Midlife cardiovascular risk factors and risk of dementia in late life

The relationship between heart disease and cognitive impairment

Neurodegenerative dementias, such as Alzheimer's disease, and vascular cognitive impairment were once considered unrelated processes. Emerging evidence, however, shows that both conditions often coexist and that vascular risk factors in midlife predispose to the development of cognitive decline later in older adults. In addition, recent advanced in basic science research have elucidated key underpinnings of this association. In this chapter, we review the clinical and basic science data that explain the relationship between vascular risk factors, heart disease, and cognitive decline.

Hypertension and Hypercholesterolemia Modify Dementia Risk in Relation to APOEɛ4 Status

BACKGROUND

There is significant interest in understanding the role of modifiable vascular risk factors contributing to dementia risk across age groups.

OBJECTIVE

Risk of dementia onset was assessed in relation to vascular risk factors of hypertension and hypercholesterolemia among cognitively normal APOEɛ4 carriers and non-carriers.

METHODS

In a sample of prospectively characterized longitudinal cohort from the National Alzheimer's Coordinating Center database, 9,349 participants met criteria for normal cognition at baseline, had a CDR-Global (CDR-G) score of zero, and had concomitant data on APOEɛ4 status and medical co-morbidities including histories of hypertension and hypercholesterolemia. Multivariable Cox proportional hazards models adjusted for well-known potential confounders were used to compare dementia onset among APOEɛ4 carriers and non-carriers by young (≤65 years) and old (> 65 year) age groups.

RESULTS

519 participants converted to dementia within an average follow up of 5.97 years. Among older APOEɛ4 carriers, hypercholesterolemia was related to lower risk of dementia (HR (95% CI), 0.68 (0.49-0.94), p = 0.02). Among older APOEɛ4 non-carriers, hypertension was related to higher risk of dementia (HR (95% CI), 1.44 (1.13-1.82), p = 0.003). These results were corroborated among a subset with autopsy data characterizing underlying neuropathology. Among younger participants, vascular risk factors did not impact dementia risk, likely from a lower frequency of vascular and Alzheimer's as etiologies of dementia among this cohort.

CONCLUSION

A history of hypercholesterolemia related to a lower risk of dementia among older APOEɛ4 carriers, while hypertension related to a higher risk of dementia among older APOEɛ4 non-carriers.

LDL cholesterol and uridine levels in blood are potential nutritional biomarkers for clinical progression in Alzheimer's disease: The NUDAD project

INTRODUCTION

We examined associations between nutritional biomarkers and clinical progression in individuals with subjective cognitive decline (SCD), mild cognitive impairment (MCI), and Alzheimer's disease (AD)-type dementia.

METHODS

We included 528 individuals (64 ± 8 years, 46% F, follow-up 2.1 ± 0.87 years) with SCD (n = 204), MCI (n = 130), and AD (n = 194). Baseline levels of cholesterol, triglycerides, glucose, homocysteine, folate, vitamin A, B12, E and uridine were measured in blood and S-adenosylmethionine and S-adenosylhomocysteine in cerebrospinal fluid. We determined associations between nutritional biomarkers and clinical progression using Cox proportional hazard models.

RESULTS

Twenty-two (11%) patients with SCD, 45 (35%) patients with MCI, and 100 (52%) patients with AD showed clinical progression. In SCD, higher levels of low-density lipoprotein (LDL) cholesterol were associated with progression (hazard ratio [HR] [95% confidence interval (CI)] 1.88 [1.04 to 3.41]). In AD, lower uridine levels were associated with progression (0.79 [0.63 to 0.99]).

DISCUSSION

Our findings suggest that LDL cholesterol and uridine play a-stage-dependent-role in the clinical progression of AD.

Evaluation of Cognitive Performance following Fish-Oil and Curcumin Supplementation in Middle-Aged and Older Adults with Overweight or Obesity

BACKGROUND

Obesity accelerates age-related cognitive decline, which is partly mediated by vascular dysfunction.

OBJECTIVE

The aim was to test the hypothesis that supplementation with fish oil and curcumin can enhance cognitive performance by improving cerebral circulatory function in overweight or obese middle-aged to older adults.

METHODS

In a 16-wk double-blind, placebo-controlled intervention trial, adults [50-80 y; BMI (kg/m2): 25-40] were randomly assigned to either fish oil (2000 mg/d DHA + 400 mg/d EPA), curcumin (160 mg/d), or a combination. Effects on cerebrovascular function (primary outcome) and cardiovascular risk factors were reported previously. Effects on cognitive performance and cerebrovascular responsiveness (CVR) to cognitive stimuli are reported herein. One-factor ANOVA with post hoc analyses was conducted between groups in the whole cohort and in males and females separately. Two-factor ANOVA was conducted to assess independent effects of fish oil and curcumin and a potential interaction. Correlations between outcomes (those obtained herein and previously reported) were also examined.

RESULTS

Compared with placebo, fish oil improved CVR to a processing speed test (4.4% ± 1.9% vs. -2.2% ± 2.1%; P = 0.023) and processing speed in males only (Z-score: 0.6 ± 0.2 vs. 0.1 ± 0.2; P = 0.043). Changes in processing speed correlated inversely with changes in blood pressure (R = -0.243, P = 0.006) and C-reactive protein (R = -0.183, P = 0.046). Curcumin improved CVR in a working memory test (3.6% ± 1.2% vs. -0.2% ± 0.2%, P = 0.026) and, in males only, performance of a verbal memory test compared with placebo (Z-score: 0.2 ± 0.1 vs. -0.5 ± 0.2, P = 0.039). Combining fish oil with curcumin did not produce additional benefits.

