The negative effects of obesity and poor glycemic control on cognitive function: a proposed model for possible mechanisms

Impact of inflammation on cognitive function in patients with highly inflammatory rheumatoid arthritis

OBJECTIVE

To evaluate cognitive function in patients with rheumatoid arthritis (RA) and inflammatory activity.

PATIENTS AND METHODS

We performed a cross-sectional study of a cohort of patients with RA initiating their first biological treatment due to moderate-to-high inflammation and a healthy control group (no inflammatory diseases) matched for age, sex and educational level. All participants underwent a comprehensive neuropsychological assessment, with cognitive impairment defined as a Montreal Cognitive Assessment (MoCA) score<26. Additional assessments included various cognitive tests (STROOP, forward and backward digit spans), anxiety and depression scales (Hospital Anxiety and Depression Scale), quality of life measures (Quality of Life-Rheumatoid Arthritis) and average inflammatory activity according to the 28-joint Disease Activity Score (DAS28)-C-reactive protein (CRP) into high activity (DAS28≥3.2) and low activity (DAS28<3.2) groups, also CRP levels and interleukin 6 (IL-6) levels were measured using an ELISA.

RESULTS

The study population comprised 140 participants, 70 patients with RA and 70 controls. Patients more frequently experienced cognitive impairment than controls (60% vs 40%; p=0.019) and had lower mean (SD) values in the MoCA (23.6 (3.9) vs 25.1 (3.4); p=0.019. As for subtests of the MoCA, involvement was more marked in patients than in controls for the visuospatial-executive (p=0.030), memory (p=0.026) and abstraction (p=0.039) domains. Additionally, patients scored lower on executive function, as assessed by the backward digit span test (4.0 (1.7) vs 4.7 (1.9); p=0.039). Cognitive impairment is associated with age and a lower educational level in the general population, and among patients with RA with educational level, obesity and average inflammatory activity (DAS28, CRP, and IL-6).

CONCLUSIONS

Patients with RA with high inflammatory activity are more susceptible to cognitive impairment, which specifically affects the domains of visuospatial, memory, abstraction and executive function.

Association between P300 parameters and cognitive function in people with diabetic neuropathy

Purpose

The purpose of this study was to investigate the association between event-related potential (ERP) P300 with cognitive function in people with diabetic peripheral neuropathy (DPN).

Methods

We performed a cross-sectional analysis of 19 type 2 diabetes mellitus (T2DM) patients, aged 18 and older with DPN. The participants were assessed for neuropathy, cognitive function, & dual-task performance. DPN was examined via the administration of diabetic neuropathy symptom score (DNSS) and vibration perception threshold (VPT). Cognitive dysfunction was evaluated using Mini-mental state examination (MMSE), trail making test-B (TMT-B), and ERP P300 wave latency & amplitude. For assessing dual-task performance, the dual-task cost (DTC) was calculated using the timed-up and go (TUG) test and TUG with dual task (TUG-DT).

Results

P300 latency was linearly related to TMT-B (R = 0.31, p = 0.01) and DTC (R = 0.22, p = 0.04). A similar trend was observed in TMT-B (R = 0.13, p = 0.04) & DTC (R =0 .67, p = 0.001) with respect to P300 amplitude. MMSE did not relate with P300 latency (R = 0.14, p = 0.58) & amplitude (R = 0.63, p = .44).

Conclusion

P300 latency and amplitude are associated with cognitive function and DTC of individuals with DPN.

Rho-kinase inhibition ameliorates non-alcoholic fatty liver disease in type 2 diabetic rats

Non-alcoholic fatty liver disease (NAFLD) is linked to type 2 diabetes mellitus (T2DM), obesity, and insulin resistance. The Rho/ROCK pathway had been involved in the pathophysiology of diabetic complications. This study was designed to assess the possible protective impacts of the Rho/Rho-associated coiled-coil containing protein kinase (Rho/ROCK) inhibitor fasudil against NAFLD in T2DM rats trying to elucidate the underlying mechanisms. Animals were assigned into control rats, non-treated diabetic rats with NAFLD, and diabetic rats with NAFLD that received fasudil treatment (10 mg/kg per day) for 6 weeks. The anthropometric measures and biochemical analyses were performed to assess metabolic and liver function changes. The inflammatory and oxidative stress markers and the histopathology of rat liver tissues were also investigated. Groups with T2DM showed increased body weight, serum glucose, and insulin resistance. They exhibited disturbed lipid profile, enhancement of inflammatory cytokines, and deterioration of liver function. Fasudil administration reduced body weight, insulin resistance, and raised liver enzymes. It improved the disturbed lipid profile and attenuated liver inflammation. Moreover, it slowed down the progression of high fat diet (HFD)-induced liver injury and reduced the caspase-3 expression. The present study demonstrated beneficial amelioration effect of fasudil on NAFLD in T2DM. The mechanisms underlying these impacts are improving dyslipidemia, attenuating oxidative stress, downregulated inflammation, improving mitochondrial architecture, and inhibiting apoptosis.

