Differential longitudinal changes of neuronal and glial damage markers in anorexia nervosa after partial weight restoration

A transdiagnostic and diagnostic-specific approach on inflammatory biomarkers in eating disorders: A meta-analysis and systematic review

Eating disorders (EDs) are severe mental illnesses with a multifactorial etiology and a chronic course. Among the biological factors related to pathogenesis and maintenance of EDs, inflammation acquired growing scientific interest. This study aimed to assess the inflammatory profile of EDs, focusing on anorexia nervosa, bulimia nervosa, and including for the first time binge eating disorder. A comprehensive research of existing literature identified 51 eligible studies for meta-analysis, comparing levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), osteoprotegerin (OPG), soluble receptor activator of nuclear factor kappa-B ligand (sRANKL), interleukin-1β (IL-1β), and interleukin-10 (IL-10) between patients with EDs and healthy controls (HCs). The systematic review explored other inflammatory biomarkers of interest, which did not meet the meta-analysis criteria. Results revealed significantly elevated levels of TNF-α, OPG, sRANKL, and IL-1β in patients with EDs compared to HCs. Additionally, the results highlighted the heterogeneity of inflammatory state among patients with EDs, emphasizing the need for further research into the association between inflammatory biomarkers and psychopathological correlates. This approach should transcend categorical diagnoses, enabling more precise subcategorizations of patients. Overall, this study contributed to the understanding of the inflammatory pathways involved in EDs, emphasizing potential implications for diagnosis, staging, and targeted interventions.

New perspectives on the role of biological factors in anorexia nervosa: Brain volume reduction or oxidative stress, which came first?

Anorexia nervosa (AN) is an eating disorder (ED) that has seen an increase in its incidence in the last thirty years. Compared to other psychosomatic disorders, ED can be responsible for many major medical complications, moreover, in addition to the various systemic impairments, patients with AN undergo morphological and physiological changes affecting the cerebral cortex. Through immunohistochemical studies on portions of postmortem human brain of people affected by AN and healthy individuals, and western blot studies on leucocytes of young patients and healthy controls, this study investigated the role in the afore-mentioned processes of altered redox state. The results showed that the brain volume reduction in AN could be due to an increase in the rate of cell death, mainly by apoptosis, in which mitochondria, main cellular organelles affected by a decreased dietary intake, and a highly compromised intracellular redox balance, may play a pivotal role.

Effect of serum concentrations of IL-6 and TNF-α on brain structure in anorexia nervosa: a combined cross-sectional and longitudinal study

Previous studies of brain structure in anorexia nervosa (AN) have reported reduced gray matter in underweight patients, which largely normalizes upon weight gain. One underlying biological mechanism may be glial cell alterations related to low-grade inflammation. Here, we investigated relationships between brain structure as measured by magnetic resonance imaging and serum concentrations of two pro-inflammatory cytokines (interleukin-6 and tumor necrosis factor alpha) cross-sectionally in 82 underweight adolescent and young adult female patients (mean age 16.8 years; 59 of whom were observed longitudinally after short-term weight restoration; mean duration 2.8 months), 20 individuals long-term weight-recovered from AN (mean age 22.7 years) and 105 healthy control (HC) participants (mean age 17.2 years). We measured cortical thickness, subcortical volumes and local gyrification index, a measure of cortical folding. In contrast to most previous studies of cytokine concentrations in AN, we found no cross-sectional group differences (interleukin-6: p = 0.193, tumor necrosis factor alpha: p = 0.057) or longitudinal changes following weight restoration (interleukin-6: p = 0.201, tumor necrosis factor alpha: p = 0.772). As expected, widespread gray matter reductions (cortical thickness, subcortical volumes, cortical folding) were observed in underweight patients with AN compared to HC. However, we found no evidence of associations between cytokine concentrations and structural brain measures in any participant group. Furthermore, longitudinal changes in cytokine concentrations were unrelated to changes in gray matter. In conclusion, we did not identify any association between (sub-)inflammatory processes and structural brain changes in AN. Future studies are needed to elucidate which other factors besides nutritional status may contribute to brain morphological alterations.

