Central nervous pathways of insulin action in the control of metabolism and food intake

Neuropathological links between T2DM and LOAD: systematic review and meta-analysis

Recent decades have described parallel neuropathological mechanisms increasing the risk for developing late-onset Alzheimer's dementia (LOAD) in type 2 diabetes mellitus (T2DM); however, still little is known of the role of diabetic encephalopathy and brain atrophy in LOAD. The aim of this systematic review is to provide a comprehensive view on diabetic encephalopathy/cerebral atrophy, taking into account neuroimaging data, neuropathology, metabolic and endocrine mechanisms, amyloid formation, brain perfusion impairments, neuroimmunology, and inflammasome activation. Key switches were identified, to further meta-analyze genomic candidate loci and epigenetic modifications. For the qualitative meta-analysis of genomic bases extracted, human linkage studies were examined; for epigenetic mechanisms, data from both human and animal studies are described. For the systematic review of pathophysiological mechanisms, 1,259 publications were evaluated and 93 gene loci extracted for candidate risk linkages. Sixty-six publications were evaluated for genomic association and descriptions of epigenomic modifications. Overall accumulated results highlight the insulin signaling system, vascular markers, inflammation and inflammasome pathways, amylin interactions, and glycosylation mechanisms. The protocol was registered with PROSPERO (ID: CRD42023440535).

Treatments for weight gain in schizophrenia

PURPOSE OF REVIEW

Obesity and related metabolic disorders are extremely common in psychiatric patients, particularly in those with schizophrenia. Elucidating this link's neurobiology may inform clinicians and researchers of rational therapeutic approaches necessary to optimize clinical outcomes.

RECENT FINDINGS

Current literature highlights the pivotal role of the inflammation-oxidative stress-insulin resistance loop in the pathophysiology of both metabolic and neuropsychiatric disorders. The concept of 'diabetophrenia' is put forward to highlight the overlapping neurobiological mechanisms underlying metabolic dysfunction and schizophrenia symptoms. Innovative treatments, including the combination of xanomeline with trospium and incretin-based medicines, demonstrate encouraging potential in addressing such complex health challenges.

SUMMARY

The nuanced dynamics of chronic inflammation and psychiatric symptomatology underscore the significance of addressing both metabolic and mental health factors in a cohesive fashion while considering unique psychosocial contexts, dietary preferences, and lifestyle choices. A multidisciplinary strategy is essential for incorporating counseling, dietary interventions, behavioral therapies, and pharmacotherapy into the management of schizophrenia. The ensuing enhanced collaboration among healthcare professionals may render obsolete the prevailing siloed conceptualizations of mental disorders, opening new vistas for generating synergistic insights into the mind-body systems and leading to improved health and quality of life for patients with schizophrenia and other psychiatric conditions.

Elevated Cholinesterase Activity and the Metabolic Syndrome-Dissecting Fatty Liver, Insulin Resistance and Dysglycaemia

BACKGROUND AND AIMS

While low plasma butyrylcholinesterase (BChE) is a well-established marker of reduced liver synthesis capacity, the clinical significance of elevated BChE is unclear. In small studies, high BChE has long been suspected in hepatic steatosis and metabolic syndrome. We aimed to clarify the relation between BChE, liver fat and glucose metabolism in deeply phenotyped cohorts.

METHODS

Plasma BChE activity was measured in 844 humans (554 women) of the cross-sectional Tübingen Diabetes Family Study, with a wide BMI range (17.7-55.1 kg/m2). It was furthermore measured before and after two independent lifestyle intervention studies in 215 and 116 participants. Liver fat was quantified with 1H-MR-spectroscopy, and metabolism was assessed by oral glucose tolerance tests.

RESULTS

BChE was positively associated with liver fat, independent of sex, age and BMI. BChE was higher in participants with metabolic syndrome. BChE was positively associated with fasting and 2-h glycaemia, independent of sex, age and BMI. BChE was negatively associated with insulin sensitivity, independent of sex, age, BMI and liver fat. The reduction of liver fat and improvement in insulin sensitivity during lifestyle interventions are associated with the reduction in BChE, independent of body weight loss.

CONCLUSIONS

Higher plasma BChE activity is linked to liver fat accumulation, as well as impaired glucose tolerance and insulin resistance, independent of liver fat. This suggests that BChE could be a marker for processes in hepatocytes that contribute to impaired glucose metabolism. Further investigations are needed to clarify the mechanistic contribution and potential diagnostic value of elevated BChE in hepatic steatosis and metabolic diseases.

Influence of insulin sensitivity on food cue evoked functional brain connectivity in children

OBJECTIVE

Insulin resistance during childhood is a risk factor for developing type 2 diabetes and other health problems later in life. Studies in adults have shown that insulin resistance affects regional and network activity in the brain which are vital for behavior, including ingestion and metabolic control. To date, no study has investigated how brain connections during exposure to food cues are association with peripheral insulin sensitivity in children.

METHODS

We included 53 children (36 girls) between the age of 7-11 years, who underwent an oral Glucose Tolerance Test (oGTT) to estimate peripheral insulin sensitivity (ISI). Brain responses were measured using functional magnetic resonance imaging (fMRI) before and after glucose ingestion. We compared food-cue task-based activity and functional connectivity (FC) between children with lower and higher ISI, adjusted for age and BMIz.

RESULTS

Independent of prandial state (i.e., glucose ingestion), children with lower ISI showed higher FC between the anterior insula and caudate and lower FC between the posterior insula and mid temporal cortex than children with higher ISI. Sex differences were found based on prandial state and peripheral insulin sensitivity in the insular FC. No differences were found on mean brain responses to food cues.

CONCLUSIONS

In response to food cues, children with lower peripheral insulin sensitivity exhibited distinctive patterns of neural connectivity, notably in the insula's functional connections, when contrasted with their counterparts with higher peripheral insulin sensitivity. These differences might influence eating behavior and future risk of developing diabetes.

Repeated net-tDCS of the hypothalamus appetite-control network enhances inhibitory control and decreases sweet food intake in persons with overweight or obesity

BACKGROUND

Reduced inhibitory control is associated with obesity and neuroimaging studies indicate that diminished prefrontal cortex activity influence eating behavior and metabolism. The hypothalamus regulates energy homeostasis and is functionally connected to cortical and subcortical regions especially the frontal areas.

OBJECTIVES

We tested network-targeted transcranial direct current stimulation (net-tDCS) to influence the excitability of brain regions involved in appetite control.

METHODS

In a randomized, double-blind parallel group design, 44 adults with overweight or obesity (BMI 30.6 kg/m2, 52.3 % female) received active (anodal or cathodal) or sham 12-channel net-tDCS on the hypothalamus appetite-control network for 25 min on three consecutive days while performing a Stop-Signal-Task to measure response inhibition. Before and after stimulation, state questionnaires assessed changes in desire to eat and food craving. Directly after stimulation, participants received a breakfast buffet to evaluate ad-libitum food intake. An oral glucose tolerance test was conducted at follow-up. Resting-state functional MRI was obtained at baseline and follow-up.

RESULTS

The Stop-Signal Reaction Time (SSRT) was shorter in both active groups versus sham, indicating improved response inhibition. Additionally, a stronger increase in hypothalamic functional connectivity was associated with shorter SSRT. Caloric intake of sweet food was lower in the anodal group versus sham, but no main effects between groups were observed on total and macronutrient intake, food craving ratings and desire to eat. At follow-up, no differences were observed between groups on peripheral metabolism.

CONCLUSION

Our study suggests that modulating hypothalamic functional network connectivity patterns via net-tDCS may improve food choice and inhibitory control.

