The risk of overweight/obesity in mid-life and late life for the development of dementia: a systematic review and meta-analysis of longitudinal studies

5,7,3',4',5'-pentamethoxyflavone (PMF) exhibits anti-obesity and neuroprotective effects in an obese zebrafish model

Obesity is a multi-chronic illness characterized by superfluous fat accumulation, contributing to significant metabolic and neurological complications. Current therapeutic approaches have limited efficacy and notable side effects, underscoring an urgent demand for novel, safer alternatives. This study is the first to investigate the anti-obesity potential of 5,7,3',4',5'-pentamethoxyflavone (PMF) in vivo using a zebrafish model. Our findings demonstrate that PMF administration exerts pronounced anti-obesogenic effects, evidenced by reductions in blood glucose, plasma triglycerides, total cholesterol, hepatic low-density lipoproteins (LDL), and high-density lipoproteins (HDL). Mechanistically, PMF suppressed hepatic adipogenic and lipogenic gene expression while promoting lipid catabolism through activation of peroxisome proliferator-activated receptor-alpha (PPAR-α) and its downstream enzymes, including acyl-CoA oxidase 1 (ACOX1), medium-chain acyl-CoA dehydrogenase (ACADM), and carnitine palmitoyl transferase 1B (CPT-1β). Additionally, PMF markedly mitigated oxidative stress by lowering malondialdehyde (MDA) and nitric oxide (NO) levels, accompanied by increased antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione S-transferase (GST). Notably, PMF effectively prevented obesity by suppressing food intake, downregulating orexigenic genes, and enhancing anorexigenic signals. Furthermore, PMF exhibited neuroprotective properties by elevating brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin receptor kinase B2 (TrkB2), revealing a novel link between metabolic and neurological regulation. This study provides pioneering, comprehensive in vivo evidence supporting PMF as a promising therapeutic candidate with dual beneficial roles in metabolic health and neuroprotection.

Cardiovascular risk and obesity impact loss of grey matter volume earlier in males than females

BACKGROUND

It remains imperative to discover the time course that cardiovascular risk factors influence neurodegeneration in males and females and decipher whether the apolipoprotein (APOE) genotype mediates this relationship. Here we perform a large-scale evaluation of the influence of cardiovascular risk and obesity on brain volume in males and females in different age groups.

METHODS

34 425 participants between the ages of 45 and 82 years were recruited from the UK Biobank database https://www.ukbiobank.ac.uk. T1-weighted structural MR images (n=34 425) were downloaded locally for all participants, and voxel-based morphometry was performed to characterise the volumetric changes of the whole brain. The influence of Framingham cardiovascular risk (general cardiovascular risk), abdominal subcutaneous adipose tissue, and visceral adipose tissue volume (obesity) on cortical grey matter volume across different decades of life was evaluated with voxel-wise analysis.

RESULTS

In males, cardiovascular risk and obesity demonstrated the greatest influence on lower grey matter volume between 55-64 years of age. Female participants showed the greatest effect on lower grey matter volume between 65-74 years of age. Associations remained significant in APOE ε4 carriers and APOE ε4 non-carriers when evaluated separately.

CONCLUSIONS

The strongest influence of cardiovascular risk and obesity on reduced brain volume was between 55-64 years of age in males, whereas women were most susceptible to the detrimental effects of cardiovascular risk a decade later between 65-74 years of age. Here we elucidate the timing that targeting cardiovascular risk factors and obesity should be implemented in males and females to prevent neurodegeneration and Alzheimer's disease development.

Modifiable risk factors for stroke, dementia and late-life depression: a systematic review and DALY-weighted risk factors for a composite outcome

BACKGROUND

At least 60% of stroke, 40% of dementia and 35% of late-life depression (LLD) are attributable to modifiable risk factors, with great overlap due to shared pathophysiology. This study aims to systematically identify overlapping risk factors for these diseases and calculate their relative impact on a composite outcome.

METHODS

A systematic literature review was performed in PubMed, Embase and PsycInfo, between January 2000 and September 2023. We included meta-analyses reporting effect sizes of modifiable risk factors on the incidence of stroke, dementia and/or LLD. The most relevant meta-analyses were selected, and disability-adjusted life year (DALY) weighted beta (β)-coefficients were calculated for a composite outcome. The β-coefficients were normalised to assess relative impact.

RESULTS

Our search yielded 182 meta-analyses meeting the inclusion criteria, of which 59 were selected to calculate DALY-weighted risk factors for a composite outcome. Identified risk factors included alcohol (normalised β-coefficient highest category: -34), blood pressure (130), body mass index (70), fasting plasma glucose (94), total cholesterol (22), leisure time cognitive activity (-91), depressive symptoms (57), diet (51), hearing loss (60), kidney function (101), pain (42), physical activity (-56), purpose in life (-50), sleep (76), smoking (91), social engagement (53) and stress (55).

CONCLUSIONS

This study identified overlapping modifiable risk factors and calculated the relative impact of these factors on the risk of a composite outcome of stroke, dementia and LLD. These findings could guide preventative strategies and serve as an empirical foundation for future development of tools that can empower people to reduce their risk of these diseases.

PROSPERO REGISTRATION NUMBER

CRD42023476939.

Association of Early- to Midlife Weight Trajectories With Mid- to Late-Life Cognitive Decline in the ELSA-Brasil Study

BACKGROUND AND OBJECTIVES

While midlife obesity is consistently associated with cognitive decline in later life, there is limited understanding of how weight variations from early life to midlife affect cognitive decline. We investigated the association between early- to midlife weight trajectories and mid- to late-life cognitive decline.

METHODS

This is a longitudinal cohort study that used data from 3 waves (2008-2019) of the Brazilian Longitudinal Study of Adult Health, a multicenter cohort study that enrolled active and retired public servants aged 35+ years from public universities in Brazil. Participants with a history of stroke, missing cognitive data at baseline, and with incomplete body shape data were excluded from the analyses. Self-reported body shapes from ages 5 to 40 using the Stunkard Figure Rating Scale were categorized as underweight, normal, overweight, and obese. Sequence analysis and hierarchical clustering identified weight trajectories. Global cognition Z-scores were derived from memory (immediate recall, delayed recall, and recognition of a word list), phonemic and semantic verbal fluency, and Trail Making Test part B (TMT-B). Linear mixed models adjusted for sociodemographic, clinical, and lifestyle covariates investigated associations between clusters of weight trajectories and global cognition Z-scores. Inverse probability of attrition weighting was used to account for attrition bias.

RESULTS

Among 11,361 participants (mean age: 51.5 ± 8.6, 55% women, 42.4% Black/mixed race), "normal to overweight," "underweight to normal," and "stable overweight" trajectories exhibited faster global cognitive decline than "stable normal" trajectory (β = -0.024; 95% CI -0.043 to -0.005; p = 0.015; β = -0.026; 95% CI -0.040 to -0.012; p < 0.001; β = -0.034; 95% CI -0.066 to -0.001; p = 0.043, respectively), representing 4.6-6.5 excess years of cognitive aging over a median follow-up of 8 years. Cognitive decline associated with weight trajectories was driven mainly by declines in memory and TMT-B performance. Associations were observed only in Black/mixed races and women when stratified.

DISCUSSION

Weight gain and stable overweight trajectories from early life to midlife were associated with faster cognitive decline than stable normal weight trajectories. Weight management during early life may mitigate cognitive decline. Study limitations include reliance on self-reported body shape data, potential recall bias, and residual confounding from unmeasured early-life factors.

Association of Body Mass Index in Late Life, and Change from Midlife to Late Life, With Incident Dementia in the ARIC Study Participants

BACKGROUND AND OBJECTIVES

Midlife obesity is a risk factor of dementia, but late-life obesity has been associated with lower dementia risk. We investigated this paradox by exploring the relationship between late-life body mass index (BMI) category and dementia, with and without considering midlife to late-life BMI change.

METHODS

This observational cohort study included participants of the community-based Atherosclerosis Risk in Communities (ARIC) study who were dementia-free at visit 5 (2011-2013). Dementia was ascertained by expert-adjudicated, algorithmic classification from an in-person neuropsychological battery, as well as telephone interviews and International Classification of Diseases codes from medical records. We first assessed the association of incident dementia with visit 5 BMI categories (normal weight, overweight, obese). Next, we used a cross-classification of visit 5 BMI categories with visit 4-visit 5 BMI change (decrease [loss of ≥2 kg/m2], increase [gain of ≥2 kg/m2], or stable [loss or gain of <2 kg/m2]) occurring during the 15 years before baseline. Cox regression was used.

RESULTS

A total of 5,129 participants were included in the study (59% female; 22% identified as Black; mean (standard deviation) age at visit 5 of 75 (5) years). Over 8 years of follow-up, 20% of the sample developed dementia (n = 1,026). After covariate adjustment, participants with high late-life BMI had a lower risk of dementia; the hazard ratio (95% CI) was 0.86 (0.73-1.00) for overweight and 0.81 (0.68-0.96) for obesity. In stratified models, elevated dementia risk was observed only for participants of each late-life BMI category whose BMI had decreased from midlife to late life. Compared with normal-weight individuals who had maintained BMI from midlife to late life, the hazard ratio (95% CI) for those with BMI loss was 2.08 (1.62-2.67) for normal-weight individuals, 1.62 (1.25-2.10) for those with overweight, and 1.36 (1.00-1.85) for those with obesity.

DISCUSSION

Our results provide insight into the dementia obesity paradox at older ages, tempering a causal interpretation of high late-life BMI as protective against dementia. Instead, they highlight the importance of considering weight loss from midlife to late life in conjunction with late-life BMI in dementia risk stratification.