Introducing neurofilament light chain measure in psychiatry: current evidence, opportunities, and pitfalls

The recent introduction of new-generation immunoassay methods allows the reliable quantification of structural brain markers in peripheral matrices. Neurofilament light chain (NfL), a neuron-specific cytoskeletal component released in extracellular matrices after neuroaxonal impairment, is considered a promising blood marker of active brain pathology. Given its sensitivity to a wide range of neuropathological alterations, NfL has been suggested for the use in clinical practice as a highly sensitive, but unspecific tool to quantify active brain pathology. While large efforts have been put in characterizing its clinical profile in many neurological conditions, NfL has received far less attention as a potential biomarker in major psychiatric disorders. Therefore, we briefly introduce NfL as a marker of neuroaxonal injury, systematically review recent findings on cerebrospinal fluid and blood NfL levels in patients with primary psychiatric conditions and highlight the opportunities and pitfalls. Current evidence suggests an elevation of blood NfL levels in patients with major depression, bipolar disorder, psychotic disorders, anorexia nervosa, and substance use disorders compared to physiological states. However, blood NfL levels strongly vary across diagnostic entities, clinical stage, and patient subgroups, and are influenced by several demographic, clinical, and analytical factors, which require accurate characterization. Potential clinical applications of NfL measure in psychiatry are seen in diagnostic and prognostic algorithms, to exclude neurodegenerative disease, in the assessment of brain toxicity for different pharmacological compounds, and in the longitudinal monitoring of treatment response. The high inter-individual variability of NfL levels and the lack of neurobiological understanding of its release are some of the main current limitations. Overall, this primer aims to introduce researchers and clinicians to NfL measure in the psychiatric field and to provide a conceptual framework for future research directions.

Anorexia nervosa: diagnostic, therapeutic, and risk biomarkers in clinical practice

In anorexia nervosa (AN), measurable biological parameters can inform the process of treating patients. Such biomarkers include established laboratory parameters as well as a range of potential future biomarkers, including genetic, metabolomic, microbiomic, endocrine, immunological, hematological, electrophysiological, and neuroimaging parameters. In this opinion article we discuss how these biomarkers can support diagnosic and therapeutic processes at specific steps during the AN treatment cycle, that is, the diagnosis, diagnostic specification, risk management, choice of therapy, therapy monitoring, and treatment review. History-taking, physical and neuropsychological examination, clinical observation, and judgment about treatment success by the patient, their carers, and members of the multidisciplinary team are essential to interpret laboratory and imaging data appropriately and to assess the full clinical picture.

Differential longitudinal changes of hippocampal subfields in patients with anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is a mental disorder characterized by dietary restriction, fear of gaining weight, and distorted body image. Recent studies indicate that the hippocampus, crucial for learning and memory, may be affected in AN, yet subfield-specific effects remain unclear. We investigated hippocampal subfield alterations in acute AN, changes following weight restoration, and their associations with leptin levels.

METHODS

T1-weighted magnetic resonance imaging scans were processed using FreeSurfer. We compared 22 left and right hemispheric hippocampal subfield volumes cross-sectionally and longitudinally in females with acute AN (n = 165 at baseline, n = 110 after partial weight restoration), healthy female controls (HCs; n = 271), and females after long-term recovery from AN (n = 79) using linear models.

RESULTS

We found that most hippocampal subfield volumes were significantly reduced in patients with AN compared with HCs (~-3.9%). Certain areas such as the subiculum exhibited no significant reduction in the acute state of AN, while other areas, such as the hippocampal tail, showed strong decreases (~-9%). Following short-term weight recovery, most subfields increased in volume. Comparisons between participants after long-term weight-recovery and HC yielded no differences. The hippocampal tail volume was positively associated with leptin levels in AN independent of body mass index.