Novel Thyroid Hormone Receptor-β Agonist TG68 Exerts Anti-Inflammatory, Lipid-Lowering and Anxiolytic Effects in a High-Fat Diet (HFD) Mouse Model of Obesity

Recent advances in drug development allowed for the identification of THRβ-selective thyromimetic TG68 as a very promising lipid lowering and anti-amyloid agent. In the current study, we first investigated the neuroprotective effects of TG68 on in vitro human models of neuroinflammation and β-amyloid neurotoxicity in order to expand our knowledge of the therapeutic potential of this novel thyromimetic. Subsequently, we examined metabolic and inflammatory profiles, along with cognitive changes, using a high-fat diet (HFD) mouse model of obesity. Our data demonstrated that TG68 was able to prevent either LPS/TNFα-induced inflammatory response or β-amyloid-induced cytotoxicity in human microglial (HMC3) cells. Next, we demonstrated that in HFD-fed mice, treatment with TG68 (10 mg/kg/day; 2 weeks) significantly reduced anxiety-like behavior in stretch-attend posture (SAP) tests while producing a 12% BW loss and a significant decrease in blood glucose and lipid levels. Notably, these data highlight a close relationship between improved serum metabolic parameters and a reduction of anxious behavior. Moreover, TG68 administration was observed to efficiently counteract HFD-altered central and peripheral expressions in mice with selected biomarkers of metabolic dysfunction, inflammation, and neurotoxicity, revealing promising neuroprotective effects. In conclusion, our work provides preliminary evidence that TG68 may represent a novel therapeutic opportunity for the treatment of interlinked diseases such as obesity and neurodegenerative diseases.

Repetitive transcranial magnetic stimulation elicits weight loss and improved insulin sensitivity in type 2 diabetic rats

BACKGROUND

Type 2 diabetes (T2D) accounts for the majority of diabetes incidences and remains a widespread global chronic disorder. Apart from early lifestyle changes, intervention options for T2D are mainly pharmaceutical.

METHODS

Repetitive transcranial magnetic stimulation (rTMS) has been approved by the FDA as a therapeutic intervention option for major depressive disorders, with further studies also indicating its role in energy metabolism and appetite. Considering its safe and non-invasive properties, we evaluated the effects of rTMS on systemic metabolism using T2D rats.

RESULTS

We observed that rTMS improved glucose tolerance and insulin sensitivity in T2D rats after a 10-day exposure. Improved systemic insulin sensitivity was maintained after a 21-day treatment period, accompanied by modest yet significant weight loss. Circulating serum lipid levels, including those of cholesteryl ester, tryglyceride and ceramides, were also reduced following rTMS application. RNA-seq analyses further revealed a changed expression profile of hepatic genes that are related to sterol production and fatty acid metabolism. Altered expression of hypothalamic genes that are related to appetite regulation, neural activity and ether lipid metabolism were also implicated.

CONCLUSION

In summary, our data report a positive impact of rTMS on systemic insulin sensitivity and weight management of T2D rats. The underlying mechanisms via which rTMS regulates systemic metabolic parameters partially involve lipid utilization in the periphery as well as central regulation of energy intake and lipid metabolism.

Relationships Between Brain Glucose Metabolism Patterns and Impaired Glycemic Status: A Systematic Review of FDG-PET Studies With a Focus on Alzheimer's Disease

It is well-established that individuals with type 2 diabetes have an increased risk of developing cognitive impairment and Alzheimer's disease (AD). However, it is not fully determined how insulin resistance and type 2 diabetes are related to AD-related brain glucose metabolism abnormalities. For this aim, we performed a systematic review of the studies investigating the association between cerebral glucose metabolism and glycemic status, including diabetes, insulin resistance, or hyperglycemia. Medline, Embase, and Cochrane databases were searched (till February 2, 2025). All English full-text papers studying 18F-FDG-PET that investigated the association between cerebral FDG uptake or cerebral metabolism rate and glycemic status were included. These studies were reviewed for quality assessment, data extraction, and qualitative synthesis. After screening titles and abstracts of 718 unique records identified from our search, 23 studies (5308 participants) addressing the association between brain glucose metabolism alterations, as assessed by FDG-PET scan, and glycemic status were included for qualitative analysis. Of these 23 studies, 22 studies suggested that hyperglycemia or insulin resistance is related to global or regional cerebral glucose hypometabolism. The regional brain metabolism reductions were mostly in the frontal cortex, parietotemporal cortex, posterior cingulate cortex, and precuneus cortex, known as AD-signature areas. Hyperglycemia, diabetes, and insulin resistance are associated with cerebral glucose hypometabolism in similar regions compared to AD. This can suggest that even in cognitively normal individuals, insulin resistance can potentially increase the predisposition to abnormal AD-like glucose metabolism.

A short-term, high-caloric diet has prolonged effects on brain insulin action in men

Brain insulin responsiveness is linked to long-term weight gain and unhealthy body fat distribution. Here we show that short-term overeating with calorie-rich sweet and fatty foods triggers liver fat accumulation and disrupted brain insulin action that outlasted the time-frame of its consumption in healthy weight men. Hence, brain response to insulin can adapt to short-term changes in diet before weight gain and may facilitate the development of obesity and associated diseases.

Prediabetes remission to reduce the global burden of type 2 diabetes

Prediabetes is a highly prevalent and increasingly common condition affecting a significant proportion of the global population. The heterogeneous nature of prediabetes presents a challenge in identifying individuals who particularly benefit from lifestyle or other therapeutic interventions aiming at preventing type 2 diabetes (T2D) and associated comorbidities. The phenotypic characteristics of individuals at risk for diabetes are associated with both specific risk profiles for progression and a differential potential to facilitate prediabetes remission and reduce the risk of future T2D. This review examines the current definition and global prevalence of prediabetes and evaluates the potential of prediabetes remission to reduce the alarming increase in the global burden of T2D.

High-fat diet and neuroinflammation: The role of mitochondria

In recent years, increasing evidence has supported that high-fat diet (HFD) can induce the chronic, low-grade neuroinflammation in the brain, which is closely associated with the impairment of cognitive function. As the key organelles responsible for energy metabolism in the cell, mitochondria are believed to involved in the pathogenesis of a variety of neurological disorders. This review summarizes the current progress in the field of the relationship between HFD exposure and neurodegenerative diseases, and outline the major routines of HFD induced neuroinflammation and its pathological significance in the pathogenesis of neurodegenerative diseases. Furthermore, the article highlights the pivotal role of mitochondrial dysfunction in driving the neuroinflammation in the setting of HFD. Danger-associated molecular patterns (DAMPs) from damaged mitochondria can activate innate immune signaling pathways, while mitochondrial dysfunction itself can lead to metabolic remodeling of inflammatory cells, thus inducing neuroinflammation. More importantly, mitochondrial damage, neuroinflammation, and insulin resistance caused by HFD form a mutually reinforcing vicious cycle, ultimately leading to the death of neurons and promoting the progression of neurodegenerative diseases. Thus, in-depth elucidation of the role and underlying mechanisms of mitochondrial dysfunction in HFD-induced metabolic disorders may not only expand our understanding of the mechanistic linkages between HFD and etiology of neurodegenerative diseases, but also help develop the specific strategies for the prevention and treatment of neurodegenerative diseases.

The Mechanism and Treatment of Cognitive Dysfunction in Diabetes: A Review

Diabetes mellitus (DM) is one of the fastest growing diseases in terms of global incidence and seriously affects cognitive function. The incidence rate of cognitive dysfunction is up to 13% in diabetes patients aged 65-74 years and reaches 24% in those aged >75 years. The mechanisms and treatments of cognitive dysfunction associated with diabetes mellitus are complicated and varied. Previous studies suggest that hyperglycemia mainly contributes to cognitive dysfunction through mechanisms involving inflammation, autophagy, the microbial-gut-brain axis, brain-derived neurotrophic factors, and insulin resistance. Antidiabetic drugs such as metformin, liraglutide, and empagliflozin and other drugs such as fingolimod and melatonin can alleviate diabetes-induced cognitive dysfunction. Self-management, intermittent fasting, and repetitive transverse magnetic stimulation can also ameliorate cognitive impairment. In this review, we discuss the mechanisms linking diabetes mellitus with cognitive dysfunction and propose a potential treatment for cognitive decline associated with diabetes mellitus.

