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Hippocampal subfield volumes in major depressive disorder and bipolar disorder
Kyu-Man Han1, Aram Kim2, Wooyoung Kang2
1Department of Psychiatry, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Republic of Korea.
Background:
The hippocampus is not a uniform structure, but rather consists of multiple, functionally specialized subfields. Few studies have explored hippocampal subfield volume difference in the same sample of major depressive disorder (MDD) and bipolar disorder (BD) cases. We aimed to investigate the difference of hippocampal subfield volume between patents with MDD and BD and healthy controls (HCs).
Methods:
A total of 102 MDD and 55 BD patients and 135 HCs were recruited and underwent T1-weighted image. Hippocampal subfield volume was calculated by automated segmentation and volumetric procedures developed by Iglesias et al. and implemented in FreeSurfer. Volume differences between the groups were analyzed using the analysis of covariance and controlling for age, sex, and total intracranial cavity volume.
Results:
Patients with MDD had significantly reduced volumes in the bilateral cornu ammonis 1 (CA1), CA4, the granule cell layer (GCL), molecular layer (ML), whole hippocampus, the left CA2/3, and right presubiclum and subiculum. Patients with BD had significantly reduced volumes in the right CA1, GCL, and the whole hippocampus as compared to HCs. No significant volume differences were observed between the MDD and BD groups. Illness duration was negatively correlated with volumes of the left CA1, CA4, ML, presubiculum, subiculum, and the whole hippocampus in patients with BD.
Conclusion:
We observed hippocampal subfield volume reductions in both MDD and BD, a finding which more prominent in MDD. The inverse correlation between BD illness duration and hippocampal subfield volume may evidence the neuroprogressive nature of BD.
Insights
Major depressive disorder (MDD) and bipolar disorder (BD) patients show reduced hippocampal subfield volumes compared to healthy controls. These volume reductions were more pronounced in MDD and suggest a neuroprogressive nature in BD.
Area of Science:
- Neuroscience
- Psychiatry
- Radiology
Background:
- The hippocampus, crucial for memory and emotion, comprises specialized subfields.
- Few studies have compared hippocampal subfield volumes in major depressive disorder (MDD) and bipolar disorder (BD) within the same cohort.
- Investigating these differences is vital for understanding mood disorders.
Purpose of the Study:
- To compare hippocampal subfield volumes among patients with MDD, BD, and healthy controls (HCs).
- To identify specific subfields affected by MDD and BD.
- To explore the relationship between illness duration and hippocampal volume in BD.
Main Methods:
- 102 MDD patients, 55 BD patients, and 135 HCs underwent T1-weighted MRI scans.
- Automated segmentation using FreeSurfer calculated hippocampal subfield volumes.
- Analysis of covariance controlled for age, sex, and total intracranial volume.
Main Results:
- MDD patients exhibited reduced volumes in bilateral cornu ammonis 1 (CA1), CA4, granule cell layer (GCL), molecular layer (ML), and whole hippocampus, as well as left CA2/3, right presubiculum, and subiculum.
- BD patients showed reduced volumes in right CA1, GCL, and the whole hippocampus compared to HCs.
- No significant volume differences were found between MDD and BD groups; however, longer illness duration in BD correlated with smaller hippocampal subfield volumes.
Conclusions:
- Both MDD and BD are associated with hippocampal subfield volume reductions, more prominent in MDD.
- The inverse correlation between BD illness duration and hippocampal volume suggests a potential neuroprogressive course for BD.
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