The age of depression has begun to decline. Juvenile depressive disorder refers to the onset of adolescence. Epidemiology data shows that the prevalence of adolescent depressive disorders is approximately 14 % (Liu et al., 2021). Depressive disorders are among the most prevalent and disabling mental health conditions in adolescents worldwide. They not only affect growth, family relationships, and social interactions but are also more likely to continue into adulthood. Compared to adults with depressive disorders, these patients have a greater psychological burden, but their psychological adjustment ability is weak, leading to an increased suicide risk (Ugonabo et al., 2021, Szanto et al., 2018, Sileo et al., 2022). According to the World Health Organization, suicide is one of the three leading causes of death in people aged 15-44 worldwide and the second leading cause of death in people aged 15-29. In recent years, the reported rate of suicidal ideation in children and adolescents has been 14.2 %, with a suicide attempt rate of 4.5 % (Lim et al., 2019). Therefore, adolescent suicide is an important public health problem, both in our country and worldwide. Identifying the mechanisms of suicide in adolescents with depressive disorders and providing regular screening and effective interventions for suicidal behaviors is crucial.

In fMRI, the low-frequency fluctuation amplitude (amplitude of low-frequency fluctuation, ALFF) can be used to effectively assess local brain activity related to the disease and better understand the underlying brain mechanisms of suicidal behavior in depression (Logothetis et al., 2001). In a comparison of the four groups of patients with suicide attempts, suicide ideation, no suicide depression, and healthy controls, ALFF values were elevated in the thalamus and hippocampus and differentiated between suicide attempters (Wagner et al., 2021). In the study of adolescents, previous studies found that prefrontal, temporal, and occipital cortex brain function changes and the left superior frontal and left middle frontal gyrus ALFF value reduction will increase suicide susceptibility and suicidal behavior tendency, show high impulsivity, and can be used as brain imaging-based biomarkers for evaluating and monitoring adolescents with depressive disorders and increased suicide risk (Cao et al., 2016). Studies have also found that ALFF values are increased in the inferior temporal gyrus of adolescents with depressive disorders, and ALFF values in the left inferior temporal gyrus and right fusiform gyrus are higher in adolescents with depressive disorder than in adolescents with depressive disorder without suicide attempts, with a unique neural activity pattern (Hu et al., 2023). These studies enhance our understanding of the neural correlates of suicide in adolescents with depressive disorders and provide unique insights into the neurobiology and neuropathology of suicidal behaviors in adolescents with depression (Cheng et al., 2025, Zhang et al., 2024).

Extensive evidence shows that individuals with depressive disorders have social cognitive impairment, particularly significant defects in the theory of mind, and that the degree of impairment in the theory of mind is significantly associated with the severity of depressive symptoms (Harkness et al., 2011, Wilbertz et al., 2010). The theory of mind (ToM) represents the ability to place oneself in the shoes of others. Social cognitive ability is categorized into two components: the theory of cognitive psychology, which refers to understanding others’ thoughts, and the theory of emotional psychology, which refers to understanding others’ feelings (Sanvicente-Vieira and Brietzke, 2012). However, it is unclear which specific aspects of psychological theory act as impaired patterns in depressive disorders, which are unable to detect abnormal underlying characteristics related to theories of mind in depressive disorders, and a subtype-specific analysis of depressive disorders is lacking. Only a few studies have shown psychological theory impairment in patients with depression, a history of suicide attempts, and significantly lower scores on the eye-reading test (Reading the Mind in the Eyes) (Senna et al., 2022). The theory of mind development occurs throughout infancy, childhood, adolescence, and youth and is crucial for social functioning throughout the life cycle (Symeonidou et al., 2016). Therefore, the theory of mind is important for teenagers. In the field of adolescent research, few studies have found a theoretical psychological impairment in adolescent inpatients, which seems to have a significant relationship with recent suicidal ideas and behaviors (Hatkevich et al., 2019).

Although many previous brain imaging studies of adolescent suicide attempters with depression have focused on the function of the abnormal brain areas, including the frontoparietal network, default network, and limbic system, involving the brain area of excessive activation or insufficient response, these findings suggest that the occurrence of suicidal behavior is the result of a large-scale abnormal brain network of interaction. In addition, only a few studies involving the psychological theoretical damage of depressed patients with suicide attempts have investigated the psychological theoretical damage and clinical correlation, but without further study of brain imaging evidence, and no studies confirming the specific psychological theoretical damage involving the brain area and are unable to determine whether the brain area is overactivated or underresponsive. Therefore, this study is the first to present the correlation between brain imaging and theoretical psychological damage in depressed adolescents with suicide attempts and to identify specific brain regions. We hypothesized that there would be differences in psychological theories and brain imaging in patients with depression with and without suicide attempts and that a correlation would exist between psychological theories and brain imaging.