Metabolic syndrome and dementia risk in a multiethnic elderly cohort

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 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.

The effect of lipid metabolism on age-associated cognitive decline: Lessons learned from model organisms and human

Lipids are required as integral building blocks of cells to support cellular structures and functions. The intricate mechanisms underpinning lipid homeostasis are essential for the health and maintenance of the central nervous system. Here we summarize the recent advances in dissecting the effect of lipid metabolism on cognitive function and its age-associated decline by reviewing relevant studies ranging from invertebrate model organisms to mammals including human.

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.

Blood pressure and Alzheimer's disease: A review of meta-analysis

Background

Alzheimer's disease (AD) is a neurological disorder of unknown cause, resulting in the death of brain cells. Identifying some of the modifiable risk factors for AD could be crucial for primary prevention and could lead to a reduction in the incidence of AD.

Objective

This study aimed to perform a meta-meta-analysis of studies in order to assess the effect of blood pressure (BP) on the diagnosis of AD.

Method

The search was restricted to meta-analyses assessing high systolic BP (SBP) and diastolic BP (DBP) and AD. We applied the PRISMA guidelines.

Results

A total of 214 studies were identified from major databases. Finally, five meta-analyses (52 studies) were analyzed in this review. Results confirm that high SBP is associated with AD. The exploration of parameters (sex, age, study design, region, and BP measurements) shows that only region significantly moderates the relationship between BP and AD. Asian people are those whose SBP levels >140 mmHg are associated with AD. BP is associated with AD in both people aged ≤65 years and those aged ≥65 years and in cross-sectional and longitudinal studies. In the case of DBP, only women are at a higher risk of AD, particularly when its levels are >90.

Conclusion

SBP is associated with both cerebrovascular disease and AD. Therefore, future studies should use other uncontrolled factors, such as cardiovascular diseases, diabetes, and stroke, to explain the relationship between SBP and AD.

Genetic Insights into the Risk of Metabolic Syndrome and Its Components on Dementia: A Mendelian Randomization

BACKGROUND

The role of metabolic syndrome (MetS) on dementia is disputed.

OBJECTIVE

We conducted a Mendelian randomization to clarify whether the genetically predicted MetS and its components are casually associated with the risk of different dementia types.

METHODS

The genetic predictors of MetS and its five components (waist circumference, hypertension, fasting blood glucose, triglycerides, and high-density lipoprotein cholesterol [HDL-C]) come from comprehensive public genome-wide association studies (GWAS). Different dementia types are collected from the GWAS in the European population. Inverse variance weighting is utilized as the main method, complemented by several sensitivity approaches to verify the robustness of the results.

RESULTS

Genetically predicted MetS and its five components are not causally associated with the increasing risk of dementia (all p > 0.05). In addition, no significant association between MetS and its components and Alzheimer's disease, vascular dementia, frontotemporal dementia, dementia with Lewy bodies, and dementia due to Parkinson's disease (all p > 0.05), except the association between HDL-C and dementia with Lewy bodies. HDL-C may play a protective role in dementia with Lewy bodies (OR: 0.81, 95% CI: 0.72-0.92, p = 0.0010).

CONCLUSIONS

From the perspective of genetic variants, our study provides novel evidence that MetS and its components are not associated with different dementia types.

Associations of Lipids and Lipid-Lowering Drugs with Risk of Vascular Dementia: A Mendelian Randomization Study

Accumulating observational studies suggested that hypercholesterolemia is associated with vascular dementia (VaD); however, the causality between them remains unclear. Hence, the aim of this study is to infer causal associations of circulating lipid-related traits [including high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), apolipoprotein A-I (apoA-I), and apolipoprotein B (apoB)] with VaD jointly using univariable MR (uvMR), multivariable MR (mvMR) and bidirectional two-sample MR methods. Then, the summary-data-based MR (SMR) and two-sample MR analysis were conducted to investigate the association of lipid-lowering drugs target genes expression (including HMGCR, PCSK9, NPC1L1, and APOB) and LDL-C level mediated by these target genes with VaD. The results of forward MR analyses found that genetically predicted HDL-C, LDL-C, TG, apoA-I, and apoB concentrations were not significantly associated with the risk of VaD (all p > 0.05). Notably, there was suggestive evidence for a causal effect of genetically predicted VaD on HDL-C via reverse MR analysis [odds ratio (OR), 0.997; 95% confidence interval (CI), 0.994−0.999; p = 0.022]. On the contrary, the MR results showed no significant relationship between VaD with LDL-C, TG, apoA-I, and apoB. The results for the SMR method found that there was no evidence of association for expression of HMGCR, PCSK9, NPC1L1, and APOB gene with risk of VaD. Furthermore, the result of MR analysis provided evidence for the decreased LDL-C level mediated by gene HMGCR reduced the risk of VaD (OR, 18.381; 95% CI, 2.092−161.474; p = 0.009). Oppositely, none of the IVW methods indicated any causal effects for the other three genes. Using genetic data, this study provides evidence that the VaD risk may cause a reduction of HDL-C level. Additionally, the finding supports the hypothesis that lowering LDL-C levels using statins may be an effective prevention strategy for VaD risk, which requires clinical trials to confirm this result in the future.

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

OBJECTIVE

Previous research suggests an inconsistent association between Metabolic syndrome (MetS) and incident dementia. We examined the role of number of MetS components and age at their assessment for incident dementia.

RESEARCH DESIGN AND METHODS

MetS components (fasting glucose, triglycerides, waist circumference, blood pressure, and HDL cholesterol) on 7,265, 6,660, and 3,608 participants at <60, 60 to <70, and ≥70 years of age were used to examine associations with incident dementia using cause-specific Cox regression.

RESULTS

Analyses of MetS measured at <60, 60 to <70, and ≥70 years involved 393 (5.4%), 497 (7.5%), and 284 (7.9%) dementia cases over a median follow-up of 20.8, 10.4, and 4.2 years, respectively. Every additional MetS component before 60 (hazard ratio [HR] 1.13 [95% CI 1.05, 1.23]) and 60 to <70 (HR 1.08 [95% CI 1.00, 1.16]) but not ≥70 years (HR 1.04 [95% CI 0.96, 1.13]) was associated with higher dementia risk. MetS defined conventionally (≥3 components) before 60 years (HR 1.23 [95% CI 0.96, 1.57]), between 60 and 70 years (HR 1.14 [95% CI 0.91, 1.42]), or >70 years of age (HR 1.10 [95% CI 0.86, 1.40]) was not associated with incident dementia. Multistate models showed higher risk of dementia in those with ≥1 (HR 1.99 [95% CI 1.08, 3.66]) and ≥2 MetS components (HR 1.69 [95% CI 1.12, 2.56]) before 60 years of age, even when they remained free of cardiovascular disease over the follow-up.

CONCLUSIONS

Risk of incident dementia increases with every additional MetS component present in midlife rather than after accumulation of three components; only part of this risk is mediated by cardiovascular disease.

OUP accepted manuscript

Cognitive deficits in Alzheimer’s disease, specifically amnestic (memory dominant) deficits, are associated with cholinergic degeneration in the basal forebrain. The cholinergic nucleus within the basal forebrain, the nucleus basalis of Meynert, exhibits local atrophy and reduced cortical tract integrity on MRI, and reveals amyloid-β and phosphorylated-tau pathology at autopsy. To understand the pathophysiology of nucleus basalis of Meynert atrophy and its neocortical projections in Alzheimer’s disease, we used a combined post-mortem in situ MRI and histopathology approach. A total of 19 Alzheimer’s disease (10 amnestic and nine non-amnestic) and nine non-neurological control donors underwent 3 T T₁-weighted MRI for anatomical delineation and volume assessment of the nucleus basalis of Meynert, and diffusion-weighted imaging for microstructural assessment of the nucleus and its projections. At subsequent brain autopsy, tissue dissection and immunohistochemistry were performed for amyloid-β, phosphorylated-tau and choline acetyltransferase. Compared to controls, we observed an MRI-derived volume reduction and altered microstructural integrity of the nucleus basalis of Meynert in Alzheimer’s disease donors. Furthermore, decreased cholinergic cell density was associated with reduced integrity of the nucleus and its tracts to the temporal lobe, specifically to the temporal pole of the superior temporal gyrus, and the parahippocampal gyrus. Exploratory post hoc subgroup analyses indicated that cholinergic cell density could be associated with cortical tract alterations in amnestic Alzheimer’s disease donors only. Our study illustrates that in Alzheimer’s disease, cholinergic degeneration in the nucleus basalis of Meynert may contribute to damaged cortical projections, specifically to the temporal lobe, leading to cognitive deterioration.

