Morphometric and functional alterations of amygdale and hippocampus in patients with depression: a MRI study

Objective To explore the morphometric and functional alterations of amygdale and hippocampus in patients with depression by anatomical and functional MRI, and try to reveal the pattern and pathogenesis of the changes in depression. Methods Sixty patients (divided equally into mild, moderate and major groups according to patient′s scores of HAMD) and 20 healthy control groups were scanned using T1WI and fMRI. The outlines of hippocampus and amygdale were drawn manually by observer and the volumes were calculated and normalized subsequently. Functional MRI was processed using SPM5 and individual activation map was got subsequently. Dunnett-t test and Pearson correlation analysis were separately used to analyze the morphometric and functional changes and the correlations between cerebral changes and clinical severity. Results The hippocampal volumes of control groups were 2296±202 left for left side and 2283±199 for right side. The hippocampal volumes of depressive patients were smaller than those of control groups, especially for the major group (left 1978±176,Dunnett-t=-10.0,P 0.05,right 2210±191,Dunnett-t=-1.6,P>0.05). The amygdale′s volumes of control groups was 1762±185,the right was 1749±182, while those in patient group reduced along with the patient′s condition, i.e., the mild groups (left 1992±200,Dunnett-t=4.8,P<0.01,right 1989±191, Dunnett-t=5.0,P<0.001), the moderate groups (left 1889±192, Dunnett-t=2.8,P<0.05,right 1896±195,Dunnett-t=2.8,P<0.05), and the major groups (left 1539±178,Dunnett-t=-6.8,P<0.01,right 1543±180,Dunnett-t=-7.0,P<0.01).For fMRI study, patient group demonstrated more activation of the amygdale and hippocampus under the stimulations of negative images than controls. Furthermore, the strengthens of activation decreased along with the patient′s condition, i.e., the major ones showed the weakest activation among the patients, though it was higher than that of control group. In patient group, both the volumes and activations of hippocampus and amygdale showed significant negative correlations with HAMD scores(r=-0.80--0.90,P＜0.05). Conclusion The hippocampal volumes of depressive patients reduced, which may be due to the change of the amygdale, and the amygdale′s volumes were changed along with the patient′s condition. There were more activation in the amygdale and hippocampus of depressive patients under the stimulations of negative images. Key words: Amygdala;  Hippocampus;  Depressive disorder;  Magnetic resonance imaging