Sibling relationships of female adolescents with nonsuicidal self-injury disorder in comparison to a clinical and a nonclinical control group.

Background: Adolescents' nonsuicidal self-injury (NSSI) leads to distress that affects the whole family system, and siblings are reported to suffer from disrupted family communication and functioning. So far, no studies have examined the quality of relationships between adolescents with NSSI and their siblings. The aim of the present study was to examine the sibling relationship quality of adolescents with NSSI, adolescents with other mental disorders without NSSI (clinical controls, CC), and adolescents without current or past experience of mental disorders (nonclinical controls, NC).

Methods: 139 female adolescents aged 13-20 years (mean age = 16.18 years, SD  = 1.62, NSSI: n  = 56, CC: n  = 33, NC: n  = 50) and 73 siblings aged 10-28 years (mean age = 16.88 years, SD  = 4.02, 60.3% female) participated. Self-report measures were used to assess psychopathology and sibling relationship quality.

Results: Siblings reported a wide range of negative emotional and familial consequences, such as feeling left alone with their sister's issues or a distressing family situation, as a result of their sister's NSSI. Siblings of adolescents with NSSI experienced significantly more coercion in the relationship with their sister compared to CC ( d  = 1.08) and NC ( d  = 0.67) siblings, indicating an imbalance of dominance and control in their relationship. Further, adolescents with NSSI reported significantly less warmth and empathy in the sibling relationship and higher rivalry scores between their siblings and themselves than NC adolescents, suggesting higher levels of parental favoritism among parents of adolescents with NSSI compared to NC parents ( d  = 0.93). Among siblings of adolescents with NSSI, high levels of warmth, conflict, and empathy were significantly associated with internalizing problems. For adolescents with NSSI a significant association was found between internalizing problems and coercion and externalizing problems and similarity.

Conclusions: Given the negative impact of NSSI on siblings' emotional well-being and family life, efforts should be made to offer siblings psychoeducation and support to help them cope with the emotional and familial consequences of their sister's NSSI. Given adequate support, siblings can in turn be a source of emotional support for their sister.