The association between metabolic syndrome and successful aging- using an extended definition of successful aging

Objectives

To examine the association between metabolic syndrome (MetS) and successful aging among community-dwelling older adults.

Methods

Adults aged ≥ 65 years who participated in the senior health checkup program at National Taiwan University Hospital during 2011–2013 were recruited (N = 467 at baseline). The participants were followed after 4 years and 6 years. MetS was assessed at baseline. Successful aging was evaluated at baseline, 4-year follow-up, and 6-year follow-up. We adopted an extended definition of successful aging, which was defined as three major domains: physiological, psychological, and sociological and economic domains. Generalized linear mixed models were used to assess the association between MetS and successful aging adjusting for time (follow-up years), age, sex, years of education, alcohol consumption and MetS×time interaction term.

Results

The mean age of the study population was 72.9 (SD 5.5) years. The absence of baseline MetS had a positive effect on the probability of successful aging over six years. The absences of abdominal obesity, hyperglycemia, reduced high-density lipoprotein cholesterol, and hypertension were associated with the physiological successful aging. The absence of hypertension was the most significant predictor of physiological successful aging [aOR (95% CI) = 2.76 (1.67–4.58), p<0.001]. Significant increased trend was found in the overall and physiological successful aging across MetS status (No MetS, pre MetS, MetS; P_trend <0.001).

Conclusions

We found that MetS is a risk factor of successful aging among community-dwelling older adults. Public health policy should aim at avoidance of MetS in order to facilitate successful aging in older population.

Diabetes/Dementia in Sub-saharian Africa and Nigerian Women in the Eye of Storm

In the next few years, the prevalence of diabetes mellitus (DM) is projected to dramatically increase globally, but most of the cases will occur in low-to-middle-income countries. Some of the major risk factors for diabetes accelerate the development of dementia in African-Americans, thus leading to a higher prevalence of dementia than Caucasians. Sub-Saharan Africa women have a disproportionately two-to-eight fold increased prevalence of dementia. In the eye of this storm, Nigeria holds the highest number of diabetics on the African continent, and its prevalence is rising in parallel to obesity, hypertension, and the population's aging. The socio-economic impact of the rising prevalence of DM and dementia will be huge and unsustainable for the healthcare system in Nigeria, as has been recognized in developed economies. Here, we analyze the current situation of women's health in Nigeria and explore future perspectives and directions. The complex interplay of factors involved in diabetes and dementia in Nigerian women include key biological agents (metabolic syndrome, vascular damage, inflammation, oxidative stress, insulin resistance), nutritional habits, lifestyle, and anemia, that worsen with comorbidities. In addition, restricted resources, lack of visibility, and poor management result in a painful chain that increases the risk and burden of disease in Nigerian women from youth to elderly ages. Heath policies to increase the ra- tio of mental health professionals per number of patients, mostly in rural areas, foment of proactive primary care centers, and interventions targeting adolescents and adult women and other specific mothers-children pairs are strongly required for a sustainable development goal.

Effect of Metabolic Syndrome on the Incidence of Dementia Based on National Insurance Data in Korea

Background: To evaluate the association between metabolic syndrome (MetS) and the incidence of dementia using big data from national health claims and health examinations. Methods: This study involved 3,619,388 subjects categorized with MetS of three status based on the results of health examinations conducted in 2009. This was a longitudinal study of the incidence of dementia based on the national health claims from the date of health examinations in 2009 until December 31, 2018. This study was conducted for men and women aged 50 to 69 years living in Korea. A Cox proportional hazard regression was performed to analyze the risk of dementia according to the status of MetS. Results: The cumulative incidence of Alzheimer dementia was 0.41% in the non-Mets group, 0.54% in the pre-MetS group, and 0.67% in the MetS group. The cumulative incidence of vascular dementia was 0.19% in the non-Mets group, 0.27% in the pre-MetS group, and 0.34% in the MetS group. The risk of Alzheimer dementia in the pre-MetS group compared to the non-Mets group was 1.20-fold greater (95% confidence interval, CI: 1.14-1.26) and was 1.39-fold (95% CI: 1.31-1.48) greater in the MetS group. The risk of vascular dementia in the pre-MetS group compared to the non-Mets group was 1.30-fold greater (95% CI: 1.21-1.40) and the risk of vascular dementia was 1.53-fold (95% CI: 1.44 1.71) greater. Conclusions: This study showed that pre-MetS and MetS were related to an increased incidence of Alzheimer dementia and vascular dementia. Also, these results support efforts to decrease the incidence of Alzheimer dementia and vascular dementia through managing the Mets.

Serum Adiponectin in Alzheimer's Disease (AD): Association with AD Biomarkers and Cognitive Outcome

BACKGROUND

The association between dementia and serum adiponectin has been evaluated in many studies; however, conclusions remain mixed.

OBJECTIVE

We investigated the cross-sectional associations of adiponectin with cognitive function and Alzheimer's disease (AD) biomarkers and whether serum adiponectin levels can predict cognitive outcomes.

METHODS

This study included 496 participants from the Alzheimer's Disease Neuroimaging Initiative 1 (ADNI1) with available serum adiponectin levels at baseline and ≥65 years of age. Subjects were stratified based on sex and apolipoprotein ɛ4 (APOE4) carrier status to determine associations between adiponectin and cognitive function. The linear mixed model was used to analyze associations between adiponectin level and cognitive outcome in amnestic mild cognitive impairment (aMCI) patients.

RESULTS

Serum adiponectin levels were higher in aMCI and AD than in CN subjects among APOE4 non-carrier males (adiponectin in CN, aMCI, and AD: 0.54±0.24, 0.74±0.25, and 0.85±0.25, respectively, p < 0.001). In this group, serum adiponectin levels were associated with age (p = 0.001), ADAS13 (p < 0.001), memory function (p < 0.001), executive function (p < 0.001), total tau (p < 0.001), and phosphorylated tau (p < 0.001) measures in cerebrospinal fluid (CSF). Higher adiponectin level was not associated with cognitive outcome in aMCI patients in the linear mixed model analysis over 5.3±2.6 years of mean follow-up.

CONCLUSION

Serum adiponectin level was associated with cognitive function and CSF AD biomarkers among APOE4 non-carrier males. However, serum adiponectin level was not associated with longitudinal cognitive function outcome in aMCI.

Cognitive impairment and depression: Meta-analysis of structural magnetic resonance imaging studies

Longitudinal comorbidity of depression and cognitive impairment has been reported by number of epidemiological studies but the underlying mechanisms explaining the link between affective problems and cognitive decline are not very well understood. Imaging studies have typically investigated patients with major depressive disorder (MDD) and mild cognitive impairment (MCI) separately and thus have not identified a structural brain signature common to these conditions that may illuminate potentially targetable shared biological mechanisms. We performed a meta-analysis of. 48 voxel-based morphometry (VBM) studies of individuals with MDD, MCI, and age-matched controls and demonstrated that MDD and MCI patients had shared volumetric reductions in a number of regions including the insula, superior temporal gyrus (STG), inferior frontal gyrus, amygdala, hippocampus, and thalamus. We suggest that the shared volumetric reductions in the insula and STG might reflect communication deficits and infrequent participation in mentally or socially stimulating activities, which have been described as risk factors for both MCI and MDD. We also suggest that the disease-specific structural changes might reflect the disease-specific symptoms such as poor integration of emotional information, feelings of helplessness and worthlessness, and anhedonia in MDD. These findings could contribute to better understanding of the origins of MDD-MCI comorbidity and facilitate development of early interventions.

Relationship between Central Obesity and the incidence of Cognitive Impairment and Dementia from Cohort Studies Involving 5,060,687 Participants

Central obesity, measured by the waist circumference (WC) or waist-to-hip ratio, has been linked with metabolic dysfunction and structural abnormalities in the brain, two risk factors for cognitive impairment and dementia. The current analysis was performed to understand the influence of central obesity on the incidence of cognitive impairment and dementia. It included 21 studies involving 5,060,687 participants and showed that a high WC was associated with a greater risk of cognitive impairment and dementia (HR = 1.10, 95 % CI: 1.05-1.15), compared with a low WC. Sub-group analysis showed that a high WC increased the likelihood of developing cognitive impairment and dementia in individuals older than 65 years of age (HR = 1.13, 95 % CI: 1.08-1.19), whereas no association was observed in individuals younger than 65 years of age (HR = 1.04, 95 % CI: 0.93-1.16). Furthermore, dose-response meta-analysis confirmed that a high WC was a risk factor for cognitive impairment and dementia. In conclusion, central obesity, as measured by WC, was associated with a risk of cognitive impairment and dementia.