Abdominal Obesity: An Independent Influencing Factor of Visuospatial and Executive/Language Ability and the Serum Levels of Aβ40/Aβ42/Tau Protein

BACKGROUND

Although obesity affects human health and cognitive function, the influence of abdominal obesity on cognitive function is still unclear.

METHODS

The MoCA scale was used to evaluate the overall cognitive function and the function of each subitem of 196 subjects, as well as the SDMT and TMT-A scales for evaluating the attention and information processing speed. In addition, radioimmunoassay was used to detect the serum levels of Aβ40, Aβ42, and tau protein in 45 subjects. Subjects were divided into abdominal and nonabdominal obesity groups. Before and after correcting confounding factors, the differences in cognitive scale evaluation indexes and three protein levels between the two groups were compared. We also explore further the correlation between various cognitive abilities and the waist circumference/levels of the three proteins. Linear regression was used to identify the independent influencing factors of various cognitive functions and three protein levels.

RESULTS

After correcting for multiple factors, we observed the lower scores of visuospatial function, execution, and language in the MoCA scale, as well as higher levels of Aβ40 and tau protein in the abdominal obesity group, supported by the results of correlation analysis. Abdominal obesity was identified as an independent negative influencing factor of MoCA visual space, executive power, and language scores and an independent positive influencing factor of Aβ40, Aβ42, and tau protein levels.

CONCLUSION

Abdominal obesity may play a negative role in visuospatial, executive ability, and language function and a positive role in the Aβ40, Aβ42, and tau protein serum levels.

The Association Between Plasma Fatty Acid and Cognitive Function Mediated by Inflammation in Patients with Type 2 Diabetes Mellitus

PURPOSE

To verify the mediating role of inflammatory factors in plasma fatty acid-induced changes in cognitive function in patients with type 2 diabetes mellitus (T2DM).

PATIENTS AND METHODS

In this study, we evaluated the cognitive function of 372 Chinese patients (the average age was 58.00 (52.50, 63.00) years) with T2DM by using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA), with plasma fatty acids measured by gas chromatography analysis and inflammatory cytokines determined by immune turbidimetric analysis and enzyme-linked immunosorbent assay (ELISA) to investigate whether there was a correlation between the plasma fatty acids, inflammatory cytokine levels and cognitive test scores in Chinese patients with T2DM.

RESULTS

We found that the increase of waist circumference and hip circumference might lead to cognitive impairment and induce the inflammatory response. Higher saturated fatty acids (SFAs) levels in plasma were linked to cognitive decline, while higher monounsaturated fatty acids (MUFAs) intake might be a protective factor for cognitive function. In addition, higher levels of plasma n-6 polyunsaturated fatty acids (n-6 PUFAs) stood out as having association with lower cognitive function scores, while higher level of plasma C22:6 n-3 could be a predictor of better cognitive function. In our study, higher SFAs led to higher proinflammatory factor levels. Apart from that, MUFAs and stearoyl-CoA desaturase-18 (SCD-18) were positively related to hypersensitive C-reactive protein (hs-CRP). Meanwhile, higher level of plasma C20:0 could lead to better MMSE delayed recall by reduce the expression of hs-CRP.

CONCLUSION

Levels of plasma SFAs, C18:3 n-6, and C20:3 n-6 could be a predictor for worse cognitive function, while MUFAs and C22:6 n-3 could be a predictor for better cognitive function. The level of hs-CRP could be a mediator of C20:0 induced the change of cognitive function.

