BackgroundMetacognition， the capacity to monitor and control one's cognitive processes， has been identified as a crucial component of effective decision-making and behavioral adaptation. Previous research has revealed cognitive deficits in patients with major depressive disorder （MDD）， while findings about metacognitive capacities in patients with MDD have been inconsistent across studies， and the exact relationship between metacognitive capacities and clinical symptoms in MDD patients remains uncertain. ObjectiveTo examine the metacognitive capacities of adolescent hospitalized patients with MDD and to explore its relationship with depressive and anxiety symptoms， thus providing an unprecedented insight into the prevention of MDD. MethodsA coherent 56 adolescent hospitalized patients with MDD in the Psychiatry Department at the Affiliated Hospital of Southwest Medical University from March 2022 to June 2023 and met the diagnostic criteria for depression as defined by the Diagnostic and Statistical Manual of Mental Disorders， fourth edition （DSM-IV） were enrolled as MDD group. At the same time， 62 healthy individuals matched with the age and sex of the MDD group residing in Luzhou were concurrently selected as control group. The metacognitive ability of the two groups was evaluated by perceptual decision-making task and confidence rating task， and the indicators included confidence deviation， reaction time of confidence evaluation and metacognitive efficiency. Additionally， the severity of depressive and anxiety symptoms was measured with Beck Depression Inventory （BDI） and Beck Anxiety Inventory （BAI）. Pearson correlation analysis was utilized to examine the relationship between metacognitive capacities and clinical symptoms. ResultsMDD group scored higher on BDI and BAI when compared with control group （t=-13.722， -9.674， P<0.01）. In terms of decision-making performance， no statistically significant difference was noted in accuracy and response time between two groups （t=-0.655， 0.975， P>0.05）. In terms of metacognitive performance， MDD group reported a reduction in overall confidence， confidence in correct decisions， confidence in incorrect decisions and metacognitive efficiency compared with control group （t=3.044， 2.769， 2.836， 3.667， P<0.01）. MDD group demonstrated significantly longer confidence evaluation response time than that of control group （t=-2.561， P<0.05）. Correlation analysis revealed that among the MDD patients， overall confidence， confidence in correct decisions and confidence in incorrect decisions were negatively correlated with BDI score （r=-0.310， -0.307， -0.298， P<0.05）， and the overall confidence and confidence in correct decisions were negatively correlated with BAI score （r=-0.284， -0.280， P<0.05）， while no statistical significance existed in the correlation between confidence in incorrect decisions and BAI score （r=-0.229， P>0.05）. Furthermore， metacognitive efficiency in MDD patients exhibited negative correlation with both BDI and BAI scores （r=-0.269， -0.290， P<0.05）. ConclusionHospitalized adolescent patients with MDD have impaired metacognition， and metacognitive capacity is found to be associated with severity of depressive and anxiety symptoms. ［Funded by Luzhou Science and Technology Bureau-Southwest Medical University Collaborative Project （number， 2019LZXNYDJ39）； Southwest Medical University Institutional Research Project （number， 2022ZD004）］