CONCLUSIONS

Improvements in processing speed following fish-oil supplementation in middle-aged to older males might be mediated by improvements in circulatory function. Mechanisms underlying the cognitive benefit seen with curcumin are unknown. As cognitive benefits were found in males only, further evaluation of sex differences in responsiveness to supplementation is warranted. This trial was registered at the Australian and New Zealand Clinical Trial Register at https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=370788 as ACTRN12616000732482p.

Health benefits attributed to 17α-estradiol, a lifespan-extending compound, are mediated through estrogen receptor α

Metabolic dysfunction underlies several chronic diseases, many of which are exacerbated by obesity. Dietary interventions can reverse metabolic declines and slow aging, although compliance issues remain paramount. 17α-estradiol treatment improves metabolic parameters and slows aging in male mice. The mechanisms by which 17α-estradiol elicits these benefits remain unresolved. Herein, we show that 17α-estradiol elicits similar genomic binding and transcriptional activation through estrogen receptor α (ERα) to that of 17β-estradiol. In addition, we show that the ablation of ERα completely attenuates the beneficial metabolic effects of 17α-E2 in male mice. Our findings suggest that 17α-E2 may act through the liver and hypothalamus to improve metabolic parameters in male mice. Lastly, we also determined that 17α-E2 improves metabolic parameters in male rats, thereby proving that the beneficial effects of 17α-E2 are not limited to mice. Collectively, these studies suggest ERα may be a drug target for mitigating chronic diseases in male mammals.

Sex-specific associations between lipids and cognitive decline in the middle-aged and elderly: a cohort study of Chinese adults

Background

Studies regarding the lipid-cognition relationship have increasingly gained popularity but have generated much mixed results. To date, few studies have focused on the difference between sexes.

Methods

This study included 6792 Chinese adults aged over 45 years (women, 48.56%; mean age, 57.28 years), who were free of severe conditions known to affect cognitive function at the baseline (2011). Blood concentrations of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), and triglycerides (TG) were assessed at baseline, and both continuous and categorical values were used in final analyses. Global cognitive functions were assessed by the word recall test and the mental status test in 2011, 2013, and 2015, respectively. We graded participants into three groups according to the cognitive change slopes: no decline (≥ 0), moderate decline (median to 0), and severe decline (< median). Sex-specific associations between blood lipids and cognitive decline were analyzed using ordinal logistic models, adjusting for sociodemographic information, lifestyle behaviors, and health status.

Results

Higher baseline TC and LDL-C concentrations exhibited no significant association with 5-year cognitive decline in men but were significantly associated with greater 5-year cognitive decline in women [odds ratio (OR) 1.026, 95% confidence interval (CI) 1.003, 1.050; OR 1.026, CI 1.002, 1.051, respectively]. For higher serum HDL-c levels, a significantly protective effect on cognition was observed in men, but a slightly adverse effect was found in women (not significant after Bonferroni correction). TG presented almost no effect on later cognition in either sex.

Conclusion

Different associations between sexes were observed for the lipid-cognition relationship, and maintaining serum cholesterol levels at an appropriate range may have a positive effect on cognitive health.

Association of mid-life serum lipid levels with late-life brain volumes: The atherosclerosis risk in communities neurocognitive study (ARICNCS)

BACKGROUND

Limited information exists regarding the association between midlife lipid levels and late-life total and regional brain volumes.

METHODS

We studied 1872 participants in the longitudinal community-based Atherosclerosis Risk in Communities Neurocognitive Study. Serum lipid levels were measured in 1987-1989 (mean age, 53 ± 5 years). Participants underwent 3T brain MRI scans in 2011-2013. Brain volumes were measured using FreeSurfer image analysis software. Linear regression models were used to assess the associations between serum lipids and brain volumes modeled in standard deviation (SD) units, adjusting for potential confounders.

RESULTS

In adjusted analyses, one SD higher low-density lipoprotein cholesterol (LDL) levels were associated with larger total brain volumes (β 0.033, 95% CI 0.006-0.060) as well as larger volumes of the temporal (β 0.038, 95% CI 0.003-0.074) and parietal lobes (β 0.044, 95% CI 0.009-0.07) and Alzheimer disease-related region (β 0.048, 95% CI 0.048-0.085). Higher triglyceride levels were associated with smaller total brain volumes (β -0.033, 95% CI -0.060, -0.007). The associations between LDL levels and brain volumes were modified by age (P for interaction <0.001), with higher LDL levels associated with larger total and regional brain volumes only among adults >53 years at baseline, and were attenuated after application of weights to account for informative attrition, although associations with the parietal and Alzheimer's disease-related region remained significant. High-density lipoprotein cholesterol was not associated with brain volumes.

CONCLUSION

Higher LDL levels in late midlife were associated with larger brain volumes later in life, while higher triglyceride levels were associated with smaller brain volumes. These associations were driven by adults >53 years at baseline.