Metabolic syndrome and the risk of late onset Alzheimer's disease: An updated review and meta-analysis

AIMS

This study aims to provide an updated systematic review and meta-analysis on the risk of Alzheimer's disease (AD) in patients with metabolic syndrome (MetS) and to analyze the contribution of each MetS component on AD onset.

DATA SYNTHESIS

The study was performed according to the PRISMA guideline. Data were obtained searching MEDLINE, Scopus, Web of Science, and EMBASE for studies published between January 1, 2010 and July 30, 2020, evaluating the association between MetS and AD risk. A total of 255 articles were retrieved and 6 investigations (4 prospective and 2 retrospective) met the inclusion criteria. Overall, 9.788.021 patients with a mean follow-up of 4.5 years were analyzed. The pooled analysis revealed a slight increased risk of AD in MetS (hazard ratio, HR: 1.10, 95% and confidence interval, CI: 1.05-1.15). Egger's test indicated the absence of publication bias (t = 2.095 and p = 0.104). However, while analysis based on prospective studies failed to show a significant association between MetS and AD (HR: 0.80 and 95% CI: 0.61-1.05), analysis based on retrospective studies demonstrated a significant, slight increased risk (HR:1.11 and 95% CI: 1.08-1.66). With regard to MetS components, the risk was: arterial hypertension, HR: 1.05 (95% CI: 1.04-10.6); hyperglycemia/diabetes, HR: 1.19 (95% CI: 1.18-1.99); low high-density lipoprotein cholesterol (HDL-C), HR: 1.07 (95% CI: 1.06-1.07); hypertriglyceridemia, HR: 1.06 (95% CI: 1.05-1.06); and abdominal obesity, HR: 0.84 (95% CI: 0.74-0.95).

CONCLUSIONS

We found a significant association between MetS and AD, mainly driven by large retrospective studies. Our data also support the association of single MetS components with AD incidence, while increased waist circumference seems to have a "protective role" probably due to reverse causality.

Metabolic Syndrome and Cognition: Follow-Up Study of Chinese Over-55-Year-Olds

BACKGROUND/AIM

Studies of the associations of the metabolic syndrome (MetS) with cognitive function and decline are inconclusive. We investigated the associations of the MetS with cognitive functions in 823 Chinese >55-year-olds followed up over 4.5 years.

METHODS

The relationships between the MetS and baseline and follow-up z-scores of cognitive domain functions were examined using mixed model analysis.

RESULTS

There were specific inverse cross-sectional associations of single cardiometabolic risk factors with cognition, such as hyperglycemia with processing speed (p = 0.045). The MetS was negatively associated with 3 out of 4 cognitive domains (p = 0.018 to p = 0.003), and the count of cardiometabolic risk factors with all cognitive domains (p = 0.025 to p = 0.002). Longitudinally, dyslipidemia was associated with worse decline in memory and learning (p = 0.022). The count of cardiometabolic risk factors was associated with worse declines in cognition (p = 0.032 for global cognition).

CONCLUSION

Among middle-aged and older Asians, an increased number of component cardiometabolic risk factors of the MetS was associated with a worse decline in cognitive function over time.

Metabolic Syndrome: Is It Time to Add the Central Nervous System?

Metabolic syndrome (MS) is a set of cardio-metabolic risk factors that includes central obesity, hyperglycemia, hypertension, and dyslipidemias. The syndrome affects 25% of adults worldwide. The definition of MS has evolved over the last 80 years, with various classification systems and criteria, whose limitations and benefits are currently the subject of some controversy. Likewise, hypotheses regarding the etiology of MS add more confusion from clinical and epidemiological points of view. The leading suggestion for the pathophysiology of MS is insulin resistance (IR). IR can affect multiple tissues and organs, from the classic “triumvirate” (myocyte, adipocyte, and hepatocyte) to possible effects on organs considered more recently, such as the central nervous system (CNS). Mild cognitive impairment (MCI) and Alzheimer’s disease (AD) may be clinical expressions of CNS involvement. However, the association between MCI and MS is not understood. The bidirectional relationship that seems to exist between these factors raises the questions of which phenomenon occurs first and whether MCI can be a precursor of MS. This review explores shared pathophysiological mechanisms between MCI and MS and establishes a hypothesis of a possible MCI role in the development of IR and the appearance of MS.

Reassessment of Pioglitazone for Alzheimer's Disease

Alzheimer's disease is a quintessential 'unmet medical need', accounting for ∼65% of progressive cognitive impairment among the elderly, and 700,000 deaths in the United States in 2020. In 2019, the cost of caring for Alzheimer's sufferers was $244B, not including the emotional and physical toll on caregivers. In spite of this dismal reality, no treatments are available that reduce the risk of developing AD or that offer prolonged mitiagation of its most devestating symptoms. This review summarizes key aspects of the biology and genetics of Alzheimer's disease, and we describe how pioglitazone improves many of the patholophysiological determinants of AD. We also summarize the results of pre-clinical experiments, longitudinal observational studies, and clinical trials. The results of animal testing suggest that pioglitazone can be corrective as well as protective, and that its efficacy is enhanced in a time- and dose-dependent manner, but the dose-effect relations are not monotonic or sigmoid. Longitudinal cohort studies suggests that it delays the onset of dementia in individuals with pre-existing type 2 diabetes mellitus, which small scale, unblinded pilot studies seem to confirm. However, the results of placebo-controlled, blinded clinical trials have not borne this out, and we discuss possible explanations for these discrepancies.

Docosahexaenoic and Arachidonic Acids as Neuroprotective Nutrients throughout the Life Cycle

The role of docosahexaenoic acid (DHA) and arachidonic acid (AA) in neurogenesis and brain development throughout the life cycle is fundamental. DHA and AA are long-chain polyunsaturated fatty acids (LCPUFA) vital for many human physiological processes, such as signaling pathways, gene expression, structure and function of membranes, among others. DHA and AA are deposited into the lipids of cell membranes that form the gray matter representing approximately 25% of the total content of brain fatty acids. Both fatty acids have effects on neuronal growth and differentiation through the modulation of the physical properties of neuronal membranes, signal transduction associated with G proteins, and gene expression. DHA and AA have a relevant role in neuroprotection against neurodegenerative pathologies such as Alzheimer's disease and Parkinson's disease, which are associated with characteristic pathological expressions as mitochondrial dysfunction, neuroinflammation, and oxidative stress. The present review analyzes the neuroprotective role of DHA and AA in the extreme stages of life, emphasizing the importance of these LCPUFA during the first year of life and in the developing/prevention of neurodegenerative diseases associated with aging.

Associations between metabolic syndrome and type of dementia: analysis based on the National Health Insurance Service database of Gangwon province in South Korea

BACKGROUND

Metabolic syndrome is a cluster of conditions that occur together, increasing the risk of cardiovascular disease. However, the relationship between metabolic syndrome and dementia has remained controversial. Using nationwide population cohort data, we investigated the association between metabolic syndrome and dementia, according to the dementia type.

METHODS

We analyzed data of 84,144 individuals, in the aged group of more than 60 years, between January 1, 2009, to December 31, 2009, at Gangwon province by using the information of the (Korean) National Health Insurance Service. After eight years of gap, in 2017, we investigated the relationship between metabolic syndrome and dementia. We classified Dementia either as dementia of the Alzheimer type (AD) or vascular dementia (VD). AD and VD were defined as per the criteria of International Classification of Disease, Tenth Revision, Clinical Modification codes. Multiple logistic regression analyses examined the associations between metabolic syndrome or five metabolic syndrome components and dementia. Analyses included factors like age, sex, smoking, alcohol, physical inactivity, previous stroke, and previous cardiac disease.

