Amygdalae morphometry in late‐life depression

Abstract

SUMMARYObjective The amygdalae have been a focus of mood disorder research due to their key role in processing emotional information. It has been long known that depressed individuals demonstrate impaired functional performance while engaged in emotional tasks. The structural basis for these functional differences has been investigated via volumetric analysis with mixed findings. In this study, we examined the morphometric basis for these functional changes in late-life depression (LLD) by analyzing both the size and shape of the amygdalae with the hypothesis that shape differences may be apparent even when overall volume differences are inconsistent. Methods Magnetic resonance imaging data were acquired from 11 healthy, elderly individuals and 14 depressed, elderly individuals. Amygdalar size was quantified by computing total volume and amygdalar shape was quantified with a shape analysis method that we have developed.Results No significant volumetric differences were found for either amygdala. Nevertheless, localized regions of significant shape variation were detected for the left and right amygdalae. The most significant difference was contraction (LLD subjects as compared to control subjects) in a region typically associated with the basolateral nucleus, which plays a key role in emotion recognition in neurobiologic models of depression. Conclusions In this LLD study, we have shown that, despite insignificant amygdalar volumetric findings, variations of amygdalar shape can be detected and localized. With further investigation, morphometric analysis of various brain structures may help elucidate the neurobiology associated with LLD and other mood disorders.

Amygdalar shape analysis method using surface contour aligning, spherical mapping, and probabilistic subregional segmentation

“…The posteromedial cortical nucleus was greater in the male rat [37] while there was no difference in basolateral nucleus [28]. Results of our shape analysis are generally in line with these prior animal studies on sex differences [14,28,37]. Men and women are different in cognition and emotional event processing and have a different neural basis for these processes [9,20,35].…”

“…Previous rodent studies reported that the volume of the posterodorsal medial nucleus in the amygdala of the male rodents was larger than that of the female [14], which may have been affected by androgen [11]. The posteromedial cortical nucleus was greater in the male rat [37] while there was no difference in basolateral nucleus [28]. Results of our shape analysis are generally in line with these prior animal studies on sex differences [14,28,37].…”

Repeated restraint stress-induced atrophy of glutamatergic pyramidal neurons and decreases in glutamatergic efflux in the rat amygdala are prevented by the antidepressant agomelatine

“…These same investigators reported that amygdalar volumes were decreased in late-life depressive illness patients and that these volumetric reductions were predictive of treatment responsiveness (Sheline et al, 2012). Additional studies reported similar decreases in amygdalar volumes in late-life depressive illness patients (Andreescu et al, 2008;Burke et al, 2011), while other studies suggested that late-life depression was associated with changes in amygdalar shape (Tamburo et al, 2009). These studies and others (von Gunten et al, 2000;Hastings et al, 2004) support the concept that decreases in amygdalar volume is a neuroanatomical deficit characteristic of major depressive illness.…”

190. Social Cognition in Early Schizophrenia: Exploratory Factor Analysis and Subcortical Biomarkers

“…This is due to the fact that while most volumetric analyses of subcortical structures look at the entire structure, shape provides an advantage in its vertex-wise approach (Voineskos et al, 2015). Comparison studies of methodologies support this having found that while volume measures indicated no differences between populations, shape metrics did (Tamburo et al, 2009;Posener et al, 2003).…”