Joseph Harris, Eva Loth and Vaheshta Sethna
What the research suggests
Harris and colleagues reviewed research examining potential mediators between complex trauma before age 18 and later CPTSD. Across 15 studies, they identified 24 potential mediators grouped into five areas: dissociative processes, relationship with self, emotional development, social development, and systemic and contextual factors.
These included processes such as dissociation, self-criticism, maladaptive schemas, self-compassion, emotion regulation, attachment insecurity, social support, and how other people respond to trauma disclosure. The findings suggest that the consequences of complex trauma may develop through multiple interacting pathways rather than through one predictable progression from trauma to symptoms.
Importantly, some of those pathways extend beyond the individual. Whether someone is supported, believed, able to disclose safely, or met with disapproval may also influence what follows a traumatic experience.
Why I care
This gets closer to what interests me about complex trauma than simply expanding the list of symptoms associated with PTSD.
If repeated traumatic experiences occur while someone is developing ways of regulating emotion, understanding themselves, navigating relationships, and determining what is safe, then their effects may become embedded in those processes. The original danger can end while ways of relating to oneself, other people, emotion, and threat continue.
That helps me think about complex trauma less as a collection of additional symptoms and more as a question about how experience can shape patterns over time.
How it connects to my clinical thinking
Someone might describe shame, dissociation, emotional reactivity, avoidance, difficulty trusting other people, and anxiety as separate problems. Sometimes they are. Sometimes a useful formulation may reveal relationships among them.
This research makes me interested in developmental pathways rather than diagnostic ownership: instead of asking which diagnosis gets to claim a symptom, asking how a pattern developed, what maintains it now, and what function it serves.
It also supports treating formulation as a hypothesis rather than an answer. Trauma may help explain how several difficulties became connected for one person and be much less relevant for another.
What it doesn’t establish
The proposed mediators are not established causal mechanisms. Fourteen of the 15 studies were cross-sectional, and most were rated as methodologically moderate or weak. Statistical mediation cannot tell us whether a process actually developed after trauma and then produced later CPTSD.
Some proposed mediators also overlap conceptually with CPTSD symptoms themselves, making cause and outcome difficult to separate. The evidence is better understood as a map of processes worth investigating than proof of how complex trauma works in an individual person.