Glucose metabolism impairment in major depressive disorder

Major depressive disorder (MDD) is a common mental disorder with chronic tendencies that seriously affect regular work, life, and study. However, its exact pathogenesis remains unclear. Patients with MDD experience systemic and localized impairments in glucose metabolism throughout the disease course, disrupting various processes such as glucose uptake, glycoprotein transport, glycolysis, the tricarboxylic acid cycle (TCA), and oxidative phosphorylation (OXPHOS). These impairments may result from mechanisms including insulin resistance, hyperglycemia-induced damage, oxidative stress, astrocyte abnormalities, and mitochondrial dysfunction, leading to insufficient energy supply, altered synaptic plasticity, neuronal cell death, and functional and structural damage to reward networks. These mechanical changes contribute to the pathogenesis of MDD and severely interfere with the prognosis. Herein, we summarized the impairment of glucose metabolism and its pathophysiological mechanisms in patients with MDD. In addition, we briefly discussed potential pharmacological interventions for glucose metabolism to alleviate MDD, including glucagon-like peptide-1 receptor agonists, metformin, topical insulin, liraglutide, and pioglitazone, to encourage the development of new therapeutics.

Genetically predicted brain cortical structure mediates the causality between insulin resistance and cognitive impairment

Background

Insulin resistance is tightly related to cognition; however, the causal association between them remains a matter of debate. Our investigation aims to establish the causal relationship and direction between insulin resistance and cognition, while also quantifying the mediating role of brain cortical structure in this association.

Methods

The publicly available data sources for insulin resistance (fasting insulin, homeostasis model assessment beta-cell function and homeostasis model assessment insulin resistance, proinsulin), brain cortical structure, and cognitive phenotypes (visual memory, reaction time) were obtained from the MAGIC, ENIGMA, and UK Biobank datasets, respectively. We first conducted a bidirectional two-sample Mendelian randomization (MR) analysis to examine the susceptibility of insulin resistance on cognitive phenotypes. Additionally, we applied a two-step MR to assess the mediating role of cortical surficial area and thickness in the pathway from insulin resistance to cognitive impairment. The primary Inverse-variance weighted, accompanied by robust sensitivity analysis, was implemented to explore and verify our findings. The reverse MR analysis was also performed to evaluate the causal effect of cognition on insulin resistance and brain cortical structure.

Results

This study identified genetically determined elevated level of proinsulin increased reaction time (beta=0.03, 95% confidence interval [95%CI]=0.01 to 0.05, p=0.005), while decreasing the surface area of rostral middle frontal (beta=-49.28, 95%CI=-86.30 to -12.27, p=0.009). The surface area of the rostral middle frontal mediated 20.97% (95%CI=1.44% to 40.49%) of the total effect of proinsulin on reaction time. No evidence of heterogeneity, pleiotropy, or reverse causality was observed.

Conclusions

Briefly, our study noticed that elevated level of insulin resistance adversely affected cognition, with a partial mediation effect through alterations in brain cortical structure.

Ketogenic Diet as a Nutritional Metabolic Intervention for Obsessive-Compulsive Disorder: A Narrative Review

The substantial evidence supporting the ketogenic diet (KD) in epilepsy management has spurred research into its effects on other neurological and psychiatric conditions. Despite differences in characteristics, symptoms, and underlying mechanisms, these conditions share common pathways that the KD may influence. The KD reverses metabolic dysfunction. Moreover, it has been shown to support neuroprotection through mechanisms such as neuronal energy support, inflammation reduction, amelioration of oxidative stress, and reversing mitochondrial dysfunction. The adequate intake of dietary nutrients is essential for maintaining normal brain functions, and strong evidence supports the role of nutrition in the treatment and prevention of many psychiatric and neurological disorders. Obsessive-compulsive disorder (OCD) is a neuropsychiatric condition marked by persistent, distressing thoughts or impulses (obsessions) and repetitive behaviors performed in response to these obsessions (compulsions). Recent studies have increasingly examined the role of nutrition and metabolic disorders in OCD. This narrative review examines current evidence on the potential role of the KD in the treatment of OCD. We explore research on the KD's effects on psychiatric disorders to assess its potential relevance for OCD treatment. Additionally, we identify key gaps in the preclinical and clinical research that warrant further study in applying the KD as a metabolic therapy for OCD.

Exposure to gestational diabetes mellitus in utero impacts hippocampal functional connectivity in response to food cues in children

OBJECTIVES

Intrauterine exposure to gestational diabetes mellitus (GDM) increases the risk of obesity in the offspring, but little is known about the underlying neural mechanisms. The hippocampus is crucial for food intake regulation and is vulnerable to the effects of obesity. The purpose of the study was to investigate whether GDM exposure affects hippocampal functional connectivity during exposure to food cues using functional magnetic resonance imaging (fMRI).

METHODS

Participants were 90 children age 7-11 years (53 females) who underwent an fMRI-based visual food cue task in the fasted state. Hippocampal functional connectivity (FC) was examined using generalized psychophysiological interaction in response to food versus non-food cues. Hippocampal FC was compared between children with and without GDM exposure, while controlling for possible confounding effects of age, sex and waist-to-hip ratio. In addition, the influence of childhood and maternal obesity were investigated using multiple regression models.

RESULTS

While viewing high caloric food cues compared to non-food cure, children with GDM exposure exhibited higher hippocampal FC to the insula and striatum (i.e., putamen, pallidum and nucleus accumbens) compared to unexposed children. With increasing BMI, children with GDM exposure had lower hippocampal FC to the somatosensory cortex (i.e., postcentral gyrus).

CONCLUSIONS

Intrauterine exposure to GDM was associated with higher food-cue induced hippocampal FC especially to reward processing regions. Future studies with longitudinal measurements are needed to clarify whether altered hippocampal FC may raise the risk of the development of metabolic diseases later in life.

Structural and functional alterations of the hippocampal subfields in T2DM with mild cognitive impairment and insulin resistance: A prospective study

BACKGROUND

Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance (IR) and is often accompanied by mild cognitive impairment (MCI). The detrimental effects of T2DM and IR on the hippocampus have been extensively demonstrated. Few studies have examined the effects of IR on structure and function of hippocampal subfields in T2DM-MCI patients.

METHOD

A total of 104 T2DM patients were recruited in this prospective study and divided into four groups (T2DM-MCI-higherIR, n = 17; T2DM-MCI-lowerIR, n = 32; T2DM-nonMCI-higherIR, n = 19; T2DM-nonMCI-lowerIR, n = 36). Structure and function MRI data were captured. Clinical variables and neuropsychological scores were determined for all participants. Hippocampal subfield volume and functional connectivity were compared among four groups. Partial correlation analysis was performed between imaging indicators, clinical variables, and neuropsychological scores in all patients.

RESULTS

T2DM-MCI-higher IR group had the smallest volumes of bilateral hippocampal tail, right subiculum-body, right GC-ML-DG-body, and right CA4-body. IR in right hippocampal tail, right subiculum-body, and right GC-ML-DG-body exerted main effect. Furthermore, elevated functional connectivity was found between right subiculum-body and bilateral dorsolateral prefrontal cortex and right anterior cingulate-medial prefrontal cortex. Hippocampal subfield volume positively correlates with total cholesterol and triglycerides and negatively correlates with fasting insulin.

CONCLUSION

The present study found that T2DM-MCI patients have structural and functional alterations in hippocampal subfields, and IR is a negative factor influencing the alteration of hippocampal subfields volume. These findings support the importance of IR in T2DM-MCI patients and might be potential neuroimaging biomarkers of cerebral impairment in T2DM-MCI patients.

Role of short-chain fatty acids in host physiology

Short-chain fatty acids (SCFAs) are major metabolites produced by the gut microbiota through the fermentation of dietary fiber, and they have garnered significant attention due to their close association with host health. As important mediators between the gut microbiota and the host, SCFAs serve as energy substrates for intestinal epithelial cells and maintain homeostasis in host immune and energy metabolism by influencing host epigenetics, activating G protein-coupled receptors, and inhibiting pathogenic microbial infections. This review provides a comprehensive summary of SCFAs synthesis and metabolism and offering an overview of the latest research progress on their roles in protecting gut health, enhancing energy metabolism, mitigating diseases such as cancer, obesity, and diabetes, modulating the gut-brain axis and gut-lung axis, and promoting bone health.

Abnormal resting-state functional connectivity of hippocampal subregions in type 2 diabetes mellitus-associated cognitive decline

Objective

Type 2 diabetes mellitus (T2DM) over time predisposes to inflammatory responses and abnormalities in functional brain networks that damage learning, memory, or executive function. The hippocampus is a key region often reporting connectivity abnormalities in memory disorders. Here, we investigated peripheral inflammatory responses and resting-state functional connectivity (RSFC) changes characterized of hippocampal subregions in type 2 diabetes-associated cognitive decline (T2DACD).

