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Reduced gray matter volume of the hippocampal tail in melancholic depression: evidence from an MRI study
Zhaosong Chu1,2, Lijin Yuan1,2, Kun Lian1,2
1Department of Psychiatry, The First Affiliated Hospital of Kunming Medical University, 650032, Kunming, China.
Background:
Melancholic depression (MD) is one of the most prevalent and severe subtypes of major depressive disorder (MDD). Previous studies have revealed inconsistent results regarding alterations in grey matter volume (GMV) of the hippocampus and amygdala of MD patients, possibly due to overlooking the complexity of their internal structure. The hippocampus and amygdala consist of multiple and functionally distinct subregions, and these subregions may play different roles in MD. This study aims to investigate the volumetric alterations of each subregion of the hippocampus and amygdala in patients with MD and non-melancholic depression (NMD).
Methods:
A total of 146 drug-naïve, first-episode MDD patients (72 with MD and 74 with NMD) and 81 gender-, age-, and education-matched healthy controls (HCs) were included in the study. All participants underwent magnetic resonance imaging (MRI) scans. The subregional segmentation of hippocampus and amygdala was performed using the FreeSurfer 6.0 software. The multivariate analysis of covariance (MANCOVA) was used to detect GMV differences of the hippocampal and amygdala subregions between three groups. Partial correlation analysis was conducted to explore the relationship between hippocampus or amygdala subfields and clinical characteristics in the MD group. Age, gender, years of education and intracranial volume (ICV) were included as covariates in both MANCOVA and partial correlation analyses.
Results:
Patients with MD exhibited a significantly lower GMV of the right hippocampal tail compared to HCs, which was uncorrelated with clinical characteristics of MD. No significant differences were observed among the three groups in overall and subregional GMV of amygdala.
Conclusions:
Our findings suggest that specific hippocampal subregions in MD patients are more susceptible to volumetric alterations than the entire hippocampus. The reduced right hippocampal tail may underlie the unique neuropathology of MD. Future longitudinal studies are required to better investigate the associations between reduced right hippocampal tail and the onset and progression of MD.
Insights
Melancholic depression patients show reduced grey matter volume in the right hippocampal tail. This specific subregion alteration, unlike the whole hippocampus, may indicate unique neuropathology in melancholic depression.
Area of Science:
- Neuroscience
- Psychiatry
- Radiology
Background:
- Melancholic depression (MD) is a severe subtype of major depressive disorder (MDD).
- Previous studies on hippocampal and amygdala grey matter volume (GMV) in MD patients yielded inconsistent results.
- Subregional differences within the hippocampus and amygdala may be crucial for understanding MD's neuropathology.
Purpose of the Study:
- To investigate volumetric alterations in subregions of the hippocampus and amygdala in patients with MD and non-melancholic depression (NMD).
- To compare GMV of hippocampal and amygdala subregions between MD, NMD, and healthy controls (HCs).
Main Methods:
- Included 146 first-episode, drug-naïve MDD patients (72 MD, 74 NMD) and 81 HCs.
- Utilized magnetic resonance imaging (MRI) and FreeSurfer 6.0 for subregional segmentation of the hippocampus and amygdala.
- Employed MANCOVA for group comparisons and partial correlation analysis for clinical associations, controlling for age, gender, education, and ICV.
Main Results:
- MD patients exhibited significantly lower GMV in the right hippocampal tail compared to HCs.
- No significant differences in amygdala subregional GMV were found among MD, NMD, and HC groups.
- The observed reduction in the right hippocampal tail GMV was not correlated with clinical characteristics of MD.
Conclusions:
- Specific hippocampal subregions, like the right hippocampal tail, are more vulnerable to volumetric changes in MD than the entire hippocampus.
- Reduced right hippocampal tail GMV may be a key neuropathological feature distinguishing MD.
- Longitudinal studies are needed to explore the relationship between the right hippocampal tail and MD onset/progression.
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