Short-term ketone monoester supplementation improves cerebral blood flow and cognition in obesity: A randomized cross-over trial

Adults with obesity are at increased risk of neurocognitive impairments, partly as a result of reduced cerebral blood flow and brain-derived neurotrophic factor (BDNF). Ketone supplements containing β-hydroxybutyrate (β-OHB) are a purported therapeutic strategy for improving brain health in at-risk populations. We tested the hypothesis that short-term β-OHB supplementation will elevate cerebral blood flow and BDNF, as well as improve cognition in adults with obesity. In a placebo-controlled double-blind, cross-over design, 14 adults with obesity (10 females; aged 56 ± 12 years; body mass index = 33.8 ± 6.9 kg m^-2 ) consumed 30 mL (12 g) of β-OHB or placebo thrice-daily for 14 days. Blood flow (Q) and cerebrovascular conductance (CVC) were measured in the common carotid (CCA), internal carotid (ICA) and vertebral (VA) arteries by duplex ultrasound. BDNF was measured by an enzyme-linked immunosorbent assay. Cognition was assessed by the digit-symbol substitution (DSST), Stroop and task-switching tests. Following 14 days of ketone supplementation, we observed significant improvements in cerebrovascular outcomes including Q_CCA (+12%), Q_VA (+11%), VA_CVC (+12%) and VA shear rate (+10%). DSST performance significantly improved following ketone supplementation (+2.7 correct responses) and improved DSST performance was positively associated improvements in cerebrovascular outcomes including Q_CCA , CCA_CVC , Q_VA and VA_CVC . By contrast to one hypothesis, β-OHB did not impact fasting serum and plasma BDNF. β-OHB supplementation improved cognition in adults with obesity, which may be partly facilitated by improvements in cerebral blood flow. β-OHB supplementation was well-tolerated and appears to be safe for cerebrovascular health, suggesting potential therapeutic benefits of β-OHB in a population at risk of neurocognitive impairment. KEY POINTS: People with obesity are at increased risk of neurocognitive dysfunction, partly as a result of -induced reductions in cerebral blood flow (CBF) and brain-derived neurotrophic factor (BDNF). Ketone supplements containing β-hydroxybutyrate (β-OHB) reduce postprandial hyperglycaemia, which may increase CBF and BDNF, thereby protecting against obesity-related cognitive dysfunction. We show for the first time that 14 days of thrice-daily β-OHB supplementation improves aspects of cognition and increases cerebrovascular flow, conductance and shear rate in the extracranial arteries of adults with obesity. Our preliminary data indicate a significant positive relationship between elevated CBF and improved cognition following β-OHB supplementation. This trial provides a foundation for the potential non-pharmacological therapeutic application of β-OHB supplementation in patient groups at risk of hyperglycaemic cerebrovascular disease and cognitive dysfunction.

Dieckol Decreases Caloric Intake and Attenuates Nonalcoholic Fatty Liver Disease and Hepatic Lymphatic Vessel Dysfunction in High-Fat-Diet-Fed Mice

Increased inflammation is the main pathophysiology of nonalcoholic fatty liver disease (NAFLD). Inflammation affects lymphatic vessel function that contributes to the removal of immune cells or macromolecules. Dysfunctional lymphatic vessels with decreased permeability are present in NAFLD. High-fat diet (HFD) is known to increase body weight, food intake, and inflammation in the liver. Previously, it was reported that Ecklonia cava extracts (ECE) decreased food intake or weight gain, and low-calorie diet and weight loss is known as a treatment for NAFLD. In this study, the effects of ECE and dieckol (DK)-which is one component of ECE that decreases inflammation and increases lymphangiogenesis and lymphatic drainage by controlling lymphatic permeability in high-fat diet (HFD)-fed mice-on weight gain and food intake were investigated. ECE and DK decreased weight gain and food intake in the HFD-fed mice. NAFLD activities such as steatosis, lobular inflammation, and ballooning were increased by HFD and attenuated by ECE and DK. The expression of inflammatory cytokines such as IL-6 and TNF-α and infiltration of M1 macrophages were increased by HFD, and they were decreased by ECE or DK. The signaling pathways of lymphangiogenesis, VEGFR-3, PI3K/pAKT, and pERK were decreased by HFD, and they were restored by either ECE or DK. The expression of VE-cadherin (which represents lymphatic junctional function) was increased by HFD, although it was restored by either ECE or DK. In conclusion, ECE and DK attenuated NAFLD by decreasing weight gain and food intake, decreasing inflammation, and increasing lymphangiogenesis, as well as modulating lymphatic vessel permeability.

