Cognition, Brain Structure, and Brain Function in Individuals with Obesity and Related Disorders

A comparative study of cognitive function and reaction time in obese and non-obese adults

OBJECTIVE

Obesity may negatively affect the physical health and cognitive functions of individuals and delay their reaction time to stimuli. However, the association among obesity, cognitive functions, and reaction times is yet to be fully elucidated. The aim of this study was to assess the effect of obesity on cognitive functions and visual and auditory reaction times in adults.

METHODS

Data of 100 participants (50 obese and 50 normal) were analyzed in the study. Anthropometric parameters and 24-h dietary recall data were recorded. The Montreal Cognitive Assessment (MoCA) was used to evaluate the cognitive functions, Simple Reaction Time Task (SRTT)-Visual and SRTT-Auditory were used to assess visual and auditory reaction times of the participants, respectively.

RESULTS

The mean MoCA score of the obese was significantly lower than normal (17.46 and 25.22, respectively; p < 0.001). In addition, the mean auditory (p < 0.001) and visual (p < 0.05) reaction times of obese were significantly longer than normal. Similarly, this condition was also observed for the fastest and lowest values of auditory and visual reaction times. Additionally, obesity caused a decrease in the MoCA score (β = -0.762; p < 0.001) and delayed visual (β = 0.423; p < 0.001) and auditory (β = 0.590; p < 0.001) reactions. The negative effect of obesity was maintained after controlling for potential factors (MoCA, β = -0.594; p < 0.001; SRTT-Auditory, β = 0.409; p < 0.01; SRTT-Visual, β = 0.330; p < 0.05).

CONCLUSION

Obese participants showed worse cognitive, auditory and visual performance. Additional research will be necessary in the future to shed light on the fundamental mechanisms involved.

Normal-weight obesity subtypes and 10-year risks of major vascular diseases in 0.3 million adults

BACKGROUND & AIMS

Obesity directly contributes to the progression of cardiovascular disease, but little is known about the association and risk attribution of normal-weight obesity subtypes with the incidence of major vascular events (MVEs) and their subtypes.

METHODS

This is a prospective cohort study based on the China Kadoorie Biobank (CKB). A total of 308,071 individuals with no prior vascular diseases or cancer were included at baseline. The incidence of MVEs and their subtypes were recorded during follow-up. Adjusted hazard ratios (HRs) for each disease were yielded by Cox regression.

RESULTS

During a median follow-up of 10.3 years, 62,040 MVEs occurred, with the adjusted HRs (95 % confidence intervals) were 1.11 (1.09-1.13) for normal-weight general obesity (NWGO), 1.27 (1.23-1.31) for normal-weight central obesity (NWCO), and 1.30 (1.27-1.33) for normal-weight central and general obesity (NWCGO). For subtypes of MVEs, increased waist circumference (WC) was associated with excess risk of ischaemic heart disease (IHD) independent of body fat percent (BF%) levels (HR range: 1.30-1.69 in men; 1.36-1.55 in women), while the risk plateaued with rising BF% within each WC quartile. However, even in men with lower WC (≤78 cm [median]), the risks of cerebrovascular disease (CeVD), particularly ischaemic stroke (IS), were increased with higher BF% (all P < 0.01). Conversely, in women, independent dose-response associations were primarily observed between increasing WC and CeVD, with the highest risk observed for IS (HR 1.38, 1.31-1.47).

CONCLUSIONS

This study provided novel, sex-specific evidence that normal-weight obesity subtypes were associated with distinct risks of subtypes of MVEs, with elevated risks predominantly attributable to WC in women and both WC and BF% in men.

Altered gray matter structural covariance networks in young adults with obesity

BACKGROUND

Overwhelming evidence showed that obesity was associated with abnormal brain functional networks. However, the changes of structural covariance networks (SCNs) based on cortical thickness (CT) and cortical surface area (CSA) in obesity is still unclear.

METHODS

In this study, 243 young adults with obesity and matched 243 lean individuals were enrolled from the Human Connectome Project Release S1200 dataset. All participants underwent magnetic resonance imaging scans following clinical and neuropsychological assessments. SCNs matrices were constructed by Brain Connectivity Toolbox based on both CT and CSA. Nonparametric permutation tests were adopted to examine group differences of these matrices.

RESULTS

Young adults with obesity exhibited lower CSA of left entorhinal cortex, but higher CT of both left rostral anterior cingulate cortex and right superior parietal lobule, as well as lower CT of left temporal pole. While in terms of global network measures, there were no significant group differences; in terms of nodal network measures, young adults with obesity exhibited alterations in widespread brain regions including left posterior cingulate cortex, bilateral superior frontal gyrus, left entorhinal cortex and right insula.

CONCLUSIONS

Young adults with obesity exhibited abnormal nodal network measures in widespread brain regions involved in default mode network, central executive network and salience network. These findings indicate the adverse effects of obesity on young adults might be associated with the altered triple network.

Cardiorespiratory Fitness and Sleep, but not Physical Activity, are Associated with Functional Connectivity in Older Adults

BACKGROUND

Aging results in changes in resting state functional connectivity within key networks associated with cognition. Cardiovascular function, physical activity, sleep, and body composition may influence these age-related changes in the brain. Better understanding these associations may help clarify mechanisms related to brain aging and guide interventional strategies to reduce these changes.

METHODS

In a large (n = 398) sample of healthy community dwelling older adults that were part of a larger interventional trial, we conducted cross sectional analyses of baseline data to examine the relationships between several modifiable behaviors and resting state functional connectivity within networks associated with cognition and emotional regulation. Additionally, maximal aerobic capacity, physical activity, quality of sleep, and body composition were assessed. Associations were explored both through correlation and best vs. worst group comparisons.

RESULTS

Greater cardiovascular fitness, but not larger quantity of daily physical activity, was associated with greater functional connectivity within the Default Mode (p = 0.008 r = 0.142) and Salience Networks (p = 0.005, r = 0.152). Better sleep (greater efficiency and fewer nighttime awakenings) was also associated with greater functional connectivity within multiple networks including the Default Mode, Executive Control, and Salience Networks. When the population was split into quartiles, the highest body fat group displayed higher functional connectivity in the Dorsal Attentional Network compared to the lowest body fat percentage (p = 0.011; 95% CI - 0.0172 to - 0.0023).

CONCLUSION

These findings confirm and expand on previous work indicating that, in older adults, higher levels of cardiovascular fitness and better sleep quality, but not greater quantity of physical activity, total sleep time, or lower body fat percentage are associated with increased functional connectivity within key resting state networks.

Metabolic dysfunction-associated steatotic liver disease is associated with effects on cerebral perfusion and white matter integrity

It is unclear whether early metabolic and inflammatory aberrations in the liver are associated with detrimental changes in brain structure and cognitive function. This cross-sectional study examines putative associations between metabolic dysfunction-associated steatotic liver disease (MASLD) and brain health in 36-55 year-old participants with obesity (n = 70) from the BARICO study (BAriatric surgery Rijnstate and Radboudumc neuroImaging and Cognition in Obesity). The participants underwent brain magnetic resonance imaging to study brain volumes and cortical thickness (3T MRI including T1-weighted magnetization-prepared rapid gradient-echo sequence), cerebral blood perfusion (arterial spin labeling) and white matter integrity (diffusion weighted imaging to assess mean-skeletonized mean diffusivity and fluid-attenuated inversion recovery to detect the presence of white matter hyperintensities (WMH)). The participants additionally performed neuropsychological tests to assess global cognition, working and episodic memory, verbal fluency and the ability to shift attention. Liver biopsies were collected and liver dysfunction was examined with histopathological, biochemical, and gene expression analyses. Linear regression analyses were performed between liver and brain parameters and the influence of body-mass index, diabetes and hypertension was explored. Early stages of liver disease were not associated with cognitive status but with cerebrovascular changes independently of age, sex, BMI, diabetes and hypertension: hepatic fibrosis development was associated with higher spatial coefficient of variation (sCoV) in the nucleus accumbens (NAcc), reflecting greater variations in cerebral perfusion and reduced vascular efficiency. Elevated hepatic levels of free cholesterol and cholesteryl esters were associated with increased WMH, indicating cerebral small vessel disease. RNA-seq and pathway analyses identified associations between sCoV in NAcc and WMH and the expression of hepatic genes involved in inflammation and cellular stress. Additionally, sCoV in NAcc correlated with plasma IL-6 levels suggesting that systemic-low grade inflammation may, at least partly, mediate this relationship. In conclusion, this study demonstrates that specific features of liver dysfunction (e.g. free cholesterol, onset of fibrosis) are associated with subtle cerebrovascular impairments, when changes in cognitive performance are not yet noticeable. These findings highlight the need for future research on therapeutic strategies that normalize metabolic-inflammatory aberrations in the liver to reduce the risk of cognitive decline.

Association of obesity to reaction time and visual memory in schizophrenia

Background

Both overweight and cognitive deficits are common among people with schizophrenia (SZ) and schizoaffective disorder. The results in earlier studies have been inconsistent on whether overweight is associated with cognitive deficits in psychotic disorders.

Aims

Our aim in this study was to detect possible associations between obesity and cognitive deficits among study participants with SZ and schizoaffective disorder.

Methods

The study sample included 5382 participants with a clinical diagnosis of SZ or schizoaffective disorder selected from the Finnish SUPER study. Obesity was measured both with body-mass index and waist circumference. The cognitive performance was evaluated with two tests from the Cambridge automated neuropsychological test battery: Reaction time was evaluated with the 5-choice serial reaction time task. Visual memory was evaluated with the paired associative learning test. The final analysis included a total sample of 4498 participants applicable for the analysis of the reaction time and 3967 participants for the analysis of the visual memory.