Dietary vitamin D intake and 2-year changes in cognitive function in older adults with overweight or obesity and metabolic syndrome

The protective role of dietary vitamin D intake on cognitive function is of interest, but evidence remains inconsistent. We aimed to evaluate the association between dietary vitamin D intake and 2-year cognitive changes in older adults at risk of cognitive decline. This longitudinal study comprised 5454 individuals (aged 55-75 years in men and 60-75 years in women) who exhibited overweight/obesity and metabolic syndrome. Data on dietary vitamin D intake was assessed using a validated 143-item food frequency questionnaire. Cognitive function was assessed through five composite scores derived from a comprehensive battery of eight neuropsychological tests, encompassing global cognitive function, general cognitive function, attention, executive function, and language domains. Multivariable-adjusted linear regression models were fitted to examine the association between energy-adjusted cumulative average dietary vitamin D intake over time and 2-year changes in cognitive function. After adjusting for multiple covariates, energy-adjusted cumulative average dietary vitamin D intake as a continuous variable was associated with greater 2-year improvements in global cognitive function (β 1.18 × 10-2; 95% CI 0.19 × 10-2 to 2.17 × 10-2), executive function (β 1.12 × 10-2; 95% CI 0.03 × 10-2 to 2.21 × 10-2), and language (β 1.61 × 10-2; 95% CI 0.43 × 10-2 to 2.78 × 10-2). Additionally, the higher cumulative average dietary vitamin D intake quartile was associated with an increase in global cognitive function (β 7.10 × 10-2; 95% CI 0.59 × 10-2 to 13.6 × 10-2), language (β 7.07 × 10-2; 95% CI - 0.52 × 10-2 to 14.7 × 10-2), and a lower decline in attention (β 9.58 × 10-2; 95% CI 1.60 × 10-2 to 17.5 × 10-2). A higher dietary vitamin D intake was associated with modest favorable changes in cognitive function and a reduced cognitive decline over a 2-year period. These findings highlight the need for further research to explore the potential benefits of boosting dietary vitamin D intake for cognitive health in older adults.

Causal cardiovascular risk factors for dementia: insights from observational and genetic studies

The escalating prevalence of dementia worldwide necessitates preventive strategies to mitigate its extensive health, psychological, and social impacts. As the prevalence of dementia continues to rise, gaining insights into its risk factors and causes becomes paramount, given the absence of a definitive cure. Cardiovascular disease has emerged as a prominent player in the complex landscape of dementia. Preventing dyslipidaemia, unhealthy western-type diets, hypertension, diabetes, being overweight, physical inactivity, smoking, and high alcohol intake have the potential to diminish not only cardiovascular disease but also dementia. The purpose of this review is to present our current understanding of cardiovascular risk factors for Alzheimer's disease and vascular dementia (VaD) by using clinical human data from observational, genetic studies and clinical trials, while elaborating on potential mechanisms. Hypertension and Type 2 diabetes surface as significant causal risk factors for both Alzheimer's disease and VaD, as consistently illustrated in observational and Mendelian randomization studies. Anti-hypertensive drugs and physical activity have been shown to improve cognitive function in clinical trials. Important to note is that robust genome-wide association studies are lacking for VaD, and indeed more and prolonged clinical trials are needed to establish these findings and investigate other risk factors. Trials should strategically target individuals at the highest dementia risk, identified using risk charts incorporating genetic markers, biomarkers, and cardiovascular risk factors. Understanding causal risk factors for dementia will optimize preventive measures, and the implementation of well-known therapeutics can halt or alleviate dementia symptoms if started early. Needless to mention is that future health policies should prioritize primordial prevention from early childhood to prevent risk factors from even occurring in the first place. Together, understanding the role of cardiovascular risk factors in dementia, improving genome-wide association studies for VaD, and advancing clinical trials are crucial steps in addressing this significant public health challenge.

The Effect of Topiramate on the Cerebellum of the Obese Female Rats: A Stereological, Histochemical and Bioinformatical Study by Investigation of TNF-α Interaction

The rising incidence of obesity underscores the necessity for alternative obesity treatments. Patients commonly prefer medication aiding in weight reduction. Topiramate, an antiepileptic drug, is gaining popularity among obese patients for its weight loss benefits. This study aims to explore Topiramate's impact on the cerebella of obese female rats. In the experiment, 24 female rats (200-250 g) were divided into four groups: non-obese control (NOC), obese control (OC), non-obese topiramate (NOT) and obese topiramate (OT). The non-obese rats were given a standard diet, while the obese rats received a high-fat diet (40% fat). After 9 weeks, topiramate was administered intraperitoneally daily for 6 weeks. Following this, the rats were euthanised, and their cerebella were removed. The volume of the cerebellum and mean numerical density of the molecular neurons, granular neurons and Purkinje cells were estimated using stereological methods, and the link between obesity-caused cerebellum damage and TNF-α was assessed through immunohistochemical and bioinformatic techniques. Additionally, histopathological evaluations of the tissues were conducted. The cerebellar volume in the OC group was decreased compared to the NOC group. The topiramate groups exhibited a decrease in molecular or/and granular neuron numbers in the NOT and OT groups. Notably, neurons with dark cytoplasm were observed in the topiramate-treated groups, alongside neuronal degeneration was seen in the obese groups. The connection between TNF-α and obesity or obesity-caused cerebellum damage was confirmed through both immunohistochemical and bioinformatics analyses. These findings suggest that topiramate might have a degenerative effect on the cerebellum, especially following obesity.

Data-driven discovery of midlife cardiometabolic profile associated with incident early-onset and late-onset dementia

BACKGROUND

Cardiometabolic risk factors have been associated with the risk of late-onset dementia. However, evidence regarding early-onset dementia was inconsistent, and the impact of clustered cardiometabolic risk factors was unclear. We aimed to investigate the associations of cardiometabolic profiles with incident early-onset and late-onset dementia.

METHODS

Among 289 494 UK Biobank participants, cluster analysis was built on 12 common cardiometabolic markers. Analyses were performed on those aged <65 years at baseline (n = 249 870) for early-onset dementia and those ≥65 at the end of follow-up (n = 191 213) for late-onset dementia.

RESULTS

During a median follow-up of 14.1 years, 279 early-onset dementia cases and 3167 late-onset dementia cases were documented. Among the five clusters of cardiometabolic profiles identified (cluster 1 [obesity-dyslipidemia pattern], cluster 2 [high blood pressure pattern], cluster 3 [high liver enzymes pattern], cluster 4 [inflammation pattern] and cluster 5 [relatively healthy pattern]), cluster 3 was significantly associated with higher risks of both early-onset and late-onset dementia; however, the risk estimate for early-onset dementia (hazard ratio 2.58, 95% CI 1.61-4.14) was larger than that for late-onset dementia (1.36, 1.09-1.71). Cluster 4 was associated with a higher risk of late-onset dementia (hazard ratio 1.39, 95% CI 1.13-1.72). No significant interactions were observed between cardiometabolic clusters and apolipoprotein E ε4 genotype.

CONCLUSIONS

Cardiometabolic patterns characterised by relatively high liver enzyme levels or systemic inflammation were associated with increased risks of early-onset and late-onset dementia. Identification of high-risk subgroups according to distinct cardiometabolic patterns might help develop more precise strategies for dementia prevention regardless of apolipoprotein E (APOE) ε4 status.

Peripheral Inflammation and Insulin Resistance: Their Impact on Blood-Brain Barrier Integrity and Glia Activation in Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, memory impairment, and synaptic dysfunction. The accumulation of amyloid beta (Aβ) plaques and hyperphosphorylated tau protein leads to neuronal dysfunction, neuroinflammation, and glial cell activation. Emerging evidence suggests that peripheral insulin resistance and chronic inflammation, often associated with type 2 diabetes (T2D) and obesity, promote increased proinflammatory cytokines, oxidative stress, and immune cell infiltration. These conditions further damage the blood-brain barrier (BBB) integrity and promote neurotoxicity and chronic glial cell activation. This induces neuroinflammation and impaired neuronal insulin signaling, reducing glucose metabolism and exacerbating Aβ accumulation and tau hyperphosphorylation. Indeed, epidemiological studies have linked T2D and obesity with an increased risk of developing AD, reinforcing the connection between metabolic disorders and neurodegeneration. This review explores the relationships between peripheral insulin resistance, inflammation, and BBB dysfunction, highlighting their role in glial activation and the exacerbation of AD pathology.

Ceramides may Play a Central Role in the Pathogenesis of Alzheimer's Disease: a Review of Evidence and Horizons for Discovery

While several hypotheses have been proposed to explain the underlying mechanisms of Alzheimer's disease, none have been entirely satisfactory. Both genetic and non-genetic risk factors, such as infections, metabolic disorders and psychological stress, contribute to this debilitating disease. Multiple lines of evidence indicate that ceramides may be central to the pathogenesis of Alzheimer's disease. Tumor necrosis factor-α, saturated fatty acids and cortisol elevate the brain levels of ceramides, while genetic risk factors, such as mutations in APP, presenilin, TREM2 and APOE ε4, also elevate ceramide synthesis. Importantly, ceramides displace sphingomyelin and cholesterol from lipid raft-like membrane patches that connect the endoplasmic reticulum and mitochondria, disturbing mitochondrial oxidative phosphorylation and energy production. As a consequence, the flattening of lipid rafts alters the function of γ-secretase, leading to increased production of Aβ42. Moreover, ceramides inhibit the insulin-signaling cascade via at least three mechanisms, resulting in the activation of glycogen synthase kinase-3 β. Activation of this kinase has multiple consequences, as it further deteriorates insulin resistance, promotes the transcription of BACE1, causes hyperphosphorylation of tau and inhibits the transcription factor Nrf2. Functional Nrf2 prevents apoptosis, mediates anti-inflammatory activity and improves blood-brain barrier function. Thus, various seemingly unrelated Alzheimer's disease risk factors converge on ceramide production, whereas the elevated levels of ceramides give rise to the well-known pathological features of Alzheimer's disease. Understanding and targeting these mechanisms may provide a promising foundation for the development of novel preventive and therapeutic strategies.

Acupuncture treatment of vascular cognitive impairment through peripheral nerve stimulation pathway: a scoping review

Objective

This study aims to explore the central effects of acupuncture on vascular cognitive impairment (VCI) through peripheral nerve stimulation.

