Association of Metabolic Syndrome With Incident Dementia: Role of Number and Age at Measurement of Components in a 28-Year Follow-up of the Whitehall II Cohort Study

Investigating the nexus of metabolic syndrome, serum uric acid, and dementia risk: a prospective cohort study

BACKGROUND

The global dementia prevalence is surging, necessitating research into contributing factors. We aimed to investigate the association between metabolic syndrome (MetS), its components, serum uric acid (SUA) levels, and dementia risk.

METHODS

Our prospective study comprised 466,788 participants without pre-existing MetS from the UK Biobank. We confirmed dementia diagnoses based on the ICD-10 criteria (F00-03). To evaluate the dementia risk concerning MetS, its components, and SUA levels, we applied Cox proportional hazards models, while adjusting for demographic factors.

RESULTS

Over a median follow-up of 12.7 years, we identified 6845 dementia cases. Individuals with MetS had a 25% higher risk of all-cause dementia (hazard ratio [HR] = 1.25, 95% confidence interval [CI] = 1.19-1.31). The risk increased with the number of MetS components including central obesity, dyslipidemia for high-density lipoprotein (HDL) cholesterol, hypertension, hyperglycemia, and dyslipidemia for triglycerides. Particularly for those with all five components (HR = 1.76, 95% CI = 1.51-2.04). Dyslipidemia for HDL cholesterol, hypertension, hyperglycemia, and dyslipidemia for triglycerides were independently associated with elevated dementia risk (p < 0.01). MetS was further linked to an increased risk of all-cause dementia (11%) and vascular dementia (VD, 50%) among individuals with SUA levels exceeding 400 μmol/L (all-cause dementia: HR = 1.11, 95% CI = 1.02-1.21; VD: HR = 1.50, 95% CI = 1.28-1.77).

CONCLUSIONS

Our study provides robust evidence supporting the association between MetS, its components, and dementia risk. These findings emphasize the importance of considering MetS and SUA levels in assessing dementia risk, offering valuable insights for prevention and management strategies.

Association of Metabolic Dysfunction-Associated Fatty Liver Disease with Cognitive Impairment and All-Cause Dementia: A Comprehensive Review

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a significant public health concern, affecting one-third of the global population and posing a risk for progressive liver disease. MAFLD is characterized by hepatic steatosis and impaired metabolic status, which not only impact the liver but also other systems of the human body, making it a multisystemic disorder. Emerging evidence suggests that MAFLD and its associated pathological pathways may contribute to cognitive impairment, potentially through neuroinflammation and neurodegeneration. Studies have detected cognitive impairment in patients with MAFLD using magnetic resonance imaging, which revealed decreased brain volume and cerebral perfusion, in addition to self-reported cognitive tests. While numerous studies have demonstrated an association between MAFLD and cognitive impairment, the relationship between MAFLD and all-cause dementia remains controversial. However, the shared pathological pathways between MAFLD and dementia, such as systemic inflammation, insulin resistance, gut dysbiosis, hyperammonemia, and vascular dysfunction, indicate the possibility of a common prevention strategy for both diseases. In this review, we provide a summary of the current evidence regarding the association between cognitive impairment, all-cause dementia, and MAFLD.

Association between metabolic syndrome and risk of incident dementia in UK Biobank

INTRODUCTION

The association between metabolic syndrome (MetS) and incident dementia remains inconclusive.

METHODS

In 176,249 dementia-free UK Biobank participants aged ≥60 years at baseline, Cox proportional-hazards models were used to investigate the association between MetS and incident dementia. MetS was defined as the presence of ≥3 of the following: elevated waist circumference, triglycerides, blood pressure, blood glucose, and reduced high-density lipoprotein cholesterol.

RESULTS

Over 15 years of follow-up (median = 12.3), 5255 participants developed dementia. MetS was associated with an increased risk of incident dementia (hazard ratio [HR]: 1.12, 95% confidence interval [CI]: 1.06, 1.18). The association remained consistent when restricting to longer follow-up intervals: >5 to 10 years (HR: 1.17, 95% CI: 1.07, 1.27) and >10 years (HR: 1.22, 95% CI: 1.12, 1.32). Stronger associations were observed in those with ≥4 MetS components and in apolipoprotein-E (APOE)-ε4 non-carriers.

DISCUSSION

In this large population-based prospective cohort, MetS was associated with an increased risk of dementia.

