White matter tracts characteristics in habitual decision-making circuit underlie ritual behaviors in anorexia nervosa

Abstract

Anorexia nervosa (AN) is a difficult to treat, pernicious psychiatric disorder that has been linked to decision-making abnormalities. We examined the structural characteristics of habitual and goal-directed decision-making circuits and their connecting white matter tracts in 32 AN and 43 healthy controls across two independent data sets of adults and adolescents as an explanatory sub-study. Total bilateral premotor/supplementary motor area-putamen tracts in the habit circuit had a significantly higher volume in adults with AN, relative to controls. Positive correlations were found between both the number of tracts and white matter volume (WMV) in the habit circuit, and the severity of ritualistic/compulsive behaviors in adults and adolescents with AN. Moreover, we found a significant influence of the habit circuit WMV on AN ritualistic/compulsive symptom severity, depending on the preoccupations symptom severity levels. These findings suggest that AN is associated with white matter plasticity alterations in the habit circuit. The association between characteristics of habit circuit white matter tracts and AN behavioral symptoms provides support for a circuit based neurobiological model of AN, and identifies the habit circuit as a focus for further investigation to aid in development of novel and more effective treatments based on brain-behavior relationships.

White matter microstructure in habit and reward circuits in anorexia nervosa: Insights from a neurite orientation dispersion and density imaging study

“…With regard to the habit tract, we found no significant differences in myelin density, neurite density, or neurite orientation in those with AN. In a previous examination of SMA-toputamen tracts in a partially overlapping cohort of adolescents with AN and controls, we similarly found no significant differences in FA (nor in white matter volume or number of streamlines) (25). The present study also did not find significant differences, despite including a larger sample and examining multiple indices of WM microstructure rather than gross volume and tract number (which should afford greater sensitivity to detect white matter abnormalities associated with specific clinical conditions (55)).…”

Mesolimbic Neurobehavioral Mechanisms of Reward Motivation in Anorexia Nervosa: A Multimodal Imaging Study

“…The current study, examining a different part of the reward circuit, showed an opposite direction of abnormalities: decreases in both the white matter integrity and functional connectivity during reward motivation in the VTA-to-NAcc connection. In a separate study, we found evidence in AN of increased structural connectivity (higher volume of white matter fibers compared with controls) in a habitual decision-making circuit consisting of tracts connecting the posterolateral putamen to the premotor/supplementary area ( 72 ). Further, there was a significant positive correlation between volume of white matter fibers and the severity of eating disorder-related ritualistic behaviors in the weight-restored AN cohort.…”

Large-scale exploration of whole-brain structural connectivity in anorexia nervosa: alterations in the connectivity of frontal and subcortical networks

“…The current findings differ somewhat from prior investigations of region-to-region white matter connectivity. Two prior studies testing group differences in individual tracts reported stronger connectivity in intra-hemispheric frontostriatal tracts amongst individuals with AN, both between the nucleus accumbens and OFC (12, 55), and between the putamen and motor areas (13). These differences were not found in the current study, which could result from the unit of analysis here being constellations of connected white matter connections rather than individual tracts.…”

“…Several diffusion tractography studies of AN have been reported, but here too, there have been important limitations. Most notably, tractography studies of AN have been constrained by small sample sizes, and consistent findings across studies have not emerged (11-13). The single tractography study that had a relatively large sample (n= 96 AN and 96 HC (14)) used deterministic tractography, an approach that assumes that all white matter fibers within a voxel are oriented in the same direction.…”