Results

Obesity measured with body-mass index was associated with better performance in reaction time task among both female and male participants. Among male participants, overweight was associated with better performance in the visual memory test. The waist circumference was not associated with cognitive measures.

Conclusions

The results suggest that obesity in people with SZ or schizoaffective disorder might not be associated with cognitive deficits but instead with better cognitive performance. The results were opposite from earlier literature on the general population. More research is required to better understand whether the results might be partly caused by the differences in the etiology of obesity between the general population and people with SZ.

Inflammation and weight change related to neurocognitive and functional impairment in diabetes and psychiatric disorders

INTRODUCTION

Obesity is a global pandemic associated with various cardio-metabolic and psychiatric disorders. Neurocognitive and functional deficits have been associated with several somatic and psychiatric disorders. Adiposity-related inflammation has recently emerged as a key risk factor for neurocognitive and functional impairments. This prospective transdiagnostic study aimed to investigate the role of adiposity-related inflammatory markers in neurocognitive and functional outcomes associated with weight changes.

METHODS

Peripheral blood inflammatory and oxidative stress biomarkers and neurocognitive and functional performance were assessed twice over 1 year in 165 individuals, including 30 with schizophrenia, 42 with bipolar disorder, 35 with major depressive disorder, 30 with type 2 diabetes mellitus (T2DM), and 28 healthy controls. Participants were stratified by body mass index into categories of type 2 obesity (T2OB; n=30), type 1 obesity (T1OB; n=42), overweight (OW; n=53), and average weight (NW; n=40). Mixed one-way analysis of covariance and linear and binary logistic regression analyses were performed.

RESULTS

Compared with NW, T2OB and T1OB were significantly associated with impaired neurocognitive and functional performance (p<0.01; η2p=0.06-0.12) and higher levels of C-reactive protein and platelets (PLT) (p<0.01; η2p=0.08-0.16), with small-to-moderate effect sizes. IL-6, IL-10, and PLT were key factors for detecting significant weight changes in T1OB and T2OB over time. Regression models revealed that inflammatory and oxidative stress biomarkers and cellular adhesion molecules were significantly associated with neurocognitive and functional performance (p<0.05).

DISCUSSION

Obesity is characterized by neurocognitive and functional impairments alongside low-grade systemic inflammation. Adiposity-related inflammatory biomarkers may contribute to neurocognitive and functional decline in individuals with T2DM and psychiatric disorders. Our data suggest that these biomarkers facilitate the identification of specific subgroups of individuals at higher risk of developing obesity.

Fatness but Not Fitness Linked to BrainAge: Longitudinal Changes in Brain Aging during an Exercise Intervention

PURPOSE

Fitness, physical activity, body composition, and sleep have all been proposed to explain differences in brain health. We hypothesized that an exercise intervention would result in improved fitness and body composition and would be associated with improved structural brain health.

METHODS

In a randomized controlled trial, we studied 485 older adults who engaged in an exercise intervention ( n = 225) or a nonexercise comparison condition ( n = 260). Using magnetic resonance imaging, we estimated the physiological age of the brain (BrainAge) and derived a predicted age difference compared with chronological age (brain-predicted age difference (BrainPAD)). Aerobic capacity, physical activity, sleep, and body composition were assessed and their impact on BrainPAD explored.

RESULTS

There were no significant differences between experimental groups for any variable at any time point. The intervention group gained fitness, improved body composition, and increased total sleep time but did not have significant changes in BrainPAD. Analyses of changes in BrainPAD independent of group assignment indicated significant associations with changes in body fat percentage ( r (479) = 0.154, P = 0.001), and visceral adipose tissue (VAT) ( r (478) = 0.141, P = 0.002), but not fitness ( r (406) = -0.075, P = 0.129), sleep ( r (467) range, -0.017 to 0.063; P range, 0.171 to 0.710), or physical activity ( r (471) = -0.035, P = 0.444). With linear regression, changes in body fat percentage and VAT significantly predicted changes in BrainPAD ( β = 0.948, P = 0.003) with 1-kg change in VAT predicting 0.948 yr of change in BrainPAD.

CONCLUSIONS

In cognitively normal older adults, exercise did not appear to impact BrainPAD, although it was effective in improving fitness and body composition. Changes in body composition, but not fitness, physical activity, or sleep impacted BrainPAD. These findings suggest that focus on weight control, particularly reduction of central obesity, could be an interventional target to promote healthier brains.

Hippocampal proteomic changes in high-fat diet-induced obese mice associated with memory decline

Substantial evidence suggest that chronic consumption of high-fat diets (HFDs) can lead to obesity, abnormal metabolism, as well as cognitive impairment. Molecular and cellular changes regarding hippocampal dysfunctions have been identified in multiple HFD animal models. Therefore, in-depth identification of expression changes of hippocampal proteins is critical for understanding the mechanism of HFD-induced cognitive deficits. In this study, we fed 3-week-old male mice with HFD for 3 months to generate obese mice who exhibit systemic metabolic abnormality and learning and memory decline. Using an iTRAQ-labeled proteomic analysis, we identified a total of 82 differentially expressed proteins (DEPs) in the hippocampus upon HFD with 35 up-regulated proteins and 47 down-regulated proteins. Functional enrichment indicated that these DEPs were predominantly enriched in regulation of catabolic process, dendritic shaft, neuron projection morphogenesis and GTPase regulator activity. Protein-protein interaction enrichment showed that the DEPs are mostly enriched in postsynaptic functions; and of them, six proteins (i.e., DLG3, SYNGAP1, DCLK1, GRIA4, GRIP1, and ARHGAP32) were involved in several functional assemblies of the postsynaptic density including G-protein signaling, scaffolding and adaptor, kinase and AMPA signaling, respectively. Collectively, our findings suggest that these DEPs upon HFD might contribute to memory decline by disturbing neuronal and postsynaptic functions in the hippocampus.

Sex-Specific Association of Body Mass Index with Hippocampal Subfield Volume and Cognitive Function in Non-Demented Chinese Older Adults

Recent research suggests a possible association between midlife obesity and an increased risk of dementia in later life. However, the underlying mechanisms remain unclear. Little is known about the relationship between body mass index (BMI) and hippocampal subfield atrophy. In this study, we aimed to explore the associations between BMI and hippocampal subfield volumes and cognitive function in non-demented Chinese older adults. Hippocampal volumes were assessed using structural magnetic resonance imaging. Cognitive function was evaluated using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). A total of 66 participants were included in the final analysis, with 35 females and 31 males. We observed a significant correlation between BMI and the hippocampal fissure volume in older females. In addition, there was a negative association between BMI and the RBANS total scale score, the coding score, and the story recall score, whereas no significant correlations were observed in older males. In conclusion, our findings revealed sex-specific associations between BMI and hippocampal subfield volumes and cognitive performance, providing valuable insights into the development of effective interventions for the early prevention of cognitive decline.

Swimming training and caffeine supplementation protects against metabolic syndrome-induced nuclear factor-κB activation and cognitive deficits in rats

Metabolic syndrome (MS) is a disorder that increasingly affects the world population, mainly because of changes in lifestyle and dietary habits. In this regard, both physical exercise and caffeine are low-cost and easily accessible therapies that separately have shown positive effects against metabolic disorders. Therefore, we hypothesized that physical exercise combined with caffeine could have a synergistic effect in the treatment of MS, risk factors, and cognitive deficits. Animals were divided into 8 groups and received fructose (15% w/v) or vehicle for 10 weeks. Swimming training and caffeine (6 mg/kg) started 4 weeks after fructose administration. Trained animals presented decreased body weight and visceral fat mass and increased soleus weight compared with untrained fructose-treated animals. Caffeine supplementation also prevented the gain of visceral fat mass induced by fructose. Furthermore, both treatments reversed fructose-induced decrease in glucose clearance over time and fructose-induced increase in 4-hydroxynonenal and nuclear factor-κB immunoreactivity. Physical training also improved the lipidic profile in fructose-treated animals (high-density lipoprotein, low-density lipoprotein, and triglycerides), improved short-term, long-term, and localization memory, and reversed the fructose-induced deficit in short-term memory. Physical training also increased nuclear factor erythroid 2-related factor 2 immunoreactivity per se. Considering that physical training and caffeine reversed some of the damages induced by fructose it is plausible to consider these treatments as alternative, nonpharmacological, and low-cost therapies to help reduce MS-associated risk factors; however, combined treatments did not show additive effects as hypothesized.

Palmitic acid, but not other long-chain saturated fatty acids, increases S100B protein and TNF-α secretion by astrocytes

Obesity is a health problem that involves fat accumulation in adipose and other tissues and causes cell dysfunction. Long-chain saturated fatty acids can induce and propagate inflammation, which may also contribute to the brain alterations found in individuals with obesity. Fatty acids accumulate in astrocytes in situations of blood‒brain barrier disruption, such as inflammatory conditions. Furthermore, the increase in tumor necrosis factor-alpha (TNF-α) and S100 calcium-binding protein B (S100B) secretion is considered an essential component of the inflammatory response. We hypothesize that through their action on astrocytes, long-chain saturated fatty acids mediate some of the brain alterations observed in individuals with obesity. Here, we investigate the direct effect of long-chain fatty acids on astrocytes. Primary astrocyte cultures were incubated for 24 hours with myristic, palmitic, stearic, linoleic, or α-linolenic acids (25-100 µM). All saturated fatty acids tested led to an increase in TNF-α secretion, but only palmitic acid, one of the most common fatty acids, increased S100B secretion, indicating that S100B secretion is probably not caused in response to TNF-α release. Palmitic acid also caused nuclear migration of nuclear factor kappa B. Long-chain saturated fatty acids did not alter cell viability or redox status. In conclusion, long-chain saturated fatty acids can alter astrocytic homeostasis and may contribute to brain disorders associated with obesity, such as neuroinflammation.