CONCLUSIONS

Our study provides evidence of differential volumetric differences in hippocampal subfields between individuals with AN and HC and almost complete normalization after weight rehabilitation. These alterations are spatially inhomogeneous and more pronounced compared with other major mental disorders (e.g. major depressive disorder and schizophrenia). We provide novel insights linking hypoleptinemia to hippocampal subfield alterations hinting towards clinical relevance of leptin normalization in AN recovery.

Serum neurofilament light concentrations are associated with cortical thinning in anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is characterized by severe emaciation and drastic reductions of brain mass, but the underlying mechanisms remain unclear. The present study investigated the putative association between the serum-based protein markers of brain damage neurofilament light (NF-L), tau protein, and glial fibrillary acidic protein (GFAP) and cortical thinning in acute AN.

METHODS

Blood samples and magnetic resonance imaging scans were obtained from 52 predominantly adolescent, female patients with AN before and after partial weight restoration (increase in body mass index >14%). The effect of marker levels before weight gain and change in marker levels on cortical thickness (CT) was modeled at each vertex of the cortical surface using linear mixed-effect models. To test whether the observed effects were specific to AN, follow-up analyses exploring a potential general association of marker levels with CT were conducted in a female healthy control (HC) sample (n = 147).

RESULTS

In AN, higher baseline levels of NF-L, an established marker of axonal damage, were associated with lower CT in several regions, with the most prominent clusters located in bilateral temporal lobes. Tau protein and GFAP were not associated with CT. In HC, no associations between damage marker levels and CT were detected.

CONCLUSIONS

A speculative interpretation would be that cortical thinning in acute AN might be at least partially a result of axonal damage processes. Further studies should thus test the potential of serum NF-L to become a reliable, low-cost and minimally invasive marker of structural brain alterations in AN.

Fibre-specific white matter changes in anorexia nervosa

A large body of literature exists on white matter (WM) abnormalities in individuals with anorexia nervosa (AN). However, these studies have primarily relied on the diffusion tensor imaging (DTI), a technique known for its limited ability to resolve complex WM fibre arrangements. To overcome limitations of DTI, this study employed fixel-based analysis (FBA) to investigate fibre-specific WM abnormalities in AN. FBA, which incorporates information on connectivity and crossing-fibres, offers greater anatomical specificity and interpretability than DTI. Twenty-six acute AN patients and thirty-one healthy controls underwent diffusion-weighted imaging scanning, and FBA and DTI metrics were compared between groups. Results revealed significant reductions in fibre-bundle cross-section within the anterior corona radiata and genu of corpus callosum, indicating morphological atrophy in AN patients. These specific tracts, identified by FBA, connect brain regions involved in the symptomatology of AN. DTI showed increased axial diffusivity in the cerebellar peduncles of AN patients but did not show significant differences in other metrics. Notably, there was no overlap between findings of FBA and DTI analyses. Overall, this study highlights the potential of FBA to detect WM abnormalities not accounted for by DTI and suggests that myelin loss contributes to the observed clinical picture in AN patients.

The association of body mass index and body composition with plasma amyloid beta levels

Blood-based analysis of amyloid-β is increasingly applied to incrementally establish diagnostic tests for Alzheimer's disease. To this aim, it is necessary to determine factors that can alter blood-based concentrations of amyloid-β. We cross-sectionally analysed amyloid-β-40 and amyloid-β-42 concentrations and the 40/42 ratio in 440 community-dwelling adults and associations with body mass index, waist-to-height ratio and body composition assessed using bioelectrical impedance analysis. Body mass index and waist-to-height ratio were inversely associated with plasma amyloid-β-42 concentrations. Body fat mass, but not body cell mass and extracellular mass, was inversely associated with amyloid-β-42 levels. The results indicate that plasma concentrations of amyloid-β-42 are lower in those with increased body mass index and body fat, and associations with amyloid-β-40 did not reach significance after controlling for multiple testing. The findings support the use of body mass index as an easy-to-measure factor that should be accounted for in diagnostic models for plasma amyloid-β.

