Background: Although reduced hippocampal volume (HCV) is a common finding in depression, it is unclear whether the structural alterations leading to reduction of HCV are pre-existing risk factors before the onset of clinical symptoms or a cumulative process that begins with the onset of clinical symptoms. The aim of the present study was to understand the anatomical status of the hippocampus prior to the clinical symptoms in subjects with high familial risk for depression.
Methods: Twenty-seven young women (mean age: 22.3 ± 2.1 years) who were at high risk for familial unipolar depression and 26 age- and gender-matched healthy controls (mean age: 22.1 ± 2.1 years) with low familial risk for depression were included in the study. Total hippocampal volumes were measured by manual tracing. For 3D shape differences, the spherical harmonic basis functions (SPHARM) software was used. The segmented images were parameterized, and the point-to-point based group difference was compared by the Hotelling's T-squared test with total brain volume and Beck Depression Scale as covariates.
Results: Although there was no difference in overall HCVs, shape analyses revealed a contracted area on the Cornu Ammonis (CA) 1 region of the right hippocampus head in the high-risk group compared to the low-risk group. Cross-sectional design and small sample size, including only females, were the main limitations of this study.
Conclusion: This study with shape analyses provided data suggesting that local structural hippocampal alterations in the CA1 region might be associated with depression vulnerability in women at high risk.
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