The Clinical Significance of Posterior Insular Volume in Adolescent Anorexia Nervosa

Abstract

Objective The diagnostic criterion disturbance in the experience of the body remains a poorly understood and persistent feature of anorexia nervosa (AN). Increased sophistication in understanding the structure of the insular cortex - a neural structure that receives and integrates visceral sensations with action and meaning - may elucidate the nature of this disturbance. We explored age, weight-status, illness severity, and self-reported body dissatisfaction associations with insular cortex volume. Methods Structural MRI data were collected from 21 adolescents with a history of AN and 20 age, sex, and BMI-matched controls. Insular cortical volumes (bilateral anterior and posterior regions) were identified using manual tracing. Results Volumes of the right posterior insula demonstrated: 1) a significant age by clinical status interaction (β = −0.018 ± 0.008; t = 2.32, p = 0.02) and 2) larger volumes were associated with longer duration of illness (r = .48, p < .04). In contrast, smaller volumes of the right anterior insula were associated with longer duration of illness (r = −.50, p < .03). The associations of insular volume with body dissatisfaction were of moderate effect size, also of opposite direction, but a statistical trend in right posterior (r = .40, p < .10 in right posterior; r = −.49, p < .04 in right anterior). Conclusions In this exploratory study, findings of atypical structure of the right posterior insular cortex point to the importance of future work investigating the role of visceral afferent signaling in understanding disturbance in body experience in AN.

Lower gray matter volumes of frontal lobes and insula in adolescents with anorexia nervosa restricting type: Findings from a Brain Morphometry Study

“…Moreover, the sensory aspects of taste are primarily an insula-related phenomenon, whereas higher cortical areas modulate pleasure, motivation, and cognitive aspects of taste [53,54,55]. It is worth noting that the laterality of our findings differs from the study by Zucker et al [26], where an altered structure of the right posterior insular cortex was detected. A possible explanation for this difference could be based on the underlying imbalance in the network implicating both insular cortices, as previously suggested [56].…”

“…A GM reduction of the insula could reflect disturbances in the limbic system, which is involved in interoceptive deficit [51], body dissatisfaction, and low self-esteem. The insular cortex represents a node of convergence for signals composing emotional and cognitive states, which emerge from the coordination between external and internal milieus, and mediating frontotemporal interaction in social and emotional context processing [25,26,52]. Moreover, the sensory aspects of taste are primarily an insula-related phenomenon, whereas higher cortical areas modulate pleasure, motivation, and cognitive aspects of taste [53,54,55].…”

“…Several cerebral structures are thought to be involved in AN, such as the frontal lobes (connected with deficits in executive function and central coherence), the parietal cortex (related to body image distortions), the amygdala (related to anxiety), and the striatum (connected with obsessive-compulsive behavior). It has also been suggested that a malfunction of the insula could play a central role in orchestrating the signals regarding the external environment and internal homeostasis [25,26]. Various brainimaging techniques have been used to investigate these brain structures and their function in order to better understand AN underlying neurobiology.…”

Anorexia Nervosa and a Lost Emotional Self: A Psychological Formulation of the Development, Maintenance, and Treatment of Anorexia Nervosa

“…It is argued that the anterior insula, alongside the amygdala, nucleus accumbens and orbitofrontal cortex are key to supporting our conscious awareness of emotion and integrating this with our sense of self ( Seth, 2013 ). Further, the posterior insula receives and encodes visceral interoceptive input, and increased right posterior insular volume correlates with disorder duration and severity in AN suggesting that difficulties in integrating bottom-up interoceptive information increase with length of disorder ( Zucker et al, 2017 ). Moreover, patterns of insula responding to unpleasant interoceptive states are significantly different for those in remission from AN versus healthy comparison participants ( Berner et al, 2018 ).…”

Interoceptive Axes Dissociation in Anorexia Nervosa: A Single Case Study With Follow Up Post-recovery Assessment

“…Several interoceptive alterations have been found in AN and neuroimaging evidence suggested that this pathology can compromise numerous key cortical structures within the interoceptive network. Specifically, AN subjects exhibited white matter abnormality and altered resting state functionality (Gaudio et al, 2015, 2017) of the anterior cingulate cortex (ACC), along with volume reduction of the right posterior insular cortex (Zucker et al, 2017) also in weight-restored AN patients (Kerr et al, 2016). Besides, AN alterations are not only limited to neurophysiological levels.…”