Differential longitudinal changes of hippocampal subfields in patients with anorexia nervosa

Increased Serum Neurofilament Light Chain Concentration Associated With Microglial Morphology Changes in Chronically-Starved Mice

OBJECTIVE

Anorexia nervosa (AN) is associated with hyperactivity, amenorrhea, and brain atrophy. Weight rehabilitation reversed these symptoms, although the underlying pathophysiological mechanisms are mostly unknown. Serum neurofilament light chain (NfL) levels are widely used as a biomarker of neurodegeneration. Based on neuroimaging studies and increased serum NfL levels, we assume that neurodegeneration is a core neuropathological feature in AN patients.

METHOD

Female mice were given a limited amount of food once a day and had unlimited access to a running wheel until they reached a 25% weight reduction, which was maintained for 2 weeks to mimic chronic starvation. This was followed by 3 weeks of refeeding. Running activity was measured by wheel sensors, while amenorrhea was determined by analyzing vaginal smears. Brain sections were used to investigate brain volumes. NfL levels were determined using a NF-light assay. Behavioral tests such as forced swim and elevated plus maze assessed behavioral changes. Immunohistochemistry was used to quantify the density of microglia, while their morphological analysis was performed using Neurolucida 360.

RESULTS

Chronic starvation led to AN-related symptoms of hyperactivity and amenorrhea. The decreased cerebral cortex, hippocampal, and corpus callosum volumes were paralleled by increased NfL levels after chronic starvation. A behavioral association was reduced anxiety-like behavior after chronic starvation. Starvation induced decreased microglial density, increased soma area, and prolonged microglial processes.

DISCUSSION

Chronic starvation led to an increase in NfL levels and changed microglial morphology in a mouse model of AN, suggesting that neuronal pathophysiology may contribute to the disease.

The Impact of Age on Gray Matter Volume Reduction in Anorexia Nervosa: A Systematic Review

Objective

This study examines the relationship between gray matter (GM) volume reduction and age in individuals with Anorexia Nervosa (AN). Specifically, it investigates whether the magnitude and direction of GM volume differences between AN and healthy controls remain consistent across a range of age groups. Additionally, we reviewed regional GM alterations reported in the literature to characterize unique regional brain profiles observed in AN. By synthesizing neuroimaging studies and mean-age stratified analysis, this work provides insights into the possible impact aging can have on GM reduction in patients with AN.

Methods

Systematic review and meta-analysis were conducted using MRI-based neuroimaging studies assessing GM volume in AN patients and controls. A primary meta-analysis was run for all feasible studies combined, followed by a stratified analysis approach examining "younger mean-age" studies and "older mean-age" studies separately. Random effects models were used for the meta-analysis. Meta-regression was used to determine the influence of age on GM volume differences and was controlled for the body mass index to minimize the confounding effect recovery status has on the GM differences between groups. Regional GM alterations were reviewed and discussed.

Results

44 studies, including 1391 individuals with AN and 1566 healthy controls, were included in the primary meta-analysis. No substantial heterogeneity was found across studies. Compared to their respective control groups, the younger-age studies, defined by studies with AN subject of mean age less than 18, exhibited greater significant GM volume loss (-5.39, 95% CI: -7.76 to -3.01, p<0.05) compared to older-age studies (-3.09, 95% CI: -4.16 to -2.03, p<0.05). Meta-regression subgroup results suggest that having older age in AN subjects is linked to less severe GM reduction relative controls. Our review of the regional GM literature reveals that alterations in the hippocampus, amygdala, and precuneus of the medial parietal lobe were more frequently reported than other brain regions in AN. In these regions, we also noticed that younger individuals with AN had more consistent volume reductions across studies, whereas studies with older AN showed greater variability.

Conclusion

Grey matter volume loss in AN is more pronounced in younger patients even after controlling for the effect of the recovery status. Having older age appears to contribute to less deficit in brain volume loss in AN, suggesting a protective mechanism underlying GM alteration in older AN patients. These findings reinforce the need for early intervention and prolonged recovery support and emphasize the need to develop lifespan-specific disorder management approaches. Future research should explore long-term GM recovery trajectories and the aging effect on GM alteration for older patients to refine strategies for neuroprotection in AN.