Methods

This scoping review followed the methodological framework proposed by Arksey and O'Malley and the PRISMA-ScR guidelines. A comprehensive search of databases, including PubMed, Web of Science, MEDLINE, and Embase, was conducted, including 79 studies on acupuncture interventions for VCI. Acupoints and their underlying anatomical structures related to peripheral nerves were summarized, and the potential pathways of acupuncture effects via different peripheral nerves were explored.

Results

The results showed that acupuncture, by stimulating specific acupoints on the head, face, torso, and limbs, significantly affects peripheral nerve networks, including the cervical, lumbar, and sacral plexuses, thoracic nerves, vagus nerve, trigeminal nerve and its branches. The nerve stimulation effects of acupuncture can enhance the regulation of cerebral blood flow, modulate neuroimmune responses, improve brain function, and promote neuroplasticity through multiple central nervous system pathways, ultimately improving cognitive function and treating VCI.

Conclusion

Acupuncture is a treatment modality that influences the central nervous system through peripheral nerve stimulation to treat VCI. A deeper understanding of the central effects induced by acupuncture-triggered neural reflexes can contribute to the improvement of existing therapies and help elucidate the scientific principles underlying acupuncture's therapeutic effects.

Impact of obesity on neuropsychiatric symptoms in Alzheimer's disease: Insights from the ADNI cohort

BackgroundObesity is a major global health issue linked to increased risks of dementia, including Alzheimer's disease (AD). While the association between obesity and neuropsychiatric symptoms (NPS) in AD remains underexplored, identifying these links could aid in weight management in AD patients.ObjectiveThis study investigates the relationship between body mass index (BMI) and NPS in AD dementia patients, focusing on the potential mediating role of systemic inflammation.MethodsWe employed Generalized Additive Models (GAMs) to explore the relationship between BMI and NPS, as measured by the Neuropsychiatric Inventory Questionnaire (NPI-Q). Participants were classified into ideal, overweight, and obese groups based on WHO criteria. Longitudinal analyses assessed the trajectory of NPI-Q scores in different groups over a one-year follow-up.ResultsBMI significantly affects NPI-Q total scores and specific symptoms, including delusions, hallucinations, agitation/aggression, elation/euphoria, disinhibition, irritability/lability, aberrant motor behavior, nighttime disturbances, and appetite/eating disturbances. Obese patients exhibited higher NPI-Q total scores and greater severity in symptoms such as hallucinations, agitation/aggression, elation/euphoria, apathy/indifference, disinhibition, aberrant motor behavior, and nighttime disturbances. Additionally, CRP and complement C3 were identified as mediators in the relationship between obesity and NPS, highlighting the role of systemic inflammation.ConclusionsThis study demonstrates that obesity is associated with a heightened burden of NPS in AD dementia patients. The identification of CRP and complement C3 as mediators suggests inflammation plays a crucial role in the association between obesity and NPS. These findings underscore the importance of addressing obesity and its inflammatory consequences in managing NPS among this vulnerable population.

Sex differences in body mass index and waist circumference trajectories and dementia risk: the HUNT4 70+ study

We examined associations between body mass index (BMI), waist circumference (WC), and dementia risk, and differences in BMI and WC trajectories before dementia diagnosis. We included 9,739 participants (54% women) aged 70+ from the Trøndelag Health Study (HUNT4 70+). BMI was measured four times (1984-2019) and WC three times (1995-2019). Dementia diagnoses were clinically assessed at HUNT4 70+ . Women and men with dementia had higher midlife BMI and WC than those without dementia. These differences diminished closer to diagnosis, especially in women. Midlife obesity in both sexes and midlife overweight, high WC, and overweight/obesity with high WC in men were linked to higher dementia risk. Lower dementia risk was observed with late-life overweight for both sexes, late-life high WC in women, late-life overweight/obesity with normal WC in men or high WC in women. Adiposity measures and their changes influence dementia risk differently in women and men.

Association of adiposity evaluated by anthropometric and bioelectrical impedance analysis measures with cognitive performance in the ELSA-Brasil study

BACKGROUND

While midlife obesity is linked to cognitive decline, this association is inconsistent in older adults, possibly due to the limitations of body mass index (BMI) in accurately assessing adiposity at older ages. Most studies focused on White or Asian populations, did not include other adiposity measures besides BMI, adjusted the analyses for mediators, and did not investigate potential subgroup-specific associations. We compared the associations of adiposity measured by anthropometrical and bioelectrical impedance analysis (BIA) with cognitive performance in a diverse population, examining modifications by age, sex, and race, and investigating the mediating effects of obesity-related comorbidities.

METHODS

Cross-sectional analysis of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) cohort (n = 12,636). Adiposity was evaluated using BMI, waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), and body fat percentage (BFP). A composite global cognition score was derived from immediate, delayed recall, and word recognition word list, phonemic and semantic verbal fluency, and trail-making tests. Adjusted linear regression models were used to investigate associations. We included an interaction term in the regression models to verify if age, sex, and race were modifiers of these associations and used causal mediation methods to assess the mediating role of obesity-related comorbidities.

RESULTS

Among 10,725 participants [mean age (SD): 58.9 (8.6) years; 55.8% women, 54.4% White], larger WHR and WHtR were associated with worse global cognitive performance. These associations were not modified by age, sex, or race. An association of BFP with cognition was observed only in younger adults. Mediation analysis identified only indirect effects of these adiposity measures on cognitive performance and no direct effects.

CONCLUSION

WHR and WHtR were more consistently associated with cognitive performance than BMI. BIA measures of adiposity were associated with cognition only in younger adults. Obesity-related comorbidities fully mediated the associations of adiposity with cognition.

Plasma adiponectin and biomarker-confirmed Alzheimer's disease in a tertiary memory clinic

Alzheimer's disease (AD) is associated with early metabolic dysfunction and adiponectin, which may play a pathophysiological role. Adiponectin is implicated in the regulation of energy homeostasis, carbohydrate, and lipid metabolism, as well as in inflammation modulation. The aim of this study was to study whether plasma adiponectin levels were different between patients with AD confirmed by biomarkers and neurological control subjects. We performed a monocentric, retrospective, cross-sectional, observational study in AD patients and neurological controls recruited from daily clinical practice in a tertiary memory clinic. Plasma adiponectin levels were measured using a chemiluminescent enzyme immunoassay. We analyzed the relationship between adiponectin and AD using linear regression models including age, gender, and BMI. We also described the distribution of adiponectin concentrations, across age, and gender categories. Two hundred and six patients (142 AD patients and 64 neurological controls) were included, with mean age = 68.8 ± 10.0 years, and 56% were women. Higher adiponectin concentrations were observed in females and in older adults. Plasma adiponectin levels were significantly higher in AD patients (mean = 6.45 ± 3.42 μg/mL) than neurological controls (4.85 ± 3.54 μg/mL) (p < .001). This association was mediated by age, gender, and BMI, which were significantly and independently associated with plasma adiponectin levels (p < .01 for each), while adiponectin was no longer associated with AD in multivariate models. Patients with AD showed higher adiponectin levels, but this association was driven by older age, female gender, and lower BMI in the AD group. Further studies are needed to better characterize the hormonal signature of AD.

Role of obesity-related anthropometric indicators on cognitive function in obese older adults: A systematic review and meta-analysis

OBJECTIVES

The association between obesity and cognitive function in older adults remains inconsistent due to the use of various anthropometric indicators, such as body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR). More conclusive evidence is warranted. The aim of this study was to systematically summarize and synthesize the association between specific obesity-related anthropometric indicators (BMI, WC, and WHR) and cognitive function in obese older adults. Higher BMI, WC, or WHR is linked to cognitive decline in this population.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A comprehensive literature search was carried out using PubMed, CINAHL, Scopus, Embase, and the Cochrane Library (from their inception to October 2023). Studies investigating the association between obesity indicators, including BMI, WC, WHR, and cognitive performance in older adults were included. The weighted mean difference (WMD), Odds Ratio, and 95 % confidence interval (CI) were used to estimate the pooled effect size. A random-effects model was employed as the main method. Subgroup analyses and the certainty of evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach were assessed (registered number: CRD42023461770).

RESULTS

Thirty-three eligible studies, involving 83,251 participants, were included. Obese older adults, as assessed by WC, had lower Mini-Mental State Examination (MMSE) scores than non-obese counterparts (WMD -0.84, 95 % CI -1.64 to -0.05, very low certainty). Those measured by WHR had a 31 % higher risk of cognitive impairment (OR 1.31, 95 % CI 1.12 to 1.53, moderate certainty). Subgroup analysis revealed a lower Montreal Cognitive Assessment (MoCA) score in obese group classified by WHO criteria compared to controls (WMD -1.67, 95 % CI -2.94 to -0.39).

CONCLUSION

This review suggests an association between obesity, as measured by WHR and WC, and poorer cognitive performance in older adults. WHR is moderately recommended for identifying cognitive impairment-related obesity, while WC recommendations are limited by very low evidence certainty.

Unravelling Convergent Signaling Mechanisms Underlying the Aging-Disease Nexus Using Computational Language Analysis

Multiple lines of evidence suggest that multiple pathological conditions and diseases that account for the majority of human mortality are driven by the molecular aging process. At the cellular level, aging can largely be conceptualized to comprise the progressive accumulation of molecular damage, leading to resultant cellular dysfunction. As many diseases, e.g., cancer, coronary heart disease, Chronic obstructive pulmonary disease, Type II diabetes mellitus, or chronic kidney disease, potentially share a common molecular etiology, then the identification of such mechanisms may represent an ideal locus to develop targeted prophylactic agents that can mitigate this disease-driving mechanism. Here, using the input of artificial intelligence systems to generate unbiased disease and aging mechanism profiles, we have aimed to identify key signaling mechanisms that may represent new disease-preventing signaling pathways that are ideal for the creation of disease-preventing chemical interventions. Using a combinatorial informatics approach, we have identified a potential critical mechanism involving the recently identified kinase, Dual specificity tyrosine-phosphorylation-regulated kinase 3 (DYRK3) and the epidermal growth factor receptor (EGFR) that may function as a regulator of the pathological transition of health into disease via the control of cellular fate in response to stressful insults.