Alisol A Exerts Neuroprotective Effects Against HFD-Induced Pathological Brain Aging via the SIRT3-NF-κB/MAPK Pathway

Chronic consumption of a high-fat diet (HFD) has profound effects on brain aging, which is mainly characterized by cognitive decline, inflammatory responses, and neurovascular damage. Alisol A (AA) is a triterpenoid with therapeutic potential for metabolic diseases, but whether it has a neuroprotective effect against brain aging caused by a HFD has not been investigated. Six-month-old male C57BL6/J mice were exposed to a HFD with or without AA treatment for 12 weeks. Behavioral tasks were used to assess the cognitive abilities of the mice. Neuroinflammation and changes in neurovascular structure in the brains were examined. We further assessed the mechanism by which AA exerts neuroprotective effects against HFD-induced pathological brain aging in vitro and in vivo. Behavioral tests showed that cognitive function was improved in AA-treated animals. AA treatment reduced microglia activation and inflammatory cytokine release induced by a HFD. Furthermore, AA treatment increased the number of hippocampal neurons, the density of dendritic spines, and the expression of tight junction proteins. We also demonstrated that AA attenuated microglial activation by targeting the SIRT3-NF-κB/MAPK pathway and ameliorated microglial activation-induced tight junction degeneration in endothelial cells and apoptosis in hippocampal neurons. The results of this study show that AA may be a promising agent for the treatment of HFD-induced brain aging.

Combination Therapy: A New Tool for the Management of Obesity

Obesity is a chronic lifestyle issue with devastating results. Behavioral changes are one of the initial lines of management strategies for obesity, but they are not very efficient management strategies. Many people also use surgical intervention to maintain a healthy weight, now considered to be the most common and effective obesity management. Chemically synthesized medicines fill the gap between lifestyle interventions and minimally invasive surgical management of obesity. The most common issue associated with monotherapy without side effects is its moderate effectiveness and higher dose requirement. Combination therapy is already used for many serious and complicated disease treatments and management and has shown efficacy as well. Generally, we use two or more medicines with different mechanisms of action for a better effect. The commonly used combination therapy for obesity management includes low-dose phentermine and prolonged and slow-releasing mechanism topiramate; naltrexone, and bupropion. Phentermine with inhibitors of Na-glucose cotransporter-2 or glucagon-like peptide-1 (GLP-1) agonists with gastric hormone or Na-glucose cotransporter-2 are two more viable combo therapy. This combination strategy aims to achieve success in bariatric surgery and the scientific community is working in this direction.

Inflammatory Pathways in Overweight and Obese Persons as a Potential Mechanism for Cognitive Impairment and Earlier Onset Alzeihmer's Dementia in the General Population: A Narrative Review

The overweight status or obesity can be confirmed through classical methods such as the body mass index (BMI) and the waist-to-hip ratio (WHR). Apart from metabolic issues such as atherosclerosis, liver steatosis, or diabetes mellitus, long-term obesity or overweight status can pose a risk for cardiovascular and neurovascular complications. While some acute adverse events like coronary syndromes of strokes are well-documented to be linked to an increased body mass, there are also chronic processes that, due to their silent onset and evolution, are underdiagnosed and not as thoroughly studied. Through this review, we aimed to collect all relevant data with regard to the long-term impact of obesity on cognitive function in all ages and its correlation with an earlier onset of dementia such as Alzheimer's disease (AD). The exact mechanisms through which a decline in cognitive functions occurs in overweight or obese persons are still being discussed. A combination of factors has been acknowledged as potential triggers, such as a sedentary lifestyle and stress, as well as a genetic predisposition, for example, the apolipoprotein E (ApoE) alleles in AD. Most research highlights the impact of vascular dysfunction and systemic inflammation on the nervous system in patients with obesity and the subsequent neurological changes. Obesity during the early to mid-ages leads to an earlier onset of cognitive dysfunction in various forms. Also, lifestyle intervention can reverse cognitive dysfunction, especially dieting, to encourage weight loss.

Cognition and obesity in adults with epilepsy

Introduction

Objective: to assess the occurrence of overweight/obesity in patient with epilepsy (PWEs) and to relate it to cognitive aspects and clinical variables. Methodology: the measurements of waist circumference, calf circumference, arm circumference, and the body mass index were related to the scores of the Mini-Mental State Examination and the Brief Cognitive Battery-Edu, as well as to the clinical variables of 164 PWEs, with a significance level of p < 0.05. Data were compared to a similar control group (CG) comprising 71 cases. Linear and multiple logistic regression models were used to assess factors related to cognitive aspects. Results: the mean age of the PWEs was 49.8 ± 16.6 years with a mean length of epilepsy of 22 ± 15.9 years. Overweight/obesity occurred in 106 (64.6 %) PWEs and in 42 (59.1 %) CG subjects. The PWEs had a worse performance in several cognitive functions when compared to CG subjects. In the PWEs, overweight/obesity was associated with lower educational level, older age, and cognitive impairment. Greater waist circumference, overweight, age at the first seizure, and use of polytherapy with antiseizure medications were predictive factors of memory impairment in multiple linear regression. Greater arm and calf circumference values were associated with better performance in several cognitive areas. Conclusion: the occurrence of overweight/obesity in PWEs and CG subjects was high. Cognitive impairment occurred in a high number of PWEs and was associated with overweight, greater waist circumference values, and clinical aspects of epilepsy. Better cognitive performance was associated with greater arm and calf circumference.

Mutation in the FUS nuclear localisation signal domain causes neurodevelopmental and systemic metabolic alterations

Variants in the ubiquitously expressed DNA/RNA-binding protein FUS cause aggressive juvenile forms of amyotrophic lateral sclerosis (ALS). Most FUS mutation studies have focused on motor neuron degeneration; little is known about wider systemic or developmental effects. We studied pleiotropic phenotypes in a physiological knock-in mouse model carrying the pathogenic FUSDelta14 mutation in homozygosity. RNA sequencing of multiple organs aimed to identify pathways altered by the mutant protein in the systemic transcriptome, including metabolic tissues, given the link between ALS-frontotemporal dementia and altered metabolism. Few genes were commonly altered across all tissues, and most genes and pathways affected were generally tissue specific. Phenotypic assessment of mice revealed systemic metabolic alterations related to the pathway changes identified. Magnetic resonance imaging brain scans and histological characterisation revealed that homozygous FUSDelta14 brains were smaller than heterozygous and wild-type brains and displayed significant morphological alterations, including a thinner cortex, reduced neuronal number and increased gliosis, which correlated with early cognitive impairment and fatal seizures. These findings show that the disease aetiology of FUS variants can include both neurodevelopmental and systemic alterations.

Body mass index, systemic inflammation and cognitive performance in adolescents: A cross-sectional study

BACKGROUND

Excessive body weight has been related to lower cognitive performance. One of the mechanisms through which excess body weight may affect cognition is inflammation.

HYPOTHESIS

Our hypothesis is that both body mass index (BMI) and circulating levels of inflammatory biomarkers will be negatively related to cognitive performance.

DESIGN

Cross-sectional study.

SETTING

Users of the public health centres of the Consorci Sanitari de Terrassa (Terrassa, Spain) between 2010 and 2017 aged 12-21 years.

PARTICIPANTS

One hundred and five adolescents (46 normoweight, 18 overweight, 41 obese).

MEASUREMENTS

Levels of high sensitivity C-reactive protein, interleukin 6, tumour necrosis factor α (TNFα) and fibrinogen were determined from blood samples. Cognitive performance was evaluated and six cognitive composites were obtained: working memory, cognitive flexibility, inhibitory control, decision-making, verbal memory, and fine motor speed. A single multivariate general lineal model was used to assess the influence of the four inflammatory biomarkers, as well as participants' BMI, sex, and age on the 6 cognitive indexes.

RESULTS

An inverse relationship between BMI and inhibitory control (F = 5.688, p = .019; β = -0.212, p = .031), verbal memory (F = 5.404, p = .022; β = -0.255, p = .009) and fine motor speed (F = 9.038, p = .003; β = -0.319, p = .001) was observed. Levels of TNFα and fibrinogen were inversely related to inhibitory control (F = 5.055, p = .027; β = -0.226, p = .021) and verbal memory (F = 4.732, p = .032; β = -0.274, p = .005), respectively.

LIMITATIONS

The cross-sectional nature of the study, the use of cognitive tests designed for clinical purposes, and the use of BMI as a proxy for adiposity are limitations of our study that must be taken into account when interpreting results.

CONCLUSIONS

Our data indicate that some components of executive functions, together with verbal memory, are sensitive to specific obesity-related inflammatory agents at early ages.

