Altered thalamic subregional connectivity with default mode and frontoparietal networks in adolescents with depression.

BACKGROUND: The thalamus plays a pivotal role in the pathophysiology of adolescent depression, with its subregions showing functional heterogeneity. Abnormalities in the default mode (DMN) and frontoparietal networks (FPN) are associated with depressive symptoms, and both networks are closely coupled with the thalamus. This study examined, at a finer granularity, functional connectivity (FC) changes between thalamic subregions and these networks in depressed adolescents, aiming to reveal underlying mechanisms and explore their potential as diagnostic biomarkers.

METHOD: This study included 64 depressed adolescents and 54 matched healthy controls. All participants underwent functional magnetic resonance imaging. Using thalamic subregions as seeds, we calculated the FC of these seeds with the DMN and FPN. We correlated FC values exhibiting group differences with clinical scores and constructed a machine learning model to evaluate clinical relevance and predictive accuracy.

RESULTS: Compared to healthy controls, depressed adolescents exhibited reduced connectivity between the right ventral posterior (VP) thalamus and bilateral anterior cingulate cortex, and between the left VP thalamus and the right supramarginal gyrus (SMG) and inferior parietal lobule. The FC strength between the left VP thalamus and right SMG was negatively correlated with self-esteem. The classifier incorporating these altered FCs demonstrated moderate discriminative ability between the groups, where each feature contributed to the model decision.

CONCLUSION: This study identified abnormal FC between thalamic subregions and the DMN and FPN. These alterations may contribute to the onset and progression of adolescent depression and show promise as potential biomarkers, thus providing a more objective basis for clinical diagnosis.