HIGHLIGHTS

MetS was associated with a 12% increased risk of incident all-cause dementia. Associations remained similar after restricting the analysis to those with longer follow-up. The presence of four or five MetS components was significantly associated with dementia. Stronger associations were observed in those with a low genetic risk for dementia.

High intake of ultra-processed food is associated with dementia in adults: a systematic review and meta-analysis of observational studies

BACKGROUND AND AIMS

Poor cardiometabolic health is associated with dementia. Considering previous meta-analyses have confirmed associations between ultra-processed foods (UPFs) and cardiometabolic disease, we were interested in the contribution of UPF consumption to the risk of developing dementia.

METHODS

We performed a systematic review and meta-analysis of all records registered on Ovid Medline and Web of Science from inception until December 2022 [PROSPERO (CRD42023388363)]. Studies that assessed UPF consumption in adults, determined according to NOVA, and that reported dementia (Alzheimer's disease, vascular dementia and mild cognitive impairment) determined by clearly stated diagnostic criteria (including formal assessment of dementia or use of diagnostic codes) were included. The association between UPF consumption and dementia was assessed using random-effects meta-analysis, controlling for confounding variables. Study quality was assessed using the Newcastle Ottawa Scale and evidence credibility evaluated using the NutriGrade system.

RESULTS

Seven thousand ten records were screened, and 122 records underwent full text review. From these, 10 observational (8 longitudinal) studies, analysing 867,316 individuals, were included. Included studies adjusted for age, socioeconomic status and co-morbidity, alongside other confounders. High (vs. low) intake of UPF was associated with increased risk of dementia (pooled relative risk 1.44 (95% confidence interval 1.09-1.90) (p = 0.02)) (I2 = 97.0%), although moderate (vs. low) intake of UPF was not (1.12 (0.96-1.31) (0.13)) (85.0%). Funnel plots demonstrate low risk of publication bias.

CONCLUSION

High UPF consumption is associated with dementia. Public health measures to reduce overconsumption of UPFs are imperative to reduce the burden of dementia.

Gut microbiota: an ideal biomarker and intervention strategy for aging

Population aging is a substantial challenge for the global sanitation framework. Unhealthy aging tends to be accompanied by chronic diseases such as cardiovascular disease, diabetes, and cancer, which undermine the welfare of the elderly. Based on the fact that aging is inevitable but retarding aging is attainable, flexible aging characterization and efficient anti-aging become imperative for healthy aging. The gut microbiome, as the most dynamic component interacting with the organism, can affect the aging process through its own structure and metabolites, thus holding the potential to become both an ideal aging-related biomarker and an intervention strategy. This review summarizes the value of applying gut microbiota as aging-related microbial biomarkers in diagnosing aging state and monitoring the effect of anti-aging interventions, ultimately pointing to the future prospects of microbial intervention strategies in maintaining healthy aging.

Is metabolic-healthy obesity associated with risk of dementia? An age-stratified analysis of the Whitehall II cohort study

BACKGROUND

Metabolically healthy obesity is hypothesized to be a benign condition but whether this is the case for dementia remains debated. We examined the role of age at assessment of metabolic-obesity phenotypes in associations with incident dementia.

METHODS

Obesity (body mass index ≥ 30 kg/m2) and poor metabolic health (≥ 2 of elevated serum triglycerides, low HDL-C, elevated blood pressure, and elevated serum fasting glucose) were used to define four metabolic-obesity phenotypes (metabolically healthy (MHNO) and unhealthy non-obesity (MUNO), metabolically healthy (MHO) and unhealthy obesity (MUO)) at < 60, 60 to < 70, and ≥ 70 years using 6 waves of data from the Whitehall II study and their associations with incident dementia was examined using Cox regression.

RESULTS

Analyses with exposures measured < 60, 60 to < 70, and ≥ 70 years involved 410 (5.8%), 379 (5.6%), and 262 (7.4%) incident dementia cases over a median follow-up of 20.8, 10.3, and 4.2 years respectively. In analyses of individual components, obesity before 60 years (HR 1.41, 95% CI: [1.08, 1.85]) but not at older ages was associated with dementia; unhealthy metabolic status when present < 60 years (HR 1.33, 95% CI: [1.08, 1.62]) and 60 to < 70 years (HR 1.32, 95% CI: [1.07, 1.62]) was associated with dementia. Compared to the metabolically healthy non-obesity group, the risk of dementia was higher in those with metabolically healthy obesity before 60 years (1.69; 95% CI: [1.16, 2.45]); this was not the case when metabolic-obesity phenotype was present at 60 to < 70 years or ≥ 70 years. Analyses at older ages were on smaller numbers due to death and drop-out but inverse probability weighting to account for missing data yielded similar results.