Mitochondria and Brain Disease: A Comprehensive Review of Pathological Mechanisms and Therapeutic Opportunities

Mitochondria play a vital role in maintaining cellular energy homeostasis, regulating apoptosis, and controlling redox signaling. Dysfunction of mitochondria has been implicated in the pathogenesis of various brain diseases, including neurodegenerative disorders, stroke, and psychiatric illnesses. This review paper provides a comprehensive overview of the intricate relationship between mitochondria and brain disease, focusing on the underlying pathological mechanisms and exploring potential therapeutic opportunities. The review covers key topics such as mitochondrial DNA mutations, impaired oxidative phosphorylation, mitochondrial dynamics, calcium dysregulation, and reactive oxygen species generation in the context of brain disease. Additionally, it discusses emerging strategies targeting mitochondrial dysfunction, including mitochondrial protective agents, metabolic modulators, and gene therapy approaches. By critically analysing the existing literature and recent advancements, this review aims to enhance our understanding of the multifaceted role of mitochondria in brain disease and shed light on novel therapeutic interventions.

Overweight or Obesity among Chinese Han People with Schizophrenia: Demographic, Clinical and Cognitive Correlations

People with schizophrenia are more likely to be afflicted by obesity or overweight compared to the general population. This study aimed to explore the incidence of overweight and obesity, clinical features and cognitive performance of Chinese Han patients with chronic schizophrenia who had overweight or obesity. We obtained data from 985 schizophrenia inpatients about overweight and obesity through body mass index (BMI). All patients were evaluated with the positive and negative syndrome scale, the Mini-mental State Examination (MMSE) and the repeated battery for evaluation of the neuropsychological status (RBANS) scale. We collected demographic and clinical data using self-reported questionnaires. We divided patients into normal weight (BMI < 24 kg/m2), overweight (24 ≤ BMI < 28 kg/m2) and obese (≥28 kg/m2) groups according to the Working Group on Obesity in China (WGOC) criteria. We compared the clinical data between the three groups and then conducted binary logistic regression and linear regression to assess variables that were significantly associated with overweight and obesity and higher BMI. Of the sample, 324 (32.9%) and 191 (19.4%) patients had overweight and obesity, respectively. Patients who had overweight and obesity were younger, had less education, had higher waist and hip circumferences, higher rates of diabetes and a higher sumPANSP score (compared with patients in the normal group, p < 0.05). There were more female patients with obesity (compared with patients in the normal and overweight groups, p < 0.05). Logistic regression analysis indicated that overweight and obesity were associated with sumPANSP (OR = 1.03, 95%CI = 1-1.061, p = 0.049) and diabetes (OR = 1.891, 95%CI = 1.255-2.849, p = 0.002). Further linear regression showed that age (B = -0.004, t = -2.83, p = 0.005), educational level (B = -0.037, t = -2.261, p = 0.024), diabetes (B = 0.133, t = 2.721, p = 0.007) and sumPANSP (B = 0.008, t = 2.552, p = 0.011) were risk factors for higher BMI. We did not find cognitive performance differences between patients with or without overweight and obesity. Overweight and obesity were associated with some demographic and clinical factors in patients with persistent schizophrenia.

Factors Associated with Poor Olfaction and Olfactory Decline in Older Adults in the ARIC Neurocognitive Study

Olfactory function has significant implications for human health, but few risk factors for olfactory decline have been identified. We examined the factors associated with olfactory status and decline over five years in the Atherosclerosis Risk in Communities (ARIC) Neurocognitive Study. A 12-item odor identification test was used to assess olfaction in 6053 participants in 2011-2013 (ARIC visit 5, mean age: 75.6, 41% male, 23% Black race) and in 3235 participants in 2016-2017 (visit 6). We used Poisson regression models to examine cross-sectional associations of a range of potential factors with the total odor identification errors (mean errors: 2.8 ± 2.4) in visit 5 participants. We used mixed-effect Poisson regression to examine associations with olfactory decline between visits 5 and 6. We also examined associations with visit 5 anosmia prevalence (847 cases, 14%) and incident anosmia between the two visits (510 cases, 16%) using Poisson models. Older age, male sex, lower education, Black race, APOE ε4 alleles, and diabetes were associated with higher odor identification errors and higher anosmia prevalence, and greater physical activity and hypertension with better olfaction. Age, male sex, lower education, Black race, APOE ε4 allele, and vitamin B12 levels were associated with incident anosmia over 5 years. Older age was associated with faster olfactory decline. Future studies with longer follow-ups are warranted.

The Obesity Paradox: Effect of Body Mass Index and Waist Circumference on Post-Stroke Cognitive Impairment

Background

Obesity is a risk factor for dementia within the old population however not within the middle-aged population, that is referred to the "obesity paradox". This study explored the association of body mass index (BMI) and waist circumference (WC) with post-stroke cognitive impairment (PSCI) in middle-aged (40-65 years) versus old population (≥ 65 years).

Methods

The current study enrolled 1735 individuals over the age of 40 who had their first ischemic stroke from the Impairment of Cognition and Sleep (ICONS) subgroup of the China National Stroke Registry-3 (CNSR-3). BMI and WC were used for the diagnosis of obesity and central obesity, respectively. PSCI was diagnosed according to the Montreal Cognitive Assessment (MoCA). The main clinical outcome was the incidence of PSCI assessed at three months after stroke. Multivariable regression analysis was performed to evaluate the association between obesity and three-month PSCI. Stratified analysis was also performed to explore the effect of age on the relationship between obesity and PSCI.

Results

In the general population, multivariable logistic regression found that the adjusted odds ratio (OR) with 95% confidence interval (CI) of general obesity was 1.45 (1.06-1.98) and that of central obesity was 1.54 (1.24-1.91) for the three-month incidence of PSCI. Stratified analysis by age showed that the adjusted OR with a 95% CI of general obesity was 1.84 (1.24-2.72) in middle-aged patients and 0.89 (0.52-1.54) in elderly patients (p-value for interaction = 0.05). Central obesity was associated with PSCI in all age groups: 1.57 (1.18-2.09) in middle-aged patients and 1.52 (1.08-2.15) in elderly patients (p-value for interaction= 0.93).

Conclusion

General obesity was related to an increased risk of PSCI in middle-aged but not elderly patients, whereas central obesity was associated with an increased risk of PSCI in all age groups, suggesting that the obesity paradox arises only obesity is outlined by BMI.

Neuro-Vulnerability in Energy Metabolism Regulation: A Comprehensive Narrative Review

This comprehensive narrative review explores the concept of neuro-vulnerability in energy metabolism regulation and its implications for metabolic disorders. The review highlights the complex interactions among the neural, hormonal, and metabolic pathways involved in the regulation of energy metabolism. The key topics discussed include the role of organs, hormones, and neural circuits in maintaining metabolic balance. The review investigates the association between neuro-vulnerability and metabolic disorders, such as obesity, insulin resistance, and eating disorders, considering genetic, epigenetic, and environmental factors that influence neuro-vulnerability and subsequent metabolic dysregulation. Neuroendocrine interactions and the neural regulation of food intake and energy expenditure are examined, with a focus on the impact of neuro-vulnerability on appetite dysregulation and altered energy expenditure. The role of neuroinflammation in metabolic health and neuro-vulnerability is discussed, emphasizing the bidirectional relationship between metabolic dysregulation and neuroinflammatory processes. This review also evaluates the use of neuroimaging techniques in studying neuro-vulnerability and their potential applications in clinical settings. Furthermore, the association between neuro-vulnerability and eating disorders, as well as its contribution to obesity, is examined. Potential therapeutic interventions targeting neuro-vulnerability, including pharmacological treatments and lifestyle modifications, are reviewed. In conclusion, understanding the concept of neuro-vulnerability in energy metabolism regulation is crucial for addressing metabolic disorders. This review provides valuable insights into the underlying neurobiological mechanisms and their implications for metabolic health. Targeting neuro-vulnerability holds promise for developing innovative strategies in the prevention and treatment of metabolic disorders, ultimately improving metabolic health outcomes.

Ldlr-/-.Leiden mice develop neurodegeneration, age-dependent astrogliosis and obesity-induced changes in microglia immunophenotype which are partly reversed by complement component 5 neutralizing antibody

Introduction

Obesity has been linked to vascular dysfunction, cognitive impairment and neurodegenerative diseases. However, experimental models that recapitulate brain pathology in relation to obesity and vascular dysfunction are still lacking.

Methods

In this study we performed the histological and histochemical characterization of brains from Ldlr-/-.Leiden mice, an established model for obesity and associated vascular disease. First, HFD-fed 18 week-old and 50 week-old Ldlr-/-.Leiden male mice were compared with age-matched C57BL/6J mice. We then assessed the effect of high-fat diet (HFD)-induced obesity on brain pathology in Ldlr-/-.Leiden mice and tested whether a treatment with an anti-complement component 5 antibody, a terminal complement pathway inhibitor recently shown to reduce vascular disease, can attenuate neurodegeneration and neuroinflammation. Histological analyses were complemented with Next Generation Sequencing (NGS) analyses of the hippocampus to unravel molecular pathways underlying brain histopathology.