RESULTS

Metabolic syndrome was associated with AD (OR = 11.48, 95% CI 9.03-14.59), not with VD. Each of five components of metabolic syndrome were also associated with AD. (high serum triglycerides: OR = 1.87, 95% CI 1.60-2.19; high blood pressure: OR = 1.85, 95% CI 1.55-2.21; high glucose: OR = 1.77, 95% CI 1.52-2.06; abdominal obesity: OR = 1.88, 95% CI 1.57-2.25; low serum high-density lipoprotein cholesterol: OR = 1.91, 95% CI 1.63-2.24) However, among components of metabolic syndrome, only the high glucose level was associated with VD. (OR = 1.26, 95% CI 1.01-1.56) body mass index (BMI), fasting glucose, and smoking were also associated with AD. (BMI: OR = 0.951, 95% CI 0.927-0.975; fasting glucose: OR = 1.003, 95% CI 1.001-1.005; smoking: OR = 1.020, 95% CI 1.003-1.039) A history of the previous stroke was associated with both AD and VD. (AD: OR = 1.827, 95% CI 1.263-2.644; VD: OR 2.775, 95% CI 1.747-4.406) CONCLUSIONS: Metabolic syndrome was associated with AD but not with VD. Patients with metabolic syndrome had an 11.48 times more likeliness to develop AD compared to those without metabolic syndrome. VD was associated only with several risk factors that could affect the vascular state rather than a metabolic syndrome. We suggested that the associations between metabolic syndrome and dementia would vary depending on the type of dementia.

Risk of mild cognitive impairment among older adults in the United States by ethnoracial group

OBJECTIVES

To compare the risk of mild cognitive impairment (MCI) among a wide range of ethnoracial groups in the US.

DESIGN

Non-probabilistic longitudinal clinical research.

SETTING

Participants enrolling into the National Alzheimer's Coordinating Center Unified Data Set recruited via multiple approaches including clinician referral, self-referral by patients or family members, or active recruitment through community organizations.

PARTICIPANTS

Cognitively normal individuals 55 and older at the initial visit, who reported race and ethnicity information, with at least two visits between September 2005 and November 2018.

MEASUREMENTS

Ethnoracial information was self-reported and grouped into non-Latino Whites, Asian Americans, Native Americans, African Americans (AAs), and individuals simultaneously identifying as AAs and another minority race (AA+), as well as Latinos of Caribbean, Mexican, and Central/South American origin. MCI was evaluated clinically following standard criteria. Four competing risk analysis models were used to calculate MCI risk adjusting for risk of death, including an unadjusted model, and models adjusting for non-modifiable and modifiable risk factors.

RESULTS

After controlling for sex and age at initial visit, subhazard ratios of MCI were statistically higher than non-Latino Whites among Native Americans (1.73), Caribbean Latinos (1.80), and Central/South American Latinos (1.55). Subhazard ratios were higher among AA+ compared to non-Latino Whites only in the model controlling for all risk factors (1.40).

CONCLUSION

Compared to non-Latino Whites, MCI risk was higher among Caribbean and South/Central American Latinos as well as Native Americans and AA+. The factors explaining the differential MCI risk among ethnoracial groups are not clear and warrant future research.

GERO Cohort Protocol, Chile, 2017-2022: Community-based Cohort of Functional Decline in Subjective Cognitive Complaint elderly

BACKGROUND

With the global population aging and life expectancy increasing, dementia has turned a priority in the health care system. In Chile, dementia is one of the most important causes of disability in the elderly and the most rapidly growing cause of death in the last 20 years. Cognitive complaint is considered a predictor for cognitive and functional decline, incident mild cognitive impairment, and incident dementia. The GERO cohort is the Chilean core clinical project of the Geroscience Center for Brain Health and Metabolism (GERO). The objective of the GERO cohort is to analyze the rate of functional decline and progression to clinical dementia and their associated risk factors in a community-dwelling elderly with subjective cognitive complaint, through a population-based study. We also aim to undertake clinical research on brain ageing and dementia disorders, to create data and biobanks with the appropriate infrastructure to conduct other studies and facilitate to the national and international scientific community access to the data and samples for research.

METHODS

The GERO cohort aims the recruitment of 300 elderly subjects (> 70 years) from Santiago (Chile), following them up for at least 3 years. Eligible people are adults not diagnosed with dementia with subjective cognitive complaint, which are reported either by the participant, a proxy or both. Participants are identified through a household census. The protocol for evaluation is based on a multidimensional approach including socio-demographic, biomedical, psychosocial, neuropsychological, neuropsychiatric and motor assessments. Neuroimaging, blood and stool samples are also obtained. This multidimensional evaluation is carried out in a baseline and 2 follow-ups assessments, at 18 and 36 months. In addition, in months 6, 12, 24, and 30, a telephone interview is performed in order to keep contact with the participants and to assess general well-being.

DISCUSSION

Our work will allow us to determine multidimensional risks factors associated with functional decline and conversion to dementia in elderly with subjective cognitive complain. The aim of our GERO group is to establish the capacity to foster cutting edge and multidisciplinary research on aging in Chile including basic and clinical research.

TRIAL REGISTRATION

NCT04265482 in ClinicalTrials.gov. Registration Date: February 11, 2020. Retrospectively Registered.

Association of mild cognitive impairment and metabolic syndrome in patients with hypertension

AIM

The aim of this study was to evaluate the prevalence of mild cognitive impairment (MCI) in patients with hypertension and to evaluate the association of MCI with metabolic syndrome (MetS).

METHODOLOGY

186 subjects with hypertension were evaluated on Montreal Cognitive Assessment (MoCA) and Patient Health Questionnaire (PHQ-9) for cognitive decline and depression, respectively and MetS was diagnosed as per the Consensus definition.

RESULTS

The prevalence of MCI was 65.6 % and that of MetS was 45.7 %. Compared to those without MetS, those with MetS had significantly poorer cognitive functioning on the all cognitive domain of the MoCA, even after controlling for age, education, severity of the depression and duration of illness. Low High-Density Lipoprotein (HDL) was found to have a positive correlation with MoCA. Higher age, lower education, higher duration of illness and use of higher numbers of medications were associated with significantly lower score on MoCA.

CONCLUSION

Presence of MetS among persons with hypertension is associated with cognitive decline. Hence, there is a need to monitor and manage other parameters of MetS among patients with hypertension, to reduce the risk of cognitive decline and future dementia.

Tracking the potential involvement of metabolic disease in Alzheimer's disease-Biomarkers and beyond

There is a vast literature linking systemic metabolic conditions to dementia due to Alzheimer's disease (AD). Advances in in vivo measurements of AD neuropathology using brain imaging, cerebrospinal fluid (CSF), and/or blood biomarkers have led to research in AD that uses in vivo biomarkers as outcomes, focusing primarily on amyloid, tau, and neurodegeneration as constructs. Studies of Type 2 Diabetes Mellitus (T2DM) and AD biomarkers seem to show that T2DM is not related to amyloid deposition, but is related to neurodegeneration and tau deposition. There is a dearth of studies examining adiposity, insulin resistance, and metabolic syndrome in relation to AD biomarkers and the associations in these studies are inconsistent. Metabolomics studies have reported associations of unsaturated fatty acids with AD neuropathology at autopsy, and sphingolipids and glycerophospholipids in relation to neurodegeneration and amyloid and tau. There are other neurodegenerative diseases, such as Lewy body disease that may overlap with AD, and specific biomarkers for these pathologies are being developed and should be integrated into AD biomarker research. More longitudinal studies are needed with concurrent assessment of metabolic factors and AD biomarkers in order to improve the opportunity to assess causality. Ideally, AD biomarkers should be integrated into clinical trials of interventions that affect metabolic factors. Advances in blood-based AD biomarkers, which are less costly and invasive compared with CSF and brain imaging biomarkers, could facilitate widespread implementation of AD biomarkers in studies examining the metabolic contribution to AD.

Depression, Anxiety, and Apathy in Mild Cognitive Impairment: Current Perspectives

Objective: Mild cognitive impairment (MCI) is an important risk state for dementia, particularly Alzheimer's disease (AD). Depression, anxiety, and apathy are commonly observed neuropsychiatric features in MCI, which have been linked to cognitive and functional decline in daily activities, as well as disease progression. Accordingly, the study's objective is to review the prevalence, neuropsychological characteristics, and conversion rates to dementia between MCI patients with and without depression, anxiety, and apathy. Methods: A PubMed search and critical review were performed relating to studies of MCI, depression, anxiety, and apathy. Results: MCI patients have a high prevalence of depression/anxiety/apathy; furthermore, patients with MCI and concomitant depression/anxiety/apathy have more pronounced cognitive deficits and progress more often to dementia than MCI patients without depression/anxiety/apathy. Conclusions and Implications: Depression, anxiety, and apathy are common in MCI and represent possible risk factors for cognitive decline and progression to dementia. Further studies are needed to better understand the role and neurobiology of depression, anxiety, and apathy in MCI.