CONCLUSIONS

Individuals with metabolically healthy obesity before age 60 had a higher risk of incident dementia over a 27-year follow-up; the excess risk dissipates when metabolic health and obesity are measured after 70 years.

Vascular cognitive impairment - Past, present, and future challenges

Vascular cognitive impairment (VCI) is a lifelong process encompassing a broad spectrum of cognitive disorders, ranging from subtle or mild deficits to prodromal and fully developed dementia, originating from cerebrovascular lesions such as large and small vessel disease. Genetic predisposition and environmental exposure to risk factors such as unhealthy lifestyles, hypertension, cardiovascular disease, and metabolic disorders will synergistically interact, yielding biochemical and structural brain changes, ultimately culminating in VCI. However, little is known about the pathological processes underlying VCI and the temporal dynamics between risk factors and disease mechanisms (biochemical and structural brain changes). This narrative review aims to provide an evidence-based summary of the link between individual vascular risk/disorders and cognitive dysfunction and the potential structural and biochemical pathophysiological processes. We also discuss some key challenges for future research on VCI. There is a need to shift from individual risk factors/disorders to comorbid vascular burden, identifying and integrating imaging and fluid biomarkers, implementing a life-course approach, considering possible neuroprotective influences of positive life exposures, and addressing biological sex at birth and gender differences. Finally, this review highlights the need for future researchers to leverage and integrate multidimensional data to advance our understanding of the mechanisms and pathophysiology of VCI.

Association of earlier age at menopause with risk of incident dementia, brain structural indices and the potential mediators: a prospective community-based cohort study

Background

To date, there is no homogeneous evidence of whether earlier age at menopause is associated with incident dementia. In addition, the underlying mechanism and driven mediators are largely unknown. We aimed to fill these knowledge gaps.

Methods

This community-based cohort study included 154,549 postmenopausal women without dementia at enrolment (between 2006 and 2010) from the UK Biobank who were followed up until June 2021. We followed up until June 2021. Age at menopause was entered as a categorical variable (<40, 40-49, and ≥50 years) with ≥50 years taken as a reference. The primary outcome was all-cause dementia in a time-to-event analysis and the secondary outcomes included Alzheimer's disease, vascular dementia, and other types of dementia. In addition, we investigated the association between magnetic resonance (MR) brain structure indices with earlier menopause, and explored the potential underlying driven mediators on the relationship between earlier menopause and dementia.

Findings

2266 (1.47%) dementia cases were observed over a median follow-up period of 12.3 years. After adjusting for confounders, women with earlier menopause showed a higher risk of all-cause dementia compared with those ≥50 years (adjusted-HRs [95% CIs]: 1.21 [1.09-1.34] and 1.71 [1.38-2.11] in the 40-49 years and <40 years groups, respectively; P for trend <0.001). No significant interactions between earlier menopause and polygenic risk score, cardiometabolic factors, type of menopause, or hormone-replacement therapy strata were found. Earlier menopause was negatively associated with brain MR global and regional grey matter indices, and positively associated with white matter hyperintensity. The relationship between earlier menopause and dementia was partially mediated by menopause-related comorbidities including sleep disturbance, mental health disorder, frailty, chronic pain, and metabolic syndrome, with the proportion (95% CI) of mediation effect being 3.35% (2.18-5.40), 1.38% (1.05-3.20), 5.23% (3.12-7.83), 3.64% (2.88-5.62) and 3.01% (2.29-4.40), respectively. Multiple mediator analysis showed a combined effect being 13.21% (11.11-18.20).

Interpretation

Earlier age at menopause was associated with risk of incident dementia and deteriorating brain health. Further studies are warranted to clarify the underlying mechanisms by which earlier age at menopause is linked to an increased risk of dementia, and to determine public health strategies to attenuate this association.

Funding

National Natural Science Foundation of China, the Science and Technology Program of Guangzhou, the Key Area Research and Development Program of Guangdong Province, the China Postdoctoral Science Foundation, and the Guangdong Basic and Applied Basic Research Foundation.