Results

We show that chow-fed Ldlr-/-.Leiden mice have more severe neurodegeneration and show an age-dependent astrogliosis that is not observed in age-matched C57BL/6J controls. This was substantiated by pathway enrichment analysis using the NGS data which showed that oxidative phosphorylation, EIF2 signaling and mitochondrial dysfunction pathways, all associated with neurodegeneration, were significantly altered in the hippocampus of Ldlr-/-.Leiden mice compared with C57BL/6J controls. Obesity-inducing HFD-feeding did not aggravate neurodegeneration and astrogliosis in Ldlr-/-.Leiden mice. However, brains from HFD-fed Ldlr-/-.Leiden mice showed reduced IBA-1 immunoreactivity and increased CD68 immunoreactivity compared with chow-fed Ldlr-/-.Leiden mice, indicating alteration of microglial immunophenotype by HFD feeding. The systemic administration of an anti-C5 treatment partially restored the HFD effect on microglial immunophenotype. In addition, NGS data of hippocampi from Ldlr-/-.Leiden mice showed that HFD feeding affected multiple molecular pathways relative to chow-fed controls: HFD notably inactivated synaptogenesis and activated neuroinflammation pathways. The anti-C5 treatment restored the HFD-induced effect on molecular pathways to a large extent.

Conclusion

This study shows that the Ldlr-/-.Leiden mouse model is suitable to study brain histopathology and associated biological processes in a context of obesity and provides evidence of the potential therapeutic value of anti-complement therapy against obesity-induced neuroinflammation.

Genetic Insights into Obesity and Brain: Combine Mendelian Randomization Study and Gene Expression Analysis

As a major public-health concern, obesity is imposing an increasing social burden around the world. The link between obesity and brain-health problems has been reported, but controversy remains. To investigate the relationship among obesity, brain-structure changes and diseases, a two-stage analysis was performed. At first, we used the Mendelian-randomization (MR) approach to identify the causal relationship between obesity and cerebral structure. Obesity-related data were retrieved from the Genetic Investigation of ANthropometric Traits (GIANT) consortium and the UK Biobank, whereas the cortical morphological data were from the Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) consortium. Further, we extracted region-specific expressed genes according to the Allen Human Brian Atlas (AHBA) and carried out a series of bioinformatics analyses to find the potential mechanism of obesity and diseases. In the univariable MR, a higher body mass index (BMI) or larger visceral adipose tissue (VAT) was associated with a smaller global cortical thickness (pBMI = 0.006, pVAT = 1.34 × 10-4). Regional associations were found between obesity and specific gyrus regions, mainly in the fusiform gyrus and inferior parietal gyrus. Multivariable MR results showed that a greater body fat percentage was linked to a smaller fusiform-gyrus thickness (p = 0.029) and precuneus surface area (p = 0.035). As for the gene analysis, region-related genes were enriched to several neurobiological processes, such as compound transport, neuropeptide-signaling pathway, and neuroactive ligand-receptor interaction. These genes contained a strong relationship with some neuropsychiatric diseases, such as Alzheimer's disease, epilepsy, and other disorders. Our results reveal a causal relationship between obesity and brain abnormalities and suggest a pathway from obesity to brain-structure abnormalities to neuropsychiatric diseases.

Recent Development in the Understanding of Molecular and Cellular Mechanisms Underlying the Etiopathogenesis of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that leads to dementia and patient death. AD is characterized by intracellular neurofibrillary tangles, extracellular amyloid beta (Aβ) plaque deposition, and neurodegeneration. Diverse alterations have been associated with AD progression, including genetic mutations, neuroinflammation, blood-brain barrier (BBB) impairment, mitochondrial dysfunction, oxidative stress, and metal ion imbalance.Additionally, recent studies have shown an association between altered heme metabolism and AD. Unfortunately, decades of research and drug development have not produced any effective treatments for AD. Therefore, understanding the cellular and molecular mechanisms underlying AD pathology and identifying potential therapeutic targets are crucial for AD drug development. This review discusses the most common alterations associated with AD and promising therapeutic targets for AD drug discovery. Furthermore, it highlights the role of heme in AD development and summarizes mathematical models of AD, including a stochastic mathematical model of AD and mathematical models of the effect of Aβ on AD. We also summarize the potential treatment strategies that these models can offer in clinical trials.

The Preventive Effect of Exercise and Oral Branched-Chain Amino Acid Supplementation on Obesity-Induced Brain Changes in Ldlr−/−.Leiden Mice

Exercise and dietary interventions are promising approaches to tackle obesity and its obesogenic effects on the brain. We investigated the impact of exercise and possible synergistic effects of exercise and branched-chain amino acids (BCAA) supplementation on the brain and behavior in high-fat-diet (HFD)-induced obese Ldlr−/−.Leiden mice. Baseline measurements were performed in chow-fed Ldlr−/−.Leiden mice to assess metabolic risk factors, cognition, and brain structure using magnetic resonance imaging. Thereafter, a subgroup was sacrificed, serving as a healthy reference. The remaining mice were fed an HFD and divided into three groups: (i) no exercise, (ii) exercise, or (iii) exercise and dietary BCAA. Mice were followed for 6 months and aforementioned tests were repeated. We found that exercise alone changed cerebral blood flow, attenuated white matter loss, and reduced neuroinflammation compared to non-exercising HFD-fed mice. Contrarily, no favorable effects of exercise on the brain were found in combination with BCAA, and neuroinflammation was increased. However, cognition was slightly improved in exercising mice on BCAA. Moreover, BCAA and exercise increased the percentage of epididymal white adipose tissue and muscle weight, decreased body weight and fasting insulin levels, improved the circadian rhythm, and transiently improved grip strength. In conclusion, BCAA should be supplemented with caution, although beneficial effects on metabolism, behavior, and cognition were observed.

Effect of semaglutide and empagliflozin on cognitive function and hippocampal phosphoproteomic in obese mice

Objective: Based on the 4D label-free phosphoproteomic technique, we examined the differences in cognitive function and hippocampal phosphorylated protein expression in high-fat diet-induced obese mice after the intervention of semaglutide and empagliflozin, as well as the effects of both on protein activity and function in obese mice’s hippocampal tissues and the signaling pathways involved.

Methods: Thirty-two C57BL/6JC male mice were assigned to two groups randomly: A control group (group C, 10% of energy is from fat, n = 8) and a high-fat diet group (group H, 60% of energy is from fat, n = 24). The high-fat diet-induced obese mice were screened after 12 weeks of feeding based on the criterion that the bodyweight of mice in fat rich diet group was greater than or equal to 20% of the average body weight of the mice in the blank control group. Group H separate into group H (n = 8), group Semaglutide (group S, n = 8), and group empagliflozin (group E, n = 8). For a total of 12 weeks, group S received 30 nmol/kg/d bodyweight of semaglutide intraperitoneally, group E received 10 mg/kg/d bodyweight of empagliflozin via gavage, and groups C and H received equal amounts of saline by intraperitoneal injection and gavage. At the end of treatment, the mice were appraised for cognitive function employing the Morris water maze (MWM), and serum fasting glucose, lipids, and inflammatory parameters were measured. The 4D label-free phosphoproteomics method was employed to screen the differential phosphoproteins and loci in hippocampal tissues of mice in different treatment groups, and bioinformatics was used to analyze the biological processes, signaling pathways, and related protein–protein interaction (PPI) network analysis of these differentially phosphorylated proteins.

Results: In comparison to normal controls, The escape latency of obese mice induced by high-fat diet was prolonged, the percentage of swimming time in the target quadrant was reduced, and the number of times of crossing the platform was reduced, whereas semaglutide and empagliflozin treatment reduced escape latency, increase the percentage of swim time in the target quadrant and increase the frequency of passing through the platform area, although there is little difference in the effect of the two drugs. The phosphoproteomic results showed 20,493 unique phosphorylated peptides, representing 21,239 phosphorylation sites and 4,290 phosphorylated proteins. Further analysis revealed that the proteins corresponding to these differentially phosphorylated sites are jointly distributed in signaling pathways such as dopaminergic synapses and axon guidance, and are involved in biological processes such as neuronal projection development, synaptic plasticity, and axonogenesis. Notably, the key factors voltage-dependent L-type calcium channel subunit alpha-1D (CACNA1D), voltage-dependent P/Q-type calcium channel subunit alpha-1A (CACNA1A), and voltage-dependent N-type calcium channel subunit alpha-1B (CACNA1B) were all found to be involved in the dopaminergic synapse pathway, and their expression was upregulated by semaglutide and empagliflozin.

Conclusion: We found for the first time that a high-fat diet decreased CACNA1D, CACNA1A, and CACNA1B protein serine phosphorylation, which may affect neuronal development, synaptic plasticity, and cognitive function in mice. Notably, semaglutide and empagliflozin increased the phosphorylation of these proteins.

Butyrate and obesity: Current research status and future prospect

Over the past few decades, increasing prevalence of obesity caused an enormous medical, social, and economic burden. As the sixth most important risk factor contributing to the overall burden of disease worldwide, obesity not only directly harms the human body, but also leads to many chronic diseases such as diabetes, cardiovascular diseases (CVD), nonalcoholic fatty liver disease (NAFLD), and mental illness. Weight loss is still one of the most effective strategies against obesity and related disorders. Recently, the link between intestinal microflora and metabolic health has been constantly established. Butyrate, a four-carbon short-chain fatty acid, is a major metabolite of the gut microbiota that has many beneficial effects on metabolic health. The anti-obesity activity of butyrate has been demonstrated, but its mechanisms of action have not been fully described. This review summarizes current knowledge of butyrate, including its production, absorption, distribution, metabolism, and the effect and mechanisms involved in weight loss and obesity-related diseases. The aim was to contribute to and advance our understanding of butyrate and its role in obesity. Further exploration of butyrate and its pathway may help to identify new anti-obesity.

