Aberrant white matter structural connectivity of nucleus accumbens in patients with major depressive disorder: A probabilistic fibre tracing study.

Background: Extensive neuroimaging studies have established that functional abnormalities and morphological alterations in the nucleus accumbens (NAc) are implicated in major depressive disorder (MDD), but changes in its white matter structural connectivity (SC) remain unclear. We aimed to elucidate the changes in the white matter fibre connectivity of the NAc in MDD patients.

Methods: This study used probabilistic fibre tracking to analyze the diffusion tensor imaging (DTI) data of 125 MDD patients and 129 healthy controls (HCs), calculating the strength of SC (sSC) from bilateral NAc to the entire brain and its correlation with depressive symptoms.

Results: Compared to HCs, MDD exhibited increased sSC between the left NAc (L.NAc) and regions involving the left middle frontal gyrus, bilateral cingulate gyrus (CG), bilateral hippocampus, left caudate, left medial superior occipital gyrus, right globus pallidus, right superior and middle temporal gyrus, right precuneus, right insula, and right posterior parietal thalamus. Enhanced sSC was also observed between the right NAc (R.NAc) and the left temporal lobe, left posterior superior temporal sulcus (pSTS), bilateral lateral occipital cortex, left hippocampus, right putamen and right ventral occipital cortex. The sSC of L.NAc-left CG and R.NAc-left pSTS was positively correlated with HAMD scores in MDD.

Conclusions: Abnormal white matter connectivity of the NAc primarily affects the cortico-limbic circuit, cortico-basal ganglia circuit, and the temporal-occipital cortical regions in patients with MDD, along with the asymmetrical features of the inter-hemispheric SC related to NAc. These alteration may underlie the dysfunction of reward processing and emotion regulation in MDD.