Acupuncture therapy and cognitive dysfunction in patients with type 2 diabetes: A protocol for systematic review

BACKGROUND

With the aging of society, the incidence of type 2 diabetes (T2DM) is increasing every year, and there is a clear correlation between T2DM and cognitive dysfunction. Acupuncture therapy has been widely used in the treatment of T2DM, but there is no systematic review on the treatment of T2DM associated with cognitive impairment. Therefore, this study aimed to conduct a meta-analysis of acupuncture in the treatment of T2DM with cognitive impairment to clarify its efficacy.

METHODS

A structured and systematic literature search will be conducted in the following databases up to April 26, 2021: PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science (WOS), China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Database (CBM), Chinese Scientific and Journal Database (VIP), and Wan Fang database (Wanfang). We will use the Review Manager 5.4 software provided by the Cochrane Collaborative Network for statistical analysis. We then assessed the quality and risk of the included studies and observed the outcome measures.

RESULTS

This meta-analysis further determined the beneficial effects of acupuncture on T2DM with cognitive impairment.

CONCLUSION

The purpose of this meta-analysis was to explore the effect of acupuncture on patients T2DM with and cognitive impairment patients, and provide more options for clinicians and patients to treat T2DM with cognitive impairment.

ETHICS AND DISSEMINATION

This systematics review will evaluate the efficacy and safety of acupuncture in the treatment of T2DM with cognitive impairment. Since all the data included were published, the systematic review did not require ethical approval.

REGISTRATION NUMBER

CRD42021245681.

The relationship between type 2 diabetes mellitus with cognitive functions

Background

Type 2 diabetes mellitus (T2DM) has been associated with impairment of cognitive functions. Since the majority of patients with diabetes in the Saudi population are between the ages of 40 and 69 years, it is crucial to ascertain whether the control of blood glucose level negatively correlates with the level of cognitive function scores similar to the way it correlates in those who are not controlling their blood glucose level with medications.

Aims

To assess cognitive functions in patients with T2DM and examine the effect of glycemic control on cognitive functions impairment in Saudi adults with T2DM.

Methods and material

Seventy-nine patients with T2DM underwent cognitive assessment testing using the Cambridge neuropsychological test automated battery (CANTAB), Mini-Mental State Examination (MMSE), and Fatigue severity scale. Their cognitive function scores were then correlated with their blood glucose levels, duration of diabetes, and levels of education. Poor glycemic control was defined as glycated hemoglobin levels more than 7.5. We excluded patients with depression or neurocognitive disorders as well as those over 75 years of age.

Results

Attention switching task (AST) total latency (P = 0.003), AST congruent score (P = 0.002), AST incongruent score (P = 0.003), AST block 3 (p = 0.004), and AST Block 7 (p = 0.006) were significantly higher in poorly-controlled DM. The intra-extra dimensional set shift (IED) total errors were significantly higher in poorly-controlled patients (p = 0.023). The difference in IED stages completed (p = 0.716) and spatial span (SSP) (p = 0.782) were not significant between the two groups. The mini-mental state exam (p = 0.336) and the fatigue severity scale (P = 0.167) did not show any statistical significance between good and poor control of T2DM. There was a significant positive correlation between the duration of T2DM and AST latencies for AST total latency, AST congruent score, and AST incongruent score.

Conclusions

Patients with T2DM have a statistically significant association between their cognitive functions and their glycemic control. Patients with uncontrolled T2DM showed decreased cognitive scores. Moreover, worsened cognitive scores were associated with longer disease duration.

Effects of exercise, cognitive, and dual-task interventions on cognition in type 2 diabetes mellitus: A systematic review and meta-analysis

Introduction

Previous evidence has shown significant effects of exercise, cognitive and dual-task training for improving cognition in healthy cohorts. The effects of these types of interventions in type 2 diabetes mellitus is unclear. The aim of this research was to systematically review evidence, and estimate the effect, of exercise, cognitive, and dual-task interventions on cognition in type 2 diabetes mellitus.

Method

Electronic databases including PubMed, EMBASE, CINAHL, PsycINFO, SPORTDiscus, and MEDLINE were searched for ongoing and completed interventional trials investigating the effect of either an exercise, cognitive or dual-task intervention on cognition in type 2 diabetes mellitus.