The Association of Obesity and Overweight with Executive Functions in Community-Dwelling Older Women

Among the risk factors reported for cognitive decline, the literature highlights changes in body composition. Thus, the aim of the present study was to examine the relationship between obesity/overweight and executive functions in cognitively normal older adult women. This cross-sectional study included 224 individuals (60-80 years), stratified into normal weight (n = 45), overweight (n = 98), and obesity (n = 81). As outcomes, body mass index (BMI), waist circumference (WC), and Trail Making Test Parts A and B were assessed. We found positive correlations of BMI and WC with completion times of TMT-A and TMT-B, and a negative correlation of BMI and WC with education. ANCOVA showed an association between higher BMI and slower completion time of TMT-A, TMT-B, and ΔTMT (B-A). Impairment of executive functions of cognitively normal older women may be positively associated with obesity and negatively associated with years of education. The findings may contribute to designing strategies that make it possible to prevent cognitive decline in women during aging.

Effect of fasting on short-term visual plasticity in adult humans

Brain plasticity and function is impaired in conditions of metabolic dysregulation, such as obesity. Less is known on whether brain function is also affected by transient and physiological metabolic changes, such as the alternation between fasting and fed state. Here we asked whether these changes affect the transient shift of ocular dominance that follows short-term monocular deprivation, a form of homeostatic plasticity. We further asked whether variations in three of the main metabolic and hormonal pathways affected in obesity (glucose metabolism, leptin signalling and fatty acid metabolism) correlate with plasticity changes. We measured the effects of 2 h monocular deprivation in three conditions: post-absorptive state (fasting), after ingestion of a standardised meal and during infusion of glucagon-like peptide-1 (GLP-1), an incretin physiologically released upon meal ingestion that plays a key role in glucose metabolism. We found that short-term plasticity was less manifest in fasting than in fed state, whereas GLP-1 infusion did not elicit reliable changes compared to fasting. Although we confirmed a positive association between plasticity and supraphysiological GLP-1 levels, achieved by GLP-1 infusion, we found that none of the parameters linked to glucose metabolism could predict the plasticity reduction in the fasting versus fed state. Instead, this was selectively associated with the increase in plasma beta-hydroxybutyrate (B-OH) levels during fasting, which suggests a link between neural function and energy substrates alternative to glucose. These results reveal a previously unexplored link between homeostatic brain plasticity and the physiological changes associated with the daily fast-fed cycle.

Prevalence of motoric cognitive risk syndrome among older adults: a systematic review and meta-analysis

OBJECTIVE

Motoric cognitive risk syndrome (MCR) is a newly proposed pre-dementia syndrome. Several studies on the prevalence of MCR have been published; however, the data vary across studies with different epidemiological characteristics. Thus, this study aimed to quantitatively analyse the overall prevalence and associated epidemiological characteristics of MCR among older adults aged ≥ 60 years.

METHODS

The Cochrane Library, PubMed, Web of Science, CINAHL, Embase, Scopus, PsycInfo, China National Knowledge Infrastructure, Weipu Database, China Biology Medicine disc and Wanfang Database were searched from their inception to January 2022. A modified Newcastle-Ottawa Scale evaluated the risk of bias. Statistical heterogeneity among the included studies was analysed using Cochran's Q and I² tests. A random effect model calculated pooled prevalence owing to study heterogeneity. Begg's and Egger's tests were used to assess the publication bias. Additionally, subgroup analysis and meta-regression were performed based on different epidemiological characteristics to determine heterogeneity sources.

RESULTS

Sixty-two studies comprising 187,558 samples were obtained. The pooled MCR prevalence was 9.0% (95% confidence interval: 8.3-9.8). A higher MCR prevalence was observed in females, older adults with a low educational level, depression and cardiovascular risk factors, South American populations, and studies with small sample sizes and cross-section designs. Furthermore, subjective cognitive complaint using scale score and gait speed using instrument gait showed higher MCR prevalence.

CONCLUSION

MCR is common in older adults, and various epidemiological characteristics influence its prevalence. Thus, preventive measures are required for older adults with higher MCR prevalence.

Fatness, fitness and the aging brain: A cross sectional study of the associations between a physiological estimate of brain age and physical fitness, activity, sleep, and body composition

Introduction

Changes in brain structure and function occur with aging. However, there is substantial heterogeneity both in terms of when these changes begin, and the rate at which they progress. Understanding the mechanisms and/or behaviors underlying this heterogeneity may allow us to act to target and slow negative changes associated with aging.

Methods

Using T1 weighted MRI images, we applied a novel algorithm to determine the physiological age of the brain (brain-predicted age) and the predicted age difference between this physiologically based estimate and chronological age (BrainPAD) to 551 sedentary adults aged 65 to 84 with self-reported cognitive complaint measured at baseline as part of a larger study. We also assessed maximal aerobic capacity with a graded exercise test, physical activity and sleep with accelerometers, and body composition with dual energy x-ray absorptiometry. Associations were explored both linearly and logistically using categorical groupings.

Results

Visceral Adipose Tissue (VAT), Total Sleep Time (TST) and maximal aerobic capacity all showed significant associations with BrainPAD. Greater VAT was associated with higher (i.e,. older than chronological) BrainPAD (r = 0.149 p = 0.001)Greater TST was associated with higher BrainPAD (r = 0.087 p = 0.042) and greater aerobic capacity was associated with lower BrainPAD (r = - 0.088 p = 0.040). With linear regression, both VAT and TST remained significant (p = 0.036 and 0.008 respectively). Each kg of VAT predicted a 0.741 year increase in BrainPAD, and each hour of increased TST predicted a 0.735 year increase in BrainPAD. Maximal aerobic capacity did not retain statistical significance in fully adjusted linear models.

Discussion

Accumulation of visceral adipose tissue and greater total sleep time, but not aerobic capacity, total daily physical activity, or sleep quantity and/or quality are associated with brains that are physiologically older than would be expected based upon chronological age alone (BrainPAD).

Physical activity and exercise alter cognitive abilities, and brain structure and activity in obese children

The prevalence of childhood obesity is increasing to such an extent that it has become a major global public health problem in the 21st century. Obesity alters children’s brain structure and activity and impairs their cognitive abilities. On the basis of these findings, it is necessary for educational and healthcare institutions to combat childhood obesity through preventive and therapeutic strategies. In general, exercise and physical activity are considered common but effective methods for improving physical, psychological, and brain health across the life span. Therefore, this review article mainly focuses on existing neuroimaging studies that have used magnetic resonance imaging (MRI), and functional magnetic resonance imaging (fMRI)to assess children’s brain anatomy and neural activity. We intended to explore the roles of physical activity and exercise in modulating the associations among childhood obesity, cognitive abilities, and the structure and activity of the brain.

An atlas of glucose uptake across the entire human body as measured by the total-body PET/CT scanner: a pilot study

Glucose uptake differs in organs and tissues across the human body. To date, however, there has been no single atlas providing detailed glucose uptake profiles across the entire human body. Therefore, we aimed to generate a detailed profile of glucose uptake across the entire human body using the uEXPLORER positron emission tomography/computed tomography scanner, which offers the opportunity to collect glucose metabolic imaging quickly and simultaneously in all sites of the body. The standardized uptake value normalized by lean body mass (SUL) of 18F-fluorodeoxyglucose was used as a measure of glucose uptake. We developed a fingerprint of glucose uptake reflecting the mean SULs of major organs and parts across the entire human body in 15 healthy-weight and 18 overweight subjects. Using the segmentation of organs and body parts from the atlas, we uncovered the significant impacts of age, sex, and obesity on glucose uptake in organs and parts across the entire body. A difference was recognized between the right and left side of the body. Overall, we generated a total-body glucose uptake atlas that could be used as the reference for the diagnosis and evaluation of disordered states involving dysregulated glucose metabolism.

Acute sleep loss increases CNS health biomarkers and compromises the ability to stay awake in a sex-and weight-specific manner

Night shift work impairs vigilance performance, reduces the ability to stay awake, and compromises brain health. To investigate if the magnitude of these adverse night shift work effects differs between sexes and weight groups, 47 men and women with either normal weight or obesity participated in one night of sleep and one night of total sleep loss. During the night of sleep loss, participants' subjective sleepiness, vigilance performance, and ability to stay awake during 2-min quiet wake with eyes closed were repeatedly assessed. In addition, blood was collected in the morning after sleep loss and sleep to measure central nervous system (CNS) health biomarkers. Our analysis showed that women were sleepier during the night of sleep loss (P < 0.05) and spent more time in microsleep during quiet wake testing (P < 0.05). Finally, higher blood levels of neurofilament light chain, a biomarker of axonal damage, were found among women in the morning after sleep loss (P < 0.002). Compared with normal-weight subjects, those with obesity were more prone to fall asleep during quiet wake (P < 0.05) and exhibited higher blood levels of the CNS health biomarker pTau181 following sleep loss (P = 0.001). Finally, no differences in vigilance performance were noted between the sex and weight groups. Our findings suggest that the ability to stay awake during and the CNS health biomarker response to night shift work may differ between sexes and weight groups. Follow-up studies must confirm our findings under more long-term night shift work conditions.