Methods

The study included 16 patients with T2DM, 16 patients with T2DACD and 25 healthy controls (HCs). Subjects were assessed for cognitive performance, tested for the expression of inflammatory factors IL-6, IL-10 and TNF-α in peripheral serum, underwent resting-state functional magnetic resonance imaging scans, and analyzed for RSFC using the hippocampal subregions as seeds. We also calculated the correlation between cognitive performance and RSFC of hippocampal subregion, and analyzed the significantly altered RSFC values of T2DACD for Receiver Operating Characteristic (ROC) analysis.

Results

T2DACD patients showed a decline in their ability to complete cognitive assessment scales and experimental paradigms, and T2DM did not show abnormal cognitive performance. IL-6 expression was increased in peripheral serum in both T2DACD and T2DM. Compared with HCs, T2DACD showed abnormalities RSFC of the left anterior hippocampus with left precentral gyrus and left angular gyrus. T2DM showed abnormalities RSFC of the left middle hippocampus with right medial frontal gyrus, right anterior and middle hippocampus with left precuneus, left anterior hippocampus with right precuneus and right posterior middle temporal gyrus. Compared with T2DM, T2DACD showed abnormalities RSFC of the left posterior hippocampus and right middle hippocampus with left precuneus. In addition, RSFC in the left posterior hippocampus with left precuneus of T2DACD was positively correlated with Flanker conflict response time (r=0.766, P=0.001). In the ROC analysis, the significantly altered RSFC values of T2DACD achieved significant performance.

Conclusions

T2DACD showed a significant decrease in attentional inhibition and working memory, peripheral pro-inflammatory response increased, and abnormalities RSFC of the hippocampal subregions with default mode network and sensory-motor network. T2DM did not show a significant cognitive decline, but peripheral pro-inflammatory response increased and abnormalities RSFC of the hippocampus subregions occurred in the brain. In addition, the left precuneus may be a key brain region in the conversion of T2DM to T2DACD. The results of this study may provide a basis for the preliminary diagnosis of T2DACD.

Impact of blood glucose on cognitive function in insulin resistance: novel insights from ambulatory assessment

BACKGROUND/OBJECTIVES

Insulin resistance (IR)-related disorders and cognitive impairment lead to reduced quality of life and cause a significant strain on individuals and the public health system. Thus, we investigated the effects of insulin resistance (IR), and blood glucose fluctuations on cognitive function under laboratory and free-living conditions, using ecological momentary assessment (EMA).

SUBJECTS/METHODS

Baseline assessments included neuropsychological tests and blood analysis. Individuals were classified as either insulin-sensitive (<2) or insulin-resistant (≥2), based on their Homeostatic Model Assessment (HOMA-IR) values. Continuous glucose monitoring (CGM) using a percutaneous sensor was performed for 1 week. Using multiple linear regression, we examined the effects of HOMA-IR and CGM metrics on cognitive domains. Working memory (WM) performance, which was assessed using EMA, 4 times a day for 3 consecutive days, was matched to short-term pre-task CGM metrics. Multilevel analysis was used to map the within-day associations of HOMA-IR, short-term CGM metrics, and WM.

RESULTS

Analyses included 110 individuals (mean age 48.7 ± 14.3 years, 59% female, n = 53 insulin-resistant). IR was associated with lower global cognitive function (b = -0.267, P = 0.027), and WM (b = -0.316; P = 0.029), but not with executive function (b = -0.216; P = 0.154) during baseline. EMA showed that higher HOMA-IR was associated with lower within-day WM performance (β = -0.20, 95% CI -0.40 to -0.00). CGM metrics were not associated with cognitive performance.

CONCLUSIONS

The results confirm the association between IR and decrements in global cognitive functioning and WM, while no effects of CGM metrics were observed, making IR a crucial time point for intervention. Targeting underlying mechanisms (e.g., inflammation) in addition to glycemia could be promising to minimize adverse cognitive effects. Registered under https://drks.de/register/de identifier no. DRKS00022774.

The insulin resistant brain: impact on whole-body metabolism and body fat distribution

Insulin exerts its actions not only on peripheral organs but is also transported into the brain where it performs distinct functions in various brain regions. This review highlights recent advancements in our understanding of insulin's actions within the brain, with a specific emphasis on investigations in humans. It summarises current knowledge on the transport of insulin into the brain. Subsequently, it showcases robust evidence demonstrating the existence and physiological consequences of brain insulin action, while also introducing the presence of brain insulin resistance in humans. This pathophysiological condition goes along with an impaired acute modulation of peripheral metabolism in response to brain insulin action, particularly in the postprandial state. Furthermore, brain insulin resistance has been associated with long-term adiposity and an unfavourable adipose tissue distribution, thus implicating it in the pathogenesis of subgroups of obesity and (pre)diabetes that are characterised by distinct patterns of body fat distribution. Encouragingly, emerging evidence suggests that brain insulin resistance could represent a treatable entity, thereby opening up novel therapeutic avenues to improve systemic metabolism and enhance brain functions, including cognition. The review closes with an outlook towards prospective research directions aimed at further elucidating the clinical implications of brain insulin resistance. It emphasises the critical need to establish feasible diagnostic measures and effective therapeutic interventions.

Cerebral Microbleeds Associate with Brain Endothelial Cell Activation-Dysfunction and Blood-Brain Barrier Dysfunction/Disruption with Increased Risk of Hemorrhagic and Ischemic Stroke

Globally, cerebral microbleeds (CMBs) are increasingly being viewed not only as a marker for cerebral small vessel disease (SVD) but also as having an increased risk for the development of stroke (hemorrhagic/ischemic) and aging-related dementia. Recently, brain endothelial cell activation and dysfunction and blood-brain barrier dysfunction and/or disruption have been shown to be associated with SVD, enlarged perivascular spaces, and the development and evolution of CMBs. CMBs are a known disorder of cerebral microvessels that are visualized as 3-5 mm, smooth, round, or oval, and hypointense (black) lesions seen only on T2*-weighted gradient recall echo or susceptibility-weighted sequences MRI images. CMBs are known to occur with high prevalence in community-dwelling older individuals. Since our current global population is the oldest recorded in history and is only expected to continue to grow, we can expect the healthcare burdens associated with CMBs to also grow. Increased numbers (≥10) of CMBs should raise a red flag regarding the increased risk of large symptomatic neurologic intracerebral hemorrhages. Importantly, CMBs are also currently regarded as markers of diffuse vascular and neurodegenerative brain damage. Herein author highlights that it is essential to learn as much as we can about CMB development, evolution, and their relation to impaired cognition, dementia, and the exacerbation of neurodegeneration.

Examining the evidence between screen time and night eating behaviour with dietary intake related to metabolic syndrome: A narrative review

Screen time (ST) on digital devices has increased in recent decades due to digital development. Furthermore, constant engagement with digital devices alters sleep patterns, leading to nocturnal eating behaviour among users. These phenomena are therefore of great concern, as digital device addiction and night eating are associated with unhealthy food intake, increasing the metabolic syndrome (MetS) risks. The purpose of this review was to examine the evidence of the influence of ST and night eating behaviour (NEB) on dietary intake and its association with MetS based on previous literature. Prolonged ST and NEB have an association with excessive intake of energy from overconsumption of high-sugar and high-fat foods. However, the relationship between digital content and its influence on food intake is inconsistent. A higher MetS risk was found in individuals with longer ST due to a sedentary lifestyle, while positive energy balance and a shift in circadian rhythm contributed to night eaters. ST and NEB presented with a significant influence on food intake in adults. Additionally, unhealthy food intake due to excessive consumption of empty-calorie foods such as sweet and fatty foods due to addiction to electronic devices and eating at night has a detrimental effect on metabolic function. Therefore, improving food intake by reducing ST and night binges is essential to reduce the risk of MetS.

