The 11th version of the International Classification of Diseases (ICD-11) includes complex posttraumatic
stress disorder (CPTSD) as a separate diagnostic entity alongside posttraumatic stress disorder (PTSD).
ICD-11 CPTSD is defined by six sets of symptoms, three that are shared with PTSD (reexperiencing in the
here and now, avoidance, and sense of current threat) and three (affective dysregulation, negative self-concept, and disturbances in relationships) representing pervasive “disturbances in self-organization”
(DSO). There is considerable evidence supporting the construct validity of ICD-11 CPTSD, but no
theoretical account of its development has thus far been presented. A theory is needed to explain several
phenomena that are especially relevant to ICD-11 CPTSD such as the role played by prolonged and repeated
trauma exposure, the functional independence between PTSD and DSO symptoms, and diagnostic
heterogeneity following trauma exposure. The memory and identity theory of ICD-11 CPTSD states
that single and multiple trauma exposure occur in a context of individual vulnerability which interact to give
rise to intrusive, sensation-based traumatic memories and negative identities which, together, produce the
PTSD and DSO symptoms that define ICD-11 CPTSD. The model emphasizes that the two major and
related causal processes of intrusive memories and negative identities exist on a continuum from
pre-reflective experience to full self-awareness. Theoretically derived implications for the assessment
and treatment of ICD-11 CPTSD are discussed, as well as areas for future research and model testing