Abstract
Many previous studies have noticed obvious alterations in different white matter tracts among patients with major depressive disorder (MDD). Growing evidence also strongly suggest a role of leptin in the pathogenesis of MDD, but with conflicting results of leptin levels. However, no previous studies have examined the relationship between leptin and white matter integrity of patients with MDD. Therefore, we aimed in this study to investigate the relationship between white matter alterations and plasma leptin levels in both drug-naïve and medicated MDD patients. We measured plasma leptin levels and white matter integrity using diffusion tensor imaging (DTI) and voxel-based analysis (VBA) in 140 participants (40 drug-naïve MDD patients; 40 medicated MDD patients; 60 healthy controls) aged between 18 and 49 years old. A significant reduced fractional anisotropy (FA) value in the dorsomedial thalamus was found for both drug-naïve and medicated MDD patients compared to the healthy non-depressed participants (p < 0.01, corrected). In addition, leptin levels were significantly higher in the drug-naïve MDD patients and were negatively correlated with the detected white matter alteration. Our results suggest that the elevated plasma leptin levels in the drug-naïve MDD group might be associated with the changes of the white matter integrity in the dorsomedial thalamus region.
Highlights
White matter tracts are key components of a big complicated network that participates in somehow directly or indirectly in the course of major depressive disorder (MDD)
The applied one-way analysis of variance (ANOVA) detected one cluster in the white matter at p < 0.01 showing significant different between the three groups located in the left thalamus, in the dorsomedial thalamus (MNI coordinates for the maximal point of difference: x = −6 mm, y = −20 mm, z = 8 mm, number of voxels 99 and cluster size 73, F = 7.850, p < 0.01, corrected)
MDD patients had an obvious alteration of the white matter integrity in the thalamus region, a significant reduced fractional anisotropy (FA) value in the dorsomedial thalamus was found for both drug-naïve and medicated MDD patients compared to the healthy non-depressed participants
Summary
White matter tracts are key components of a big complicated network that participates in somehow directly or indirectly in the course of major depressive disorder (MDD). Many studies have noticed this relation and discovered various anatomical and functional abnormalities of the white matter fibers which were associated to the severity and relieve of the depressive symptoms (Bessette et al, 2014; de Diego-Adelino et al, 2014). WM and Leptin in MDD measure which can reflect the directionality of water diffusion and is used to indicate the location and strength of white matter fibers. In many DTI studies, FA values were found to be lower for patients with MDD compared to healthy individuals in different white matter regions such as the thalamus, frontal lobe, uncinate fasciculus, corpus callosum, cerebellum, parietal lobe, and superior longitudinal fasciculus (Wu et al, 2011; Bessette et al, 2014; Xia et al, 2018).
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