Pinctada martensii Hydrolysate Modulates the Brain Neuropeptidome and Proteome in Diabetic (db/db) Mice via the Gut-Brain Axis

Pinctada martensii hydrolysate (PMH) has been proved to have the effect of ameliorating disorders of glucose and lipid metabolism in db/db mice, but the mechanism of its hyperglycemia effect is still unclear. Bacterial communities in fecal samples from a normal control group, a diabetic control group, and a PMH-treated diabetes mellitus type 2 (T2DM) group were analyzed by 16S gene sequencing. Nano LC-MS/MS was used to analyze mice neuropeptides and proteomes. The 16S rDNA sequencing results showed that PMH modulated the structure and composition of the gut microbiota and improved the structure and composition of Firmicutes and Bacteroidetes at the phylum level and Desulfovibrionaceae and Erysipelatoclostridiaceae at the family level. Furthermore, the expressions of functional proteins of the central nervous system, immune response-related protein, and proteins related to fatty acid oxidation in the brain disrupted by an abnormal diet were recovered by PMH. PMH regulates the brain neuropeptidome and proteome and further regulates blood glucose in diabetic mice through the gut-brain axis. PMH may be used as a prebiotic agent to attenuate T2DM, and target-specific microbial species may have unique therapeutic promise for metabolic diseases.

Network-targeted transcranial direct current stimulation of the hypothalamus appetite-control network: a feasibility study

The hypothalamus is the key regulator for energy homeostasis and is functionally connected to striatal and cortical regions vital for the inhibitory control of appetite. Hence, the ability to non-invasively modulate the hypothalamus network could open new ways for the treatment of metabolic diseases. Here, we tested a novel method for network-targeted transcranial direct current stimulation (net-tDCS) to influence the excitability of brain regions involved in the control of appetite. Based on the resting-state functional connectivity map of the hypothalamus, a 12-channel net-tDCS protocol was generated (Neuroelectrics Starstim system), which included anodal, cathodal and sham stimulation. Ten participants with overweight or obesity were enrolled in a sham-controlled, crossover study. During stimulation or sham control, participants completed a stop-signal task to measure inhibitory control. Overall, stimulation was well tolerated. Anodal net-tDCS resulted in faster stop signal reaction time (SSRT) compared to sham (p = 0.039) and cathodal net-tDCS (p = 0.042). Baseline functional connectivity of the target network correlated with SSRT after anodal compared to sham stimulation (p = 0.016). These preliminary data indicate that modulating hypothalamus functional network connectivity via net-tDCS may result in improved inhibitory control. Further studies need to evaluate the effects on eating behavior and metabolism.

Circadian desynchrony and glucose metabolism

The circadian timing system controls glucose metabolism in a time-of-day dependent manner. In mammals, the circadian timing system consists of the main central clock in the bilateral suprachiasmatic nucleus (SCN) of the anterior hypothalamus and subordinate clocks in peripheral tissues. The oscillations produced by these different clocks with a period of approximately 24-h are generated by the transcriptional-translational feedback loops of a set of core clock genes. Glucose homeostasis is one of the daily rhythms controlled by this circadian timing system. The central pacemaker in the SCN controls glucose homeostasis through its neural projections to hypothalamic hubs that are in control of feeding behavior and energy metabolism. Using hormones such as adrenal glucocorticoids and melatonin and the autonomic nervous system, the SCN modulates critical processes such as glucose production and insulin sensitivity. Peripheral clocks in tissues, such as the liver, muscle, and adipose tissue serve to enhance and sustain these SCN signals. In the optimal situation all these clocks are synchronized and aligned with behavior and the environmental light/dark cycle. A negative impact on glucose metabolism becomes apparent when the internal timing system becomes disturbed, also known as circadian desynchrony or circadian misalignment. Circadian desynchrony may occur at several levels, as the mistiming of light exposure or sleep will especially affect the central clock, whereas mistiming of food intake or physical activity will especially involve the peripheral clocks. In this review, we will summarize the literature investigating the impact of circadian desynchrony on glucose metabolism and how it may result in the development of insulin resistance. In addition, we will discuss potential strategies aimed at reinstating circadian synchrony to improve insulin sensitivity and contribute to the prevention of type 2 diabetes.

Aberrant Brain Triple-Network Effective Connectivity Patterns in Type 2 Diabetes Mellitus

INTRODUCTION

Aberrant brain functional connectivity network is thought to be related to cognitive impairment in patients with type 2 diabetes mellitus (T2DM). This study aims to investigate the triple-network effective connectivity patterns in patients with T2DM within and between the default mode network (DMN), salience network (SN), and executive control network (ECN) and their associations with cognitive declines.

METHODS

In total, 92 patients with T2DM and 98 matched healthy controls (HCs) were recruited and underwent resting-state functional magnetic resonance imaging (rs-fMRI). Spectral dynamic causal modeling (spDCM) was used for effective connectivity analysis within the triple network. The posterior cingulate cortex (PCC), medial prefrontal cortex (mPFC), lateral prefrontal cortex (LPFC), supramarginal gyrus (SMG), and anterior insula (AINS) were selected as the regions of interest. Group comparisons were performed for effective connectivity calculated using the fully connected model, and the relationships between effective connectivity alterations and cognitive impairment as well as clinical parameters were detected.

RESULTS

Compared to HCs, patients with T2DM exhibited increased or decreased effective connectivity patterns within the triple network. Furthermore, diabetes duration was significantly negatively correlated with increased effective connectivity from the r-LPFC to the mPFC, while body mass index (BMI) was significantly positively correlated with increased effective connectivity from the l-LPFC to the l-AINS (r = - 0.353, p = 0.001; r = 0.377, p = 0.004).

CONCLUSION

These results indicate abnormal effective connectivity patterns within the triple network model in patients with T2DM and provide new insight into the neurological mechanisms of T2DM and related cognitive dysfunction.

Food Cravings and Obesity in Women with Polycystic Ovary Syndrome: Pathophysiological and Therapeutic Considerations

Polycystic ovary syndrome (PCOS), the most common endocrine disorder in women of reproductive age, constitutes a metabolic disorder frequently associated with obesity and insulin resistance (IR). Furthermore, women with PCOS often suffer from excessive anxiety and depression, elicited by low self-esteem due to obesity, acne, and hirsutism. These mood disorders are commonly associated with food cravings and binge eating. Hypothalamic signaling regulates appetite and satiety, deteriorating excessive food consumption. However, the hypothalamic function is incapable of compensating for surplus food in women with PCOS, leading to the aggravation of obesity and a vicious circle. Hyperandrogenism, IR, the reduced secretion of cholecystokinin postprandially, and leptin resistance defined by leptin receptors' knockout in the hypothalamus have been implicated in the pathogenesis of hypothalamic dysfunction and appetite dysregulation. Diet modifications, exercise, and psychological and medical interventions have been applied to alleviate food disorders, interrupting the vicious circle. Cognitive-behavioral intervention seems to be the mainstay of treatment, while the role of medical agents, such as GLP-1 analogs and naltrexone/bupropion, has emerged.

Molecular adaptations underlying high-frequency hearing in the brain of CF bats species

BACKGROUND

The majority of bat species have developed remarkable echolocation ability, especially for the laryngeally echolocating bats along with high-frequency hearing. Adaptive evolution has been widely detected for the cochleae in the laryngeally echolocating bats, however, limited understanding for the brain which is the central to echolocation signal processing in the auditory perception system, the laryngeally echolocating bats brain may also undergo adaptive changes.

RESULT

In order to uncover the molecular adaptations related with high-frequency hearing in the brain of laryngeally echolocating bats, the genes expressed in the brain of Rhinolophus ferrumequinum (CF bat) and Myotis pilosus (FM bat) were both detected and also compared. A total of 346,891 genes were detected and the signal transduction mechanisms were annotated by the most abundant genes, followed by the transcription. In hence, there were 3,088 DEGs were found between the two bat brains, with 1,426 highly expressed in the brain of R. ferrumequinum, which were significantly enriched in the neuron and neurodevelopmental processes. Moreover, we found a key candidate hearing gene, ADCY1, playing an important role in the R. ferrumequinum brain and undergoing adaptive evolution in CF bats.

CONCLUSIONS

Our study provides a new insight to the molecular bases of high-frequency hearing in two laryngeally echolocating bats brain and revealed different nervous system activities during auditory perception in the brain of CF bats.

