Non-suicidal self-injury (NSSI) is defined as the repetitive, direct, and deliberate destruction of one’s body tissue without an intention to die. Existing cross-sectional research indicates that the association between maternal/peer attachment and NSSI is mediated by identity synthesis and confusion. However, longitudinal confirmation of the aforementioned mediation models is necessary as cross-sectional models are known to be biased. Consequently, the aim of the present study was to investigate whether identity formation mediates the association between attachment and NSSI in a longitudinal design. Three waves of self-report questionnaires data (1 year apart) were collected on maternal and peer attachment, identity, and NSSI from students of a high school in Belgium (at Time 1: Mean age = 15.0 years, SD = 1.85, range = 11–19 years, 50.6% female). Both cross-lagged (between-person) and parallel process latent growth curve (within-person) mediation analyses were used to test the mediation models. Findings of the cross-lagged analyses indicated unidirectional associations among the study variables, that is, from attachment to identity to NSSI. Parallel process latent growth mediation analyses showed that the association between the slope of maternal attachment and the slope of NSSI was mediated by the slopes of identity synthesis and confusion. Peer attachment models did not fit the data. The current work demonstrated that dysfunctional maternal and peer attachment may lead to disturbances in identity formation, which, in turn, may lead to increased NSSI. Additionally, within-person analysis indicated that the growth rate of maternal attachment predicted the growth rate of NSSI through the growth rate of identity synthesis and confusion. The clinical relevance of these findings is discussed.

Increasing research has indicated a strong association between identity functioning and eating disorder (ED) symptomatology. However, a detailed investigation of identity throughout ED treatment is lacking. The present longitudinal study examined identity in inpatients with an ED and explored its simultaneous change with ED symptomatology throughout treatment. A total of 225 female patients completed questionnaires at admission. From these 225 patients participating at admission (Wave 1), 110 also participated in at least one additional measurement wave, with 43.64% (n = 48) participating at admission and during treatment, 16.36% (n = 18) participating at admission and at discharge, and 40% (n = 44) participating at admission, during treatment and at discharge. Questionnaires on identity synthesis, identity confusion, identity processes, and ED symptomatology were completed. Latent growth curve modeling was used to address the research questions. Throughout treatment, a decrease in identity confusion and an increase in identity synthesis and adaptive identity processes were found. Accordingly, increases in identity synthesis and identification with commitment were related to general decreases in the drive for thinness and body dissatisfaction. Similarly, such decreases in ED symptoms were related to general decreases in identity confusion and ruminative exploration. The present study points to an increase in identity functioning throughout treatment, and longitudinal associations between identity functioning and ED symptomatology were found. Helping patients to decrease their ruminative exploration and to increase their identification with previously made life commitments and treating body/weight concerns could both be helpful in ED treatment.

Increasing research has indicated a strong association between identity functioning and eating disorder (ED) symptomatology. However, a detailed investigation of identity throughout ED treatment is lacking. The present longitudinal study examined identity in inpatients with an ED and explored its co-development with ED symptomatology throughout treatment. At admission (Wave 1), 110 women with an ED (Mage=21, SD=6.08, range:14-45) participated, of whom 83.64% participated during treatment (Wave 2) and 55.45% at discharge (Wave 3). Questionnaires on identity synthesis, identity confusion, identity processes, and ED symptomatology were completed. Latent growth curve modeling was used to address the research questions. Throughout treatment, a decrease in identity confusion and an increase in identity synthesis and adaptive identity processes were found. Accordingly, increases in identity synthesis and identification with commitment were related to general decreases in drive for thinness and body dis-satisfaction. Similarly, such decreases in ED symptoms were related to general decreases in identity confusion and ruminative exploration. The present study points to an increase in identity functioning throughout treatment, and longitudinal associations between identity functioning and ED symptomatology were found. Helping the patient to decrease ruminative exploration and to increase identification with previously made life commitments seem important in ED treatment.