Association of mid-age Life's Essential 8 score with digital cognitive performance and incident Alzheimer's disease: The Framingham Heart Study

BackgroundCardiovascular health (CVH) is a modifiable risk factor for Alzheimer's disease (AD). However, studies examining the association between mid-age CVH, as indicated by Life's Essential 8 (LE8) health metrics, and digital cognitive performance or AD risk are limited.ObjectiveTo examine the associations between mid-age CVH, assessed by LE8 scores during ages 45 to 65, and digital Clock Drawing Test (dCDT) performance as well as the incidence of AD.MethodsWe included 1198 participants (51.6% women) from the Framingham Heart Study (FHS) Offspring cohort. Linear regression and Cox proportional hazards models were applied to examine the associations between mid-age CVH and dCDT performance, as well as the incidence of AD.ResultsOver a median follow-up of 17.5 years, 45 participants developed AD. Each standard deviation (SD) higher mid-age LE8 total score was associated with a 0.16 SD higher level of the dCDT total score (p < 0.001) and a 0.35-fold lower risk of incident AD (HR = 0.65, 95% CI: 0.49-0.87, p = 0.003). The dCDT measures showed stronger associations with mid-age LE8 and AD risk compared to the conventional CDT (cCDT). For example, the drawing score on copy tasks was more strongly associated with LE8 (beta = 0.10, p = 0.007 versus beta = 0.08, p = 0.27) and had higher discrimination for incident AD (C-statistic = 0.89 versus 0.83) compared to the cCDT.ConclusionsOur results highlight the potential of digital cognitive assessments for evaluating AD risk and emphasize the importance of mid-age CVH in shaping cognitive outcomes and the development of AD.

Associations between potential risk factors and blood-brain barrier water permeability in middle-aged and older adults

Background: Blood-brain barrier (BBB) dysfunction is suggested to be a potential mediator between vascular risk factors and cognitive impairment, leading to vascular cognitive impairment. Objective: To investigate the relationships between age, sex, and vascular risk factors and BBB water permeability as well as their relationship with cognition. Methods: To measure BBB permeability, a novel arterial spin labelling MRI technique (ME-ASL) was applied to derive the time of exchange (Tex), arterial time transit (ATT), and cerebral blood flow (CBF). The association of potential risk factors, such as age, sex, body mass index (BMI), blood pressure (BP), and medical history, with these BBB parameters were assessed in 144 community-dwelling adults (median age 59 years, 57% females). The relationship between BBB permeability and cognitive performance measured by the Montreal Cognitive Assessment (MoCA) was also assessed. Results: We found that increased BMI was significantly associated with decreased CBF (β = -0.06). Systolic BP and diastolic BP showed significant associations with all ASL parameters; systolic BP was negatively correlated with Tex (β = -0.02) and CBF (β = -0.01) but positively with ATT (β = 0.02). Diastolic BP was negatively associated with Tex (β = -0.03) and CBF (β = -0.03) but positively with ATT (β = 0.03). MoCA scores had a borderline significant association with Tex (OR = 1.51) and a significant association with CBF (OR = 1.84), which became non-significant after adjusting for confounders. Conclusions: These outcomes underscore the potential of using ME-ASL, warranting further research to strengthen these findings.

Association of body weight and serum uric acid with Alzheimer's disease biomarkers and cognitive impairment

BackgroundGiven the limited effective treatments for Alzheimer's disease (AD), obesity and serum uric acid (SUA) levels which are considered modifiable risk factors for dementia are of interest. However, research indicates conflicting results.ObjectiveWe aimed to further investigate the association of body weight (BW) and SUA with AD biomarkers and cognitive impairment.MethodsClinical data were collected from 139 adults (mean age 66.9 years) with chronic cognitive impairment. Cerebrospinal fluid (CSF) biomarkers and PET imaging were used to assess amyloid-β (A) and Tau (T) tangles load, classifying participants into AT profiles based on the results. The association of BW and SUA with AT profiles was evaluated using multivariable logistic regression, and their relationship with cognitive function (Mini-Mental State Examination (MMSE) scores) were analyzed using multivariable linear regression.ResultsLower BW levels significantly influenced the presence of Aβ positive state (A+) (p = 0.007), while SUA levels did not (p = 0.263). Higher dementia proportion (p = 0.021), lighter BW (p = 0.019), and lower mean arterial pressure (MAP) levels (p = 0.025) were associated with AD pathological progress (A-T-→A+T-→A+T+), but SUA was not observed statistically significant. Among all participants regardless of Aβ state, high education levels (p < 0.001), high BW (p = 0.010), and high SUA (p=0.036) were associated with high MMSE scores, and high serum creatinine (p = 0.003) was associated with low MMSE scores.ConclusionsLower BW may accelerate AD pathology and cause cognitive impairment, while SUA is not linked to AD pathological progression but protects cognitive function.

Obesity pharmacotherapy in older adults: a narrative review of evidence

The prevalence of obesity in older adults (people aged >60 years) is increasing in line with the demographic shift in global populations. Despite knowledge of obesity-related complications in younger adults (increased risk of type 2 diabetes, liver and cardiovascular disease and malignancy), these considerations may be outweighed, in older adults, by concerns regarding weight-loss induced reduction in skeletal muscle and bone mass, and the awareness of the 'obesity paradox'. Obesity in the elderly contributes to various obesity-related complications from cardiometabolic disease and cancer, to functional decline, worsening cognition, and quality of life, that will have already suffered an age-related decline. Lifestyle interventions remain the cornerstone of obesity management in older adults, with emphasis on resistance training for muscle strength and bone mineral density preservation. However, in older adults with obesity refractory to lifestyle strategies, pharmacotherapy, using anti-obesity medicines (AOMs), can be a useful adjunct. Recent evidence suggests that intentional weight loss in older adults with overweight and obesity is effective and safe, hence a diminishing reluctance to use AOMs in this more vulnerable population. Despite nine AOMs being currently approved for the treatment of obesity, limited clinical trial evidence in older adults predominantly focuses on incretin therapy with glucagon-like peptide-1 receptor agonists (liraglutide, semaglutide, and tirzepatide). AOMs enhance weight loss and reduce cardiometabolic events, while maintaining muscle mass. Future randomised controlled trials should specifically evaluate the effectiveness of novel AOMs for long-term weight management in older adults with obesity, carefully considering the impact on body composition and functional ability, as well as health economics.

Life-course exposure to air pollution and the risk of dementia in the Lothian Birth Cohort 1936

Background

Air pollution in later life has been associated with dementia; however, limited research has investigated the association between air pollution across the life course, either at specific life periods or cumulatively. The project investigates the association of air pollution with dementia via a life-course epidemiological approach.

Methods

Participants of the Lothian Birth Cohort, born in 1936, provided lifetime residential history in 2014. Participant's air pollution exposure for time periods 1935, 1950, 1970, 1980, 1990, 2001, and 2007 was modeled using an atmospheric chemistry transport model. Lifetime cumulative exposures were calculated as time-weighted mean exposure. Of 572 participants, 67 developed all-cause dementia [35 with Alzheimer's dementia (AD)] by wave 5 (~82 years). Cox proportional hazards and competing risk models assessed the association between all-cause dementia and AD with particulate matter (diameter of ≤2.5 µm) PM2.5 and nitrogen dioxide (NO2) exposure at specific life periods and cumulatively. False discovery rate (FDR) correction was applied for multiple testing.

Results

The mean follow-up was 11.26 years. One standard deviation (SD) higher exposure to air pollution in 1935 (PM2.5 = 14.03 μg/m3, NO2 = 5.35 μg/m3) was positively linked but not statistically significant to all-cause dementia [PM2.5 hazard ratio (HR) = 1.16, 95% confidence interval (CI) = 0.90, 1.49; NO2 HR = 1.13, 95% CI = 0.88, 1.47] and AD (PM2.5 HR = 1.38, 95% CI = 1.00, 1.91; NO2 HR = 1.35, 95% CI = 0.92, 1.99). In the competing risk model, one SD elevated PM2.5 exposure (1.12 μg/m3) in 1990 was inversely associated with dementia (subdistribution HR = 0.82, 95% CI = 0.67, 0.99) at P = 0.034 but not after FDR correction (P FDR = 0.442). Higher cumulative PM2.5 per one SD was associated with an increased risk of all-cause dementia and AD for all accumulation models except for the early-life model.

Conclusion

The in-utero and early-life exposure to PM2.5 and NO2 was associated with higher AD and all-cause dementia risk, suggesting a sensitive/critical period. Cumulative exposure to PM2.5 across the life course was associated with higher dementia risk. Midlife PM2.5 exposure's negative association with all-cause dementia risk may stem from unaddressed confounders or bias.

Association of body composition with neuroimaging biomarkers and cognitive function; a population-based study of 70-year-olds

BACKGROUND

A better understanding of body-brain links may provide insights on targets for preventing cognitive decline. The aim was to explore associations of body composition with neuroimaging biomarkers and cognitive function among dementia-free 70-year-olds.

METHODS

Dual-energy X-ray absorptiometry body composition measures in relation to neuroimaging measures of cortical thickness, hippocampal volume, small vessel disease, predicted brain age, and cognitive performance were explored in a cross-sectional study of 674 dementia-free 70-year-olds from the Swedish Gothenburg H70 Birth Cohort study. Linear or ordinal regression analyses were performed.

FINDINGS

Higher quantity of muscle mass was associated with lower predicted brain age (β: -0.31 [95% CI: -0.45, -0.16], p: 0.00013). Those with normal level muscle mass (>7.0 men, >5.5 women kg/height m2) had overall thicker cortex (β: 0.043 [95% CI: 0.023, 0.064], p: 0.00016), thicker cortex in Alzheimer's disease signature regions (β: 0.051 [95% CI: 0.025, 0.076], p: 0.00040), and larger hippocampal volume (β: 111.52 [95% CI: 25.28, 197.75], p: 0.030) compared to those with sarcopenic level muscle mass. Higher accumulation of visceral fat was associated with overall thinner cortex (β: -0.017 [95% CI: -0.028, -0.005], p: 0.024). Faster gait speed and higher handgrip strength were associated with indicators of better brain health.