Exposure to gestational diabetes mellitus in utero impacts hippocampal functional connectivity in response to food cues in children

Objectives

Intrauterine exposure to gestational diabetes mellitus (GDM) increases the risk of obesity in the offspring, but little is known about the underlying neural mechanisms. The hippocampus is crucial for food intake regulation and is vulnerable to the effects of obesity. The purpose of the study was to investigate whether GDM exposure affects hippocampal functional connectivity during exposure to food cues using functional magnetic resonance imaging.

Methods

Participants were 90 children age 7-11 years (53 females) who underwent an fMRI-based visual food cue task in the fasted state. Hippocampal functional connectivity (FC) was examined using generalized psychophysiological interaction in response to high-calorie food versus non-food cues. Food-cue induced hippocampal FC was compared between children with and without GDM exposure, while controlling for possible confounding effects of age, sex and waist-to-hip ratio.

Results

Children with GDM exposure exhibited stronger hippocampal FC to the insula and striatum (i.e., putamen, pallidum and nucleus accumbens) compared to unexposed children, while viewing high caloric food cues.

Conclusions

Intrauterine exposure to GDM was associated with higher food-cue induced hippocampal FC to reward processing regions. Future studies with longitudinal measurements are needed to clarify whether increased hippocampal FC to reward processing regions may raise the risk of the development of metabolic diseases later in life.

Global, neuronal or β cell-specific deletion of inceptor improves glucose homeostasis in male mice with diet-induced obesity

Insulin resistance is an early complication of diet-induced obesity (DIO)1, potentially leading to hyperglycaemia and hyperinsulinaemia, accompanied by adaptive β cell hypertrophy and development of type 2 diabetes2. Insulin not only signals via the insulin receptor (INSR), but also promotes β cell survival, growth and function via the insulin-like growth factor 1 receptor (IGF1R)3-6. We recently identified the insulin inhibitory receptor (inceptor) as the key mediator of IGF1R and INSR desensitization7. But, although β cell-specific loss of inceptor improves β cell function in lean mice7, it warrants clarification whether inceptor signal inhibition also improves glycaemia under conditions of obesity. We assessed the glucometabolic effects of targeted inceptor deletion in either the brain or the pancreatic β cells under conditions of DIO in male mice. In the present study, we show that global and neuronal deletion of inceptor, as well as its adult-onset deletion in the β cells, improves glucose homeostasis by enhancing β cell health and function. Moreover, we demonstrate that inceptor-mediated improvement in glucose control does not depend on inceptor function in agouti-related protein-expressing or pro-opiomelanocortin neurons. Our data demonstrate that inceptor inhibition improves glucose homeostasis in mice with DIO, hence corroborating that inceptor is a crucial regulator of INSR and IGF1R signalling.

Effects of Alterations in Acid-Base Effects on Insulin Signaling

Insulin tightly regulates glucose levels within a narrow range through its action on muscle, adipose tissue and the liver. The activation of insulin receptors activates multiple intracellular pathways with different functions. Another tightly regulated complex system in the body is acid-base balance. Metabolic acidosis, defined as a blood pH < 7.35 and serum bicarbonate < 22 mmol/L, has clear pathophysiologic consequences including an effect on insulin action. With the ongoing intake of typical acid-producing Western diets and the age-related decline in renal function, there is an increase in acid levels within the range considered to be normal. This modest increase in acidosis is referred to as "acid stress" and it may have some pathophysiological consequences. In this article, we discuss the effects of acid stress on insulin actions in different tissues.

Influence of insulin sensitivity on food cue evoked functional brain connectivity in children

Objective

Insulin resistance during childhood is a risk factor for developing type 2 diabetes and other health problems later in life. Studies in adults have shown that insulin resistance affects regional and network activity in the brain which are vital for behavior, e.g. ingestion and metabolic control. To date, no study has investigated whether brain responses to food cues in children are associated with peripheral insulin sensitivity.

Methods

We included 53 children (36 girls) between the age of 7-11 years, who underwent an oral Glucose Tolerance Test (oGTT) to estimate peripheral insulin sensitivity (ISI). Brain responses were measured using functional magnetic resonance imaging (fMRI) before and after glucose ingestion. We compared food-cue task-based activity and functional connectivity (FC) between children with low and high ISI, adjusted for age and BMIz.

Results

Independent of prandial state (i.e., glucose ingestion), children with lower ISI showed higher FC between the anterior insula and caudate and lower FC between the posterior insula and mid temporal cortex than children with higher ISI. Sex differences were found based on prandial state and peripheral insulin sensitivity in the insular FC. No differences were found on whole-brain food-cue reactivity.

Conclusions

Children with low peripheral insulin sensitivity showed differences in food cue evoked response particularly in insula functional connectivity. These differences might influence eating behavior and future risk of developing diabetes.

Mechanism of Acupuncture in Treating Obesity: Advances and Prospects

Obesity is a common metabolic syndrome that causes a significant burden on individuals and society. Conventional therapies include lifestyle interventions, bariatric surgery, and pharmacological therapies, which are not effective and have a high risk of adverse events. Acupuncture is an effective alternative for obesity, it modulates the hypothalamus, sympathetic activity and parasympathetic activity, obesity-related hormones (leptin, ghrelin, insulin, and CCK), the brain-gut axis, inflammatory status, adipose tissue browning, muscle blood flow, hypoxia, and reactive oxygen species (ROS) to influence metabolism, eating behavior, motivation, cognition, and the reward system. However, hypothalamic regulation by acupuncture should be further demonstrated in human studies using novel techniques, such as functional MRI (fMRI), positron emission tomography (PET), electroencephalogram (EEG), and magnetoencephalography (MEG). Moreover, a longer follow-up phase of clinical trials is required to detect the long-term effects of acupuncture. Also, future studies should investigate the optimal acupuncture therapeutic option for obesity. This review aims to consolidate the recent improvements in the mechanism of acupuncture for obesity as well as discuss the future research prospects and potential of acupuncture for obesity.

Exercise induces tissue-specific adaptations to enhance cardiometabolic health

The risk associated with multiple cancers, cardiovascular disease, diabetes, and all-cause mortality is decreased in individuals who meet the current recommendations for physical activity. Therefore, regular exercise remains a cornerstone in the prevention and treatment of non-communicable diseases. An acute bout of exercise results in the coordinated interaction between multiple tissues to meet the increased energy demand of exercise. Over time, the associated metabolic stress of each individual exercise bout provides the basis for long-term adaptations across tissues, including the cardiovascular system, skeletal muscle, adipose tissue, liver, pancreas, gut, and brain. Therefore, regular exercise is associated with a plethora of benefits throughout the whole body, including improved cardiorespiratory fitness, physical function, and glycemic control. Overall, we summarize the exercise-induced adaptations that occur within multiple tissues and how they converge to ultimately improve cardiometabolic health.

The magnitude and direction of the relationship between risk factor and cognition depends on age: a pooled analysis of 5 community-based studies

The mixed evidence of the association between high levels of cardiovascular risk factors (CVRF) and the risk for cognitive impairment may be due to confounding of age across studies. We pooled and harmonized individual-level data (30,967 persons, age range 42-96 years) from five prospective cohorts to investigate by 1 year age increments to investigate whether or not there is change in slope describing the association of CVRF to a cognitive outcome (Digit Symbol Substitution Test; DSST). The CVRF included: systolic and diastolic blood pressure, total cholesterol, fasting glucose and body mass index. Linear and quadratic piecewise regression models were fit to the trajectory patterns of these slopes (betas). The pattern of yearly slope changes showed higher CVRF were associated with lower DSST, but associations attenuated toward zero as age increased for all but DBP where 1 year slopes for DBP changed direction from negative to positive from mid- to late-age. Age is not only a driver of cognitive decline-age also modifies the direction and strength of the association of cognitive function to CVRF and cohort age may be one reason why the evidence for CVRF-CD association is mixed.

Food addiction and its impact on weight status in children and adolescents: The mediating role of responsive eating pattern

AIMS

This research explores the relationships between food addiction (FA), eating behaviours, and weight status in school-aged children and adolescents, aiming to understand how FA influences weight.

