Abstract
BACKGROUND: Bipolar disorder (BD) with somatic symptoms is a prevalent and refractory clinical syndrome in young patients. Interoception is an important mechanism for coordinating internal physiological and mood states to maintain individual homeostasis, and its mediating physiological systems and brain network dynamics undergo significant development from adolescence to young adulthood. It remains unclear whether interoception is altered and how it relates to somatic and mood symptoms in youths with BD. METHODS: This study recruited 71 youths (aged 14-25) with BD during maintenance status and 111 age-matched controls. Demographic characteristics, interoceptive sensitivity, somatic symptoms, and symptoms of depression and anxiety were assessed. Mann-Whitney U tests, Kruskal-Wallis H test, partial correlation analysis, and multiple linear regression were used to explore the alteration of interoception in BD patients and its association with somatic and mood symptoms. RESULTS: BD patients showed lower interoception sensitivity and higher somatic and mood symptoms than controls (p < 0.001). Those with somatic symptoms had the highest depression and anxiety (p < 0.001) but the lowest scores in not-distracting, not-worrying, self-regulation, and trust (p < 0.05). Interoceptive indicators correlated with mood and somatic symptoms (p < 0.05). Not-distracting was the sole predictor of somatic and mood issues, maintaining significance after controlling for mood symptoms (p < 0.05), highlighting attentional focus as a key factor in BD youths. CONCLUSION: BD youths exhibit deficits in interoception sensitivity, somatic symptoms, and mood issues. The not-distracting aspect of interoception significantly correlates with mood and somatic symptoms in youths with BD, providing insights and targeted strategies for managing psychosomatic symptoms in this demographic. LIMITATIONS: This study has several limitations. First, the control group's inclusion and exclusion criteria lacking clinical validation. Second, assessment for mood and somatic symptoms relied on screening tools rather than validated questionnaires, and structured clinical evaluations for BD were not conducted. Third, medication effects were not considered. Fourth, some psychiatric conditions (e.g., borderline personality disorder, obsessive-compulsive disorder, etc.) comorbid were not considered. Finally, causal relationships cannot be inferred, highlighting the need for longitudinal studies.