Cerebral Blood Flow Alterations and Obesity: A Systematic Review and Meta-Analysis

Background: Reduction in cerebral blood flow (CBF) plays an essential role in the cognitive impairment and dementia in obesity. However, current conclusions regarding CBF changes in patients with obesity are inconsistent. Objective: A systematic review and meta-analysis was performed to evaluate the relationship between obesity and CBF alterations. Methods: We systematically screened published cross-sectional and longitudinal studies focusing on the differences in CBF between obese and normal-weight individuals. Eighteen studies including 24,866 participants, of which seven articles reported longitudinal results, were evaluated in the present study. Results: The results of the meta-analysis showed that in cross-sectional studies, body mass index (BMI) was negatively associated with CBF (β= –0.31, 95% confidence interval [CI]: –0.44, –0.19). Moreover, this systematic review demonstrated that obese individuals showed global and regional reductions in the CBF and increased CBF in diverse functional areas of the frontal lobe, including the prefrontal cortex, left frontal superior orbital, right frontal mid-orbital cortex, and left premotor superior frontal gyrus. Conclusion: Our findings suggest that BMI, rather than waist circumference and waist-to-hip ratio, is inversely associated with CBF in cross-sectional studies. The CBF of obese individuals showed global and regional reductions, including the frontal lobe, temporal and parietal lobes, cerebellum, hippocampus, and thalamus.

The Effect of Short-term Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) Diet on Hunger Hormones, Anthropometric Parameters, and Brain Structures in Middle-aged Overweight and Obese Women: A Randomized Controlled Trial

Background

The rising prevalence of obesity, as well as its detrimental effects on the brain, has drawn attention to specific dietary patterns. This study aimed to examine the effect of the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) pattern on anthropometric parameters, hunger hormones, and brain structures in overweight and obese women.

Methods

This randomized trial was conducted in Shiraz between October 2018 and March 2019. We analyzed 37 healthy women with a mean age of 48±5.38 years and a Body Mass Index (BMI) of 32±0.69 Kg/m². Participants were randomly allocated to a hypocaloric modified MIND diet or a hypocaloric control diet. Differences in anthropometric, laboratory analysis, and brain structure were determined at baseline and three-month follow-up. Data were analyzed using SPSS 22.0. Independent and paired sample t test were used to determine between and within differences. We also used mixed-model ANOVA to compare the mean differences between two-factor groups.

Results

A more significant weight reduction (P<0.0001), BMI (P<0.0001), percentage of body fat (P=0.03), waist circumference (P=0.01), and Leptin concentration (P=0.03) were found in the MIND diet group. The results also showed a significant increase in Ghrelin (P=0.002) and GLP-1 (P=0.01) levels in the MIND diet group. The findings revealed no differences in the whole and regional brain structures between the two groups.

Conclusion

For the first time, this study showed that the MIND diet intervention could improve the devastating effect of obesity on metabolic profiles and anthropometric parameters. However, we could not find its effect on brain structures.Trial registration number: IRCT20190427043387N1.A preprint of this study was published at https://www.medrxiv.org/content/10.1101/2020.06.28.20142018v1.

Appetitive interoception, the hippocampus and western-style diet

Obesity, Type 2 diabetes and other metabolic disorders continue to pose serious challenges to human health and well-being. An important source of these challenges is the overconsumption of saturated fats and sugar, main staples of what has been called the Western-style diet (WD). The current paper describes a theoretical model and supporting evidence that links intake of a WD to interference with a specific brain substrate that underlies processing of interoceptive signals of hunger and satiety. We review findings from rats and humans that the capacity of these signals to modulate the strength of appetitive and eating behavior depends on the functional integrity of the hippocampus and the learning memory operations it performs. Important among these operations is the use of contextual information to retrieve memories that are associated with other events. Within our framework, satiety provides an interoceptive context that informs animals that food cues and appetitive behavior will not be followed by rewarding postingestive outcomes. This serves to prevent those cues and responses from retrieving those reward memories. The findings reviewed provide evidence that consuming a WD and the high amounts of saturated fat and sugar it contains (a) is associated with the emergence of pathophysiologies to which the hippocampus appears selectively vulnerable (b) impairs hippocampal-dependent learning and memory (HDLM) and (c) weakens behavioral control by interoceptive hunger and satiety contextual stimuli. It is hypothesized that these consequences of WD intake may establish the conditions for a vicious cycle of further WD intake, obesity, and potentially cognitive decline.

Do Physical Activity, BMI, and Wellbeing Affect Logical Thinking?

We studied 6368 people (4544 women and 1824 men; aged 18–74 years). The research goal was to determine whether the Cognitive Reflection Test score (logical thinking compared with intuitive thinking) depends—and in what way it depends—on the healthy lifestyle components and emotional health-related components as well as age (18–74 years) and gender. We established that analytical vs. intuitive thinking depended on components of a healthy lifestyle, physical activity, sleep, eating habits, smoking and alcohol consumption, specificity of sporting activity, body mass index, and emotional health-related components (stress, depression, impulsivity, subjective health, emotional intelligence), as well as age and gender. We found that logical thinking was not associated with sleep, moderate-to-vigorous PA, impulsivity, subjective health, and components of a healthy lifestyle. However, logical thinking decreases with age, gender (higher in men than in women), BMI (decreases in both genders over the second degree of obesity), depression (the more severe depression in women, the worse their logical thinking), sedentary behavior (people who sat for longer periods had more difficulty solving problems), and in professional sportswomen (logical thinking is worse in professional sportswomen than in sedentary women, amateur sportswomen, or women who use gyms). Finally, we determined inverse correlations between logical thinking, emotional intelligence, and stress.

Cognitive Functions Associated with Brain Imaging Markers in Patients with Psoriasis

Psoriasis is a severe inflammatory disease associated with a higher comorbidity of depression, cognitive dysfunction and brain atrophy. The association between psoriasis, magnetic resonance imaging (MRI) markers and cognitive impairment has rarely been investigated, and the existing results are conflicting. Methods. This study included 89 subjects (53 patients with psoriasis and 36 healthy controls). The severity of psoriasis was evaluated using the Psoriasis Area and Severity Index (PASI) score; for depression, the Hospital Anxiety and Depression Scale (HADS) scale was used. Neuropsychological tests were also applied, including a Trail Making Test (TMT) as well as Digit Span, Stroop, Verbal Fluency and Rey Auditory Verbal Learning tests. MRI scans were performed using a 1.5 T scanner. Brain volumetry, white matter lesions, grey matter and white matter were evaluated. The extent of these changes was assessed on the Fazekas scale. The differences between groups were evaluated using a Student’s t-test and a Mann-Whitney U test, and a Pearson correlation analysis was also performed. Results. Patients with psoriasis presented worse achievements on all the neuropsychological tests and showed more intense changes on MRI compared to healthy controls. The severity of psoriasis as determined by PASI scores was associated with depression, and a greater psychomotor slowness severity of changes in the brain was associated with poorer results on the neurological tests. Conclusions. Our results indicate the possibility of progressive brain atrophy related to cognitive decline in psoriasis.

Subcutaneous Administration of a Nitric Oxide-Releasing Nanomatrix Gel Ameliorates Obesity and Insulin Resistance in High-Fat Diet-Induced Obese Mice

Nitric oxide (NO) is a gaseous signaling molecule, which plays crucial roles in various biological processes, including inflammatory responses, metabolism, cardiovascular functions, and cognitive function. NO bioavailability is reduced with aging and cardiometabolic disorders in humans and rodents. NO stimulates the metabolic rate by increasing the mitochondrial biogenesis and brown fat activation. Therefore, we propose a novel technology of providing exogenous NO to improve the metabolic rate and cognitive function by promoting the development of brown adipose tissue. In the present study, we demonstrate the effects of the peptide amphiphiles-NO-releasing nanomatrix gel (PANO gel) on high-fat diet-induced obesity, insulin resistance, and cognitive functions. Eight-week-old male C57BL/6 mice were subcutaneously injected in the brown fat area with the PANO gel or vehicle (PA gel) every 2 weeks for 12 weeks. The PANO gel-injected mice gained less body weight, improved glucose tolerance, and decreased fasting serum insulin and leptin levels compared with the PA gel-injected mice. Insulin signaling in the muscle, liver, and epididymal white adipose tissue was improved by the PANO gel injection. The PANO gel reduced inflammation, increased lipolysis in the epididymal white adipose tissue, and decreased serum lipids and liver triglycerides. Interestingly, the PANO gel stimulated uncoupled protein 1 gene expression in the brown and beige fat tissues. Furthermore, the PANO gel increased the cerebral blood flow and improved learning and memory abilities. Our results suggest that using the PANO gel to supply exogenous NO is a novel technology to treat metabolic disorders and cognitive dysfunctions.

Peanut (Arachis hypogaea) sprout prevents high-fat diet-induced cognitive impairment by improving mitochondrial function

This study was performed to evaluate the improvement effect of the ethyl acetate fraction from peanut (Arachis hypogaea) sprout (EFPS) on high-fat diet (HFD)-induced cognitive deficits in C57BL/6 mice. Mice were randomly divided four groups (n = 13) as control (normal chow), HFD, EFPS 20 (20 mg/kg of body weight; intragastric administration) and EFPS 50 (50 mg/kg of body weight; intragastric administration) groups. HFD was provide for 15 weeks excepting control group. EFPS ameliorated cognitive dysfunction in Y-maze, passive avoidance test and Morris water maze test. EFPS significantly improved glucose tolerance and serum lipid profile, and reduced body weight. EFPS ameliorated oxidative stress by regulating MDA levels and SOD activity in liver and brain tissues. In addition, EFPS restored brain mitochondrial dysfunction related to energy metabolism. Moreover, the bioactive compounds of EFPS were identified as di-caffeic acid, caffeic acid, dihydrokaempferol-hexoside, di-p-coumaroyl tartaric acid isomer and group B soyasaponins using ultra-performance liquid chromatography-quadrupole-time-of-flight (UPLC-Q-TOF) mass spectrometry. These results show that EFPS can improve cognitive functions in HFD-induced diabetic mice.