METHODS

By using a cross-sectional design, 426 healthy children and their parents were enroled in Eastern China. FA was assessed using the Chinese version of the Dimensional Yale Food Addiction Scale for Children 2.0 (dYFAS-C 2.0), while eating patterns were identified using latent profile analysis (LPA) derived from the Children's Eating Behaviour Questionnaire (CEBQ). Weight status was indicated by Body Mass Index Z Score (BMIZ) and waist-to-height ratio (WHtR). The associations among FA, eating patterns, and weight status were explored using structural equation modelling (SEM).

RESULTS

Two eating patterns, the Responsive and the Controlled Eating Patterns, were identified. The Responsive Eating Pattern was characterized by high food responsiveness, enjoyment of food, emotional eating, fast eating, low satiety responsiveness, and food fussiness and was associated with FA and weight status (p < 0.001). The SEM results showed the Responsive Eating Pattern partially mediated the relationship between FA and weight status, with a mediation effect of 1.183 (95% CI [0.784, 1.629]) for BMIZ and 0.043 (95% CI [0.025, 0.063]) for WHtR.

CONCLUSION

Increased FA is associated with a higher weight status through a specific eating behaviour pattern characterized by high responsiveness to food, emotional and rapid eating habits, and low satiety. The findings suggest that targeted interventions should take these eating behaviour patterns into account to reduce the impact of FA on weight status among children and adolescents.

A Comprehensive Review of Fear of Eating Behaviour in Individuals with Diabetes: Exploring Therapeutic Interventions for Diabulimia

OBJECTIVE

This review aims to comprehensively analyse the fear of eating behaviour in individuals with diabetes, known as diabulimia or ED-DMT1. The emotional and psychological factors contributing to disordered eating behaviours, their impact on diabetes management, and potential consequences on physical health are explored. Various therapeutic interventions, including cognitive-behavioural therapy and psychological support, the role of nutrition education, individualized treatment plans support groups in managing fear of eating behaviour in diabetes are examined and discussed.

METHODS

A comprehensive literature search was conducted to identify relevant studies, articles, and guidelines related to fear of eating behaviour in diabetes. The search included databases such as PubMed and Google Scholar using appropriate keywords.

RESULTS

The review highlights the emotional and psychological factors that contribute to the fear of eating behaviour in diabetes, including body image concerns, fear of weight gain, and disordered eating patterns. These behaviours can significantly impact diabetes management, leading to poor glycaemic control, increased risk of complications, and reduced overall well-being. Various therapeutic interventions, such as cognitive-behavioural therapy and mindfulness-based interventions, have shown promise in addressing the fear of eating behaviour.

CONCLUSION

A multidisciplinary strategy combining healthcare specialists specializing in diabetes management, mental health, and nutrition is required for effective therapy of fear of eating behaviour in diabetes. Cognitive-behavioral therapy and mindfulness-based therapies, as well as psychological support, have shown potential in reducing the fear of eating habits. This analysis gives significant information for healthcare providers to help patients with diabetes who are afraid of eating and urges additional research on the topic.

Association of the Triglyceride-Glucose Index With Risk of Alzheimer's Disease: A Prospective Cohort Study

INTRODUCTION

Triglyceride-glucose index (TyG) is a reliable surrogate marker of insulin resistance, and insulin resistance has been implicated in Alzheimer's disease pathophysiology. However, the relationship between the TyG index and Alzheimer's disease remains unclear. This study aimed to evaluate the association of the TyG index with the risk of Alzheimer's disease.

METHODS

This prospective study included 2,170 participants free of Alzheimer's disease from the Framingham Heart Study Offspring Cohort Exam 7 (1998-2001), whose follow-up data were collected until 2018. The TyG index was calculated as Ln(fasting triglyceride [mg/dL] × fasting glucose [mg/dL]/2). The association of the TyG index with Alzheimer's disease was evaluated by competing risk regression model. Statistical analyses were performed in 2023.

RESULTS

During a median follow-up of 13.8 years, 163 (7.5%) participants developed Alzheimer's disease. When compared with the reference (TyG index ≤8.28), a significantly elevated risk of Alzheimer's disease was seen in the group with a triglyceride-glucose index of 8.68-9.09 (adjusted hazard ratio=1.69, 95% CI=1.02, 2.81). When the TyG index was considered as a continuous variable, each unit increment in the TyG index was not significantly associated with the risk of Alzheimer's disease (adjusted hazard ratio=1.32, 95% CI=0.98, 1.77).

CONCLUSIONS

This study showed that moderately elevated TyG index was independently associated with a higher incidence of Alzheimer's disease. TheTyG index might be used to define a high-risk population of Alzheimer's disease.

An Update on the Interdisciplinary Dental Care Approach for Geriatric Diabetic Patients

Diabetes mellitus is a prevalent health issue escalating worldwide that gives rise to numerous problems. Periodontal disorders are recognized as the sixth consequence associated with diabetes mellitus. Research shows that dental health affects overall health, and this knowledge is changing the dental field. The correct choice of glucose goal levels and the optimal selection of glucose-lowering medications are determined by a comprehensive geriatric assessment, an estimate of life expectancy, and a rationale for therapy at regular intervals in elderly diabetics. This article provides an overview of the correlation between diabetes and oral health, with a specific emphasis on xerostomia, periodontal disease, and dental caries. Thus, dentists play a significant role within the allied health profession by contributing to the provision of oral care for those diagnosed with diabetes, with a special focus on geriatric patients.

Slc12a2 loss in insulin-secreting β-cells links development of overweight and metabolic dysregulation to impaired satiation control of feeding

Male mice lacking the Na+-K+-2Cl- cotransporter Slc12a2 (Nkcc1) specifically in insulin-secreting β-cells (Slc12a2βKO) have reduced β-cell mass and mild β-cell secretory dysfunction associated with overweight, glucose intolerance, insulin resistance, and metabolic abnormalities. Here, we confirmed and extended previous results to female Slc12a2βKO mice, which developed a similar metabolic syndrome-like phenotype as males, albeit milder. Notably, male and female Slc12a2βKO mice developed overweight without consuming excess calories. Analysis of the feeding microstructure revealed that young lean Slc12a2βKO male mice ate meals of higher caloric content and at a relatively lower frequency than normal mice, particularly during the night. In addition, overweight Slc12a2βKO mice consumed significantly larger meals than lean mice. Therefore, the reduced satiation control of feeding precedes the onset of overweight and is worsened in older Slc12a2βKO mice. However, the time spent between meals remained intact in lean and overweight Slc12a2βKO mice, indicating conserved satiety responses to ad libitum feeding. Nevertheless, satiety was intensified during and after refeeding only in overweight males. In lean females, satiety responses to refeeding were delayed relative to age- and body weight-matched control mice but normalized in overweight mice. Since meal size did not change during refeeding, these data suggested that the satiety control of eating after fasting is impaired in lean Slc12a2βKO mice before the onset of overweight and independently of their reduced satiation responses. Therefore, our results support the novel hypothesis that reduced satiation precedes the onset of overweight and the development of metabolic dysregulation.NEW & NOTEWORTHY Obesity, defined as excess fat accumulation, increases the absolute risk for metabolic diseases. Although obesity is usually attributed to increased food intake, we demonstrate that body weight gain can be hastened without consuming excess calories. In fact, impaired meal termination control, i.e., satiation, is detectable before the development of overweight in an animal model that develops a metabolic syndrome-like phenotype.

Cognitive Performance during the Development of Diabetes in the Zucker Diabetic Fatty Rat

Increased insulin levels may support the development of neural circuits involved in cognition, while chronic mild inflammation may also result in cognitive impairment. This study aimed to gain more insight into whether cognition is already impacted during adolescence in a genetic rat model for obesity and type 2 diabetes. Visual discrimination learning throughout adolescence and the level of motivation during early adulthood were investigated in Zucker Diabetic Fatty (ZDF) obese and ZDF lean rats using operant touchscreens. Blood glucose, insulin, and lipids were longitudinally analyzed. Histological analyses were performed in the liver, white adipose tissues, and the prefrontal cortex. Prior to the experiments with the genetic ZDF research model, all experimental assays were performed in two groups of outbred Long Evans rats to investigate the effect of different feeding circumstances. Adolescent ZDF obese rats outperformed ZDF lean rats on visual discrimination performance. During the longitudinal cognitive testing period, insulin levels sharply increased over weeks in ZDF obese rats and were significantly enhanced from 6 weeks of age onwards. Early signs of liver steatosis and enlarged adipocytes in white adipose tissue were observed in early adult ZDF obese rats. Histological analyses in early adulthood showed no group differences in the number of prefrontal cortex neurons and microglia, nor PSD95 and SIRT1 mRNA expression levels. Together, our data show that adolescent ZDF obese rats even display enhanced cognition despite their early diabetic profile.