Differential alterations of amygdala nuclei volumes in acutely ill patients with anorexia nervosa and their associations with leptin levels

BACKGROUND

The amygdala is a subcortical limbic structure consisting of histologically and functionally distinct subregions. New automated structural magnetic resonance imaging (MRI) segmentation tools facilitate the in vivo study of individual amygdala nuclei in clinical populations such as patients with anorexia nervosa (AN) who show symptoms indicative of limbic dysregulation. This study is the first to investigate amygdala nuclei volumes in AN, their relationships with leptin, a key indicator of AN-related neuroendocrine alterations, and further clinical measures.

METHODS

T1-weighted MRI scans were subsegmented and multi-stage quality controlled using FreeSurfer. Left/right hemispheric amygdala nuclei volumes were cross-sectionally compared between females with AN (n = 168, 12-29 years) and age-matched healthy females (n = 168) applying general linear models. Associations with plasma leptin, body mass index (BMI), illness duration, and psychiatric symptoms were analyzed via robust linear regression.

RESULTS

Globally, most amygdala nuclei volumes in both hemispheres were reduced in AN v. healthy control participants. Importantly, four specific nuclei (accessory basal, cortical, medial nuclei, corticoamygdaloid transition in the rostral-medial amygdala) showed greater volumetric reduction even relative to reductions of whole amygdala and total subcortical gray matter volumes, whereas basal, lateral, and paralaminar nuclei were less reduced. All rostral-medially clustered nuclei were positively associated with leptin in AN independent of BMI. Amygdala nuclei volumes were not associated with illness duration or psychiatric symptom severity in AN.

CONCLUSIONS

In AN, amygdala nuclei are altered to different degrees. Severe volume loss in rostral-medially clustered nuclei, collectively involved in olfactory/food-related reward processing, may represent a structural correlate of AN-related symptoms. Hypoleptinemia might be linked to rostral-medial amygdala alterations.

Triangulating brain alterations in anorexia nervosa: a multimodal investigation of magnetic resonance spectroscopy, morphometry and blood-based biomarkers

The acute state of anorexia nervosa (AN) is associated with widespread reductions in cortical gray matter (GM) thickness and white matter (WM) volume, suspected changes in myelin content and elevated levels of the neuronal damage marker neurofilament light (NF-L), but the underlying mechanisms remain largely unclear. To gain a deeper understanding of brain changes in AN, we applied a multimodal approach combining advanced neuroimaging methods with analysis of blood-derived biomarkers. In addition to standard measures of cortical GM thickness and WM volume, we analyzed tissue-specific profiles of brain metabolites using multivoxel proton magnetic resonance spectroscopy, T1 relaxation time as a proxy of myelin content leveraging advanced quantitative MRI methods and serum NF-L concentrations in a sample of 30 female, predominately adolescent patients with AN and 30 age-matched female healthy control participants. In patients with AN, we found a reduction in GM cortical thickness and GM total N-acetyl aspartate. The latter predicted higher NF-L levels, which were elevated in AN. Furthermore, GM total choline was elevated. In WM, there were no group differences in either imaging markers, choline levels or N-acetyl aspartate levels. The current study provides evidence for neuronal damage processes as well as for increased membrane lipid catabolism and turnover in GM in acute AN but no evidence for WM pathology. Our results illustrate the potential of multimodal research including tissue-specific proton magnetic resonance spectroscopy analyses to shed light on brain changes in psychiatric and neurological conditions, which may ultimately lead to better treatments.