INTERPRETATION

Improving muscle mass fitness and lower visceral fat may be beneficial for brain health. Intervention studies are needed to confirm that targeting body composition can promote healthy brain ageing and reduce the risk of cognitive impairment among older adults.

FUNDING

The Swedish Research Council, Hjärnfonden, and Alzheimerfonden.

Genetic Associations between Obesity and Brain Cortical Thickness: Combined Genetic Correlation, Multi-Trait Meta-Analysis, and Mendelian Randomization

INTRODUCTION

Obesity may lead to cognitive impairment and neuropsychiatric disorders, which are associated with changes in the brain cortical structure, particularly in cortical thickness. However, the exact genetic association between obesity and brain cortical thickness remains inconclusive. We aimed to identify the relationship between obesity-related traits (body mass index [BMI], waist-hip ratio [WHR], and waist-hip ratio adjusted for BMI [WHRadjBMI]) and brain cortical thickness.

METHODS

Leveraging summary statistics of large-scale GWAS(s) conducted in European-ancestry populations on BMI (N = 806,834), WHR (N = 697,734), WHRadjBMI (N = 694,649), and brain cortex thickness (N = 33,709), we performed GWAS combining genetic correlation, multi-trait meta-analysis, and Mendelian randomization analysis.

RESULTS

Our findings revealed a strong genetic correlation between BMI and brain cortical thickness (rg = -0.0542, p = 0.0435), and a significant result was also observed for WHR and brain thickness (rg = -0.0744, p = 0.009). In addition, we identified three loci between obesity-related traits. Mendelian randomization analysis supported the causal role of BMI (inverse-variance-weighted [IVW] beta = -0.006, 95% CI = -0.011 to -3.85E-04; weighted median beta = -0.006, 95% CI = -0.013 to -0.002), WHR (IVW beta = -0.011, 95% CI = -0.018 to -0.005; weighted median beta = -0.008, 95% CI = -0.018 to -0.003), and WHRadjBMI (IVW beta = 0.011, 95% CI = -0.018 to -0.005; weighted median beta = -0.008, 95% CI = -0.018 to -0.002) in brain cortical thickness.

CONCLUSION

This study has shown that genetically predicted obesity-related traits have a causal relationship with reduced cortical thickness. These findings provide genetic evidence for a link between obesity and structural changes in the brain and suggest that obesity may be associated with neuropsychiatric disorders by affecting brain structure, particularly cortical thickness.

Timing of risk factors, prodromal features, and comorbidities of dementia from a large health claims case-control study

BACKGROUND

Many risk factors for dementia have been identified, but the timing of risk is less well understood. Here, we analyzed risk factors in a case-control study covering 10 years before an incident dementia diagnosis.

METHODS

We designed a case-control study using insurance claims of outpatient consultations of patients with German statutory health insurance between January 1, 2012, and December 31, 2022. We included patients with an incident diagnosis of dementia and controls without a diagnosis of dementia matched 1:2 for age, sex, region, and earliest year of outpatient encounter. We selected exposures based on previous systematic reviews, case-control and cohort studies reporting on risk factors, comorbidities, and prodromal features of dementia. We calculated the prevalence of risk factors in cases and controls and odds ratios for each year before the index date, along with Bonferroni-corrected confidence intervals, using conditional logistic regression.

RESULTS

We identified a total of 1,686,759 patients with incident dementia (mean (SD) age, 82.15 (6.90) years; 61.70% female) and 3,373,518 matched controls (mean (SD) age, 82.15 (6.90) years; 61.70% female). Study participants were followed up for a mean (SD) of 6.6 (2.3) years. Of the 63 risk factors and prodromal features examined, 56 were associated with an increased risk of dementia in all years during the 10th and the 1st year before the index date. These included established risk factors, such as depression, hypertension, hearing impairment, nicotine and alcohol abuse, obesity, hypercholesterolaemia, traumatic brain injury, and diabetes. The greatest risk, with odds ratios greater than 2.5, was conferred by delirium, memory impairment, mental retardation, personality and behavioral disorders, sensory disorders, schizophrenia, and psychosis. Cancer was associated with a reduced risk of dementia.

CONCLUSIONS

This large case-control study confirmed established risk factors of dementia. In addition, the study identified non-specific diagnoses that showed a steep increase in risk close to the index date, such as psychosis, conduct disorder, and other sensory disorders. Consideration of these diagnoses, which may represent prodromal features rather than risk factors for dementia, may help to identify people with dementia in routine care.

Threshold effects of sleep duration and cognitive function in older adults with BMI ≥ 25 kg/m2

Background

It has been demonstrated that older adults' cognitive capacities can be improved with sleep duration. However, the relationship between overweight, obesity, and cognitive decline remains a subject of debate. The impact of sleep duration on cognitive performance in seniors with a body mass index (BMI) ≥ 25 kg/m2 is largely unknown. This makes it an intriguing subject to explore further.

Methods

This study used data from the National Health and Nutrition Examination Survey (NHANES) (2011-2014) with 2,243 participants. Weighted multivariate linear regression and smooth curve fitting were employed to investigate linear and non-linear relationships. A two-part linear regression model was used to determine the threshold effects. Additionally, subgroup analysis and interaction tests were conducted.

Results

Results showed that a negative association was found between sleep duration and scores in the fully adjusted model in the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) test, the Animal Fluency test (AFT), and the Digit Symbol Substitution test (DSST). A two-piecewise linear regression model was then applied to explore the threshold effect of sleep duration on cognitive performance. When sleep duration was less than 5 and 6 h per day, sleep duration was positively correlated with CERAD test scores [ß (95% CI): 2.11 (1.17, 3.05), p < 0.0001], AFT scores [β (95% CI): 0.25 (-0.17, 0.67), p = 0.2376], and DSST scores [ß (95% CI): 0.49 (-0.57, 1.56), p = 0.3654]. However, there was a threshold effect where sleep duration reached the three inflection points.

Conclusion

In overweight and obese older adults, there is a clear inverted U-shaped relationship between sleep duration and cognitive function, with consistent results across different subgroups. Sleep durations of around 5-6 h may help prevent cognitive decline in older adults with a BMI ≥ 25 kg/m2.

Lifetime history of gestational diabetes and cognitive function in parous women in midlife

AIMS/HYPOTHESIS

We aimed to determine whether a history of gestational diabetes mellitus (GDM) is associated with cognitive function in midlife.

METHODS

We conducted a secondary data analysis of the prospective Nurses' Health Study II. From 1989 to 2001, and then in 2009, participants reported their history of GDM. A subset participated in a cognition sub-study in 2014-2019 (wave 1) or 2018-2022 (wave 2). We included 15,906 parous participants (≥1 birth at ≥18 years) who completed a cognitive assessment and were free of CVD, cancer and diabetes before their first birth. The primary exposure was a history of GDM. Additionally, we studied exposure to GDM and subsequent type 2 diabetes mellitus (neither GDM nor type 2 diabetes, GDM only, type 2 diabetes only or GDM followed by type 2 diabetes) and conducted mediation analysis by type 2 diabetes. The outcomes were composite z scores measuring psychomotor speed/attention, learning/working memory and global cognition obtained with the Cogstate brief battery. Mean differences (β and 95% CI) in cognitive function by GDM were estimated using linear regression.

RESULTS

The 15,906 participants were a mean of 62.0 years (SD 4.9) at cognitive assessment, and 4.7% (n=749) had a history of GDM. In models adjusted for age at cognitive assessment, race and ethnicity, education, wave of enrolment in the cognition sub-study, socioeconomic status and pre-pregnancy characteristics, women with a history of GDM had lower performance in psychomotor speed/attention (β -0.08; 95% CI -0.14, -0.01) and global cognition (β -0.06; 95% CI -0.11, -0.01) than those without a history of GDM. The lower cognitive performance in women with GDM was only partially explained by the development of type 2 diabetes.

CONCLUSIONS/INTERPRETATION

Women with a history of GDM had poorer cognition than those without GDM. If replicated, our findings support future research on early risk modification strategies for women with a history of GDM as a potential avenue to decrease their risk of cognitive impairment.

Excessive Alcohol Use as a Risk Factor for Alzheimer's Disease: Epidemiological and Preclinical Evidence

Alcohol use has recently emerged as a modifiable risk factor for Alzheimer's disease (AD). However, the neurobiological mechanisms by which alcohol interacts with AD pathogenesis remain poorly understood. In this chapter, we review the epidemiological and preclinical support for the interaction between alcohol use and AD. We hypothesize that alcohol use increases the rate of accumulation of specific AD-relevant pathologies during the prodromal phase and exacerbates dementia onset and progression. We find that alcohol consumption rates are increasing in adolescence, middle age, and aging populations. In tandem, rates of AD are also on the rise, potentially as a result of this increased alcohol use throughout the lifespan. We then review the biological processes in common between alcohol use disorder and AD as a means to uncover potential mechanisms by which they interact; these include oxidative stress, neuroimmune function, metabolism, pathogenic tauopathy development and spread, and neuronal excitatory/inhibitory balance (EIB). Finally, we provide some forward-thinking suggestions we believe this field should consider. In particular, the inclusion of alcohol use assessments in longitudinal studies of AD and more preclinical studies on alcohol's impacts using better animal models of late-onset Alzheimer's disease (LOAD).

Human gut microbiome, diet, and mental disorders

Diet is one of the most important external factor shaping the composition and metabolic activities of the gut microbiome. The gut microbiome plays a crucial role in host health, including immune system development, nutrients metabolism, and the synthesis of bioactive molecules. In addition, the gut microbiome has been described as critical for the development of several mental disorders. Nutritional psychiatry is an emerging field of research that may provide a link between diet, microbial function, and brain health. In this study, we have reviewed the influence of different diet types, such as Western, Mediterranean, vegetarian, and ketogenic, on the gut microbiota composition and function, and their implication in various neuropsychiatric and psychological disorders.