Results

Nine trials met the inclusion criteria–one dual-task, two cognitive, and six exercise. Meta-analyses of exercise trials showed no significant effects of exercise on measures of executive function (Stroop task, SMD = -0.31, 95% CI -0.71–0.09, P = 0.13, trail making test part A SMD = 0.28, 95% CI -0.20–0.77 P = 0.25, trail making test part B SMD = -0.15, 95% CI -0.64–0.34 P = 0.54, digit symbol SMD = 0.09, 95% CI -0.39–0.57 P = 0.72), and memory (immediate memory SMD = 0.20, 95% CI -0.28–0.69, P = 0.41 and delayed memory SMD = -0.06, 95% CI -0.55–0.42, P = 0.80). A meta-analysis could not be conducted using cognitive or dual-task data, but individual trials did report a favourable effect of interventions on cognition. Risk of bias was considered moderate to high for the majority of included trials.

Conclusions

Meta-analyses of exercise trials identified a small effect size (0.31), which whilst not significant warrants further investigation. Larger and more robust trials are needed that report evidence using appropriate reporting guidelines (e.g. CONSORT) to increase confidence in the validity of results.

Trial registration

Protocol was registered (CRD42017058526) on the International Prospective Register of Systematic Reviews (http://www.crd.york.ac.uk/PROSPERO).

The role of inflammation and endoplasmic reticulum stress in obesity-related cognitive impairment

The epidemiological investigations and animal model experiments have confirmed the impact of obesity on the brain, behavior, and cognition. However, the mechanism by which obesity affects cognitive function is not fully understood. With the development of an aging society, there is an increase in the economic and social burden caused by the decline in cognitive function. This manuscript reviews the effects of inflammation and endoplasmic reticulum stress (ERS) on the hypothalamus, hippocampus, and the possible impact on cognitive impairment. These findings provide new insights into the pathophysiological mechanisms that lead to the development of cognitive impairment in the context of obesity.

Neurocognitive Deficits in a Cohort With Class 2 and Class 3 Obesity: Contributions of Type 2 Diabetes and Other Comorbidities

OBJECTIVE

This study examined the relationship between specific metabolic and vascular risk factors and cognition in adults with severe obesity.

METHODS

A total of 129 adults (with BMI ≥ 35 kg/m² ) underwent a baseline clinical evaluation and neuropsychological assessment. Regression analyses examined the relationship between cognition and medical factors (BMI, hemoglobin A1c, diabetes, hypertension, continuous positive airway pressure use, obstructive sleep apnea [OSA], and osteoarthritis).

RESULTS

Diabetes was associated with deficits in overall cognitive performance and with deficits in the executive processing speed and verbal fluency domains. Hemoglobin A1c was inversely related to overall cognitive performance and deficits in the attention domain. Participants using continuous positive airway pressure to treat OSA had stronger learning and memory performance, whereas OSA was associated with reduced total learning. Elevated BMI together with diabetes diagnosis was associated with reduced verbal fluency and greater variability in sustained attention.

CONCLUSIONS

Obesity-associated comorbidities most notably appeared to have a greater relative influence on cognitive performance than BMI itself in adults with severe obesity. This likely reflects the fact that a very elevated BMI was ubiquitous and thereby probably exerted a similar influence among all adults in the cohort. Accordingly, in the context of severe obesity, diabetes and other comorbidities may have greater sensitivity to cognitive deficits than BMI alone.

Moderate- and Low-Dose of Atorvastatin Alleviate Cognition Impairment Induced by High-Fat Diet via Sirt1 Activation

