The relationship between symptoms of complex posttraumatic disorder and core concepts in Internal Family Systems therapy

Abstract

Objective: Despite the increasing practice of Internal Family Systems therapy (IFS) for treating trauma, empirical validation of IFS concepts in relation to complex posttraumatic stress disorder (CPTSD) symptoms is lacking. The study aimed to 1) examine whether childhood trauma severity predicted the presence and strength of IFS parts and polarisation, and Self; and 2) examine whether Self moderated the relationship between parts and polarisation and posttraumatic stress disorder (PTSD) and disturbances of self-organisation (DSO) symptom clusters. Method: A sample of 697 adults was recruited. Survey data were analysed using hierarchical multiple regression and moderation. Results: Childhood trauma severity negatively predicted Self and positively predicted parts and polarisation. Those with a probable CPTSD diagnosis demonstrated significantly greater parts and polarisation and reduced access to Self compared to the probable PTSD and no diagnosis groups. Self moderated the relationship between IFS concepts and DSO symptoms, demonstrating that as IFS parts and polarisation and DSO symptom severity increased, Self access decreased. This effect was small. This was not found for PTSD symptoms. Conclusions: These novel findings suggest that severity of childhood trauma predicts an individual’s internal system and that strengthening an individual’s Self may be a worthwhile therapeutic target to address DSO symptoms.