Nucleus accumbens functional connectivity and circulating endocannabinoids levels in anorexia nervosa

Introduction

Neuroimaging findings have reported aberrant functional connectivity in brain regions involved reward system in individuals with anorexia nervosa (AN) altering hedonic processing over food. Likewise, endocannabinoids such as Anandamide (AEA) and 2-Arachidonoylglycerol (2-AG) have been involved in rewarding aspects of food intake.

Objectives

To identify nucleus accumbens (NAcc) functional connectivity with whole-brain comparing between individuals with AN and controls. Furthermore, in a sub-study, to explore the interaction between NAcc functional connectivity and peripheral AEA and 2-AG levels.

Methods

A total of 60 adult women (18 to 56 years of age) took part in the present study. Twenty-six individuals belonged to the AN group (BMI<18) and 34 to the HC group (BMI=18-24.99). All participants underwent functional magnetic resonance in resting-state, and blood samples were obtained in fasting.

Results

Negative functional connectivity was observed in the AN group compared with the control group between the NAcc and the cerebellum (pFWE<.001), between the NAcc and the insula (pFWE<.001), between the NAcc and the supramarginal gyrus (pFWE=.019), and between the NAcc and the postcentral gyrus (pFWE=.010). Analyses exploring the association between NAcc functional connectivity and peripheral endocannabinoids levels displayed altered NAcc-cerebellum functional connectivity was negatively associated with peripheral 2-AG levels in the AN group (r= -.553; p=.011).

Conclusions

Understanding the interaction between the reward system and peripheral endocannabinoids in patients with AN could contribute to better elucidate the pathophysiology of this disorder. Future studies will need to further investigate the clinical and therapeutic implications of these findings in patients with AN.

Disclosure

No significant relationships.

Obesity status and obesity-associated gut dysbiosis effects on hypothalamic structural covariance

BACKGROUND

Functional connectivity alterations in the lateral and medial hypothalamic networks have been associated with the development and maintenance of obesity, but the possible impact on the structural properties of these networks remains largely unexplored. Also, obesity-related gut dysbiosis may delineate specific hypothalamic alterations within obese conditions. We aim to assess the effects of obesity, and obesity and gut-dysbiosis on the structural covariance differences in hypothalamic networks, executive functioning, and depressive symptoms.

METHODS

Medial (MH) and lateral (LH) hypothalamic structural covariance alterations were identified in 57 subjects with obesity compared to 47 subjects without obesity. Gut dysbiosis in the subjects with obesity was defined by the presence of high (n = 28) and low (n = 29) values in a BMI-associated microbial signature, and posthoc comparisons between these groups were used as a proxy to explore the role of obesity-related gut dysbiosis on the hypothalamic measurements, executive function, and depressive symptoms.

RESULTS

Structural covariance alterations between the MH and the striatum, lateral prefrontal, cingulate, insula, and temporal cortices are congruent with previously functional connectivity disruptions in obesity conditions. MH structural covariance decreases encompassed postcentral parietal cortices in the subjects with obesity and gut-dysbiosis, but increases with subcortical nuclei involved in the coding food-related hedonic information in the subjects with obesity without gut-dysbiosis. Alterations for the structural covariance of the LH in the subjects with obesity and gut-dysbiosis encompassed increases with frontolimbic networks, but decreases with the lateral orbitofrontal cortex in the subjects with obesity without gut-dysbiosis. Subjects with obesity and gut dysbiosis showed higher executive dysfunction and depressive symptoms.

CONCLUSIONS

Obesity-related gut dysbiosis is linked to specific structural covariance alterations in hypothalamic networks relevant to the integration of somatic-visceral information, and emotion regulation.

Peripheral endocannabinoids in eating disorders and obesity and its relationship with clinical and anthropometric variables

Introduction

Anandamide (AEA) and 2-Arachidonoylglycerol (2-AG) play a pivotal role in food intake and reward aspects of feeding. Aberrant functioning in the endocannabinoid system has been observed in patients with eating disorders (EDs). This dysfunction may influence the incentive processes stimulating behaviors towards food acquisition or the hedonic evaluation of ingested food.

Objectives

The aims of this study are to compare fasting peripheral levels of AEA and 2-AG in ED patients, obese subjects (OB) and healthy controls (HCs), and to explore their association with clinical and anthropometric variables.

Methods

The sample included a total of 63 adult women. Peripheral blood samples were collected to investigate fasting levels of AEA and 2-AG in 31 ED patients: 22 Anorexia Nervosa (AN) and 9 Binge Eating Disorder (BED), compared to 21 OB and 11 HCs. Several clinical and anthropometric variables were also assessed.

Results

Comparing groups, significant differences in AEA levels were found (p=0.001). Specifically, individuals with AN exhibited lower AEA than OB (p<0.001) and BED (p=0.007), while OB showed higher AEA than HCs (p=0.015). 2-AG was positively correlated with hostility dimension in EDs and negatively associated with impulsive traits in OB. AEA showed a direct association with body dissatisfaction in AN, contrary to OB. Finally, in AN, AEA negatively correlated with the body mass index, while 2-AG was positively associated with the fat mass.

Conclusions

These results suggest an interaction between biological and clinical factors defining a vulnerability pathway that could help fitting personalized therapeutic approaches in each condition.

Disclosure

No significant relationships.