Abstract
We examined amygdala subregion volumes in patients with a first episode of major depression (MD) and in healthy subjects. Covariate-adjusted linear regression was performed to compare the MD and healthy groups, and adjustments for age, gender, and total estimated intracranial volume showed no differences in amygdala subregion volumes between the healthy and MD groups. Within the MD group, we examined the association between amygdala subregion volume and the 17-item Hamilton Rating Scale for Depression (HAMD) score and the HAMD subscale score, and found no association in the left amygdala. In the right amygdala, however, there was an inverse linear association between the HAMD total and the HAMD core and lateral nucleus and anterior-amygdaloid-regions. Furthermore, an inverse linear association was seen between the HAMD psychic and the lateral nucleus, anterior-amygdaloid-regions, transition, and whole amygdala. The findings of this study suggest that the severity of MD and some symptoms of MD are associated with right amygdala volume. There have been few reports on the relationship between MD and amygdala subregional volume, and further research is needed to accumulate more data for further validation.
Highlights
The pathophysiology of major depression (MD) remains unclear, recent brain imaging studies using MRI have provided some interesting insights (Schmaal et al, 2016, 2017)
Examination of the relationship between the amygdala subregion volume and the severity of depression in the depressed group found that the greater the severity of the whole depressive symptom and the core symptoms of depression, the smaller the lateral nucleus and anterior-amygdaloid-regions in the right amygdala, and the greater the severity of anxiety and agitation, the smaller the lateral nucleus, anterior-amygdaloidregions, transition, and whole amygdala
In terms of neural circuits involved in fear conditioning, both conditioned and unconditioned stimuli are sent to the lateral nucleus of the amygdala, which is thought to be responsible for the association between conditioned and unconditioned stimuli exploring the molecular mechanisms of learning and memory (LeDoux, 2000, 2007; Johansen et al, 2011)
Summary
The pathophysiology of major depression (MD) remains unclear, recent brain imaging studies using MRI have provided some interesting insights (Schmaal et al, 2016, 2017). Previous studies of the amygdala and hippocampus have reported reduced volume as a potential biomarker of depression (Roddy et al, 2019; Sheline et al, 2019). Notwithstanding, there are fewer reports on amygdala volume than on hippocampal volume, and there is a lack of assessment of the amygdala in relation to depression. We investigated the amygdala subregional volume in patients with a first depressive episode and in healthy subjects using image analysis that can measure the amygdala subregional volume
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