Changes in Metabolic Syndrome Status and Risk of Dementia

This study investigated the effects of changes in metabolic syndrome (MS) status and each component on subsequent dementia occurrence. The study population was participants of a biennial National Health Screening Program in 2009–2010 and 2011–2012 in Korea. Participants were divided into four groups according to change in MS status during the two-year interval screening: sustained normal, worsened (normal to MS), improved (MS to normal), and sustained MS group. Risk of dementia among the groups was estimated from the second screening date to 31 December 2016 using a Cox proportional hazards model. A total of 4,106,590 participants were included. The mean follow-up was 4.9 years. Compared to the sustained normal group, adjusted hazard ratios (aHR) (95% confidence interval) were 1.11 (1.08–1.13) for total dementia, 1.08 (1.05–1.11) for Alzheimer’s disease, and 1.20 (1.13–1.28) for vascular dementia in the worsened group; 1.12 (1.10–1.15), 1.10 (1.07–1.13), and 1.19 (1.12–1.27) for the improved group; and 1.18 (1.16–1.20), 1.13 (1.11–1.15), and 1.38 (1.32–1.44) for the sustained MS group. Normalization of MS lowered the risk of all dementia types; total dementia (aHR 1.18 versus 1.12), Alzheimer’s disease (1.13 versus 1.10), and vascular dementia (1.38 versus 1.19). Among MS components, fasting glucose and blood pressure showed more impact. In conclusion, changes in MS status were associated with the risk of dementia. Strategies to improve MS, especially hyperglycemia and blood pressure, may help to prevent dementia.

Metabolic Syndrome and Cardiovascular Disease Impacts on the Pathophysiology and Phenotype of HIV-Associated Neurocognitive Disorders

Evidence from epidemiological studies on the general population suggests that midlife cardiovascular disease (CVD) and/or metabolic syndrome (MetS) are associated with an increased risk of cognitive impairment and dementia later in life. In the modern combined antiretroviral therapy (cART) era, as in the general population, CVD and MetS were strongly and independently associated with poorer cognitive performances of sustained immunovirologically controlled persons living with human immunodeficiency viruses (PLHIVs). Those findings suggest that CV/metabolic comorbidities could be implicated in the pathogenesis of HIV-associated neurocognitive disorders (HAND) and might be more important than factors related to HIV infection or its treatment, markers of immunocompetence, or virus replication. The association between CVD/MetS and cognition decline is driven by still not well-understood mechanisms, but risk might well be the consequence of increased brain inflammation and vascular changes, notably cerebral small-vessel disease. In this review, we highlight the correspondences observed between the findings concerning CVD and MetS in the general population and virus-suppressed cART-treated PLHIVs to evaluate the real brain-aging processes. Indeed, incomplete HIV control mainly reflects HIV-induced brain damage described during the first decades of the pandemic. Given the growing support that CVD and MetS are associated with HAND, it is crucial to improve early detection and assure appropriate management of these conditions.

Association Between Individual Components of Metabolic Syndrome and Cognitive Function in Northeast Rural China

AIM

The aim of this article was to examine associations between metabolic syndrome and its individual components with cognitive function among rural elderly population in northeast China.

METHODS

Our study included 1047 residents aged older than 60 years in a northeast rural area. All were interviewed and data were obtained including sociodemographic and medical histories. Cognitive function was assessed by Mini-Mental State Examination. Metabolic syndrome was defined by NCEP-ATP III.

RESULTS

After adjusted for confounding factors, metabolic syndrome was inversely associated with cognitive function (odds ratio [OR] = 1.79; 95% confidence interval [CI]: 1.06-3.01) especially in participants aged less than 70 years old (OR = 2.60; 95% CI: 1.27-5.26). In addition, participants with metabolic syndrome had worse language function, which is a part of cognitive function (OR = 2.64; 95% CI: 1.39-5.00). Individual metabolic syndrome components, especially abdominal obesity and hyperglycemia, had significant association with cognitive function (OR = 0.72, 95% CI: 0.56-0.92 and OR = 1.41; 95% CI: 1.12-1.78, respectively).

CONCLUSIONS

Abdominal obesity might be a protective factor for cognitive function. However, hyperglycemia might be a risk factor.

Pathogenetic pathways of cognitive dysfunction and dementia in metabolic syndrome

The prevalence of dementia worldwide is growing at an alarming rate. A number of studies and meta-analyses have provided evidence for increased risk of dementia in patients with metabolic syndrome (MS) as compared to persons without MS. However, there are some reports demonstrating a lack of association between MS and increased dementia risk. In this review, taking into account the potential role of individual MS components in the pathogenesis of MS-related cognitive dysfunction, we considered the underlying mechanisms in arterial hypertension, diabetes mellitus, dyslipidemia, and obesity. The pathogenesis of dementia in MS is multifactorial, involving both vascular injury and non-ischemic neuronal death due to neurodegeneration. Neurodegenerative and ischemic lesions do not simply coexist in the brain due to independent evolution, but rather exacerbate each other, leading to more severe consequences for cognition than would either pathology alone. In addition to universal mechanisms of cognitive dysfunction shared by all MS components, other pathogenetic pathways leading to cognitive deficits and dementia, which are specific for each component, also play a role. Examples of such component-specific pathogenetic pathways include central insulin resistance and hypoglycemia in diabetes, neuroinflammation and adipokine imbalance in obesity, as well as arteriolosclerosis and lipohyalinosis in arterial hypertension. A more detailed understanding of cognitive disorders based on the recognition of underlying molecular mechanisms will aid in the development of new methods for prevention and treatment of devastating cognitive problems in MS.

Metabolic Syndrome, Mild Cognitive Impairment, and Dementia: A Meta-Analysis of Longitudinal Studies

OBJECTIVE

A systematic review and a meta-analysis of both clinical and population-based studies was undertaken according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement to clarify whether Metabolic Syndrome (MetS) is a risk or a protective factor for incident dementia, Alzheimer disease (AD), and vascular dementia (VaD), and whether it's involved in progression to dementia in patients affected by mild cognitive impairment (MCI).

METHODS

Search terms included ("metabolic syndrome" OR "syndrome x" OR "plurimetabolic syndrome") AND ("dementia" OR "Alzheimer disease" OR "vascular dementia" OR "mild cognitive impairment" OR "MCI"). Research was restricted to articles published in English between January 1, 2000 and August 31, 2018. No age limit was set.

RESULTS

At the end of the selection procedure, nine longitudinal studies were selected for the meta-analysis: six studies enrolled cognitively well-functioning participants and three studies involved MCI patients. A total of 18,313 participants aged older than 40 years with mean MetS prevalence of 22.7% were followed on average for 9.41years. A fixed model was used to estimate pooled hazard ratios and 95% confidence intervals.

CONCLUSION

No statistically significant pooled association emerged between MetS and incident dementia and AD. MetS increased the incidence of pure VaD. MetS increased the risk of progression from MCI to dementia. Follow-up length might be a key factor in investigating these associations further. Because MetS is constituted by a set of potentially modifiable factors, further studies with longer follow-up and repeated assessment of both MetS and cognitive status are desirable to draw definite conclusions.

A novel healthy metabolic phenotype developed among a cohort of families enriched for longevity

BACKGROUND

Long-lived individuals and their offspring have healthier metabolic characteristics than expected, such as more favorable levels of fasting glucose, insulin, and lipids than controls without longevity. Dysregulation in metabolic pathways has also shown to predict accelerated aging. Using information from the Long Life Family Study (LLFS), a multi-center study of two-generation families selected for exceptional longevity, we developed an indicator of healthy metabolism to determine whether metabolic health was more prevalent in a subset of LLFS families and whether it was heritable and associated with other metrics of healthy aging.

METHODS

A Latent Profile Analysis was applied to age- and gender-adjusted z-scores of fasting levels of glucose, insulin, triglycerides, and high-density lipoprotein cholesterol, body mass index, waist circumference, interleukin-6, and C-reactive protein. Families were defined as meeting the healthy metabolic phenotype if ≥2 and ≥50% of their offspring were classified into a latent subgroup with a profile of healthier metabolic markers than expected given age and gender relative to all LLFS offspring.