The multifaceted role of neurofilament light chain protein in non-primary neurological diseases

The advancing validation and exploitation of CSF and blood neurofilament light chain protein as a biomarker of neuroaxonal damage has deeply changed the current diagnostic and prognostic approach to neurological diseases. Further, recent studies have provided evidence of potential new applications of this biomarker also in non-primary neurological diseases. In the present review we summarize the state of the art, future perspectives, but also limitations, of neurofilament light chain protein as a CSF and blood biomarker in several medical fields, including intensive care medicine, surgery, internal medicine and psychiatry. In particular, neurofilament light chain protein is associated with the degree of neurological impairment and outcome in patients admitted to intensive care units or in the perioperative phase and it seems to be highly interconnected with cardiovascular risk factors. Beyond that, interesting diagnostic and prognostic insights have been provided by the investigation of neurofilament light chain protein in psychiatric disorders as well as in the current coronavirus disease-19 pandemic and in normal ageing. Altogether, current data outline a multifaceted applicability of CSF and blood neurofilament light chain protein ranging from the critical clinical setting to the development of precision medicine models suggesting a strict interplay between the nervous system pathophysiology and the health-illness continuum.

Effect of Estimated Blood Volume and Body Mass Index on GFAP and NfL Levels in the Serum and CSF of Patients With Multiple Sclerosis

BACKGROUND AND OBJECTIVES

To increase the validity of biomarker measures in multiple sclerosis (MS), factors affecting their concentration need to be identified. Here, we test whether the volume of distribution approximated by the patients' estimated blood volume (BV) and body mass index (BMI) affect the serum concentrations of glial fibrillary acidic protein (GFAP). As a control, we also determine the relationship between BV/BMI and GFAP concentrations in CSF. To confirm earlier findings, we test the same hypotheses for neurofilament light chain (NfL).

METHODS

NfL and GFAP concentrations were measured in serum and CSF (sNFL/sGFAP and cNFL/cGFAP) in 157 patients (n = 106 with MS phenotype and n = 51 with other neurologic/somatoform diseases). Using multivariate linear regressions, BV was tested in the MS cohort as a predictor for each of the biomarkers while controlling for age, sex, MS phenotype, Expanded Disability Status Scale score, gadolinium-enhancing lesions, and acute relapse. In addition, overweight/obese patients (BMI ≥25 kg/m2) were compared with patients with BMI <25 kg/m2 using the general linear model. The analyses were repeated including the neurologic/somatoform controls.

RESULTS

In the MS cohort, BV predicted sGFAP (ß = -0.301, p = 0.014). Overweight/obese patients with MS had lower sGFAP concentrations compared with patients with MS and BMI <25 kg/m2 (F = 4.732, p = 0.032). Repeating the analysis after adding patients with other neurologic/somatoform diseases did not change these findings (ß = -0.276, p = 0.009; F = 7.631, p = 0.006). Although sNfL was inversely correlated with BV (r = -0.275, p = 0.006) and body weight (r = -0.258, p = 0.010), those results did not remain significant after adjusting for covariates. BV and BMI were not associated with cGFAP or cNfL concentrations.

DISCUSSION

These findings support the notion that the volume of distribution of sGFAP approximated by BV and BMI is a relevant variable and should therefore be controlled for when measuring sGFAP in MS, while this might not be necessary when measuring cGFAP concentrations.

Ketamine and Zinc: Treatment of Anorexia Nervosa Via Dual NMDA Receptor Modulation

Anorexia nervosa is a disorder associated with serious adverse health outcomes, for which there is currently considerable treatment ineffectiveness. Characterised by restrictive eating behaviours, distorted body image perceptions and excessive physical activity, there is growing recognition anorexia nervosa is associated with underlying dysfunction in excitatory and inhibitory neurometabolite metabolism and signalling. This narrative review critically explores the role of N-methyl-D-aspartate receptor-mediated excitatory and inhibitory neurometabolite dysfunction in anorexia nervosa and its associated biomarkers. The existing magnetic resonance spectroscopy literature in anorexia nervosa is reviewed and we outline the brain region-specific neurometabolite changes that have been reported and their connection to anorexia nervosa psychopathology. Considering the proposed role of dysfunctional neurotransmission in anorexia nervosa, the potential utility of zinc supplementation and sub-anaesthetic doses of ketamine in normalising this is discussed with reference to previous research in anorexia nervosa and other neuropsychiatric conditions. The rationale for future research to investigate the combined use of low-dose ketamine and zinc supplementation to potentially extend the therapeutic benefits in anorexia nervosa is subsequently explored and promising biological markers for assessing and potentially predicting treatment response are outlined.

