Self-compassion, self-referential caudate circuitry, and adolescent suicide ideation

Suicide is a leading cause of death among adolescents, with depression being a significant predictor. Identifying protective psychological factors is crucial for suicide prevention strategies. Self-compassion, characterized by self-kindness and acceptance, has shown an inverse correlation with suicide ideation. However, the neural mechanisms underlying this relationship remain unclear. Previous research indicates that both self-compassion and suicide ideation involve caudate activity during self-referential processing. This study hypothesized that caudate functional connectivity during self-appraisal mediates the association between self-compassion and suicide ideation in adolescents. Distorted self-referential processing is a characteristic of depression and is linked to suicide risk. Depressed adolescents with suicide ideation exhibit heightened attention to negative self-referential stimuli, reflected in caudate activity. Self-compassion, a psychological resource for stress management, is associated with reduced cortical midline structure hyperactivity during negative self-processing. It also engages the caudate and is linked to stronger caudate activity during positive self-referential processing. This study aimed to explore the relationship between self-compassion, caudate circuitry during self-appraisal, and suicide ideation. The researchers hypothesized that self-compassion would be linked to stronger caudate connectivity with regions involved in self-referential processing, such as the medial prefrontal cortex, anterior cingulate cortex, precuneus, and the posterior superior temporal sulcus or temporoparietal junction, during positive versus negative self-appraisals. They further tested whether caudate functional connectivity mediates the relationship between higher self-compassion and lower suicide ideation, controlling for other suicide risk factors.

Existing literature demonstrates a strong correlation between depression and suicide risk in adolescents. Studies have highlighted the inverse relationship between self-compassion and suicide ideation, suggesting that self-compassion may be a protective factor. Neuroimaging research indicates that both self-compassion and suicide ideation involve activity in the caudate nucleus, a brain region associated with self-referential processing and reward. Prior studies have shown that depressed individuals with suicide ideation display atypical caudate activity during emotionally valenced self-referential processing. Conversely, self-compassion is linked to less hyperactivity in cortical midline structures and stronger caudate activity during positive self-referential processing. However, research on the neural basis of self-compassion has primarily focused on neural activity, with limited exploration of functional connectivity.

This study recruited 79 depressed adolescents and 36 healthy controls (ages 11-17). Participants underwent fMRI during a self-appraisal task, evaluating self-descriptive phrases from different perspectives (self, mother, classmate, best friend) with positive and negative emotional valences. Self-compassion was measured using the Self-Compassion Reactions Inventory (SCR), and suicide ideation was assessed using the K-SADS-PL, CDRS-R, and SIQ. Other measures included depression severity (CDRS-R), anxiety severity (BAI-C), and non-suicidal self-injurious behavior (K-SADS). Neuroimaging data were acquired using two 3T Siemens Trio MAGNETOM scanners. Image preprocessing was performed using SPM12, correcting for head motion, co-registering with anatomical images, normalizing to the MNI template, and smoothing. Psychophysiological interaction (PPI) analysis was conducted using left and right caudate seed regions, examining functional connectivity during positive versus negative self-appraisals. Regression analysis examined the relationship between self-compassion and caudate connectivity, controlling for diagnostic group and other factors. Mediation analysis tested whether caudate functional connectivity mediated the relationship between self-compassion and suicide ideation, controlling for depression severity, anxiety, and self-injury.

Self-compassion was negatively correlated with suicide ideation (r = -0.65, p < 0.001), even when controlling for depression severity, anxiety, and self-injury. Depressed adolescents reported lower self-compassion and higher suicide ideation than healthy controls. Regression analysis showed that self-compassion, diagnostic group, and their interaction significantly predicted suicide ideation. Higher self-compassion was positively associated with stronger left caudate functional connectivity with bilateral pSTS/temporoparietal junction, left MTG, and left MOG during positive versus negative self-appraisals. This association remained significant even after controlling for depression severity, anxiety, and self-injury. Mediation analysis revealed that left caudate-left MTG connectivity mediated the relationship between self-compassion and suicide ideation, even after controlling for other factors. Left caudate connectivity with left pSTS/temporoparietal junction and left MTG during positive versus negative self-appraisals negatively correlated with suicide ideation.

The findings provide evidence for a neural mechanism underlying the protective role of self-compassion against suicide ideation. The strong association between self-compassion and left caudate-left MTG connectivity suggests that self-compassion may enhance positive emotional responses by activating reward-related brain circuits during self-referential processing. The mediating role of this connectivity highlights its importance in the relationship between self-compassion and suicide ideation. These results are consistent with previous research showing the involvement of the caudate in reward processing and self-referential processing. The study's findings have implications for developing interventions to reduce suicide ideation in adolescents, suggesting that targeting left caudate-MTG circuitry through neural stimulation or self-compassion training may be beneficial.

This study demonstrates a significant association between self-compassion, left caudate-left MTG functional connectivity, and reduced suicide ideation in adolescents. Left caudate-MTG connectivity during positive self-referential processing may serve as a potential biomarker for suicide risk. Interventions targeting this circuitry, potentially in conjunction with self-compassion training, warrant further investigation as a promising avenue for suicide prevention.

This study's correlational design limits causal inferences. Future intervention studies are needed to confirm the causal relationships among self-compassion, caudate circuitry, and suicide ideation. The use of a unidimensional measure of self-compassion limits the understanding of which specific components contribute to the findings. Future research should employ multidimensional scales to explore this aspect. Furthermore, the study focused solely on caudate circuitry; future studies should investigate other brain regions involved in self-referential processing and emotional regulation.