Metabolic syndrome components moderate the association between executive function and functional connectivity in the default mode network

Middle aged individuals with Metabolic Syndrome are at high risk for cognitive decline. Dyssynchrony in the resting state Default Mode Network is one early indicator of brain vulnerability. We set out to explore the relationship between default mode resting state functional connectivity and cognitive performance in both memory and executive domains at midlife in the presence of Metabolic Syndrome components. Seed-based Correlation Analyses were performed between the seed voxel in the posterior cingulate cortex and the medial prefrontal cortex on 200 participants (ages 40-61). Executive domain scores were significantly predicted by the interaction between number of Metabolic Syndrome components and resting state connectivity in the Default Mode Network (p = .004) such that connectivity was negatively related to executive function at higher numbers of Metabolic Syndrome components. Results were not significant for memory. Our findings indicate that clusters of cardiovascular disease risk factors alter functional relationships in the brain and highlights the need to continue exploring how compensatory techniques might operate to support cognitive performance at midlife.

Metabolic Syndrome and Cognitive Trajectories in the Framingham Offspring Study

Metabolic syndrome (MetS) has been linked to increased risk of developing cognitive impairment and dementia including Alzheimer's disease. It remains unclear whether and at what stage in the adult lifespan MetS and its components begin to alter the trajectory of cognitive performance. In the present study, 2,892 Framingham Offspring participants completed health assessments every four years since 1971 and underwent repeat neuropsychological testing from 1999 to 2014. We estimated the associations of levels and changes in cognitive trajectories with hazard of MetS using a joint growth/survival model. All models were adjusted for baseline age, sex, education, and smoking status. Findings showed that both mid-life and late-life MetS were associated with lower level of cognitive functioning but not cognitive trajectories. Associations were strongest among those who were nondemented and apolipoprotein (APOE) ɛ4 noncarriers. In addition, individuals with the most rapid cognitive decline were more likely to have MetS. The pattern of results showed that associations between MetS and cognition varied, depending upon whether the sample was stratified by genetic and cognitive status and whether we considered cognitive performance as a continuous variable or examined categorical groupings. Given that mid-life MetS was associated with poorer cognition at age 55, cognitive changes may occur early during the MetS process. Our findings suggest that those with MetS are at greater risk of dementia given their lower level of cognitive functioning and also suggest that MetS may be a risk factor for decline in the absence of known risk factors including the APOEɛ4 allele.

Association Between Cardiovascular Health and Cognitive Performance: A Twins Study

BACKGROUND/OBJECTIVE

The 2020 Strategic Impact Goal introduced by the American Heart Association (AHA) aims at improving cardiovascular health (CVH) of all Americans by 20%. AHA defined ideal CVH across seven established modifiable risk factors for cardiovascular diseases. Prior studies have indicated that ideal CVH also benefits brain health and cognitive aging, but it is possible that this association is explained by familial factors.

METHODS

We examined 272 male monozygotic and dizygotic twin pairs (total 544 subjects) free of overt cardiovascular disease and dementia from the Vietnam Era Twin Registry. Memory and learning were measured by Trail Making tests and Wechsler Memory Scale (Immediate and Delayed Memory tests and Visual Reproductive Test). Each of the seven CVH components (smoking, body mass index, physical activity, diet, total cholesterol, blood pressure, and blood glucose) was scored per established criterion.

RESULTS

The mean age of the twins was 55 years, 96% were whites, and 61% monozygotic. When considering twins as individuals, for every unit increase in CVH score (indicating better cardiovascular health), twins demonstrated faster cognitive processing speed (Trail B: - 5.6 s, 95% CI - 10.3, - 0.9; p = 0.03) and better story recall, both immediate (0.35, 95% CI 0.06, 0.62; p = 0.02) and delayed (0.39, 95% CI 0.08, 0.70; p = 0.01).

CONCLUSIONS

Better CVH is associated with better cognitive health in several domains. As suggested by within-pair analysis, this association is largely explained by familial factors, implying that early life exposures are shared determinants of both brain health and cardiovascular health.

Cognition in Vascular Aging and Mild Cognitive Impairment

Cardiovascular health declines with age, due to vascular risk factors, and this leads to an increasing risk of cognitive decline. Mild cognitive impairment (MCI) is defined as the negative cognitive changes beyond what is expected in normal aging. The purpose of the study was to compare older adults with vascular risk factors (VRF), MCI patients, and healthy controls (HC) in main dimensions of cognitive control. The sample comprised a total of 109 adults, aged 50 to 85 (M = 66.09, S.D. = 9.02). They were divided into three groups: 1) older adults with VRF, 2) MCI patients, and 3) healthy controls (HC). VRF and MCI did not differ significantly in age, educational level, or gender as was the case with HC. The tests used mainly examine inhibition, cognitive flexibility, and working memory processing. Results showed that the VRF group had more Set Loss Errors in drawing designs indicating deficits in establishing cognitive set and in cognitive shifting. MCI patients displayed lower performance in processing. Hence, different types of specific impairments emerge in vascular aging and MCI, and this may imply that discrete underlying pathologies may play a role in the development of somewhat different profiles of cognitive decline.

Age and diet modify acute microhemorrhage outcome in the mouse brain

Cerebral microhemorrhages (CMHs) are considered as asymptomatic lesions, but might impair cognition in non-demented elderly individuals. The aging process includes poor vascular health, enhanced at midlife by metabolic disturbances upon high-fat diet (HFD). The onset of CMHs could thus have more serious consequences in midlife subjects with metabolic disturbances. This hypothesis was tested through the induction of multiple CMHs, using cyclodextrin nanoparticles injection, in mice at midlife (14 month old) or at a younger stage (5 month old) after 12 months or 3 months of normal diet or HFD (40% of animal fat) respectively. When induced at 14 months of age, CMHs were not larger but were more numerous (+25%) in mice on HFD compared with mice on normal diet. They slowed down the locomotor activity significantly but caused neither a change in the working memory nor a difference in the visual recognition memory decline. When induced at 5 months of age, CMHs provoked slighter locomotor and cognitive symptoms, regardless the diet. No spontaneous progression of CMHs toward larger hemorrhages was observed after onset when HFD was prolonged up to midlife. Consistently, no precipitated cognitive decline was observed. Middle-age plus time of metabolic disturbances represent enhanced risk factors for CMH outcome.

