We analyzed subcortical structures in patients with MDD (N=15) and control (N=15) using FreeSurfer. Patients with MDD had significantly lower left thalamus (p<0,01), left putamen (p<0,05), left hippocampus (p<0,05) and some hippocampal subfields volumes, relative to control. We found correlations (p<0,05) between patient’s age and putamen volume (r= -0,56), number of depressive episodes and molecular layer volume (r= -0,52). We didn’t reveal correlation between segmentation data and MDD severity.
We analyzed subcortical structures in patients with MDD (N=15) and control (N=15) using FreeSurfer. Patients with MDD had significantly lower left thalamus (p<0,01), left putamen (p<0,05), left hippocampus (p<0,05) and some hippocampal subfields volumes, relative to control. We found correlations (p<0,05) between patient’s age and putamen volume (r= -0,56), number of depressive episodes and molecular layer volume (r= -0,52). We didn’t reveal correlation between segmentation data and MDD severity.
Major depressive disorder (MDD) is a very common psychiatric disease and is among the leading causes of disability worldwide [1]. Despite intensive research aimed at identifying neurobiological substrates of depression in the last decades, our understanding of the pathophysiological mechanisms underlying depression is still rudimentary. Histological studies have repeatedly shown the presence of atrophy and gliosis of individual subcortical structures in patients with MDD [2]. Widely available structural magnetic resonance imaging has led to hypotheses of subcortical structures being involved in MDD, but still the exact pattern of structural brain alterations associated with MDD remains unresolved [3].
Purpose
The purpose of this study was to assess the subcortical volumetric changes in patients with major depressive disorder (MDD) using the fully automatic MR-morphometry, in combination with clinical data.
Materials and methods.
The study included patients (n = 15) diagnosed with MDD (according to DSM-5), and a healthy control (n = 15). All subjects underwent a severity assessment of depression according to HDRS-17. The MRI scanning was performed on the General Electric Discovery MR750W (3.0 T) and included a high spatial resolution 3D SPGR pulse sequence (TR - 9.5 ms, TE - 4.2 ms, Voxel - 1 × 1 × 1 mm). Postprocessing was carried out using FreeSurfer software (Basic Segmentation packages, Hippocampal Subfields) and included automatic basic segmentation of subcortical structures (thalamus, caudate nucleus, putamen, pallidum, amygdala, nucleus accumbens, hippocampus) and segmentation of hippocampi into 12 standard morphological fields [4 ,5].
Results.
A decrease in the volume of the left thalamus (p <0.01), left and right putamens (p <0.05 and p = 0.057, respectively) and a left hippocampus (p <0.05) in patients with MDD compared with the control group was found. In addition, there was a significant decrease in the volumes of the molecular layer (p <0.05), dentate gyrus (p <0.05), and precubiculum (p <0.01) of the left hippocampus, and a tendency to reduce the volumes of some subfields (parasubiculum, CA1, CA3) of the left and right hippocampus. During the Pearson correlation analysis, significant (p <0.05) correlations between the age of patients with MDD and the volume of the putamen (r = -0.56) were revealed; the number of episodes of major depressive disorder and the volumes of the molecular layer of the hippocampus and the putamen (r = -0.52 and -0.64, respectively); the degree of decrease in the volumes of the putamen and thalamus (r = 0.62), the individual fields of the hippocampus. In addition, a negative correlation was found between the age of patients and a subjective assessment of the severity of depression (r = -0.73). Interestingly, there was no correlation between HDRS and automatic morphometry data.
The conclusion.
Thus, our results confirm the existence of significant changes in the mechanisms of neuroplasticity MDD patients and allow to link the clinical picture of this disease with quantitative neuroimaging data.
1. Murray C. J. L. et al. Disability-adjusted life years (DALYs) for 291 diseases and injuries in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010 //The lancet. – 2013. – Т. 380. – №. 9859. – С. 2197-2223.
2. Duman C. H., Duman R. S. Spine synapse remodeling in the pathophysiology and treatment of depression //Neuroscience letters. – 2015. – Т. 601. – С. 20-29.
3. Schmaal L. et al. Subcortical brain alterations in major depressive disorder: findings from the ENIGMA Major Depressive Disorder working group //Molecular psychiatry. – 2016. – Т. 21. – №. 6. – С. 806-812.
4. Fischl B. et al. Whole brain segmentation: automated labeling of neuroanatomical structures in the human brain //Neuron. – 2002. – Т. 33. – №. 3. – С. 341-355.
5. Iglesias J. E. et al. A computational atlas of the hippocampal formation using ex vivo, ultra-high resolution MRI: application to adaptive segmentation of in vivo MRI //Neuroimage. – 2015. – Т. 115. – С. 117-137.