well-established; and the cost to society is enormous.
Understanding the difference between Complex Trauma and PTSD
Complex trauma and Post-Traumatic Stress Disorder (PTSD) are often confused as being the same, but they are distinct conditions that can require different treatments. PTSD typically arises from a single traumatic event, such as a car accident, while complex trauma develops from prolonged exposure to traumatic experiences, often beginning in childhood and involving close relationships. Complex trauma impacts a person’s sense of self and their ability to form secure attachments and tend to occur in relationships with caregivers.
Although Complex PTSD is not yet recognised in the Diagnostic and Statistical Manual of Mental Disorders (DSM), it is included in the International Classification of Diseases (ICD-11), reflecting its acceptance as a unique condition by international experts.
The definition of complex trauma in the ICD-11 is:
“Complex post traumatic stress disorder (Complex PTSD) is a disorder that may develop following exposure to an event or series of events of an extremely threatening or horrific nature, most commonly prolonged or repetitive events from which escape is difficult or impossible (e.g. torture, slavery, genocide campaigns, prolonged domestic violence, repeated childhood sexual or physical abuse).
From a diagnostic point of view, all diagnostic requirements for PTSD are met, which include:
Re-experiencing (intrusions)
The trauma is felt as happening again now—through vivid intrusive memories, flashbacks (from brief present-sense to complete loss of awareness), or recurring thematically linked nightmares, typically with intense emotions and bodily sensations. It can be triggered by reminders or surge as overwhelming feelings even without much thinking; simply ruminating or recalling feelings without present-tense reliving doesn’t meet this criterion.
Avoidance
The person deliberately steers clear of anything likely to trigger re-experiencing—internally (pushing away thoughts/images) or externally (avoiding people, places, conversations, activities, or situations tied to the trauma). In severe cases they may change environments or routines entirely (e.g., moving house or changing jobs) to minimize reminders.
Persistent sense of current threat (hypervigilance)
There’s an ongoing feeling of immediate danger, shown by hypervigilance and an exaggerated startle to cues like unexpected noises. To feel safer, the person may constantly scan for threats and adopt safety behaviors (e.g., not sitting with their back to a door, repeatedly checking the rear-view mirror) for themselves or loved ones.
In addition, according to the ICD 11, Complex PTSD is characterised by severe and persistent
1) problems in affect regulation;
2) beliefs about oneself as diminished, defeated or worthless, accompanied by feelings of shame, guilt or failure related to the traumatic event; and
3) difficulties in sustaining relationships and in feeling close to others. These symptoms cause significant impairment in personal, family, social, educational, occupational or other important areas of functioning. “
Complex trauma often leads to more widespread, long-term difficulties, helping to explain the struggles faced by those who have experienced it. Understanding these distinctions can guide caregivers and loved ones in providing the right kind of support. For more professional resources and ideas, visit our resources section for clinically vetted websites.