The functional connectivity of the frontoparietal control network mediates the relationship between alexithymia and non-suicidal self-injury in depressive adolescents

Non-suicidal self-injury (NSSI) is common among adolescents with depression, posing a significant public health concern. Although NSSI has been linked to heightened alexithymia—characterized by difficulties in identifying and describing emotions—the neurobiological mechanisms underlying this association remain insufficiently understood in adolescents. This study included 233 adolescents diagnosed with major depressive disorder (MDD), for whom resting-state functional magnetic resonance images were acquired. All participants completed the Toronto Alexithymia Scale (TAS) and the Functional Assessment of Self-Mutilation (FASM). We estimated intra-network functional connectivity (FC) within 17 large-scale brain sub-networks and examined associations between intra-network FC, TAS scores, and NSSI. Mediation models were then fitted to examine indirect pathways among alexithymia, intra-network FC, and NSSI. Adolescents with MDD who engaged in NSSI showed higher alexithymia than those without NSSI, and NSSI frequency was positively correlated with the difficulty of identifying feelings in the NSSI group. Lower intra-network FC within the frontoparietal control network was associated with the presence of NSSI, and higher TAS total scores were linked to reduced intra-network FC in this network. Mediation analyses further indicated that intra-network FC in the frontoparietal control network partially mediated the association between TAS total scores and NSSI. These findings suggest that alexithymia and aberrant connectivity within the frontoparietal control networks are jointly associated with NSSI in adolescent MDD. The identified neural markers and pathways offer insights into potential therapeutic targets, emphasizing the importance of addressing emotion regulation deficits and alexithymia in the treatment of NSSI.