Low left amygdala volume is associated with a longer duration of unipolar depression

Abstract

The amygdala plays a crucial role in the pathogenesis of major depressive disorder (MDD). While robust findings support a negative impact of illness duration on hippocampal volume in MDD, morphometric studies of the amygdala have yielded inhomogeneous results. Considering the methodical problems of automatic segmentation methods, a standardized segmentation protocol with proven inter- and intra-rater reliability was employed using high-resolution magnetic resonance imaging. To identify the effect of MDD on amygdala morphometry, 23 unipolar depressed patients who responded to antidepressant medication and 30 age-matched healthy controls (HC) were enrolled. First, gray matter volumes (GMV) of the bilateral amygdala were delineated manually in 3D by three blinded experts using the MultiTracer. The whole brain GMV was determined by using voxel-based morphometry. Second, the differences of the whole brain and the bilateral amygdala GMV values between MDD and HC were calculated with t-statistics. The GMV of the whole brain and the amygdala did not differ between HC and MDD patients. Third, MDD characteristics were correlated with amygdala GMV. Within the normal range, the left amygdala GMV was larger in patients with later onset and smaller in cases of prolonged depression. In line with prior reports of depressed patients responding to antidepressant treatment, amygdala GMV was negatively related to illness duration, suggesting volume loss with disease progression. It remains unclear as to whether the association between illness duration and GMV reduced left amygdala volume indicates a neurotoxic effect of prolonged MDD or is rather a negative predictor of chronic depression.

Stress‐induced structural and functional modifications of astrocytes—Further implicating glia in the central response to stress

“…Human brain imaging studies demonstrate that decreases in brain tissue volume across multiple brain areas correlate with stress-related disorders such as major depressive disorder (MDD; Grieve, Korgaonkar, Koslow, Gordon, & Williams, 2013;Sheline, Wang, Gado, Csernansky, & Vannier, 1996;Zavorotnyy et al, 2018). It was initially proposed that neuronal loss was responsible for this observation in the hippocampus (Sheline et al, 1996).…”

“…The effect of MDD on glial cell density and neuron: glia ratio has also been demonstrated in the amygdala (Bowley, Drevets, Öngür, & Price, 2002), but intriguingly, these effects were observed primarily in the left amygdala (Bowley et al, 2002). Lateralization of the amygdala is a well-described phenomenon and it has been suggested that grey matter volume changes in the left amygdala can be correlated with severity of depression (Zavorotnyy et al, 2018). In the hippocampus, data have been mixed.…”

The Relationship Between Aggression and Depression: Testing the Moderating Effects of Age and Gender

“…Generally, neural plasticity in the amygdala (and other brain structures) is thought to be influenced by major depressive disorder and other types of depression in the form of atrophy and apoptosis. Similar to research on the hippocampus, volumetric changes in the amygdala have also been associated with depression in individuals (Zavorotnyy et al, 2018; see also Hastings et al, 2004).…”

“…Specifically, grey matter volume in the amygdala was found to be reduced in individuals with prolonged unipolar depression as compared to individuals with late onset depression. Results of this study suggest that grey matter volume (i.e., neuronal density) shares a negative relationship with prolonged depression, indicating retraction of neuron density, and perhaps neuronal death (Zavorotnyy et al, 2018).…”

“…Other areas of interest associated with depression include the cingulate gyrus, caudate nucleus, and cerebellum, each of which has been associated with depression, especially when coupled with brain atrophy (i.e., decreases in brain tissue and/or loss of neurons) (Videbech & Ravnkilde, 2004). Common brain structures and areas associated with depression typically studied by researchers include the hippocampus (Lee, Ogle, & Sapolsky, 2002;Posener, Wang, Price, Gado, Province, & Miller, 2003;Sheline, Mittlera, & Mintun, 2002;Videbech & Ravnkilde, 2004), amygdala (Hastings, Parsey, Oquendo, Arango, & Mann, 2004;Siegle, Thompson, Carter, Steinhauer, & Thase, 2007;Whalen, Shin, Somerville, McLean, & Kim, 2002;Zavorotnyy, Zöllner, Schulte-Güstenberg, Wulff, Schöning, & Dannlowski, 2018), and particular areas of the ventral, medial, dorsal, and lateral prefrontal cortex (Drevets, Price, & Furey, 2008;Koenigs & Grafman, 2009;McEwen, 2005).…”