Influence of Lifestyles on Mild Cognitive Impairment: A Decision Tree Model Study

Objective

To explore the effects of different lifestyle choices on mild cognitive impairment (MCI) and to establish a decision tree model to analyse their predictive significance on the incidence of MCI.

Methods

Study participants were recruited from geriatric and physical examination centres from October 2015 to October 2019: 330 MCI patients and 295 normal cognitive (NC) patients. Cognitive function was evaluated by the Mini-Mental State Examination Scale (MMSE) and Clinical Dementia Scale (CDR), while the Barthel Index (BI) was used to evaluate life ability. Statistical analysis included the χ² test, logistic regression, and decision tree. The ROC curve was drawn to evaluate the predictive ability of the decision tree model.

Results

Logistic regression analysis showed that low education, living alone, smoking, and a high-fat diet were risk factors for MCI, while young age, tea drinking, afternoon naps, social engagement, and hobbies were protective factors for MCI. Social engagement, a high-fat diet, hobbies, living condition, tea drinking, and smoking entered all nodes of the decision tree model, with social engagement as the root node variable. The importance of predictive variables in the decision tree model showed social engagement, a high-fat diet, tea drinking, hobbies, living condition, and smoking as 33.57%, 27.74%, 22.14%, 11.94%, 4.61%, and 0%, respectively. The area under the ROC curve predicted by the decision tree model was 0.827 (95% CI: 0.795~0.856).

Conclusion

The decision tree model has good predictive ability. MCI was closely related to lifestyle; social engagement was the most important factor in predicting the occurrence of MCI.

Ideal vascular health and cognitive performance in the Brazilian Longitudinal Study of Adult Health

BACKGROUND AND PURPOSE

Most evidence for the association between ideal vascular health (IVH) and cognitive performance comes from high income countries. The aim was to investigate this association in the Brazilian Longitudinal Study of Adult Health.

METHODS

Cognition was assessed using the word list, verbal fluency and trail making tests. The IVH score included ideal metrics for body mass index, smoking, physical activity, diet, blood pressure, fasting glucose and total cholesterol. Poor, intermediate and optimal health were characterized in those presenting 0-2, 3-4, 5-7 ideal metrics, respectively. To determine the association between IVH score and cognitive performance, linear regression models adjusted for age, sex, education, race, alcohol use, depression and thyroid function were used.

RESULTS

In 12 271 participants, the mean age was 51.3 ± 8.9 years, 54% were women, 57% White and 53% had poor vascular health. Participants with intermediate (β = 0.064, 95% confidence interval 0.033; 0.096) and optimal health (β = 0.108, 95% confidence interval 0.052; 0.164) had better global cognitive Z-scores. In addition, interactions of IVH score with age, education and race were found, suggesting a better cognitive performance with higher IVH in older adults, Black/Brown participants and those with lower levels of education.

CONCLUSION

Ideal vascular health was associated with better cognitive performance. Older, Black/Brown and low-educated participants had better cognition in the presence of higher IVH scores.

Carotid Atherosclerosis and Cognitive Function in a General Population Aged 63-65 Years: Data from the Akershus Cardiac Examination (ACE) 1950 Study

BACKGROUND

Studies on the relationship between carotid atherosclerosis and cognitive function in subjects from the general population are few and results have been inconsistent.

OBJECTIVE

We aimed to investigate the association between carotid atherosclerotic burden and cognitive function in a cross-sectional analysis of a population-based cohort aged 63-65 years.

METHODS

All habitants born in 1950 from Akershus County, Norway were invited to participate. A linear regression model was used to assess the association between carotid atherosclerosis and cognitive function. We used carotid plaque score as a measure of carotid atherosclerotic burden and the Montreal Cognitive Assessment (MoCA) for global cognitive function.

RESULTS

We analyzed 3,413 individuals aged 63-65 with mean MoCA score 25.3±2.9 and 87% visible carotid plaques. We found a negative correlation between carotid plaque score and MoCA score (r = -0.14, p < 0.001), but this association was lost in multivariable analysis. In contrast, diameter or area of the thickest plaque was independently associated with MoCA score. Lower educational level, male sex, current smoking, and diabetes were also associated with lower MoCA score in multivariable analysis.

CONCLUSION

Carotid atherosclerotic burden was, unlike other measures of advanced carotid atherosclerosis, not independently associated with global cognitive function.

Vascular contributions to cognitive impairment and dementia (VCID): A report from the 2018 National Heart, Lung, and Blood Institute and National Institute of Neurological Disorders and Stroke Workshop

Vascular contributions to cognitive impairment and dementia (VCID) are characterized by the aging neurovascular unit being confronted with and failing to cope with biological insults due to systemic and cerebral vascular disease, proteinopathy including Alzheimer's biology, metabolic disease, or immune response, resulting in cognitive decline. This report summarizes the discussion and recommendations from a working group convened by the National Heart, Lung, and Blood Institute and the National Institute of Neurological Disorders and Stroke to evaluate the state of the field in VCID research, identify research priorities, and foster collaborations. As discussed in this report, advances in understanding the biological mechanisms of VCID across the wide spectrum of pathologies, chronic systemic comorbidities, and other risk factors may lead to potential prevention and new treatment strategies to decrease the burden of dementia. Better understanding of the social determinants of health that affect risks for both vascular disease and VCID could provide insight into strategies to reduce racial and ethnic disparities in VCID.