Brain Structure in Acutely Underweight and Partially Weight-Restored Individuals With Anorexia Nervosa: A Coordinated Analysis by the ENIGMA Eating Disorders Working Group

BACKGROUND

The pattern of structural brain abnormalities in anorexia nervosa (AN) is still not well understood. While several studies report substantial deficits in gray matter volume and cortical thickness in acutely underweight patients, others find no differences, or even increases in patients compared with healthy control subjects. Recent weight regain before scanning may explain some of this heterogeneity. To clarify the extent, magnitude, and dependencies of gray matter changes in AN, we conducted a prospective, coordinated meta-analysis of multicenter neuroimaging data.

METHODS

We analyzed T1-weighted structural magnetic resonance imaging scans assessed with standardized methods from 685 female patients with AN and 963 female healthy control subjects across 22 sites worldwide. In addition to a case-control comparison, we conducted a 3-group analysis comparing healthy control subjects with acutely underweight AN patients (n = 466) and partially weight-restored patients in treatment (n = 251).

RESULTS

In AN, reductions in cortical thickness, subcortical volumes, and, to a lesser extent, cortical surface area were sizable (Cohen's d up to 0.95), widespread, and colocalized with hub regions. Highlighting the effects of undernutrition, these deficits were associated with lower body mass index in the AN sample and were less pronounced in partially weight-restored patients.

CONCLUSIONS

The effect sizes observed for cortical thickness deficits in acute AN are the largest of any psychiatric disorder investigated in the ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) Consortium to date. These results confirm the importance of considering weight loss and renutrition in biomedical research on AN and underscore the importance of treatment engagement to prevent potentially long-lasting structural brain changes in this population.

Traumatic Brain Injury Biomarkers, Simulations and Kinetics

This paper reviews the predictive capabilities of blood-based biomarkers to quantify traumatic brain injury (TBI). Biomarkers for concussive conditions also known as mild, to moderate and severe TBI identified along with post-traumatic stress disorder (PTSD) and chronic traumatic encephalopathy (CTE) that occur due to repeated blows to the head during one's lifetime. Since the pathways of these biomarkers into the blood are not fully understood whether there is disruption in the blood-brain barrier (BBB) and the time it takes after injury for the expression of the biomarkers to be able to predict the injury effectively, there is a need to understand the protein biomarker structure and other physical properties. The injury events in terms of brain and mechanics are a result of external force with or without the shrapnel, in the wake of a wave result in local tissue damage. Thus, these mechanisms express specific biomarkers kinetics of which reaches half-life within a few hours after injury to few days. Therefore, there is a need to determine the concentration levels that follow injury. Even though current diagnostics linking biomarkers with TBI severity are not fully developed, there is a need to quantify protein structures and their viability after injury. This research was conducted to fully understand the structures of 12 biomarkers by performing molecular dynamics simulations involving atomic movement and energies of forming hydrogen bonds. Molecular dynamics software, NAMD and VMD were used to determine and compare the approximate thermodynamic stabilities of the biomarkers and their bonding energies. Five biomarkers used clinically were S100B, GFAP, UCHL1, NF-L and tau, the kinetics obtained from literature show that the concentration values abruptly change with time after injury. For a given protein length, associated number of hydrogen bonds and bond energy describe a lower bound region where proteins self-dissolve and do not have long enough half-life to be detected in the fluids. However, above this lower bound, involving higher number of bonds and energy, we hypothesize that biomarkers will be viable to disrupt the BBB and stay longer to be modeled for kinetics for diagnosis and therefore may help in the discoveries of new biomarkers.