Sphingolipid metabolism in brain insulin resistance and neurological diseases

Sphingolipids, as members of the large lipid family, are important components of plasma membrane. Sphingolipids participate in biological signal transduction to regulate various important physiological processes such as cell growth, apoptosis, senescence, and differentiation. Numerous studies have demonstrated that sphingolipids are strongly associated with glucose metabolism and insulin resistance. Insulin resistance, including peripheral insulin resistance and brain insulin resistance, is closely related to the occurrence and development of many metabolic diseases. In addition to metabolic diseases, like type 2 diabetes, brain insulin resistance is also involved in the progression of neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. However, the specific mechanism of sphingolipids in brain insulin resistance has not been systematically summarized. This article reviews the involvement of sphingolipids in brain insulin resistance, highlighting the role and molecular biological mechanism of sphingolipid metabolism in cognitive dysfunctions and neuropathological abnormalities of the brain.

The concept of "metabolic jet lag" in the pathophysiology of bipolar disorder: implications for research and clinical care

Bipolar disorder (BD) is a potentially chronic mental disorder marked by recurrent depressive and manic episodes, circadian rhythm disruption, and changes in energetic metabolism. "Metabolic jet lag" refers to a state of shift in circadian patterns of energy homeostasis, affecting neuroendocrine, immune, and adipose tissue function, expressed through behavioral changes such as irregularities in sleep and appetite. Risk factors include genetic variation, mitochondrial dysfunction, lifestyle factors, poor gut microbiome health and abnormalities in hunger, satiety, and hedonistic function. Evidence suggests metabolic jet lag is a core component of BD pathophysiology, as individuals with BD frequently exhibit irregular eating rhythms and circadian desynchronization of their energetic metabolism, which is associated with unfavorable clinical outcomes. Although current diagnostic criteria lack any assessment of eating rhythms, technological advancements including mobile phone applications and ecological momentary assessment allow for the reliable tracking of biological rhythms. Overall, methodological refinement of metabolic jet lag assessment will increase knowledge in this field and stimulate the development of interventions targeting metabolic rhythms, such as time-restricted eating.

Brain insulin action on peripheral insulin sensitivity in women depends on menstrual cycle phase

Insulin action in the human brain modulates eating behaviour, whole-body metabolism and body fat distribution1,2. In particular, brain insulin action increases whole-body insulin sensitivity, but these studies were mainly performed in lean men3,4. Here we investigate metabolic and hypothalamic effects of brain insulin action in women with a focus on the impact of menstrual cycle ( ClinicalTrials.gov registration: NCT03929419 ).Eleven women underwent four hyperinsulinemic-euglycemic clamps, two in the follicular phase and two in the luteal phase. Brain insulin action was introduced using nasal insulin spray5-7 and compared to placebo spray in a fourfold crossover design with change in glucose infusion rate as the primary endpoint. Here we show that during the follicular phase, more glucose has to be infused after administration of nasal insulin than after administration of placebo. This remains significant after adjustment for blood glucose and insulin. During the luteal phase, no significant influence of brain insulin action on glucose infusion rate is detected after adjustment for blood glucose and insulin (secondary endpoint). In 15 other women, hypothalamic insulin sensitivity was assessed in a within-subject design by functional magnetic resonance imaging with intranasal insulin administration8. Hypothalamus responsivity is influenced by insulin in the follicular phase but not the luteal phase.Our study therefore highlights that brain insulin action improves peripheral insulin sensitivity also in women but only during the follicular phase. Thus, brain insulin resistance could contribute to whole-body insulin resistance in the luteal phase of the menstrual cycle.

The neuromedin U system: Pharmacological implications for the treatment of obesity and binge eating behavior

Neuromedin U (NMU) is a bioactive peptide produced in the gut and in the brain, with a role in multiple physiological processes. NMU acts by binding and activating two G protein coupled receptors (GPCR), the NMU receptor 1 (NMU-R1), which is predominantly expressed in the periphery, and the NMU receptor 2 (NMU-R2), mainly expressed in the central nervous system (CNS). In the brain, NMU and NMU-R2 are consistently present in the hypothalamus, commonly recognized as the main "feeding center". Considering its distribution pattern, NMU revealed to be an important neuropeptide involved in the regulation of food intake, with a powerful anorexigenic ability. This has been observed through direct administration of NMU and by studies using genetically modified animals, which revealed an obesity phenotype when the NMU gene is deleted. Thus, the development of NMU analogs or NMU-R2 agonists might represent a promising pharmacological strategy to treat obese individuals. Furthermore, NMU has been demonstrated to influence the non-homeostatic aspect of food intake, playing a potential role in binge eating behavior. This review aims to discuss and summarize the current literature linking the NMU system with obesity and binge eating behavior, focusing on the influence of NMU on food intake and the neuronal mechanisms underlying its anti-obesity properties. Pharmacological strategies to improve the pharmacokinetic profile of NMU will also be reported.

Effect and Mechanism of Sodium Butyrate on Neuronal Recovery and Prognosis in Diabetic Stroke

Ischemic stroke is a cerebrovascular lesion caused by local ischemia and hypoxia. Diabetes mellitus (DM) is a chronic inflammatory disease that disturbs immune homeostasis and predisposes patients to ischemic stroke. The mechanism by which DM exacerbates stroke remains unclear, although it may involve disturbances in immune homeostasis. Regulatory T cells (Tregs) play a regulatory role in many diseases, but the mechanism of Tregs in diabetes complicated by stroke remains unclear. Sodium butyrate is a short-chain fatty acid that increases Treg levels. This study examined the role of sodium butyrate in the prognosis of neurological function in diabetic stroke and the mechanism by which Tregs are amplified in the bilateral cerebral hemispheres. We evaluated the brain infarct volume, observed 48-h neuronal injury and 28-day behavioral changes, and calculated the 28-day survival rate in mice. We also measured Treg levels in peripheral blood and brain tissue, recorded changes in the blood‒brain barrier and water channel proteins and neurotrophic changes in mice, measured cytokine levels and peripheral B-cell distribution in bilateral hemispheres and peripheral blood, and examined the polarization of microglia and the distribution of peripheral T-cell subpopulations in bilateral hemispheres. Diabetes significantly exacerbated the poor prognosis and neurological deficits in mice with stroke, and sodium butyrate significantly improved infarct volume, prognosis, and neurological function and showed different mechanisms in brain tissue and peripheral blood. The potential regulatory mechanism in brain tissue involved modulating Tregs/TGF-β/microglia to suppress neuroinflammation, while that in peripheral blood involved improving the systemic inflammatory response through Tregs/TGF-β/T cells.

Dorsal striatal response to taste is modified by obesity and insulin resistance

OBJECTIVE

In preclinical models, insulin resistance in the dorsal striatum (DS) contributes to overeating. Although human studies support the concept of central insulin resistance, they have not investigated its effect on consummatory reward-induced brain activity.

METHODS

Taste-induced activation was assessed in the caudate and putamen of the DS with blood oxygen level-dependent (BOLD) functional magnetic resonance imaging. Three phenotypically distinct groups were studied: metabolically healthy lean, metabolically healthy obesity, and metabolically unhealthy obesity (MUO; presumed to have central insulin resistance). Participants with MUO also completed a weight loss intervention followed by a second functional magnetic resonance imaging session.

RESULTS

The three groups were significantly different at baseline consistent with the design. The metabolically healthy lean group had a primarily positive BOLD response, the MUO group had a primarily negative BOLD response, and the metabolically healthy obesity group had a response in between the two other groups. Food craving was predicted by taste-induced activation. After weight loss in the MUO group, taste-induced activation increased in the DS.

CONCLUSIONS

These data support the hypothesis that insulin resistance and obesity contribute to aberrant responses to taste in the DS, which is only partially attenuated by weight loss. Aberrant responses to food exposure may be a barrier to weight loss.