Association of visceral adiposity index and lipid accumulation product with frailty in U.S. adults: a cross-sectional study from NHANES

BACKGROUND

Frailty poses a considerable public health challenge because of its association with negative health consequences. Although obesity is recognized as a contributor to frailty, conventional measures fail to adequately account for the effects of visceral adiposity. The study aimed to investigate the associations between the visceral adiposity index (VAI) or lipid accumulation product (LAP) and frailty.

METHODS

This study used data from the National Health and Nutrition Examination Survey (NHANES), which included 5,279 participants aged ≥ 20 years. The VAI and LAP were calculated via recognized formulas, and frailty was evaluated via a deficit accumulation approach. We employed logistic regression and restricted cubic splines to assess the associations among LAP, VAI and frailty.

RESULTS

Out of 5,279 participants, 1,836 individuals were categorized as frail. According to the fully adjusted models, the highest VAI and LAP values were significantly associated with frailty, with adjusted ORs of 1.84 (95% CI: 1.40-2.42) and 2.47 (95% CI: 1.89-3.24), respectively, compared with the lowest values. A nonlinear relationship was identified between the LAP and frailty, with an inflection point of 1.589 (ln-transformed), whereas the VAI was linearly associated with frailty. Sensitivity analyses confirmed the robustness of these associations.

CONCLUSION

The VAI and LAP are significantly related to frailty, highlighting the importance of visceral adiposity in frailty risk. These results increase the understanding of the metabolic underpinnings of frailty and may guide the development of targeted prevention strategies.

Dynamic relations between longitudinal morphological, behavioral, and emotional indicators and cognitive impairment: evidence from the Chinese Longitudinal Healthy Longevity Survey

BACKGROUND

We aimed to assess the effects of body mass index (BMI), activities of daily living (ADL), and subjective well-being (SWB) on cognitive impairment and propose dynamic risk prediction models for aging cognitive decline.

METHODS

We leveraged the Chinese Longitudinal Healthy Longevity Survey from 1998 to 2018. Cognitive status was measured using the Chinese Mini-Mental State Examination. We employed repeated measures correlation to assess associations, linear mixed-effect models to characterize the longitudinal changes, and Cox proportional hazard regression to model survival time. Dynamic predictive models were established based on the Bayesian joint model and deep learning approach named dynamic-DeepHit. Marginal structural Cox models were adopted to control for time-varying confounding factors and assess effect sizes.

RESULTS

ADL, SWB, and BMI showed protective effects on cognitive impairment after controlling observed confounding factors, with respective direct hazard ratios of 0.756 (0.741, 0.771), 0.912 (0.902, 0.921), and 0.919 (0.909, 0.929). Dynamic risk predictive models manifested high accuracy (best AUC = 0.89). ADL was endowed with the best predictive capability, although the combination of BMI, ADL, and SWB showed the most remarkable performance.

CONCLUSIONS

BMI, ADL, and SWB are protective factors for cognitive impairment. A dynamic prediction model using these indicators can efficiently identify vulnerable individuals with high accuracy.

Oral administration of Porphyromonas gingivalis to mice with diet-induced obesity impairs cognitive function associated with microglial activation in the brain

Objective

Both periodontal disease and obesity are risk factors for dementia, but their links to 1brain function remain unclear. In this study, we examined the effects of oral infection with a periodontal pathogen on cognitive function in a mouse model of obesity, focusing on the roles of microglia.

Methods

To create a mouse model of diet-induced obesity and periodontitis, male C57BL/6 J mice were first fed a high-fat diet containing 60% lipid calories for 18 weeks, beginning at 12 weeks of age, to achieve diet-induced obesity. Then, Porphyromonas gingivalis administration in the oral cavity twice weekly for 6 weeks was performed to induce periodontitis in obese mice.

Results

Obese mice orally exposed to P. gingivalis showed cognitive impairment in the novel object recognition test. Increased expression levels of inflammatory cytokines (e.g. interleukin-1β and tumor necrosis factor-α) were observed in the hippocampus of P. gingivalis-treated obese mice. Immunohistochemical analysis revealed that microglia cell body size was increased in the hippocampus and prefrontal cortex of P. gingivalis-treated obese mice, indicating microglial activation. Furthermore, depletion of microglia by PLX3397, a colony-stimulating factor 1 receptor inhibitor, ameliorated cognitive dysfunction.

Conclusion

These results suggest that microglia mediate periodontal infection-induced cognitive dysfunction in obesity.

Age of menopause and dementia risk in 10,832 women from the Swedish Twin Registry

INTRODUCTION

An earlier age of menopause (AOM) is hypothesized to increase vulnerability to the neuropathological processes of dementia which begin in midlife.

METHODS

We tested this hypothesis in a sample of 10,832 women from the Swedish Twin Registry, stratified by menopause etiology. Survival models showed that a U-shaped association was present for women whose menopause occurred spontaneously. Sensitivity analyses conducted in hormone naïve, APOE ε4+ and AOM restricted subsamples showed largely analogous patterns of results.

DISCUSSION

Supporting conclusions from basic research, our results suggest that estrogens (proxied here by AOM) interact with several biological pathways mediating dementia disease processes. In line with trends in hormone research across the past century, our findings challenge the oversimplified 'more-is-better' perspective on hormone exposure. Specifically, the non-linear association we observed between AOM and dementia risk points to the involvement of distinct and interacting biological mechanisms beyond just estrogen levels.

Body mass index, waist circumference, hip circumference, abdominal volume index, and cognitive function in older Chinese people: a nationwide study

BACKGROUND

Numerous studies have indicated an obesity paradox in observational research on aging health, where being normal weight or underweight adversely affects cognitive function, while moderate obesity may offer protective benefits. This study aims to investigate the association between body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-to-height ratio (WHtR), waist-to-hip ratio (WHR), abdominal volume index (AVI), and the joint effect of BMI and HC on cognitive impairment in older Chinese people.

METHODS

A total of 10,579 participants aged 65 years and older from the 2018 Chinese Longitudinal Healthy Longevity Survey (CLHLS) were included in this cross-sectional study. BMI, WC, HC, WHtR, WHR, and AVI were calculated from height, weight, WC, and HC measurements, where weight, WC, and HC were obtained by direct measurement. Mini-Mental State Examination was used to assess cognitive impairment. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated using binary logistic regression. Non-linear correlations were investigated using restricted cubic spline curves.

RESULTS

In multivariate logistic regression models fully adjusted for confounding variables, our analyses showed significant negative associations of WC [OR 0.93 (95%CI 0.88-0.98), P = .012], HC [OR 0.92 (95%CI 0.87-0.97), P = .004], lower WHR (Q2) [OR 0.85 (95%CI 0.72-1.00), P = .044], and AVI [OR 0.93 (95%CI 0.88-0.98), P = .011] with cognitive impairment. Nonlinear curve analysis showed that the risk of cognitive impairment was lowest when the BMI was about 25.5 kg/m², suggesting that the optimal BMI for older Chinese people to maintain good cognitive ability may be in the overweight range. In addition, there was a non-linear "N" shaped relationship between HC and cognitive impairment, with HC having the highest risk of cognitive impairment at about 82 cm and the lowest risk at about 101 cm. The joint effects analysis indicated that the lowest risk was observed among those with normal or higher BMI but higher HC compared with participants with normal BMI levels and lower HC levels.

CONCLUSION

In older Chinese people, a low-waisted and high-hip circumference body figure is favorable for cognitive function in older people. It also found a significant association between AVI and cognitive impairment. The joint analysis of BMI and HC suggests that maintaining a normal or higher BMI with a higher HC may be more conducive to maintaining good cognitive function.

Associations of metabolic heterogeneity of obesity with the risk of dementia in middle-aged adults: three prospective studies

BACKGROUND

The associations of different obesity and metabolic phenotypes during midlife with the risk of incident dementia remain unclear. This study aimed to investigate the associations between metabolic heterogeneity of obesity and long-term risk of dementia.

METHODS

We conducted prospective analyses from three cohorts, including the UK Biobank (UKB), Atherosclerosis Risk in Communities (ARIC) study, and Framingham Offspring Study (FOS). Eligible participants were those aged 45-65 years with valid assessments of body mass index (BMI) and metabolic status at the study baseline. Obesity was defined as a BMI of ≥ 30.0 kg/m2, while metabolic abnormality was defined as meeting ≥ 2 of the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) criteria. Metabolic heterogeneity of obesity was evaluated based on obesity and metabolic phenotypes and grouped as metabolically normal non-obesity (MNNO), metabolically abnormal non-obesity (MANO), metabolically normal obesity (MNO), and metabolically abnormal obesity (MAO).

RESULTS

Included in this study were 295,823 participants aged 56.3 ± 5.9 years from the UKB, 12,547 participants aged 54.0 ± 5.7 years from the ARIC, and 2,004 participants aged 53.9 ± 5.9 years from the FOS. Over 4,348,208 person-years, a total of 6,190 participants (3,601 in the UKB, 2,405 in the ARIC, and 184 in the FOS) developed incident dementia. In the pooled analysis of three cohorts, metabolic abnormality was associated with a hazard ratio (HR) of 1.41 (95% confidence interval [CI]: 1.10-1.80) for dementia, while obesity was associated with an HR of 1.20 (1.03-1.41). Compared with MNNO, individuals with MANO and MAO had increased risks of dementia (pooled HR: 1.33, 95% CI: 1.04-1.71 for MANO and 1.48, 1.16-1.89 for MAO). However, there was no significant difference in the risk of dementia among MNO (pooled HR: 1.10, 95% CI: 0.98-1.24). In addition, participants who recovered from MANO to MNNO had a lower risk of dementia (pooled HR: 0.79, 95% CI: 0.64-0.97), as compared with stable MANO.

CONCLUSIONS

Metabolic abnormality has a stronger association with dementia than obesity. Metabolically abnormal non-obesity and obesity, but not metabolically normal obesity, are associated with higher risks of incident dementia as compared with metabolically normal non-obesity. Recovering from an abnormal metabolic status to normal reduces the risk of dementia in populations without obesity. Our findings highlight the important role of metabolic status in the development of dementia and recommend the stratified management of obesity based on metabolic status.