Structural alterations of thalamic nuclei and their associations with leptin levels in patients with anorexia nervosa

BACKGROUND

The thalamus is a complex subcortical brain structure that plays a role in various cognitive functions. Few studies have focused on thalamic nuclei-specific alterations and potential neurohormonal involvement in eating disorders including anorexia nervosa (AN).

METHODS

We employed a FreeSurfer segmentation tool to compare thalamic nuclei volumes cross-sectionally between females with AN (n = 131, 12-29 years) and age-matched healthy females (HC, n = 131). Potential associations with BMI, leptin, and psychiatric symptoms were analyzed via robust linear regression.

RESULTS

Most thalamic nuclei volumes were reduced in both hemispheres in AN versus HC. The spread of alterations ranged between -39.7 % and +3.8 % (average -9.8 %, ηp2 = 0.16). Left laterodorsal and pulvinar inferior nuclei showed positive associations with leptin in AN. Leptin mediated the effect of BMI on both thalamic nuclei volumes.

CONCLUSIONS

In AN, thalamic nuclei are altered to different degrees with laterodorsal nuclei emerging as substantially reduced. Leptin seems to be mechanistically involved in the reduction of some thalamic nuclei, further supporting the investigation of experimental leptin treatment for AN. Effect sizes observed for thalamic nuclei reductions in AN exceed other brain structures as well as other psychiatric disorders, which demonstrates the importance of the thalamus as a target structure in research on AN.

Eating- and Weight-Related Disorders in the Armed Forces

BACKGROUND/OBJECTIVES

Like in the general population, the prevalences of eating- and weight-related health issues in the armed forces are increasing. Relevant medical conditions include the eating disorders (EDs) anorexia nervosa, bulimia nervosa, binge eating disorder, and avoidant restrictive food intake disorder (ARFID), as well as body dysmorphic disorder, muscle dysmorphia, and the relative energy deficiency in sport (RED-S) syndrome.

METHODS

We performed a narrative literature review on eating- and weight-related disorders in the armed forces.

RESULTS

Entry standards might exclude people with obesity, with EDs, or at high risk for EDs from entering the armed forces for military reasons and to protect the individual's health. Relevant potential risk factors of eating- and weight-related disorders in the military are the emphasis on appearance and fitness in the military, high levels of stress, military sexual trauma, post-traumatic stress disorder, deployment, relocation, long commutes, consumption of ultra-processed foods and beverages, limitations on food selection and physical exercise, and intensive combat training and field exercises. Eating- and weight-related disorders negatively impact professional military appearance and lead to problems with cardiorespiratory and neuromuscular fitness; daytime sleepiness; and a higher risk of musculoskeletal injuries, and other physical and mental health problems. Current and potential future therapeutic options include occupational health measures, psychosocial therapies, neuromodulation, and drug treatments.

CONCLUSIONS

Even though randomized controlled trials (RCTs) have been performed to test treatments for obesity in the armed forces, RCTs for the treatment of EDs, body dysmorphic disorder, muscle dysmorphia, and RED-S syndrome are lacking in the military context.

Anorexia-Induced Hypoleptinemia Drives Adaptations in the JAK2/STAT3 Pathway in the Ventral and Dorsal Hippocampus of Female Rats

Leptin is an appetite-regulating adipokine that is reduced in patients with anorexia nervosa (AN), a psychiatric disorder characterized by self-imposed starvation, and has been linked to hyperactivity, a hallmark of AN. However, it remains unknown how leptin receptor (LepR) and its JAK2-STAT3 downstream pathway in extrahypothalamic brain areas, such as the dorsal (dHip) and ventral (vHip) hippocampus, crucial for spatial memory and emotion regulation, may contribute to the maintenance of AN behaviors. Taking advantage of the activity-based anorexia (ABA) model (i.e., the combination of food restriction and physical activity), we observed reduced leptin plasma levels in adolescent female ABA rats at the acute phase of the disorder [post-natal day (PND) 42], while the levels increased over control levels following a 7-day recovery period (PND49). The analysis of the intracellular leptin pathway revealed that ABA rats showed an overall decrease of the LepR/JAK2/STAT3 signaling in dHip at both time points, while in vHip we observed a transition from hypo- (PND42) to hyperactivation (PND49) of the pathway. These changes might add knowledge on starvation-induced fluctuations in leptin levels and in hippocampal leptin signaling as initial drivers of the transition from adaptative mechanisms to starvation toward the maintenance of aberrant behaviors typical of AN patients, such as perpetuating restraint over eating.