ACAT1 as a Therapeutic Target and its Genetic Relationship with Alzheimer's Disease

BACKGROUND

Alzheimer´s disease (AD) is a chronic and progressive disease which impacts caregivers, families and societies physically, psychologically and economically. Currently available drugs can only improve cognitive symptoms, have no impact on progression and are not curative, so identifying and studying new drug targets is important. There are evidences which indicate disturbances in cholesterol homeostasis can be related with AD pathology, especially the compartmentation of intracellular cholesterol and cytoplasmic cholesterol esters formed by acyl-CoA: cholesterol acyltransferase 1 (ACAT1) can be implicated in the regulation of amyloid-beta (Aβ) peptide, involved in AD. Blocking ACAT1 activity, beneficial effects are obtained, so it has been suggested that ACAT1 can be a potential new therapeutic target. The present review discusses the role of cholesterol homeostasis in AD pathology, especially with ACAT inhibitors, and how they have been raised as a therapeutic approach. In addition, the genetic relationship of ACAT and AD is discussed.

CONCLUSION

Although there are several lines of evidence from cell-based and animal studies that suggest that ACAT inhibition is an effective way of reducing cerebral Aβ, there is still an information gap in terms of mechanisms and concerns to cover before passing to the next level. Additionally, an area of interest that may be useful in understanding AD to subsequently propose new therapeutic approaches is pharmacogenetics; however, there is still a lot of missing information in this area.

Menopause and Brain Health: Hormonal Changes Are Only Part of the Story

Most studies of menopause and brain aging have focused on the role of the sex steroid hormone, estradiol, as a key mechanisms contributing to cognitive and brain aging in women. An emerging literature demonstrates that beyond endogenous estradiol levels, menopausal symptoms, particularly vasomotor symptoms (VMS), are also key determinants of menopause-related changes in cognition and brain function. Critically, that literature shows the importance of using objective techniques to identify associations of VMS with memory performance, brain structure, and brain function. While self-report measures are important patient-centered outcomes in women's health research, objective measures of VMS typically relate more strongly to indices of cognitive and brain health. Currently, it is premature to make a causal claim about VMS and memory dysfunction, but initial findings raise the possibility that women with VMS might experience an improvement in cognition with VMS treatment. More generally, these findings underscore the utility of investigating female-specific risk factors for cognitive decline.

The role of the brain renin-angiotensin system (RAS) in mild traumatic brain injury (TBI)

There is considerable interest in traumatic brain injury (TBI) induced by repeated concussions suffered by athletes in sports, military personnel from combat-and non-combat related activities, and civilian populations who suffer head injuries from accidents and domestic violence. Although the renin-angiotensin system (RAS) is primarily a systemic cardiovascular regulatory system that, when dysregulated, causes hypertension and cardiovascular pathology, the brain contains a local RAS that plays a critical role in the pathophysiology of several neurodegenerative diseases. This local RAS includes receptors for angiotensin (Ang) II within the brain parenchyma, as well as on circumventricular organs outside the blood-brain-barrier. The brain RAS acts primarily via the type 1 Ang II receptor (AT₁R), exacerbating insults and pathology. With TBI, the brain RAS may contribute to permanent brain damage, especially when a second TBI occurs before the brain recovers from an initial injury. Agents are needed that minimize the extent of injury from an acute TBI, reducing TBI-mediated permanent brain damage. This review discusses how activation of the brain RAS following TBI contributes to this damage, and how drugs that counteract activation of the AT₁R including AT₁R blockers (ARBs), renin inhibitors, angiotensin-converting enzyme (ACE) inhibitors, and agonists at type 2 Ang II receptors (AT₂) and at Ang (1-7) receptors (Mas) can potentially ameliorate TBI-induced brain damage.

Repositioning medication for cardiovascular and cerebrovascular disease to delay the onset and prevent progression of Alzheimer's disease

Alzheimer's disease (AD) is a complex, progressive, neurodegenerative disorder. As with other common chronic diseases, multiple risk factors contribute to the onset and progression of AD. Many researchers have evaluated the epidemiologic and pathophysiological association between AD, cardiovascular diseases (CVDs), and cerebrovascular diseases (CBVDs), including commonly reported risk factors such as diabetes, hypertension, and dyslipidemia. Relevant therapies of CVDs/CBVDs for the attenuation of AD have also been empirically investigated. Considering the challenges of new drug development, in terms of cost and time, multifactorial approaches such as therapeutic repositioning of CVD/CBVD medication should be explored to delay the onset and progression of AD. Thus, in this review, we discuss our current understanding of the association between cardiovascular risk factors and AD, as revealed by clinical and non-clinical studies, as well as the therapeutic implications of CVD/CBVD medication that may attenuate AD. Furthermore, we discuss future directions by evaluating ongoing trials in the field.

Longitudinal Associations Between Contact Frequency with Friends and with Family, Activity Engagement, and Cognitive Functioning

OBJECTIVES

Social engagement may be an important protective resource for cognitive aging. Some evidence suggests that time spent with friends may be more beneficial for cognition than time spent with family. Because maintaining friendships has been demonstrated to require more active maintenance and engagement in shared activities, activity engagement may be one underlying pathway that explains the distinct associations between contact frequency with friends versus family and cognition.