The relationship between brain glucose metabolism and insulin resistance in subjects with normal cognition - a study based on 18F-FDG PET

OBJECTIVE

Insulin resistance can increase the risk of cognitive dysfunction and dementia. Our purpose is to use 18F-FDG PET imaging to explore the effect of insulin resistance on brain glucose metabolism in cognitively normal subjects.

METHODS

A total of 189 cognitively normal subjects who underwent PET examinations were enrolled. The homeostasis model assessment of insulin resistance (HOMA-IR) was used to evaluate the presence of insulin resistance. Multivariate linear regression and generalized additive models were used to analyze the association between HOMA-IR and glucose metabolism in the whole brain and evaluate the effects of various covariates. The SPM12 software was used to evaluate the regional effect of insulin resistance on brain glucose metabolism.

RESULTS

After being fully adjusted for confounding factors, HOMA-IR showed an approximately linear negative correlation with brain glucose metabolism (β = -0.219, T = -3.331, P = 0.021). Compared with normal subjects, insulin-resistant subjects had reduced glucose metabolism in bilateral middle temporal gyrus, bilateral middle frontal gyrus, right precentral gyrus, right inferior frontal gyrus, right cuneiform lobe and bilateral cerebellar regions. In cognitively normal subjects, systemic insulin resistance has a significant effect on brain glucose metabolism.

CONCLUSIONS

18F-FDG brain PET imaging could be helpful for the early diagnosis and treatment of changes in brain glucose metabolism caused by insulin resistance.

Forgetting in obesity: The pregnenolone link

Cognitive dysfunction is often diagnosed in people with obesity and associated metabolic disorders. In the latest issue of Cell Metabolism, Ramírez et al. highlight an impaired production of the neurosteroid pregnenolone in the hypothalamus as a mechanism for obesity-induced cognitive impairment in both rodent models and patients with obesity.

Hypothalamic pregnenolone mediates recognition memory in the context of metabolic disorders

Obesity and type 2 diabetes are associated with cognitive dysfunction. Because the hypothalamus is implicated in energy balance control and memory disorders, we hypothesized that specific neurons in this brain region are at the interface of metabolism and cognition. Acute obesogenic diet administration in mice impaired recognition memory due to defective production of the neurosteroid precursor pregnenolone in the hypothalamus. Genetic interference with pregnenolone synthesis by Star deletion in hypothalamic POMC, but not AgRP neurons, deteriorated recognition memory independently of metabolic disturbances. Our data suggest that pregnenolone's effects on cognitive function were mediated via an autocrine mechanism on POMC neurons, influencing hippocampal long-term potentiation. The relevance of central pregnenolone on cognition was also confirmed in metabolically unhealthy patients with obesity. Our data reveal an unsuspected role for POMC neuron-derived neurosteroids in cognition. These results provide the basis for a framework to investigate new facets of POMC neuron biology with implications for cognitive disorders.

Nutritional Impact on Metabolic Homeostasis and Brain Health

Aging in modern societies is often associated with various diseases including metabolic and neurodegenerative disorders. In recent years, researchers have shown that both dysfunctions are related to each other. Although the relationship is not fully understood, recent evidence indicate that metabolic control plays a determinant role in neural defects onset. Indeed, energy balance dysregulation affects neuroenergetics by altering energy supply and thus neuronal activity. Consistently, different diets to help control body weight, blood glucose or insulin sensitivity are also effective in improving neurodegenerative disorders, dampening symptoms, or decreasing the risk of disease onset. Moreover, adapted nutritional recommendations improve learning, memory, and mood in healthy subjects as well. Interestingly, adjusted carbohydrate content of meals is the most efficient for both brain function and metabolic regulation improvement. Notably, documented neurological disorders impacted by specific diets suggest that the processes involved are inflammation, mitochondrial function and redox balance as well as ATP production. Interestingly, processes involving inflammation, mitochondrial function and redox balance as well as ATP production are also described in brain regulation of energy homeostasis. Therefore, it is likely that changes in brain function induced by diets can affect brain control of energy homeostasis and other brain functions such as memory, anxiety, social behavior, or motor skills. Moreover, a defect in energy supply could participate to the development of neurodegenerative disorders. Among the possible processes involved, the role of ketone bodies metabolism, neurogenesis and synaptic plasticity, oxidative stress and inflammation or epigenetic regulations as well as gut-brain axis and SCFA have been proposed in the literature. Therefore, the goal of this review is to provide hints about how nutritional studies could help to better understand the tight relationship between metabolic balance, brain activity and aging. Altogether, diets that help maintaining a metabolic balance could be key to both maintain energy homeostasis and prevent neurological disorders, thus contributing to promote healthy aging.

Pathways linking abdominal obesity to poor memory function: Explore the mediating role of hypertension and depressive symptoms

BACKGROUND

The negative effect of abdominal obesity on cognitive function has been widely reported, especially on memory function, however, it is unclear how the effect is mediated. We aim to investigate the mediating role of hypertension and depressive symptoms.

METHODS

Data were collected from wave 6 (2012-2013) of the English Longitudinal Study of Ageing (ELSA). Abdominal obesity was defined as a waist circumference (WC) ≥88cm for women and ≥102cm for men. Hypertension was determined on the basis of objective blood pressure measurement and previous physician diagnosis. Depressive symptoms were assessed with the 8-item version of the Center for Epidemiologic Studies (CESD) scale. Memory function was measured with the 10-word immediate and delayed recall tests. Baron and Kenny's causal steps and Karlson/Holm/Breen (KHB) method were used to examine the mediating effect.

RESULTS

A total of 7,448 participants aged ≥50 years were included in this study. We found a negative effect of abdominal obesity on memory function (β=-0.047, p=0.031). KHB method identified significant mediating effect of hypertension and depressive symptoms on the relationship between abdominal obesity and memory function, they explained 16.92 and 6.32% of the total effect of abdominal obesity on memory function, respectively.

LIMITATIONS

This study was limited by its cross-sectional design and possibility of residual confounding.

CONCLUSIONS

Hypertension and depressive symptoms might be possible pathways linking abdominal obesity and poor memory function, suggesting that collaborative interventions of abdominal obesity, hypertension and depressive symptoms are beneficial in maintaining memory function.

Gut Microbiota and Mycobiota Evolution Is Linked to Memory Improvement after Bariatric Surgery in Obese Patients: A Pilot Study

Patients with obesity are known to exhibit gut microbiota dysbiosis and memory deficits. Bariatric surgery (BS) is currently the most efficient anti-obesity treatment and may improve both gut dysbiosis and cognition. However, no study has investigated association between changes of gut microbiota and cognitive function after BS. We prospectively evaluated 13 obese patients on anthropometric data, memory functions, and gut microbiota-mycobiota before and six months after BS. The Rey Auditory Verbal Learning Test (AVLT) and the symbol span (SS) of the Weschler Memory Scale were used to assess verbal and working memory, respectively. Fecal microbiota and mycobiota were longitudinally analyzed by 16S and ITS2 rRNA sequencing respectively. AVLT and SS scores were significantly improved after BS (AVLT scores: 9.7 ± 1.7 vs. 11.2 ± 1.9, p = 0.02, and SS scores: 9.7 ± 23.0 vs. 11.6 ± 2.9, p = 0.05). An increase in bacterial alpha-diversity, and Ruminococcaceae, Prevotella, Agaricus, Rhodotorula, Dipodascus, Malassezia, and Mucor were significantly associated with AVLT score improvement after BS, while an increase in Prevotella and a decrease in Clostridium, Akkermansia,&nbsp;Dipodascus and Candida were linked to SS scores improvement. We identified several changes in the microbial communities that differ according to the improvement of either the verbal or working memories, suggesting a complex gut-brain-axis that evolves after BS.

Association between body mass index and subcortical brain volumes in bipolar disorders-ENIGMA study in 2735 individuals

Individuals with bipolar disorders (BD) frequently suffer from obesity, which is often associated with neurostructural alterations. Yet, the effects of obesity on brain structure in BD are under-researched. We obtained MRI-derived brain subcortical volumes and body mass index (BMI) from 1134 BD and 1601 control individuals from 17 independent research sites within the ENIGMA-BD Working Group. We jointly modeled the effects of BD and BMI on subcortical volumes using mixed-effects modeling and tested for mediation of group differences by obesity using nonparametric bootstrapping. All models controlled for age, sex, hemisphere, total intracranial volume, and data collection site. Relative to controls, individuals with BD had significantly higher BMI, larger lateral ventricular volume, and smaller volumes of amygdala, hippocampus, pallidum, caudate, and thalamus. BMI was positively associated with ventricular and amygdala and negatively with pallidal volumes. When analyzed jointly, both BD and BMI remained associated with volumes of lateral ventricles  and amygdala. Adjusting for BMI decreased the BD vs control differences in ventricular volume. Specifically, 18.41% of the association between BD and ventricular volume was mediated by BMI (Z = 2.73, p = 0.006). BMI was associated with similar regional brain volumes as BD, including lateral ventricles, amygdala, and pallidum. Higher BMI may in part account for larger ventricles, one of the most replicated findings in BD. Comorbidity with obesity could explain why neurostructural alterations are more pronounced in some individuals with BD. Future prospective brain imaging studies should investigate whether obesity could be a modifiable risk factor for neuroprogression.