Complex trauma


Complex trauma refers to the experience of a set of severe and sometimes pervasive adverse events that are often protracted or interpersonal in nature.

  1. In childhood, complex trauma frequently refers to experiences of abuse and neglect, including exposure to interpersonal violence. These experiences have several features. First, they typically arise within the context of a child’s relationships. Second, they occur during child development, with important implications for their potential impact. Third, they are chronic or repeated. It is important to remember there are other forms of complex trauma in childhood (e.g. repeated exposure to community violence, racial trauma or war trauma).
  2. Exposure to complex trauma can impact a child’s emotional, psychological, social and physical development. However, it does not necessarily follow that all children are affected in the same way. Some may show a limited or no adverse reaction, for others the impact is delayed, and for others still the impact is immediate and severe. These differences can result in part because of genetic, biological, psychological and social factors as well as because of differences in the nature of trauma itself. It is helpful to remember that the child’s experience of an event is different from their response to the event.

How common is complex trauma?

This deceptively simple question is in fact exceptionally difficult. However, there is good evidence that complex trauma affects a significant minority of children. For example, in the UK a community study by the National Society for the Prevention of Cruelty to Children (NSPCC) found that nearly 1 in 5 children (18.6%) experience some form of abuse or neglect [1 (PDF)], which are commonly described as complex traumas although not all cases will reach a definitional threshold. The exact prevalence of complex trauma experiences will vary depending on how it is measured and defined. There are many different approaches – asking children directly, asking parents, relying on statutory records (e.g. from social services or police) etc. There are also many different definitions, of what constitutes abuse and neglect, as well as what other experiences may constitute complex trauma. Different methods – as well as the different ways that complex trauma can be defined – will significantly influence the prevalence estimate [2].

What is the impact of complex trauma on children?

The experience of complex trauma can impact multiple aspects of child development [3]. Changes have been documented at the biological level, for example in relation to brain structure and function, levels of cortisol and levels of inflammation. There is also an impact on psychological and emotional functioning. For example, there may be changes in how a child identifies, responds to and regulates their emotions. Equally, there can be an impact on how a child develops their sense of self, their self-worth, and their sense of others – particularly in relation to trust. There is robust evidence pointing to an increased risk of mental health disorders including for example, anxiety, depression, complex post-traumatic stress disorder (Complex PTSD) and conduct disorder [4]. Children can also present with many different responses at the behavioural level, such as increased risk of self-harm, suicide and poorer educational attainment. In light of these effects, it is perhaps unsurprising that there can be a significant impact on a child’s social functioning, with increased difficulties often observed in their relationships with peers and adults. Finally, there is also evidence of an impact on physical health [3]. The mechanisms through which complex trauma affects mental and physical health may vary depending on the assessment methods used for complex trauma [2], [5], [6 (PDF)].

As we have noted, not all children will show all or indeed any of these effects. However, it is very likely that exposure to complex trauma will impact at least one or more of these aspects of development for the vast majority of children to some degree.

Complex trauma and Complex PTSD

It is important to distinguish complex trauma from Complex PTSD. Complex Post Traumatic Stress Disorder, or Complex PTSD, is a formal diagnosis of a mental health disorder. It is a relatively new diagnosis and was developed to reflect the fact that some individuals present with additional symptoms following trauma not captured with a traditional PTSD diagnosis. These can include (for example) difficulties regulating emotions, feelings of shame or guilt, experiencing intense feeling of loneliness, risky or destructive behaviour, and significant difficulties in building and maintaining relationships with others [7].

Complex PTSD may be diagnosed in adults or children who have experienced traumatic events, such as violence, neglect or abuse. However, many individuals who experience these forms of complex trauma do not develop Complex PTSD. In other words, experiencing complex trauma does not mean that an individual will develop Complex PTSD – other disorders may be precipitated, such as anxiety and depression. There is an ongoing debate about the most suitable approaches to intervention for Complex PTSD in children [8], [10].

What helps with complex trauma

How professionals seek to help children following complex trauma can be understood as falling into two categories [3]. The first response seeks to prevent the recurrence of exposure. For example, statutory agencies may act to ensure a child is no longer exposed to abuse and neglect by providing an intervention to improve family functioning. Equally, they may decide on the basis of a risk assessment that a child needs to be removed from their home and placed in an alternative safe environment. The second response is to seek to mitigate the potential impact of complex trauma. This encompasses a broad range of responses, given that different children can present with many different difficulties. For example, Trauma-Focused Cognitive Behavioural Therapy may be indicated if a child presents with PTSD. By contrast, a child presenting with depression symptoms may receive one of a number of evidence-based interventions, including (for example) CBT, psychodynamic psychotherapy or family therapy. A child presenting with no mental health problems, but behavioural difficulties at school may benefit from a systemic intervention, involving the child, their carers and their teachers. In other words, any response should be formulated on the basis of a child’s individual presentation. There remain many gaps in evidence as to what constitutes the most effective form of help for children who have experienced complex trauma. Moreover, we lack an evidence-based model of preventative help that reduces the risk of mental health problems emerging across development following trauma exposure [9].


  1. Radford, L. et al. (2011) Child Abuse and Neglect in UK Today. NSPCC, London. (PDF)
  2. Baldwin, J. R., Reuben, A., Newbury, J. B., & Danese, A. (2019). Agreement between prospective and retrospective measures of childhood maltreatment: a systematic review and meta-analysis.  JAMA Psychiatry76(6), 584-593.
  3. Danese, A., & McCrory, E. (2015). Child maltreatment. Rutter’s Child and Adolescent Psychiatry, 364-375.
  4. Lewis, S.J., Arseneault, L., Caspi, A., Fisher, H.L., Matthews, T., Moffitt, T.E., Odgers, C.L., Stahl, D., Jia Ying Teng, & Danese, A. (2019). The epidemiology of trauma and post-traumatic stress disorder in a representative cohort of young people in England and Wales. Lancet Psychiatry 2019; 6: 247–56.
  5. Danese, A. (2019). Annual Research Review: Rethinking childhood trauma-new research directions for measurement, study design and analytical strategies. Journal of Child Psycholody and Psychiatry
  6. Danese, A., & Widom, C. S. (2020). Objective and subjective experiences of child maltreatment and their relationships with psychopathology. Nature Human Behaviour(4) 811-818 (PDF).
  7. Wamser‐Nanney, R., & Vandenberg, B. R. (2013). Empirical support for the definition of a complex trauma event in children and adolescents. Journal of Traumatic Stress26(6), 671-678.
  8. Hiller, R. M., Meiser‐Stedman, R., Elliott, E., Banting, R., & Halligan, S. L. (2020). A longitudinal study of cognitive predictors of (complex) post‐traumatic stress in young people in out‐of‐home care.  Journal of Child Psychology and Psychiatry, in press
  9. McCrory, E., Gerin, M., & Viding, E. (2017). Annual Research Review: Childhood maltreatment, latent vulnerability and the shift to preventative psychiatry – the contribution of functional brain imaging. Journal of Child Psychology and Psychiatry, 338-357.
  10. Heide, F. J. J. T., Mooren, T. M., & Kleber, R. J. (2016). Complex PTSD and phased treatment in refugees: A debate piece. European journal of psychotraumatology7(1), 28687
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