METHODS

Using two waves of data from the national survey of Midlife in the United States (n = 3707, Mage = 55.80, 51% female at baseline), we examined longitudinal associations between contact frequency with friends and family, activity engagement (cognitive and physical activities), and cognition (episodic memory and executive functioning) to determine whether activity engagement mediates the relationship between contact frequency and cognition.

RESULTS

The longitudinal mediation model revealed that more frequent contact with friends, but not family, was associated with greater concurrent engagement in physical and cognitive activities, which were both associated with better episodic memory and executive functioning.

CONCLUSION

These findings suggest that time spent with friends may promote both cognitively and physically stimulating activities that could help to preserve not only these social relationships but also cognitive functioning.

Blood Pressure in Different Dementia Disorders, Mild Cognitive Impairment, and Subjective Cognitive Decline

The aim of the study was to investigate whether blood pressure (BP) differed among people with different dementia diagnoses, mild cognitive impairment, and subjective cognitive decline and whether BP differences were observed across age and sex. Our study population comprised clinical data from 6,236 patients (53.5% women) aged 45–97 years (Mean = 73.9, SD = 9.6) referred to dementia assessment in 42 outpatient clinics across Norway during 2009–2019. Patients with the following diagnoses were included: Subjective cognitive decline (SCD), Mild cognitive impairment (MCI), dementia due to Alzheimer’s disease (AD), Vascular dementia (VaD), mixed AD and VaD, and dementia in Parkinson’s disease/Lewy body disease (PDD/LBD). For all diagnostic groups, SBP increased with age until about 80 years, after which it trended downward, whereas DBP declined after 60 years of age for all diagnostic groups. Patients aged 65 years and younger with SCD had lower SBP compared to AD patients at the same age, but SBP increased rapidly with increasing age, resulting in a substantially higher SBP at 80 + years compared with all other diagnostic groups. No other differences in SBP or diastolic blood pressure (DBP) were found among patients with the different dementia diagnosis. Neither SBP nor DBP differed between MCI and AD groups. An interaction between age and gender was found for SBP at younger ages, as women started out with a lower pressure than men did but ended up with higher SBP.

Predicting resistance to amyloid-beta deposition and cognitive resilience in the oldest-old

OBJECTIVE

To explore long-term predictors of avoiding β-amyloid (Aβ) deposition and maintaining unimpaired cognition as outcomes in the oldest old.

METHODS

In a longitudinal observational cohort study, 100 former participants of the Ginkgo Evaluation of Memory Study (GEMS; 2000-2008) completed biannual Pittsburgh compound B-PET imaging and annual clinical-cognitive evaluations beginning in 2010. Most recent Aβ status and cognitive status were selected for each participant. Longitudinal outcomes included change in serial Aβ and cognitive tests. Baseline predictors from GEMS included neuropsychological tests, daily functioning, APOE genotype, lifestyle variables, occupational measures, health history, sleep, subjective memory, physical and cognitive activities, depressive symptoms, and physical performance and health indices, among others.

RESULTS

Mean age at the last cognitive evaluation was 92.0 (range 86-100) years. Mean follow-up time from baseline to last measured Aβ status was 12.3 (SD 1.9) years and to last cognitive evaluation was 14.1 (SD 1.9) years. The APOE*2 allele predicted last Aβ status (n = 34 Aβ negative vs n = 66 Aβ positive). Baseline cognition predicted cognitive status (n = 30 unimpaired vs n = 70 impaired). Predictors of cognitive status among Aβ-positive participants only (n = 14 normal cognition vs n = 52 impaired) were baseline cognitive test scores and smoking history. Baseline pulse pressure predicted longitudinal Aβ increase; paid work engagement and life satisfaction predicted less cognitive decline.

CONCLUSIONS

The APOE*2 allele and lower pulse pressure predict resistance to Aβ deposition in advanced aging. Cognitive test scores 14 years prior, likely reflecting premorbid abilities, predict cognitive status and maintenance of unimpaired cognition in the presence of Aβ. Several lifestyle factors appear protective.

Serum and CSF Metabolites in Stroke-Free Patients Are Associated With Vascular Risk Factors and Cognitive Performance

Background and purpose: The aggregation of vascular risk factors (VRFs) can aggravate cognitive impairment in stroke-free patients. Metabolites in serum and cerebrospinal fluid (CSF) may irreversibly reflect early functional deterioration. This study evaluated small-molecule metabolites (<1,000 Da) in the serum and CSF of patients with different degrees of cerebrovascular burden and investigated the correlation between metabolism and cognitive performance associated with VRFs.

Methods: The subjects were divided into a low-risk group (10-year stroke risk ≤ 5%), a middle-risk group (10-year stroke risk >5% and <15%), and a high-risk group (10 years stroke risk ≥ 15%) according to the Framingham stroke risk profile (FSRP) score, which was used to quantify VRFs. We assess the cognitive function of the participants. We semiquantitatively quantified the small molecules using liquid chromatography–tandem mass spectrometry (LC-MS/MS). The correlation between the small molecules and cognitive function, along with VRFs, was investigated to identify key small molecules and possible underlying metabolic pathways.