RESULTS

The log odds of being classified into the latent subgroup with a healthy profile of metabolic markers was heritable (h² = 0.40, p < 0.001). Among 388 families, 39 (10%) met the healthy metabolic phenotype. Participants from these families had somewhat better cognition than those from remaining families. Proband-generation participants from families who met the healthy metabolic phenotype also had better pulmonary functioning and physical performance.

CONCLUSIONS

The better cognition, pulmonary function, and physical performance among probands from families with the healthy metabolic phenotype may indicate that this subset of LLFS families have a more extreme longevity phenotype than other LLFS families since cognitive, physical, and pulmonary function are top mortality predictors for older adults. Future work is needed to determine if rare or protective alleles confer a healthy metabolic phenotype in this subset of LLFS families with exceptional metabolism.

High serum high-density lipoprotein-cholesterol is associated with memory function and gyrification of insular and frontal opercular cortex in an elderly memory-clinic population

The issue of whether serum lipid marker values are cognitively and neurologically significant for elderly individuals attending a memory clinic has been controversial. We investigated the associations of serum lipid markers with the memory function and cortical structure in 52 patients aged ≥75 years who had attended our memory clinic based on their subjective memory complaints. None had a history of medication for hyperlipidemia. The Wechsler Memory Scale-Revised (WMS-R) was administered to all patients for the assessment of their memory function. Serum low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDLC), and triglyceride (TG) were measured for each patient. Surface-based morphometry (SBM) was performed for the calculation of each patient's cortical thickness and gyrification index based on structural MRI data. Our analyses revealed that the serum HDLC level was positively and significantly correlated with the WMS-R subtests of visual paired associates I/II and logical memory I (p < 0.05). The serum TG level was negatively correlated with the logical memory I subtest. The SBM results showed positive correlations between the serum HDLC level and the gyrification indices of the bilateral insular and frontal opercular cortices, and those two gyrification indices were positively correlated with the logical memory I and visual paired associates I/II. These results suggest that in these elderly patients, a high serum HDLC level was associated with not only preserved memory function but also gyrification of the insular and frontal opercular cortex. We conclude that elderly individuals' serum lipid markers should be carefully assessed in memory clinic settings, because serum HDLC may be a biomarker for memory function and cortical structure.

Risk of dementia associated with cardiometabolic abnormalities and depressive symptoms: a longitudinal cohort study using the English longitudinal study of ageing

OBJECTIVES

Depression and cardiometabolic abnormalities are independently associated with a high risk of dementia. This study aimed to examine the association of comorbid depressive symptoms and cardiometabolic abnormalities with risk of dementia.

METHODS

The sample comprised 4859 participants aged 50 or older without baseline dementia who took part in the English Longitudinal Study of Ageing (waves 2-7). Depressive symptoms were assessed using the Center for Epidemiologic Studies-Depression tool. Cardiometabolic abnormalities were defined as three or more cardiometabolic risk factors (inflammation, central obesity, raised triglycerides, low high-density lipoprotein [HDL] cholesterol, hypertension, and hyperglycaemia or diabetes). Participants were classified into four groups based on presence of depressive symptoms and cardiometabolic abnormalities. Results were analysed using the Cox proportional hazards regression adjusted for covariates.

RESULTS

A total of 216 cases of incident dementia were reported over 10 years of follow-up. The group with high depressive symptoms only had an increased hazard of developing incident dementia during follow-up (HR = 2.68; 95%CI, 1.70-4.23), which was attenuated after adjustment for baseline cognition. No evidence was found for an association of overall cardiometabolic abnormalities with incident dementia; though hyperglycaemia, hypertension, and abdominal obesity with depressive symptoms had an unadjusted association with incident dementia. Only low-HDL cholesterol with depressive symptoms had an adjusted association with incident dementia (HR = 0.18; 95%CI, 0.04-0.75).

CONCLUSIONS

This work confirms depressive symptoms as a risk factor for incident dementia. However, low HDL-cholesterol with depressive symptoms may be protective against dementia, though more work is required to confirm this association.

The role of metabolic syndrome factors on cognition using latent variable modeling: The neurocognitive study on aging

OBJECTIVE

Although metabolic syndrome (MetS) has been shown to increase the risk of cognitive decline, it still remains unclear whether the risk is related to MetS as a whole or its individual factors. The aim of the present study was to explore whether MetS or its individual factors are associated with a lower cognitive function in older adults in a Mediterranean population using latent variable modeling.

METHOD

Neurocognitive data from 640 Greek-Cypriot community dwellers (female 59.1%), aged ≥55 years, in good general health, were analyzed. Assessments of anthropometric, blood pressure, fasting blood glucose, total cholesterol, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, and triglyceride concentrations were carried out to investigate the relationship between MetS factors and cognitive-linguistic outcomes of language, executive function, and verbal episodic memory.

RESULTS

When the MetS factors were modeled as a single latent variable, they had small negative effects on language and executive functions. Significance was not retained after age and education were controlled for. When individual MetS factors along with age and education were modeled as predictors, there were moderate negative age effects, whereas education yielded strong positive effects on all three cognitive outcomes. Weak significant negative coefficients of body mass index (BMI) and blood glucose were found for executive functions, and a weak significant positive effect of BMI was found for memory. Separate analysis by sex resulted in minor but significant differences.

CONCLUSION

BMI and blood glucose predicted cognitive performance after controlling for age and education, and thus their proper management should be taken into account for maintaining cognitive health in aging. Findings also demonstrate the importance of education and age in studies investigating cardiometabolic risk factors and cognitive function, as well as the need for further research on the effects of sex.

Alzheimer's Disease in the Latino Community: Intersection of Genetics and Social Determinants of Health

Alzheimer's disease (AD) is the most common type of dementia among individuals 65 or older. There are more than 5 million diagnosed cases in the US alone and this number is expected to triple by 2050. Therefore, AD has reached epidemic proportions with significant socioeconomic implications. While aging in general is the greatest risk factor for AD, several additional demographic factors that have contributed to the rise in AD in the US are under study. One such factor is associated with the relatively fast growth of the Latino population. Several reports indicate that AD is more prevalent among blacks and Latinos. However, the reason for AD disparity among different ethnic groups is still poorly understood and highly controversial. The Latino population is composed of different groups based on nationality, namely South and Central America, Mexico, and Caribbean Hispanics. This diversity among the Latino population represents an additional challenge since there are distinct characteristics associated with AD and comorbidities. In this review, we aim to bring attention to the intersection between social determinants of health and genetic factors associated with AD within the Latino community. We argue that understanding the interplay between identified social determinants of health, co-morbidities, and genetic factors could lead to community empowerment and inclusiveness in research and healthcare services, contributing to improved diagnosis and treatment of AD patients. Lastly, we propose that inserting a neuroethics perspective could help understand key challenges that influence healthcare disparities and contribute to increased risk of AD among Latinos.

Factors associated with cognitive impairment in elderly versus nonelderly patients with metabolic syndrome: the different roles of FGF21

Increased fibroblast growth factor 21 (FGF21) levels have been found in patients with metabolic syndrome (MetS). MetS is also associated with cognitive decline. However, the correlation between FGF21 and cognitive decline in elderly and nonelderly MetS patients has not been investigated. 116 non-elderly patients (age <65 years old) and 96 elderly patients (≥65 years old) with MetS were enrolled. Blood samples for FGF21 were collected from all participants after 12-hour fasting. Cognitive function was assessed using the Montreal cognitive assessment (MoCA) test. The MoCA score was negatively associated with age and was different among different levels of education in these MetS patients. In the non-elderly group, body mass index (BMI) showed positively correlated with MoCA score while, FGF21 level and HbA1C were negatively associated with the MoCA score in non-elderly MetS patients. BMI was the only factor which showed a negative correlation with the MoCA score in elderly MetS patients. This study demonstrated that FGF21 level was independently associated with cognitive impairment in non-elderly patients but not in elderly patients. The possible role of FGF21 level in cognitive impairment in non-elderly should be confirmed in a prospective study.