Mounting evidences have demonstrated that diet-induced obesity is associated with cognition impairment via increasing oxidative stress and inflammation in the brain. Atorvastatin (Ator, a HMG-CoA reductase inhibitor) is a cholesterol lowering drug. Studies have reported that Ator can ameliorate the development and progression of cognition impairment. Additionally, silent information regulator 1 (SIRT1) has been demonstrated to be beneficial in cognition impairment. However, the interaction between Ator and SIRT1 activation for cognition impairment remains unclear. This study aimed to identify a relationship between the use of Ator and cognition impairment induced by high-fat diet via Sirt1 activation. A total of 60 healthy male C57BL/6J mice were purchased and then divided into 6 groups, including normal diet group (control), a high-fat diet group (40%HFD, 40% energy from fat), a model group (60%HFD, 60% energy from fat), and model group treated with different doses of Ator (high-dose (80 mg), moderate-dose (40 mg), and low-dose (20 mg) groups). All interventions took place for 7 months. Metabolic phenotypes were characterized for body weight and analysis of serum lipid level. The level of cognition development was examined by Morris water maze (MWM) approach and novel object recognition test (NORT); besides, the expression of Creb1, Gap-43, BDNF, CaMKII, and ERKs of frontal cortex and hippocampus was determined by reverse transcription polymerase chain reaction (RT-PCR). Then, the levels of factors related to inflammation (TNF-a, IL-1β, HMGB1 and IL-6) and oxidation stress (SOD, MDA, CAT and GSH-Px) were assessed using commercially available kits. Finally, SIRT1 and its downstream molecules (Ac-FoxO1, Ac-p53, Ac-NF-κB, Bcl-2 and Bax) were evaluated by Western blot analysis. Compared with the 60% HFD group, body weight and serum lipid levels were significantly decreased in the Ator treated groups. The results of MWM and NORT, as well as the levels of Creb1, Gap-43, BDNF, CaMKII, and ERKs were markedly reversed in the moderate- and low-dose of Ator treated groups. Meanwhile, the expression of IL-1β, TNF-a, IL-6, HMGB1, and MDA was notably decreased, whereas the activity of SOD, CAT, and GSH-Px was increased. It was also revealed that the expression of SIRT1 was remarkably unregulated, the level of Bcl-2 was upregulated, and the content of Ac-FoxO1, Ac-p53, Ac-NF-κB, and Bax was downregulated in the moderate- and low-dose of Ator. Furthermore, results showed that the effect of moderate-dose of Ator was significantly greater than the low-dose of Ator. However, these effects were not observed in the high-dose of Ator. Our results showed that moderate- and low-dose of Ator can significantly attenuate cognition impairment induced by HFD through its antioxidant and anti-inflammatory functions related to SIRT1 activation.

The Full Spectrum of Alzheimer's Disease Is Rooted in Metabolic Derangements That Drive Type 3 Diabetes

The standard practice in neuropathology is to diagnose Alzheimer's disease (AD) based on the distribution and abundance of neurofibrillary tangles and Aβ deposits. However, other significant abnormalities including neuroinflammation, gliosis, white matter degeneration, non-Aβ microvascular disease, and insulin-related metabolic dysfunction require further study to understand how they could be targeted to more effectively remediate AD. This review addresses non-Aβ and non-pTau AD-associated pathologies, highlighting their major features, roles in neurodegeneration, and etiopathic links to deficits in brain insulin and insulin-like growth factor signaling and cognitive impairment. The discussion delineates why AD with its most characteristic clinical and pathological phenotypic profiles should be regarded as a brain form of diabetes, i.e., type 3 diabetes, and entertains the hypothesis that type 3 diabetes is just one of the categories of insulin resistance diseases that can occur independently or overlap with one or more of the others, including type 2 diabetes, metabolic syndrome, and nonalcoholic fatty liver disease.

Group cognitive remediation therapy for adults with obesity prior to behavioural weight loss treatment: study protocol for a randomised controlled superiority study (CRT study)

INTRODUCTION

Individuals with obesity show deficits in executive functioning which have been implicated in decreased weight loss outcome. Preliminary evidence suggests that cognitive remediation therapy (CRT) improves executive functioning and weight loss in obesity. However, confirmatory support, especially for pre-weight loss use, is lacking. The CRT study aims at determining the efficacy of CRT versus no treatment control in patients with obesity before entering behavioural weight loss (BWL) treatment. It is hypothesised that individuals who receive CRT will show better weight loss outcome, improved executive functioning, greater weight loss-related behavioural changes and higher attendance of BWL treatment, 6 and 12 months after cessation of CRT.

METHODS AND ANALYSIS

In a single-centre, assessor-blinded, randomised, two-armed parallel-group superiority trial, 260 adults with body mass index ≥35.0 kg/m2 are centrally randomised to 8-week group-based CRT versus no treatment, before entering BWL treatment. Primary outcome is the amount of weight loss (%) at 6-month follow-up, compared with pre-treatment, derived from measured body weight. Secondary outcomes include improvement in executive functioning post-treatment and in weight loss-related behaviour, mental and physical health, and attendance to BWL treatment at 6-month and 12-month follow-up. Maintenance of weight loss at 12-month follow-up will be determined. Mixed model analyses based on intent-to-treat will be used to compare the CRT and control groups with respect to differences in weight change between pre-treatment and 6-month follow-up. Similar models will be used for analysing 12-month follow-up data and secondary outcomes. Further analyses will include additional covariates to identify predictors of treatment outcome.

