Changes of cortical thickness in the first episode, drug-naive depression patients with and without melancholic features.

Melancholic depression (MD) is a more severe type of major depressive disorder (MDD) with a core feature of anhedonia. However, its pathophysiology remains unclear. The current study aims to investigate whether there is a significant difference in cortical thickness (CT) that can be used to differentiate MD patients from non-melancholic depression (NMD) patients. We recruited 137 first-episode drug-naive MDD patients and 75 healthy controls (HCs) for structural magnetic resonance imaging, analyzed using the Surface-based morphometry approach. Meanwhile, the MDD patients were divided into the MD and NMD subgroups according to their scores on the Montgomery-Asberg Depression Rating Scale and Hamilton Depression Rating Scale. No significant CT differences among the three groups were found. We also did not find significant CT changes between the NMD and the HCs groups or between the MD and NMD groups. However, the CT of the left postcentral gyrus and right precuneus among MD patients were larger than HCs. Moreover, the CT of the left postcentral gyrus and right precuneus were not correlated with the severity of the disease and illness duration. The findings suggest that the CT alterations of the left postcentral gyrus and the right precuneus are distinct pathological mechanisms for MD.