Results: When the FSRP scores increased, the cognitive performances of the subjects decreased, specifically the performance regarding the tasks of immediate memory, delayed recall, and executive function. Seven metabolites (2-aminobutyric acid, Asp Asp Ser, Asp Thr Arg, Ile Cys Arg, 1-methyluric acid, 3-tert-butyladipic acid, and 5α-dihydrotestosterone glucuronide) in serum and three metabolites [Asp His, 13-HOTrE(r), and 2,5-di-tert-Butylhydroquinone] in CSF were significantly increased, and one metabolite (arachidonoyl PAF C-16) in serum was significantly decreased in high-risk group subjects. Among these metabolites, 1-methyluric acid, 3-tert-butyladipic, acid and Ile Cys Arg in serum and 13-HOTrE(r), 2,5-di-tert-butylhydroquinone, and Asp His in CSF were found to be negatively related with cognitive performance in the high-risk group. Arachidonoyl PAF C-16 in serum was found to be associated with better cognitive performance. Caffeine metabolism and the tricarboxylic acid cycle (TCA cycle) were identified as key pathways.

Conclusions: 1-Methyluric acid, 3-tert-butyladipic acid, arachidonoyl PAF C-16, and Ile Cys Arg in serum and 13-HOTrE(r), 2,5-di-tert-butylhydroquinone, and Asp His in CSF were identified as potential biomarkers of vascular cognitive impairment (VCI) at the early stage. Caffeine metabolism and the TCA cycle may play important roles in the pathophysiology of VRF-associated cognitive impairment.

Education and Cognitive Functioning Across the Life Span

Cognitive abilities are important predictors of educational and occupational performance, socioeconomic attainment, health, and longevity. Declines in cognitive abilities are linked to impairments in older adults' everyday functions, but people differ from one another in their rates of cognitive decline over the course of adulthood and old age. Hence, identifying factors that protect against compromised late-life cognition is of great societal interest. The number of years of formal education completed by individuals is positively correlated with their cognitive function throughout adulthood and predicts lower risk of dementia late in life. These observations have led to the propositions that prolonging education might (a) affect cognitive ability and (b) attenuate aging-associated declines in cognition. We evaluate these propositions by reviewing the literature on educational attainment and cognitive aging, including recent analyses of data harmonized across multiple longitudinal cohort studies and related meta-analyses. In line with the first proposition, the evidence indicates that educational attainment has positive effects on cognitive function. We also find evidence that cognitive abilities are associated with selection into longer durations of education and that there are common factors (e.g., parental socioeconomic resources) that affect both educational attainment and cognitive development. There is likely reciprocal interplay among these factors, and among cognitive abilities, during development. Education-cognitive ability associations are apparent across the entire adult life span and across the full range of education levels, including (to some degree) tertiary education. However, contrary to the second proposition, we find that associations between education and aging-associated cognitive declines are negligible and that a threshold model of dementia can account for the association between educational attainment and late-life dementia risk. We conclude that educational attainment exerts its influences on late-life cognitive function primarily by contributing to individual differences in cognitive skills that emerge in early adulthood but persist into older age. We also note that the widespread absence of educational influences on rates of cognitive decline puts constraints on theoretical notions of cognitive aging, such as the concepts of cognitive reserve and brain maintenance. Improving the conditions that shape development during the first decades of life carries great potential for improving cognitive ability in early adulthood and for reducing public-health burdens related to cognitive aging and dementia.

Tremor in Vascular Cognitive Impairment Raises the Possibility of Mixed Pathology With Lewy Body Disease

Objectives

Tremor is common in patients with Lewy body disease (LBD) and not rare in normal individuals. Prevalence of tremor in patients with vascular cognitive impairment (VCI) and its association with other comorbidities are seldom studied. The aim of this study was to investigate the patient characteristics of VCI associated with tremor and to evaluate the possibility of mixed pathology with LBD in these patients.

Methods

Retrospective analysis of a large population with VCI registered in the database of a regional healthcare system was performed. VCI patients were divided into tremor and non-tremor groups. The associated characteristics including demographics, clinical features in motor and non-motor domains, vascular risk factors, and neuroimaging features were compared between the tremor group and the non-tremor group.

Results

Among 1337 patients with VCI, 292 (21.8%) had tremor, while 1045 (78.2%) did not have tremor. The tremor group had significantly higher prevalence of all motor and non-motor LBD clinical features than the non-tremor group. The tremor group also demonstrated more severe neuropsychiatric symptoms. Among patients with tremor, patients having tremor onset earlier than stroke onset showed significantly higher prevalence of rapid eye movement sleep behavior disorder. All comparisons were adjusted for age and severity of dementia.

Conclusion

Tremor is a common comorbidity of VCI. VCI patients with tremor had a higher prevalence of motor and non-motor LBD features. These findings raised the possibility of VCI patients with tremor having high possibility of mixed pathology with LBD.

The relationship between neuropsychological function and responsiveness to vitamin D supplementation using artificial neural networks

BACKGROUND

Vitamin D has recently attracted interest for its pleiotropic effects. Vitamin D supplements are a potentially important public health intervention, but the response to supplementation varies between individuals.

AIM

We aimed to assess the association between several neuropsychological parameters and the magnitude of response to vitamin D supplementation using an artificial neural network method.

METHODS

Neuropsychological function was assessed in 619 participants using standard questionnaires. The study participants received vitamin D capsules containing 50,000 IU vitamin D per week over 9 weeks. To assess the relationship between responsiveness to vitamin D supplements and the impact on these neuropsychological parameters, the best-performing artificial neural network algorithms were selected from a combination of different transfer functions in hidden and output layers and variable numbers of hidden layers (between two and 50). The performance of the artificial neural network algorithm was assessed by receiver operating characteristic analysis and variables of importance were identified.