ETHICS AND DISSEMINATION

The study was approved by the Ethical Committee of the University of Leipzig (256-15-13072015, version 'Final 1.0 from 28 May 2015). The study results will be disseminated through peer-reviewed publications.

TRIAL REGISTRATION NUMBER

DRKS00009333; Pre-results.

Streptozotocin-induced β-cell damage, high fat diet, and metformin administration regulate Hes3 expression in the adult mouse brain

Diabetes mellitus is a group of disorders characterized by prolonged high levels of circulating blood glucose. Type 1 diabetes is caused by decreased insulin production in the pancreas whereas type 2 diabetes may develop due to obesity and lack of exercise; it begins with insulin resistance whereby cells fail to respond properly to insulin and it may also progress to decreased insulin levels. The brain is an important target for insulin, and there is great interest in understanding how diabetes affects the brain. In addition to the direct effects of insulin on the brain, diabetes may also impact the brain through modulation of the inflammatory system. Here we investigate how perturbation of circulating insulin levels affects the expression of Hes3, a transcription factor expressed in neural stem and progenitor cells that is involved in tissue regeneration. Our data show that streptozotocin-induced β-cell damage, high fat diet, as well as metformin, a common type 2 diabetes medication, regulate Hes3 levels in the brain. This work suggests that Hes3 is a valuable biomarker helping to monitor the state of endogenous neural stem and progenitor cells in the context of diabetes mellitus.

The effect of a ketogenic diet versus a high-carbohydrate, low-fat diet on sleep, cognition, thyroid function, and cardiovascular health independent of weight loss: study protocol for a randomized controlled trial

Background

Many physiological health benefits observed after following a ketogenic diet (KD) can be attributed to the associated weight loss. The KD has become more prominent as a popular health choice, not only in obese/overweight individuals, but also in healthy adults. The study aims to determine the effects of a KD, independent of weight loss, on various aspects of physiological health including: sleep, thyroid function, cognition, and cardio-metabolic health. The study will also aim to determine whether a change in basal metabolic rate may be associated with any changes observed.

Methods

Twenty healthy men and women between 18 and 50 years of age will take part in this study. In a randomized controlled, cross-over design, participants will follow two isocaloric diets: a high-carbohydrate, low-fat diet (55% CHO, 20% fat, 25% protein) and a KD (15% CHO, 60% fat, 25% protein). Each dietary intervention will last for a minimum of 3 weeks, with a 1-week washout period in between. Before and after each diet, participants will be assessed for sleep quality, cognitive function, thyroid function, and basal metabolic rate. A blood sample will also be taken for the measurement of cardio-metabolic and immune markers.

Discussion

The present study will help in understanding the potential effects of a KD on aspects of physiological health in healthy adults, without the confounding factor of weight loss. The study aims to fill a significant void in the academic literature with regards to the benefits and/or risks of a KD in a healthy population, but will also explore whether diet-related metabolic changes may be responsible for the changes observed in physiological health.

Trial registration

Pan African Clinical Trial Registry (www.pactr.org), trial number: PACTR201707002406306. Registered on 20 July 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2462-5) contains supplementary material, which is available to authorized users.

Community Socioeconomic Disadvantage in Midlife Relates to Cortical Morphology via Neuroendocrine and Cardiometabolic Pathways

Residing in communities of socioeconomic disadvantage confers risk for chronic diseases and cognitive aging, as well as risk for biological factors that negatively affect brain morphology. The present study tested whether community disadvantage negatively associates with brain morphology via 2 biological factors encompassing cardiometabolic disease risk and neuroendocrine function. Participants were 448 midlife adults aged 30-54 years (236 women) who underwent structural neuroimaging to assess cortical and subcortical brain tissue morphology. Community disadvantage was indexed by US Census data geocoded to participants' residential addresses. Cardiometabolic risk was indexed by measurements of adiposity, blood pressure, glucose, insulin, and lipids. Neuroendocrine function was indexed from salivary cortisol measurements taken over 3 days, from which we computed the cortisol awakening response, area-under-the-curve, and diurnal cortisol decline. Community disadvantage was associated with reduced cortical tissue volume, cortical surface area, and cortical thickness, but not subcortical morphology. Moreover, increased cardiometabolic risk and a flatter (dysregulated) diurnal cortisol decline mediated the associations of community disadvantage and cortical gray matter volume. These effects were independent of age, sex, and individual-level socioeconomic position. The adverse risks of residing in a disadvantaged community may extend to the cerebral cortex via cardiometabolic and neuroendocrine pathways.