Gestational malnutrition, hyperemesis gravidarum, and Wernicke's encephalopathy: What is missing?

Hyperemesis gravidarum (HG), or the severe nausea and vomiting of pregnancy, is one of the most dreaded complications of gestation, affecting between 1.5% and 3.0% of pregnant women. From the late 1800s to the mid-1980s, the etiology was frequently cited to have psychological and/or-later-perhaps hormonal origins, which have numbered at least 10. Current research has unearthed a genetic basis for HG that implicates growth differentiation factor 15, insulin-like growth factor binding protein 7, and hormone receptors (namely, glial cell line-derived neurogenic factor family receptor alpha-like and the progesterone receptor). Whatever the origins of this disease, it has caused immeasurable physiological and psychological damage to women, their fetuses, and their families. The psychological trauma includes a high rate of suicidal ideation as well as posttraumatic stress disorder. Whereas the healthcare costs are substantial for the mother with HG, the lifetime costs to the neonate include that which accompanies reduced employment earnings related to cognitive compromise. Another devastating outcome of severe HG can be Wernicke's encephalopathy (WE), which has a high fetal and maternal mortality rate. Our study explored 18 current reports of HG and WE. We highlighted additional presenting features we believe also accompany, and sometimes replace, the classically taught triad components of WE: ataxia, confabulation, and nystagmus. We agree with the conclusion made by Sheehan and Ironside in 1939 that thiamin alone may not reverse WE, and we offer possible explanations. Lastly, we offer suggestions for remediation.

Longitudinal analyses of serum neurofilament light and associations with obesity indices and bioelectrical impedance parameters

Neurofilament light is a constituent of the neuronal cytoskeleton and released into the blood following neuro-axonal damage. It has previously been reported that NfL measured in blood serum is inversely related to body mass index. However, no reports exist with regard to body composition assessed using bioelectrical impedance analysis or other indicators of obesity beyond BMI. We analyzed the relationship between sNfL and body composition according to the three compartment model. Additionally, associations between sNfL, body shape index, waist-to-height ratio, and BMI were examined. The sample consisted of 769 participants assessed during the baseline examination and 693 participants examined in the course of the follow-up of the BiDirect Study. Associations between sNfL, BMI, BSI, and WtHR were separately analyzed using linear mixed models. Body compartments operationalized as fat mass, extracellular cell mass, and body cell mass were derived using BIA and the relationship with sNfL was analyzed with a linear mixed model. Lastly, we also analyzed the association between total body water and sNfL. We found significant inverse associations of sNfL with BMI and WtHR. The analysis of the three compartment model yielded significant inverse associations between sNfL, body cell mass and body fat mass, but not extracellular mass. Furthermore, total body water was also inversely related to sNfL. A potential mechanism could involve body cell mass and body fat mass as highly adaptive body constituents that either directly absorb sNfL, or promote the formation of new vasculature and thereby increase blood volume.

Neural and glial damage markers in women after long-term weight-recovery from anorexia nervosa

PURPOSE

The acute state of anorexia nervosa (AN) is accompanied by increased peripheral concentrations of brain-derived damage markers indicative of ongoing neural and glial damage processes. Although these findings correspond with well-documented structural brain changes in the disorder, it remains unclear whether abnormal levels of brain-derived damage markers persist after long-term weight-recovery from AN.

METHODS

To address this question, we used single-molecule array (Simoa) technology to measure serum levels of neurofilament light (NF-L), tau protein and glial fibrillary acidic protein (GFAP) in a group of 55 long-term weight-recovered women with a history of AN (recAN) and 55 age-matched healthy controls. Strict exclusion criteria allowed us to control for confounds present in previous studies including most importantly neurological conditions.

RESULTS

We found not only no group differences but also statistical evidence for equal damage marker levels between groups using Bayesian hypothesis testing.