The association between BMI and cognition in India: data from the Longitudinal Aging Study in India (LASI)

BACKGROUND

High body-mass index (BMI) is an established risk factor for late-life cognitive impairment and dementia, but most evidence comes from high-income contexts. Existing evidence from cross-sectional data in low- and middle-income settings is inconsistent, and many studies do not adequately address potential sources of bias.

METHODS

We used data from Wave 1 of the Longitudinal Aging Study in India (LASI) (analytic N = 56,753) to estimate the association between BMI categories and cognitive functioning among older adults aged 45 + years using survey-weighted linear regression models stratified by gender and controlling for potential confounders including demographic factors, socio-economic status (SES) characteristics, and health-related behaviors. To probe potential sources of bias, including residual confounding and reverse causation, we used weighting and trimming methods, sample restriction, and explored effect modification.

RESULTS

In fully adjusted models, relative to normal BMI underweight BMI was associated with lower cognitive scores (Men: -0.16 SD difference, 95% CI -0.18, -0.13; Women: -0.12 SD, -0.15, -0.10). Overweight and obesity were associated with higher cognitive scores in both men (overweight: 0.09; 0.07, 0.12, obese: 0.10; 0.05, 0.15) and women (overweight: 0.09; 0.07-0.12, obese: 0.12; 0.08-0.15). Estimates were similar after weighting and trimming but were attenuated after excluding those with low cognition (≥1 SD below the mean relative to those with similar demographic characteristics). Positive associations between overweight and obese BMI and cognition were attenuated or null in those living in urban settings and those with higher levels of educational attainment.

CONCLUSIONS

Underweight BMI is a risk factor for poor cognitive outcomes in adults 45 years and older and may be indicative of poor nutritional status and life-course disadvantage in India. In tandem with existing literature, supplemental analyses and effect modification results indicate that unmeasured confounding and reverse causation may explain the observed positive associations between overweight and obese BMI and cognitive functioning from cross-sectional studies in low- and middle-income settings. Future data with longitudinal follow-up will be helpful to further disentangle biases.

Oligonol enhances brain cognitive function in high-fat diet-fed mice

Oligonol, a low-molecular-weight polyphenol derived from lychee fruit, is well recognized for its antioxidant properties, blood glucose regulation, and fat mass reduction capability. However, its effect on the central nervous system remains unclear. Here, we investigated the effects of oligonol on brain in a high-fat diet (HFD) fed mouse model, and SH-SY5Y neuronal cells and primary cultured cortical neuron under insulin resistance conditions. HFD mice were orally administered oligonol (20 mg/kg) daily, and SH-SY5Y cells and primary cortical neurons were pretreated with 500 ng/mL oligonol under in vitro insulin resistance conditions. Our findings revealed that oligonol administration reduced blood glucose levels and improved spatial memory function in HFD mice. In vitro data demonstrated that oligonol protected neuronal cells and enhanced neural structure against insulin resistance. We confirmed RNA sequencing in the oligonol-pretreated insulin-resistant SH-SY5Y neuronal cells. Our RNA-sequencing data indicated that oligonol contributes to metabolic signaling and neurite outgrowth. In conclusion, our study provides insights into therapeutic potential of oligonol with respect to preventing neuronal cell damage and improving neural structure and cognitive function in HFD mice.

Iron accumulation/overload and Alzheimer's disease risk factors in the precuneus region: A comprehensive narrative review

Alzheimer's disease (AD) is a neurodegenerative disease that is characterized by amyloid plaques, neurofibrillary tangles, and neuronal loss. Early cerebral and body iron dysregulation and accumulation interact with AD pathology, particularly in the precuneus, a crucial functional hub in cognitive functions. Quantitative susceptibility mapping (QSM), a novel post-processing approach, provides insights into tissue iron levels and cerebral oxygen metabolism and reveals abnormal iron accumulation early in AD. Increased iron deposition in the precuneus can lead to oxidative stress, neuroinflammation, and accelerated neurodegeneration. Metabolic disorders (diabetes, non-alcoholic fatty liver disease (NAFLD), and obesity), genetic factors, and small vessel pathology contribute to abnormal iron accumulation in the precuneus. Therefore, in line with the growing body of literature in the precuneus region of patients with AD, QSM as a neuroimaging method could serve as a non-invasive biomarker to track disease progression, complement other imaging modalities, and aid in early AD diagnosis and monitoring.

Application of a new definition of sarcopenic obesity in middle-aged and older adults and association with cognitive function: Findings from the National Health and Nutrition Examination Survey 1999-2002

BACKGROUND & AIMS

The role of sarcopenic obesity (SO) in impaired cognitive function has been investigated in several observational studies, but results have been mixed. This study applied the proposed European Society for Clinical Nutrition and Metabolism (ESPEN)-European Association for the Study of Obesity (EASO) definition of SO to a representative population aged ≥50 years to identify the association between SO and cognitive function.

METHODS

Data from the National Health and Nutrition Examination Survey 1999-2002 waves were used. At the screening phase, body mass index or waist circumference were used to evaluate obesity; sarcopenia was identified using the SARC-F questionnaire. At the diagnostic phase I and II, sarcopenia was assessed using knee extensor isometric strength and appendicular lean mass, and fat mass percent was used to assess obesity. Cognitive function in older participants (60-85 years) was assessed using the Digit Symbol Substitution Test. A self-reported memory question was used in middle-aged individuals (50-59 years).

RESULTS

The sample included 2356 participants (men, 44.7%). The prevalence of SO was 32.3%, 21.2% and 15.0% at the screening, diagnosis I, and diagnosis II, respectively. Significant associations between SO and cognitive impairment were observed in individuals aged 60-85 at diagnosis I (OR: 2.3, 95%CI 1.4-3.8, P = 0.007) and diagnosis II (OR: 2.7, 95%CI 1.5-4.9, P = 0.004).

CONCLUSION

The new ESPEN-EASO definition of SO identified a high prevalence of SO cases. A significant association between SO and poor cognitive function in older individuals was observed.

[Cognitive impairment in patients with obesity and impaired carbohydrate metabolism (dysglycemia)]

Obesity is a chronic disease, heterogeneous in etiology and clinical manifestations, progressing with a natural course, characterized by excessive deposition of fat mass in the body. This pathological condition has taken on the scale of a global epidemic in recent years, which continues to progress steadily, currently affecting more than 2 billion people worldwide. Due to its heterogeneity, obesity has a negative impact on the work of almost all organs and systems of the body, contributing to the emergence of new concomitant diseases and pathological conditions that significantly worsen the quality of life of these patients. Thus, a close relationship between type 2 diabetes mellitus and cognitive impairment has long been known, as well as with a number of other somatic diseases: coronary heart disease, atherosclerosis, non-alcoholic fatty liver disease, dyslipidemia, malignant neoplasms and other associated pathological conditions against the background of overweight and obesity.Currently, the problem of the relationship of cognitive impairment in patients with overweight or changes in the glycemic profile is very relevant, due to the high prevalence and insufficient study of this issue.

Association of waist-to-hip ratio adjusted for body mass index with cognitive impairment in middle-aged and elderly patients with type 2 diabetes mellitus: a cross-sectional study

BACKGROUND

Numerous reports indicate that both obesity and type 2 diabetes mellitus (T2DM) are factors associated with cognitive impairment (CI). The objective was to assess the relationship between abdominal obesity as measured by waist-to-hip ratio adjusted for body mass index (WHRadjBMI) and CI in middle-aged and elderly patients with T2DM.

METHODS

A cross-sectional study was conducted, in which a total of 1154 patients with T2DM aged ≥ 40 years were included. WHRadjBMI was calculated based on anthropometric measurements and CI was assessed utilizing the Montreal Cognitive Assessment (MoCA). Participants were divided into CI group (n = 509) and normal cognition group (n = 645). Correlation analysis and binary logistic regression were used to explore the relationship between obesity-related indicators including WHRadjBMI, BMI as well as waist circumference (WC) and CI. Meanwhile, the predictive power of these indicators for CI was estimated by receiver operating characteristic (ROC) curves.

RESULTS

WHRadjBMI was positively correlated with MoCA scores, independent of sex. The Area Under the Curve (AUC) for WHRadjBMI, BMI and WC were 0.639, 0.521 and 0.533 respectively, and WHRadjBMI had the highest predictive power for CI. Whether or not covariates were adjusted, one-SD increase in WHRadjBMI was significantly related to an increased risk of CI with an adjusted OR of 1.451 (95% CI: 1.261-1.671). After multivariate adjustment, the risk of CI increased with rising WHRadjBMI quartiles (Q4 vs. Q1 OR: 2.980, 95%CI: 2.032-4.371, P for trend < 0.001).

CONCLUSIONS

Our study illustrated that higher WHRadjBMI is likely to be associated with an increased risk of CI among patients with T2DM. These findings support the detrimental effects of excess visceral fat accumulation on cognitive function in middle-aged and elderly T2DM patients.

Interactions between age, sex and visceral adipose tissue on brain ageing

AIM

To examine the associations between visceral adipose tissue (VAT) and brain structural measures at midlife and explore how these associations may be affected by age, sex and cardiometabolic factors.

METHODS

We used abdominal and brain magnetic resonance imaging data from a population-based cohort of people at midlife in the UK Biobank. Regression modelling was applied to study associations of VAT volume with total brain volume (TBV), grey matter volume (GMV), white matter volume, white matter hyperintensity volume (WMHV) and total hippocampal volume (THV), and whether these associations were altered by age, sex or cardiometabolic factors.

RESULTS

Complete data were available for 17 377 participants (mean age 63 years, standard deviation = 12, 53% female). Greater VAT was associated with lower TBV, GMV and THV (P < .001). We found an interaction between VAT and sex on TBV (P < .001), such that the negative association of VAT with TBV was greater in men (β = -2.89, 95% confidence interval [CI] -2.32 to -10.15) than in women (β = -1.32, 95% CI -0.49 to -3.14), with similar findings for GMV. We also found an interaction between VAT and age (but not sex) on WMHV (P < .001). The addition of other cardiometabolic factors or measures of physical activity resulted in little change to the models.