Changes in Cognitive Function Following Bariatric Surgery: a Systematic Review

Increased body mass is directly associated with reduced cognitive function. The aim of this study was to systematically review the effect of bariatric weight loss surgery on cognitive function. A comprehensive and unrestricted literature search was conducted using the following databases: MEDLINE, EMBASE, PubMed, Scopus, Web of Sciences, and the Cochrane Library. A total of 414 publications were identified, of which 18 were included in the final review. Cognitive function as measured by a number of different assessment tools was shown to improve following surgically induced weight loss in most studies. Significant and rapid weight loss resulting from bariatric surgery is associated with prompt and sustained improvements in cognitive function including memory, executive function, and cognitive control.

FGF21 Attenuates High-Fat Diet-Induced Cognitive Impairment via Metabolic Regulation and Anti-inflammation of Obese Mice

Accumulating studies suggest that overnutrition-associated obesity may lead to development of type 2 diabetes mellitus and metabolic syndromes (MetS). MetS and its components are important risk factors of mild cognitive impairment, age-related cognitive decline, vascular dementia, and Alzheimer's disease. It has been recently proposed that development of a disease-course modification strategy toward early and effective risk factor management would be clinically significant in reducing the risk of metabolic disorder-initiated cognitive decline. In the present study, we propose that fibroblast growth factor 21 (FGF21) is a novel candidate for the disease-course modification approach. Using a high-fat diet (HFD) consumption-induced obese mouse model, we tested our hypothesis that recombinant human FGF21 (rFGF21) administration is effective for improving obesity-induced cognitive dysfunction and anxiety-like behavior, by its multiple metabolic modulation and anti-pro-inflammation actions. Our experimental findings support our hypothesis that rFGF21 is protective to HFD-induced cognitive impairment, at least in part by metabolic regulation in glucose tolerance impairment, insulin resistance, and hyperlipidemia; potent systemic pro-inflammation inhibition; and improvement of hippocampal dysfunction, particularly by inhibiting pro-neuroinflammation and neurogenesis deficit. This study suggests that FGF21 might be a novel molecular target of the disease-course-modifying strategy for early intervention of MstS-associated cognitive decline.

Insulin Resistance and Neurodegeneration: Progress Towards the Development of New Therapeutics for Alzheimer's Disease

Alzheimer's disease (AD) should be regarded as a degenerative metabolic disease caused by brain insulin resistance and deficiency, and overlapping with the molecular, biochemical, pathophysiological, and metabolic dysfunctions in diabetes mellitus, non-alcoholic fatty liver disease, and metabolic syndrome. Although most of the diagnostic and therapeutic approaches over the past several decades have focused on amyloid-beta (Aβ42) and aberrantly phosphorylated tau, which could be caused by consequences of brain insulin resistance, the broader array of pathologies including white matter atrophy with loss of myelinated fibrils and leukoaraiosis, non-Aβ42 microvascular disease, dysregulated lipid metabolism, mitochondrial dysfunction, astrocytic gliosis, neuro-inflammation, and loss of synapses vis-à-vis growth of dystrophic neurites, is not readily accounted for by Aβ42 accumulations, but could be explained by dysregulated insulin/IGF-1 signaling with attendant impairments in signal transduction and gene expression. This review covers the diverse range of brain abnormalities in AD and discusses how insulins, incretins, and insulin sensitizers could be utilized to treat at different stages of neurodegeneration.

The Health Consequences of Obesity in Young Adulthood

Young adults are gaining weight faster than any age group. This weight gain and the appearance of obesity-related comorbidities often commence in adolescence. Psychosocial distress and mental health issues are common and debilitating, and treatment approaches are likely to be similar to those for adolescents. At the same time, young adults may have physical morbidities which will continue and worsen throughout adulthood, such as hypertension, diabetes and polycystic ovarian syndrome. Health consequences of obesity are challenging to manage in young adults as their symptoms may be minimal, they are less likely to engage with healthcare due to other life priorities and their neurocognitive developmental stage makes therapy adherence difficult. Clinicians who manage young adults with obesity need to be aware of these age-specific challenges, as well as the sexual and reproductive health concerns that are present in this age group.