Pharmacophore-based virtual screening of catechol-o-methyltransferase (COMT) inhibitors to combat Alzheimer's disease

Alzheimer's disease (AD) is one of the most significant neurodegenerative disorders and its symptoms mostly appear in aged people. Catechol-o-methyltransferase (COMT) is one of the known target enzymes responsible for AD. With the use of 23 known inhibitors of COMT, a query has been generated and validated by screening against the database of 1500 decoys to obtain the GH score and enrichment value. The crucial features of the known inhibitors were evaluated by the online ZINC Pharmer to identify new leads from a ZINC database. Five hundred hits were retrieved from ZINC Pharmer and by ADMET (absorption, distribution, metabolism, excretion, and toxicity) filtering by using FAF-Drug-3 and 36 molecules were considered for molecular docking. From the COMT inhibitors, opicapone, fenoldopam, and quercetin were selected, while ZINC63625100_413 ZINC39411941_412, ZINC63234426_254, ZINC63637968_451, and ZINC64019452_303 were chosen for the molecular dynamics simulation analysis having high binding affinity and structural recognition. This study identified the potential COMT inhibitors through pharmacophore-based inhibitor screening leading to a more complete understanding of molecular-level interactions.

Hypertension, diabetes and obesity are associated with lower cognitive performance in community-dwelling elderly: Data from the FIBRA study

Background

Systemic hypertension (SH), diabetes mellitus (DM) and abdominal obesity may negatively impact cognitive performance.

Objective

To evaluate the association between SH, DM and abdominal obesity and cognitive performance among cognitively unimpaired elderly.

Methods

A cross-sectional study of individuals aged 65+ from seven Brazilian cities was conducted. SH and DM diagnoses were self-reported and abdominal circumference was objectively measured. Individuals who scored below the education-adjusted cutoff scores on the Mini-Mental State Examination (MMSE) were excluded.

Results

Among 2,593 elderly, 321 (12.38%) had SH, DM and abdominal obesity concomitantly (Group I) and 421 (16.23%) had none of the three diseases (Group II). Group I had a higher proportion of individuals that were women, aged 70-74 years, illiterate and with lower income. Group I had a higher number of participants with low cognitive performance (28.04% vs. 17.58% in Group II). Variables associated with poor cognitive performance were: female gender (OR: 2.43, p < 0.001); and lower education (OR: 0.410, p < 0.001). The presence of the three diseases and age were not significant in the education-adjusted model.

Conclusion

There was an association between cognition and the presence of SH, DM and obesity. However, education seems to be decisive in determining cognitive performance in the presence of these three conditions.

Reduced brain response to a sweet taste in Hispanic young adults

Hispanics have an increased risk for metabolic disorders, which evidence suggests may be due to interactions between lifespan biological, genetic, and lifestyle factors. Studies show the diet of many U.S. Hispanic groups have high sugar consumption, which has been shown to influence future preference for and consumption of high-sugar foods, and is associated with increased risk for insulin-related disorders and obesity. Taste is a primary determinant of food preference and selection. Differences in neural response to taste have been associated with obesity. Understanding brain response to sweet taste stimuli in healthy Hispanic adults is an important first step in characterizing the potential neural mechanisms for this behavior. We used fMRI to examine brain activation during the hedonic evaluation of sucrose as a function of ethnicity in Hispanic and non-Hispanic young adults. Taste stimuli were administered orally while subjects were scanned at 3T. Data were analyzed with AFNI via 3dROIstats and 3dMEMA, a mixed effects multi-level analysis of whole brain activation. The Hispanic group had significantly lower ROI activation in the left amygdala and significantly lower whole brain activation in regions critical for reward processing, and hedonic evaluation (e.g. frontal, orbitofrontal, and anterior cingulate cortices) than the non-Hispanic group. Differences in processing of sweet tastes have important clinical and public health implications, especially considering increased risk of metabolic syndrome and cognitive decline in Hispanic populations. Future research to better understanding relationships between health risk and brain function in Hispanic populations is warranted to better conceptualize and develop interventions for these populations.

Defining the Relationship Between Hypertension, Cognitive Decline, and Dementia: a Review

Hypertension is a highly prevalent condition which has been established as a risk factor for cardiovascular and cerebrovascular disease. Although the understanding of the relationship between cardiocirculatory dysfunction and brain health has improved significantly over the last several decades, it is still unclear whether hypertension constitutes a potentially treatable risk factor for cognitive decline and dementia. While it is clear that hypertension can affect brain structure and function, recent findings suggest that the associations between blood pressure and brain health are complex and, in many cases, dependent on factors such as age, hypertension chronicity, and antihypertensive medication use. Whereas large epidemiological studies have demonstrated a consistent association between high midlife BP and late-life cognitive decline and incident dementia, associations between late-life blood pressure and cognition have been less consistent. Recent evidence suggests that hypertension may promote alterations in brain structure and function through a process of cerebral vessel remodeling, which can lead to disruptions in cerebral autoregulation, reductions in cerebral perfusion, and limit the brain's ability to clear potentially harmful proteins such as β-amyloid. The purpose of the current review is to synthesize recent findings from epidemiological, neuroimaging, physiological, genetic, and translational research to provide an overview of what is currently known about the association between blood pressure and cognitive function across the lifespan. In doing so, the current review also discusses the results of recent randomized controlled trials of antihypertensive therapy to reduce cognitive decline, highlights several methodological limitations, and provides recommendations for future clinical trial design.

Glycemia but not the Metabolic Syndrome is Associated with Cognitive Decline: Findings from the European Male Ageing Study

OBJECTIVE

Previous research has indicated that components of the metabolic syndrome (MetS), such as hyperglycemia and hypertension, are negatively associated with cognition. However, evidence that MetS itself is related to cognitive performance has been inconsistent. This longitudinal study investigates whether MetS or its components affect cognitive decline in aging men and whether any interaction with inflammation exists.

METHODS

Over a mean of 4.4 years (SD ± 0.3), men aged 40-79 years from the multicenter European Male Ageing Study were recruited. Cognitive functioning was assessed using the Rey-Osterrieth Complex Figure (ROCF), the Camden Topographical Recognition Memory (CTRM) task, and the Digit Symbol Substitution Test (DSST). High-sensitivity C-reactive protein (hs-CRP) levels were measured using a chemiluminescent immunometric assay.

RESULTS

Overall, 1,913 participants contributed data to the ROCF analyses and 1,965 subjects contributed to the CTRM and DSST analyses. In multiple regression models the presence of baseline MetS was not associated with cognitive decline over time (p > 0.05). However, logistic ordinal regressions indicated that high glucose levels were related to a greater risk of decline on the ROCF Copy (β = -0.42, p < 0.05) and the DSST (β = -0.39, p < 0.001). There was neither a main effect of hs-CRP levels nor an interaction effect of hs-CRP and MetS at baseline on cognitive decline.

CONCLUSION

No evidence was found for a relationship between MetS or inflammation and cognitive decline in this sample of aging men. However, glycemia was negatively associated with visuoconstructional abilities and processing speed.

Differential associations of plasma lipids with incident dementia and dementia subtypes in the 3C Study: A longitudinal, population-based prospective cohort study

BACKGROUND

Vascular risk factors have been proposed as important targets for the prevention of dementia. As lipid fractions represent easily modifiable targets, we examined the longitudinal relationship of baseline lipid fractions with 13-y incident dementia and its subtypes (Alzheimer disease [AD] and mixed or vascular dementia) in older community-dwelling persons.

METHODS AND FINDINGS

Non-institutionalized persons aged 65+ y (n = 9,294) were recruited for the Three-City Study (3C Study), a population-based cohort study from the electoral rolls of the cities of Dijon, Bordeaux, and Montpellier, France, between March 1999 and March 2001. Follow-up examinations were performed every 2 y after the baseline assessment. The final study sample comprised 7,470 participants from the 3C Study (mean age ± standard deviation [SD] 73.8 ± 5.3 y, 61.0% women) who were prospectively followed up for up to 13 y. Fasting lipid fractions (triglycerides [TGs], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C], total cholesterol [TC]) were studied as continuous variables, and results are reported per SD increase of each lipid fraction. Incident dementia and its subtypes were studied as censored variables using Cox models with age as time scale. Analyses were adjusted for sex, study center, and educational level, as well as vascular risk factors and apolipoprotein E (APOE) ε4 genotype. We corrected for multiple testing, yielding a significance threshold of 0.0169. p-Values above the significance threshold but less than 0.05 were considered nominally significant. During a mean (± SD) follow-up period of 7.9 ± 3.6 y, 779 participants developed incident dementia (n = 532 AD and n = 154 mixed or vascular dementia). Higher LDL-C and TC concentrations at baseline were associated with an increased risk of AD (hazard ratio [HR] per SD increase = 1.13 [95% CI 1.04-1.22], p = 0.0045, and HR = 1.12 [1.03-1.22], p = 0.0072, respectively). These associations were largely unchanged after adjustment for vascular risk factors and were attenuated after adjustment for APOEε4 (HR per SD increase = 1.12 [1.03-1.23], p = 0.0110, and HR = 1.12 [1.02-1.23], p = 0.0171, respectively). Higher TG concentrations at baseline were associated with an increased risk of all dementia (HR per SD increase = 1.11 [1.03-1.19], p = 0.0044) and mixed or vascular dementia (HR = 1.21 [1.04-1.41], p = 0.0163). However, these associations disappeared after adjusting for vascular risk factors (HR = 1.07 [0.98-1.17], p = 0.1374, and HR = 1.17 [0.96-1.42], p = 0.1206, respectively). Main limitations of the study include interval censoring of incident dementia cases, potential selective survival bias, and the fact that variation in lipid concentrations during follow-up could not be accounted for in the analyses.