CONCLUSION

These results provide evidence for the absence of neuronal and glial damage processes after long-term weight-recovery from AN. Together, our findings are indicative of complete normalization following long-term weight restoration provide hope that recovery from AN halts neuronal damage processes and support the need to test potential candidates for therapeutic interventions including pharmacological neuroprotection.

Neurofilament light protein as a biomarker in depression and cognitive function

PURPOSE OF REVIEW

Converging evidence suggest axonal damage is implicated in depression and cognitive function. Neurofilament light protein, measured within serum and cerebrospinal fluid, may be a biomarker of axonal damage. This article examines the emerging evidence implicating neurofilament light protein in depression and cognitive function.

RECENT FINDINGS

Preliminary cross-sectional and case-control studies in cohorts with depression have yielded inconsistent results regarding the association between neurofilament light protein and symptomatology. However, these studies had methodological limitations, requiring further investigation. Importantly, neurofilament light protein concentrations may be a marker of progression of cognitive decline and may be associated with cognitive performance within cognitively intact cohorts.

SUMMARY

Axonal damage is implicated in the neuropathology of depression and cognitive dysfunction. Consequently, neurofilament light protein is an emerging biomarker with potential in depression and cognitive function. Results are more consistent for cognition, requiring more research to assess neurofilament light protein in depression as well as other psychiatric disorders. Future longitudinal studies are necessary to determine whether neurofilament light protein can predict the onset and progression of depression and measure the effectiveness of potential psychiatric interventions and medications.

The Role of Glial Cells in Regulating Feeding Behavior: Potential Relevance to Anorexia Nervosa

Eating behavior is controlled by hypothalamic circuits in which agouti-related peptide-expressing neurons when activated in the arcuate nucleus, promote food intake while pro-opiomelanocortin-producing neurons promote satiety. The respective neurotransmitters signal to other parts of the hypothalamus such as the paraventricular nucleus as well as several extra-hypothalamic brain regions to orchestrate eating behavior. This complex process of food intake may be influenced by glia cells, in particular astrocytes and microglia. Recent studies showed that GFAP⁺ astrocyte cell density is reduced in the central nervous system of an experimental anorexia nervosa model. Anorexia nervosa is an eating disorder that causes, among the well-known somatic symptoms, brain volume loss which was associated with neuropsychological deficits while the underlying pathophysiology is unknown. In this review article, we summarize the findings of glia cells in anorexia nervosa animal models and try to deduce which role glia cells might play in the pathophysiology of eating disorders, including anorexia nervosa. A better understanding of glia cell function in the regulation of food intake and eating behavior might lead to the identification of new drug targets.

Is Serum BDNF Altered in Acute, Short- and Long-Term Recovered Restrictive Type Anorexia Nervosa?

Brain-derived neurotrophic factor (BDNF), a neurotrophin involved in the regulation of food intake and body weight, has been implicated in the development and maintenance of Anorexia nervosa (AN). The majority of previous studies reported lower BDNF levels in acutely underweight AN patients (acAN) and increasing levels after weight rehabilitation. Here, we investigated serum BDNF concentrations in the largest known AN sample to date, both before and after weight restoration therapy. Serum BDNF was measured in 259 female volunteers: 77 in-patient acAN participants of the restrictive type (47 reassessed after short-term weight rehabilitation), 62 individuals long-term recovered from AN, and 120 healthy controls. We validated our findings in a post-hoc mega-analysis in which we reanalyzed combined data from the current sample and those from our previous study on BDNF in AN (combined sample: 389 participants). All analyses carefully accounted for known determinants of BDNF (age, sex, storage time of blood samples). We further assessed relationships with relevant clinical variables (body-mass-index, physical activity, symptoms). Contrary to our hypotheses, we found zero significant differences in either cross-sectional or longitudinal comparisons and no significant relationships with clinical variables. Together, our study suggests that BDNF may not be a reliable state- or trait-marker in AN after all.