CONCLUSIONS

VAT volume is associated with poorer brain health in midlife and this relationship is greatest in men and those at younger ages.

Associations between Cognitive Impairment, Weight Status and Comorbid Conditions in Hospitalized Adults of 55 Years and Older in Guadeloupe

Cognitive decline and comorbid conditions commonly co-occur, and these conditions can affect cognitive health. We aimed to estimate the prevalence of cognitive impairment (CI) according to weight status and to evaluate the associations between CI, weight status and comorbid conditions in adults of 55 years and older. The Abbreviated Mental Test Score (AMTS) was used. Logistic regressions were performed. Overall, 415 individuals were included. The mean age was 75.7 ± 10.1 years, and the mean BMI was 26.2 ± 6.9 kg/m2. The prevalence of CI was 20.7% in the whole study group and 31%, 24.8%, 17.7% and 10.2% in underweight, normal weight, overweight and obese individuals, respectively; p < 0.004. The low folate, vitamin D and prealbumin levels were more frequently found in individuals with CI compared with those without CI. Compared with the obese individuals, a higher odds ratio of prevalent CI was noted for underweight individuals OR 3.89 (95% CI 1.54-9.80); p = 0.004. Additionally, male gender, older age, stroke, having three or more comorbid conditions and findings of undernutrition were significantly associated with CI. Being underweight was associated with an increased risk of CI. Prevention strategies including the monitoring of nutritional status may help to prevent cognitive decline and promote healthy aging.

Association of changes in predicted body composition with subsequent risk of dementia

OBJECTIVE

The effect of body composition change on the risk of dementia is not clear. This study analyzed the associations of changes in predicted lean body mass index (pLBMI), predicted appendicular skeletal muscle mass index (pASMI), and predicted body fat mass index (pBFMI) with the risk of dementia.

METHODS

In this nationwide cohort study, data were obtained from the Korean National Health Insurance Service database. The exposure was defined as changes in pLBMI, pASMI, and pBFMI derived from validated prediction equations. The outcome was dementia, defined based on the dementia diagnosis with prescription of anti-dementia medication. Cox proportional hazards regression analyses were performed to obtain the hazard ratio with a 95% confidence interval for risk of dementia according to changes in predicted body composition.

RESULTS

A total of 13,215,208 individuals with no prior record of dementia who underwent health screenings twice between 2009-2010 and 2011-2012 were included. A 1-kg/m2 increase in pLBMI and pASMI had an association with reduced risk of dementia (aHR: 0.85, 95% CI 0.84-0.87; aHR: 0.70, 95% CI 0.69-0.72, respectively for men, and aHR: 0.69, 95% CI 0.67-0.71; aHR: 0.59, 95% CI 0.57-0.61, respectively for women). A 1-kg/m2 increase in pBFMI had an association with a raised risk of dementia (aHR: 1.19, 95% CI 1.17-1.21 for men and aHR: 1.53, 95% CI 1.48-1.57 for women). These results remained consistent regardless of sex or weight change.

INTERPRETATION

Increase in pLBMI or pASMI, or reduction in pBFMI was linked to lower risk of dementia.

Time-dependent effects of high-fat diet on cognition and cerebral insulin signaling: Window for recovery and potential therapeutic target

While high-fat diet (HFD)-induced obesity is a major threat to global public health, the effect of HFD on cognition and insulin signaling during ageing remains controversial. The aim of this study was to characterize the dynamic alterations in cognition and cerebral insulin signaling during 6-month HFD consumption, and to investigate the potential therapeutic target and optimal timing to rescue obesity-related cognitive deficits. In the present study, impaired memory retention induced by 2-month HFD was recovered after 4 months on HFD. Prolonged (6-month) HFD did not further enhance tau hyperphosphorylation and β-amyloid deposition, which was consistent with the alleviation of memory retention. In brain insulin signaling, 2-month HFD increased IRS-1 and p-IRS-1(Ser307)/IRS-1, while decreasing pAKT(Ser473)/AKT, PI3K and mTOR; 4-month HFD decreased IRS-1 and pAKT(Ser473)/AKT, while increasing AKT; 6-month HFD increased IRS-1, pAKT(Ser473)/AKT, and mTOR, while decreasing p-IRS-1(Ser307)/IRS-1, PI3K and AKT. Notably, bioinformatic analysis revealed a rhythmic process presented only in 4-month HFD group, with Srebf1 emerging as a link between circadian rhythms and insulin signaling pathway. These results suggest that prolonged HFD prevents further cognitive decline and the progression of Alzheimer's disease (AD)-related pathologies during ageing. Moreover, there may be a window for recovery, in which Srebf1 acts as a self-recovery switch to address obesity-related cognitive disorders in elders.

Serum and CSF metabolomics analysis shows Mediterranean Ketogenic Diet mitigates risk factors of Alzheimer's disease

Alzheimer's disease (AD) is influenced by a variety of modifiable risk factors, including a person's dietary habits. While the ketogenic diet (KD) holds promise in reducing metabolic risks and potentially affecting AD progression, only a few studies have explored KD's metabolic impact, especially on blood and cerebrospinal fluid (CSF). Our study involved participants at risk for AD, either cognitively normal or with mild cognitive impairment. The participants consumed both a modified Mediterranean Ketogenic Diet (MMKD) and the American Heart Association diet (AHAD) for 6 weeks each, separated by a 6-week washout period. We employed nuclear magnetic resonance (NMR)-based metabolomics to profile serum and CSF and metagenomics profiling on fecal samples. While the AHAD induced no notable metabolic changes, MMKD led to significant alterations in both serum and CSF. These changes included improved modifiable risk factors, like increased HDL-C and reduced BMI, reversed serum metabolic disturbances linked to AD such as a microbiome-mediated increase in valine levels, and a reduction in systemic inflammation. Additionally, the MMKD was linked to increased amino acid levels in the CSF, a breakdown of branched-chain amino acids (BCAAs), and decreased valine levels. Importantly, we observed a strong correlation between metabolic changes in the CSF and serum, suggesting a systemic regulation of metabolism. Our findings highlight that MMKD can improve AD-related risk factors, reverse some metabolic disturbances associated with AD, and align metabolic changes across the blood-CSF barrier.

Loss of neuronal lysosomal acid lipase drives amyloid pathology in Alzheimer's disease

Underlying drivers of late-onset Alzheimer's disease (LOAD) pathology remain unknown. However, multiple biologically diverse risk factors share a common pathological progression. To identify convergent molecular abnormalities that drive LOAD pathogenesis we compared two common midlife risk factors for LOAD, heavy alcohol use and obesity. This revealed that disrupted lipophagy is an underlying cause of LOAD pathogenesis. Both exposures reduced lysosomal flux, with a loss of neuronal lysosomal acid lipase (LAL). This resulted in neuronal lysosomal lipid (NLL) accumulation, which opposed Aβ localization to lysosomes. Neuronal LAL loss both preceded (with aging) and promoted (targeted knockdown) Aβ pathology and cognitive deficits in AD mice. The addition of recombinant LAL ex vivo and neuronal LAL overexpression in vivo prevented amyloid increases and improved cognition. In WT mice, neuronal LAL declined with aging and correlated negatively with entorhinal Aβ. In healthy human brain, LAL also declined with age, suggesting this contributes to the age-related vulnerability for AD. In human LOAD LAL was further reduced, correlated negatively with Aβ1-42, and occurred with polymerase pausing at the LAL gene. Together, this finds that the loss of neuronal LAL promotes NLL accumulation to impede degradation of Aβ in neuronal lysosomes to drive AD amyloid pathology.

Neuro-Adipokine Crosstalk in Alzheimer's Disease

The connection between body weight alterations and Alzheimer's disease highlights the intricate relationship between the brain and adipose tissue in the context of neurological disorders. During midlife, weight gain increases the risk of cognitive decline and dementia, whereas in late life, weight gain becomes a protective factor. Despite their substantial impact on metabolism, the role of adipokines in the transition from healthy aging to neurological disorders remains largely unexplored. We aim to investigate how the adipose tissue milieu and the secreted adipokines are involved in the transition between biological and pathological aging, highlighting the bidirectional relationship between the brain and systemic metabolism. Understanding the function of these adipokines will allow us to identify biomarkers for early detection of Alzheimer's disease and uncover novel therapeutic options.

Associations between Physical Activity Frequency in Leisure Time and Subjective Cognitive Limitations in Middle-Aged Spanish Adults: A Cross-Sectional Study

There is a global ageing of the world's population. Ageing is associated with multiple pathologies, reductions in physical activity, and losses in cognitive function. This study aimed to analyse the associations between the frequency of leisure-time physical activity (PAF) in middle-aged Spaniards and subjective cognitive limitations (SCLs): self-reported problems for remembering or concentrating (data extracted from the 2017 National Health Survey and the 2020 European Health Survey in Spain). Furthermore, the study aimed to evaluate risk factors that could be related to a higher probability of developing SCLs. This was a cross-sectional study with 15,866 middle-aged Spaniards. The associations between FAP and SCLs were analysed using chi-square. Also, the risk factors for SCLs were evaluated using binary multiple logistic regression. The median age of participants was 55 years, with 49% men and 51% women. Associations were found between PAF and SCLs (p < 0.001). The highest prevalence of SCLs was found in physically inactive people and the lowest in very active people (13.7% vs. 5.8%, p < 0.05), and people with SCLs had a higher prevalence of inactivity than those without SCLs (47.2% vs. 33.8%, p < 0.05). Physical inactivity, low educational level, low social class, and being female were the main risk factors for SCLs. Among the actions to prevent cognitive limitations, as well as interventions in people with cognitive limitations, it would be advisable to include physical activity programmes, both as a preventive measure to delay cognitive limitations and to reduce the risk of other pathologies in people who already have them.