Static and dynamic alterations in local brain activity and their association with dysfunctional connectivity in depressed adolescents with suicide attempts and non-suicidal self-injury.

Suicide attempts (SA) and non-suicidal self-injury (NSSI) are critical public health concerns that frequently co-occur in depressed adolescents. However, the neurological mechanisms underlying these behaviors remain poorly understood. This study aimed to identify alterations in brain activity and examine the associations between these changes and clinical symptom severity in depressed adolescents with SA and NSSI. A total of 82 depressed adolescents with NSSI were divided into two groups: those with both SA and NSSI (SA + NSSI, n = 46) and those with NSSI only (n = 36). Static amplitude of low-frequency fluctuation (sALFF) and dynamic ALFF variability (dALFF variability) analyses were conducted to assess local brain activity differences between groups. Regions with abnormal neural activity were used as seeds to investigate static functional connectivity (sFC) and dynamic FC variability (dFC variability) alterations. Correlation analyses as exploratory analysis was subsequently performed. Compared to the NSSI group, the SA + NSSI group exhibited increased sALFF in the left cerebellum, increased dALFF variability in the orbitofrontal cortex and left cerebellum, and increased dFC variability between the orbitofrontal cortex and caudate. The SA + NSSI group also showed decreased sALFF and dALFF variability in the postcentral gyrus (cluster p < 0.05, FDR corrected, two-tailed). Additionally, for the SA + NSSI group, sALFF in the postcentral gyrus was negatively correlated with emotional neglect, while the dFC variability between the orbitofrontal cortex and caudate was positively correlated with internet addiction withdrawal symptoms. These findings provide novel insights into the neurological mechanisms of SA and NSSI, highlighting the potential value of combining static and dynamic functional metrics for clinical differentiation between these behaviors.