Complex Trauma was first described in 1992 by Judith Herman in her book Trauma & Recovery. Immediately after that, Van Der Kolk and others began promoting the concept of “Complex PTSD” (C-PTSD), also referred to as “Disorder of Extreme Stress Not Otherwise Specified” (DESNOS).
According to Herman, complex trauma occurs after repetitive, prolonged trauma involving sustained abuse or abandonment by a caregiver or other interpersonal relationships with an uneven power dynamic; it distorts a person's core identity, especially when prolonged trauma occurs during childhood.
DESNOS was formulated as a diagnosis with all the criteria and proposed in 2001 to be added to the DSM-5 as an option for complex trauma, but was rejected. It stated that childhood abuse and other developmentally adverse interpersonal traumas produces impairments in affective, cognitive, biological, and relational self-regulation.
Christine A. Courtois then expanded on the concepts of PTSD and DESNOS (1998) saying that complex trauma generally refers to traumatic stressors that are interpersonal —they are premeditated, planned, and caused by other humans, such as violating and/or exploitation of another person; repetitive, prolonged, or cumulative, most often interpersonal, involving direct harm, exploitation, and maltreatment including neglect/abandonment/antipathy by primary caregivers or other ostensibly responsible adults, and often occurring at developmentally vulnerable times in the victim's life, especially in early childhood or adolescence, but can also occur later in life and in conditions of vulnerability associated with disability/ disempowerment/dependency/age /infirmity, and so on.
After all the argumentation, Complex posttraumatic stress disorder (C-PTSD) has been recently proposed as a distinct clinical entity in the WHO International Classification of Diseases, 11th version (ICD-11), due to be published soon, two decades after it was first proposed. It has been said that it will be an enhanced version of the current definition of PTSD plus three additional clusters of symptoms: emotional dysregulation, negative self-cognition, and interpersonal hardship.
C-PTSD then, is defined by its threatening and entrapping context, generally interpersonal in nature, and will keep the requisite of “enduring personality change after a catastrophic experience.”
The criteria seem to be asking for significant impairment in all areas of functioning, and:
Exposure to an event(s) of an extremely threatening or horrific nature, most commonly prolonged or repetitive, from which escape is difficult or impossible;
All diagnostic requirements for PTSD, and additionally:
severe and pervasive affect dysregulation;
persistent negative beliefs about oneself;
deep-rooted feelings of shame, guilt or failure;
persistent difficulties in sustaining relationships and in feeling close to others.
In contrast, Developmental trauma has presented the dilemma of how to best organize the very complex emotional, behavioral, and neurobiological sequelae of childhood trauma only, instead of trying to encompass all ages.
Developmental Trauma Disorder (DTD) came as a proposition when some scholars (van der Kolk et al) noticed that the PTSD diagnosis does not capture the developmental effects of childhood trauma, as in:
the complex disruptions of affect regulation;
the disturbed attachment patterns;
the rapid behavioral regressions and shifts in emotional states;
the loss of autonomous striving;
the aggressive behavior against self and others;
the failure to achieve developmental competencies;
the loss of bodily regulation in the areas of sleep, food, and self-care;
the altered schemas of the world;
the anticipatory behavior and traumatic expectations;
the multiple somatic problems, from gastrointestinal distress to headaches;
the apparent lack of awareness of danger and resulting self endangering behaviors;
the self-hatred and self-blame;
and the chronic feelings of ineffectiveness.
In summary, C-PTSD is an extension of PTSD considering prolonged exposure to emotionally challenging events that are prolonged or repetitive, from which escape is difficult or impossible, while DTD recognizes the traumatization that occurs early in life.
A similar version appeared in Quora as What is the difference between C-PTSD and Developmental Trauma Disorder (DTD)?