Asal Najian - Ph.D. candidate, Department of Psychology, University of Science and Culture, Tehran, Iran.
Mohsen Kachooei - Assistant Professor, Department of Psychology, University of Science and Culture, Tehran, Iran.
Hojjatollah Farahani - Department of Psychology, Tarbiat Modares University, Tehran, Iran.

The prevalence of adolescents who self-injure each year indicates a public health problem requiring attention and intervention. This study investigated the effectiveness of mentalization-based treatment on negative affection and non-suicidal self-injury in adolescence. The research method was quasi-experimental with pre-test and post-test design with a control group. The study included ۲۲ adolescents with non-suicidal self-injury selected with a snowball sampling method and randomly divided into two groups, experimental (n=۱۱) and control (n=۱۱) from November to January ۲۰۲۱ in Tehran, Iran. To collect data, questionnaires such as the Inventory of Statements About Self-Injury and the Positive and Negative Affect Questionnaire were administered. For the experimental group, mentalization-based treatment was administered in ten sessions of ۹۰ minutes each week, while the control group received no treatment. The data were analyzed using MANOVA in SPSS software version ۲۳. The participants ranged in age from ۱۴ to ۱۸ years old, with a mean age of ۱۴.۸۹ years (SD = ۲.۰۱). The results suggest that the mentalization-based treatment had positive effects on negative affection (p < .۰۱, F_۱.۱۸ = ۹.۳۹۶) and non-suicidal self-injury (p < .۰۱, F_۱.۱۸ = ۱۰.۰۴۸) in adolescent girls with non-suicidal self-injury (p-value < .۰۱). The study found that mentalization-based treatment for negative affection and non-suicidal self-injury was an effective intervention for adolescents with non-suicidal self-injury aged ۱۴ to ۱۸.

Mentalization-Based Treatment, negative affection, non-suicidal self-injury, adolescence