CONCLUSIONS

In a large population-based sample of older community-dwelling persons with up to 13 y of follow-up, we observed that higher LDL-C and TC concentrations were associated with an increased risk of AD. This result was independent of vascular risk factors and was attenuated after adjustment for APOEε4 carrier status. TG and HDL-C concentrations were not associated with risk of incident dementia or its subtypes after accounting for vascular risk factors.

An updated meta-analysis of cohort studies: Diabetes and risk of Alzheimer's disease

BACKGROUND

In recently, several large longitudinal population-based studies have shown that the rate of cognitive decline is accelerated in elderly people with diabetes mellitus. But the relation between diabetes and AD is still an area of controversy. The objective of this review was to update the evidence for or against diabetes as a risk factor of AD.

METHODS

We searched the literature from their inception to May 2016 without restriction of language. We included all longitudinal population-based studies examining the association between diabetes and risk of AD. The meta-analysis was conducted using Stata software.

RESULTS

A total of 17 studies involving 1,746,777 individuals were included. After pooling these 17 studies, subjects with diabetes had significant higher incidence of AD than those without diabetes (RR: 1.53, 95% CI: 1.42-1.63). When stratified by ethnicity, five cohorts were identified as Eastern populations, twelve were identified as Western populations. The Relative risk of AD in Western populations and Eastern populations were 1.36(1.18-1.53) and 1.62(1.49-1.75).

CONCLUSION

The risk of AD is higher among people with diabetes than in the general population, especially in Eastern populations. So the necessary treatment measures should be taken in order to decrease the risk of AD.

Association between Metabolic Syndrome and Cognitive Impairment after Acute Ischemic Stroke: A Cross-Sectional Study in a Chinese Population

BACKGROUND AND OBJECTIVES

Metabolic syndrome (MetS), a risk factor for many vascular conditions, is associated with vascular cognitive disorders. The objective of the present study was to explore the associations of MetS and its individual components with the risks of cognitive impairment and neurological dysfunction in patients after acute stroke.

METHODS

This cross-sectional study enrolled 840 patients ranging in age from 53 to 89 years from the Tianjin area of North China. Cognitive function was evaluated using the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination. Neuropsychiatric behavior was assessed using the Neuropsychiatric Inventory Questionnaire. Emotional state was examined according to the Hamilton Depression Rating Scale, and neuromotor function was evaluated using the National Institutes of Health Stroke Scale, Barthel index, and the Activity of Daily Living test. After overnight fasting, blood samples were obtained to measure biochemistry indicators.

RESULTS

MetS and its individual components were closely correlated with MoCA score. MetS patients had high levels of inflammation and a 3.542-fold increased odds ratio (OR) for cognitive impairment [95% confidence interval (CI): 1.972-6.361]. Of the individual MetS components, central obesity (OR 3.039; 95% CI: 1.839-5.023), high fasting plasma glucose (OR 1.915; 95% CI: 1.016-3.607), and type 2 diabetes (OR 2.241; 95% CI: 1.630-3.081) were associated with an increased incidence of cognitive impairment. Consistent and significant worsening in different neurological domains was observed with greater numbers of MetS components.

CONCLUSIONS

MetS was associated with worse cognitive function, neuromotor dysfunction, and neuropsychological symptoms among Chinese acute stroke patients.

Systematic review of dementia prevalence and incidence in United States race/ethnic populations

OBJECTIVE

To identify incidence and prevalence of dementia in racial and ethnic populations in the United States.

METHODS

A systematic review of literature.

RESULTS

A total of 1215 studies were reviewed; 114 were included. Dementia prevalence rates reported for age 65+ years from a low of 6.3% in Japanese Americans, 12.9% in Caribbean Hispanic Americans, 12.2% in Guamanian Chamorro and ranged widely in African Americans from 7.2% to 20.9%. Dementia annual incidence for African American (mean = 2.6%; SD = 1%; range, 1.4%-5.5%) and Caribbean Hispanic populations were significantly higher (mean, 3.6%; SD, 1.2%; range, 2.3%-5.3%) than Mexican American and Japanese Americans and non-Latino white populations (0.8%-2.7%), P < .001.

CONCLUSIONS

Data are needed for American Indian, most Asian, and Pacific Islander populations. Disaggregation of large race/ethnic classifications is warranted due to within-population heterogeneity in incidence and prevalence. African American and Caribbean Hispanic studies showed higher incidence of dementia. A nationwide approach is needed to identify communities at high risk and to tailor culturally appropriate services accordingly.

Cognitive disorders in diabetic patients

This chapter gives an overview of the literature on cognitive dysfunction in adults with type 1 or type 2 diabetes. First, methods to evaluate cognitive functioning and the pattern and severity of cognitive dysfunction in relation to diabetes will be discussed. The reader will note that diabetes is associated with worse cognitive functioning and an increased dementia risk. Next, diabetes-associated abnormalities on brain MRI, including reductions in brain volume - i.e., cerebral atrophy - and vascular lesions, will be addressed. At the group level there are clear relations between these imaging abnormalities and cognitive dysfunction, but at the level of the individual patient these relations are often less clear. Subsequently, risk factors for cognitive performance will be discussed. Evidently, these risk factors are related to diabetes type and the age of the patients involved. For type 1 diabetes, an early age at diabetes onset is the most consistent risk factor, whereas in type 2 diabetes, vascular risk factors and vascular comorbidities are consistent indicators of increased risk. The final section of the chapter addresses possible preventive and treatment measures and implications for daily care.

The Effect of a High-Fat Diet on Brain Plasticity, Inflammation and Cognition in Female ApoE4-Knockin and ApoE-Knockout Mice

Apolipoprotein E4 (ApoE4), one of three common isoforms of ApoE, is a major risk factor for late-onset Alzheimer disease (AD). ApoE-deficient mice, as well as mice expressing human ApoE4, display impaired learning and memory functions and signs of neurodegeneration. Moreover, ApoE protects against high-fat (HF) diet induced neurodegeneration by its role in the maintenance of the integrity of the blood-brain barrier. The influence of a HF diet on the progression of AD-like cognitive and neuropathological changes was assessed in wild-type (WT), human ApoE4 and ApoE-knockout (ApoE^-/-) mice to evaluate the modulatory role of ApoE in this process. From 12 months of age, female WT, ApoE4, and ApoE^-/- mice were fed either a standard or a HF diet (19% butter, 0.5% cholate, 1.25% cholesterol) throughout life. At 15 months of age mice performed the Morris water maze, evaluating spatial learning and memory. ApoE^-/- showed increased spatial learning compared to WT mice (p = 0.009). HF diet improved spatial learning in WT mice (p = 0.045), but did not affect ApoE4 and ApoE^-/- mice. Immunohistochemical analyses of the hippocampus demonstrated increased neuroinflammation (CD68) in the cornu ammonis 1 (CA1) region in ApoE4 (p = 0.001) and in ApoE^-/- (p = 0.032) mice on standard diet. HF diet tended to increase CD68 in the CA1 in WT mice (p = 0.052), while it decreased in ApoE4 (p = 0.009), but ApoE^-/- remained unaffected. A trend towards increased neurogenesis (DCX) was found in both ApoE4 (p = 0.052) and ApoE^-/- mice (p = 0.068). In conclusion, these data suggest that HF intake induces different effects in WT mice compared to ApoE4 and ApoE^-/- with respect to markers for cognition and neurodegeneration. We propose that HF intake inhibits the compensatory mechanisms of neuroinflammation and neurogenesis in aged female ApoE4 and ApoE^-/- mice.