Abstract
Background: The thalamus and habenula are thought to be key brain regions in the etiology of major depressive disorder (MDD); however, few studies have investigated the structural connection between them. We compared the number of white matter tracts between the thalamus and habenula between patient with MDD and normal controls (NCs).Methods: The habenula and thalamus region of interest masks were extracted from brain magnetic resonance imaging data and individual tractography analysis was performed. First, we compared the number of fiber connections from the habenula to the thalamus between the MDD (n = 34) and NC (n = 37) groups and also compared hemispherical differences to investigate possible asymmetries.Results: There was a significant difference in the number of tracts in the right habenula-left mediodorsal thalamus pair between the two groups. For hemispherical fiber connections, the waytotal ratio of the right ipsilateral tract between the thalamus and habenula was significantly higher than that of the left ipsilateral tract in both groups.Conclusion: The number of right habenula-left mediodorsal thalamus tracts was higher in patients with MDD than in NCs. These results indicate that MDD is related to the disintegration of the left thalamus-right habenula tract function with an increased number of tracts as a compensational mechanism.
Highlights
Major depressive disorder (MDD) is one of the most prevalent and disabling psychiatric disorders [1], and it has led to an increase in healthcare utilization and consequent social burden and economic cost [2]
There was a significant difference in the number of tracts only in the right habenula-left mediodorsal thalamus pair between the two groups (MDD, 113.8 ± 309.6 [mean ± standard deviation]; normal controls (NCs), 35.2 ± 128.7; p = 0.004; Table 2)
The results of this study showed a thicker right habenulaleft mediodorsal thalamus tract in the patients with MDD than in the NCs
Summary
Major depressive disorder (MDD) is one of the most prevalent and disabling psychiatric disorders [1], and it has led to an increase in healthcare utilization and consequent social burden and economic cost [2]. MDD is a heterogeneous disorder in which several symptoms and signs appear due to various causes and include diverse neural tracts [6, 7]. Previous voxel-based morphometry studies have shown smaller thalamic volumes in patients with MDD than in normal controls (NCs) [9,10,11]. There was a significant difference in the volume of the bilateral thalami using an automatic segmentation tool between patients with MDD and NCs after controlling for total intracranial volume [12]. The thalamus and habenula are thought to be key brain regions in the etiology of major depressive disorder (MDD); few studies have investigated the structural connection between them. We compared the number of white matter tracts between the thalamus and habenula between patient with MDD and normal controls (NCs)
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