RESULTS

The artificial neural network algorithm with sigmoid transfer function in both hidden and output layers could predict responsiveness to vitamin D supplementation effectively. The sensitivity and specificity were between 0.60 and 0.70 and 0.66 and 0.70, respectively. Cognitive abilities (42.5%), basal vitamin D (21.3%), body mass index (9.5%), and daytime sleepiness (8%) are the most widely used variables to predict changes in serum vitamin D levels.

CONCLUSIONS

Cognitive abilities status and baseline 25-hydroxyvitamin D are important novel modifiers of the enhancement in circulating 25-hydroxyvitamin D after vitamin D supplementation.

Cardiovascular risk factors and accelerated cognitive decline in midlife: The CARDIA Study

OBJECTIVE

Increasing evidence supports an association between midlife cardiovascular risk factors (CVRFs) and risk of dementia, but less is known about whether CVRFs influence cognition in midlife. We examined the relationship between CVRFs and midlife cognitive decline.

METHODS

In 2,675 black and white middle-aged adults (mean age 50.2 ± 3.6 years, 57% female, 45% black), we measured CVRFs at baseline: hypertension (31%), diabetes mellitus (11%), obesity (43%), high cholesterol (9%), and current cigarette smoking (15%). We administered cognitive tests of memory, executive function, and processing speed at baseline and 5 years later. Using logistic regression, we estimated the association of CVRFs with accelerated cognitive decline (race-specific decline ≥1.5 SD from the mean change) on a composite cognitive score.

RESULTS

Five percent (n = 143) of participants had accelerated cognitive decline over 5 years. Smoking, hypertension, and diabetes mellitus were associated with an increased likelihood of accelerated decline after multivariable adjustment (adjusted odds ratio [AOR] 1.65, 95% confidence interval [CI] 1.00-2.71; AOR 1.87, 95% CI 1.26-2.75; AOR 2.45, 95% CI 1.54-3.88, respectively), while obesity and high cholesterol were not associated with risk of decline. These results were similar when stratified by race. The likelihood of accelerated decline also increased with greater number of CVRFs (1-2 CVRFs: AOR 1.77, 95% CI 1.02-3.05; ≥3 CVRFs: AOR 2.94, 95% CI 1.64-5.28) and with Framingham Coronary Heart Disease Risk Score ≥10 (AOR 2.29, 95% CI 1.21-4.34).

CONCLUSIONS

Midlife CVRFs, especially hypertension, diabetes mellitus, and smoking, are common and associated with accelerated cognitive decline at midlife. These results identify potential modifiable targets to prevent midlife cognitive decline and highlight the need for a life course approach to cognitive function and aging.

Stressors in Midlife and Risk of Dementia: The Role of Race and Education

BACKGROUND

Posttraumatic stress disorder is associated with increased dementia risk but less is known about stress because of everyday problems in diverse populations.

METHODS

A total of 9605 health care plan members who provided information regarding midlife stressors in 1972 to 1973 (ages, 40 to 55 y) were followed for dementia diagnosis between 1996 and 2017. Cox proportional hazard models evaluated associations between midlife stressors and dementia adjusting for demographics and lifecourse health indicators.

RESULTS

Reporting at least 1 midlife stressor was associated with 17% greater dementia risk [hazard ratio (HR), 1.17; 95% confidence interval (CI),1.07-1.27] versus 0 midlife stressors and 26% increased risk among those with less than equal to high school education (HR, 1.26; 95% CI,1.09-1.44) adjusting for demographics. Compared with whites without stressors, whites with ≥1 stressor had 13% greater dementia risk (HR, 1.13; 95% CI, 1.02-1.24), blacks without stressors 19% greater risk (HR, 1.19; 95% CI,1.08-1.32), and blacks with ≥1 stressors 47% greater risk (HR, 1.47; 95% CI,1.27-1.69) in fully adjusted models. Resource problems were associated with 20% greater risk (HR, 1.20; 95% CI, 1.01-1.42) than interpersonal problems.

CONCLUSION

Reporting ≥1 serious midlife stressor was associated with elevated dementia risk, especially stressors related to resources problems and for those with less than equal to high school education. Everyday stressors can impact brain health over the long term and may contribute to racial inequities in dementia rates, though education can be a mitigating factor.

Evaluation of frequency of occurrence of cognitive impairment in the course of arterial hypertension in an elderly population

BACKGROUND

Dementia is a very serious problem with regard to geriatric population. In the population over the age of 80 the prevalence of dementia varies by up to 20%. It is very important to answer the question - are arterial hypertension and its duration associated with cognitive performance?

METHODS

One hundred and sixty people were qualified for participation in the study, women and men, diagnosed with arterial hypertension. The patients were divided into two pairs of groups. The first pair was group 1, patients with hypertension over the age of 85 and group 2, patients with hypertension aged 75-85. The second pair was group I, patients with up to 10 years of arterial hypertension and group II, patients with over 10 years of arterial hypertension. In the study, the Mini-Mental State Examination (MMSE) was used. Interpretation of impairment depended on the obtained numerical value.

RESULTS

In the tested group of patients, for individual correlations it was found that age is the independent variable which significantly affects the MMSE score. It was found that the time of duration of arterial hypertension did not have impact on the MMSE.

CONCLUSION

Cognitive functions evaluated through the MMSE were correct for the entire population. The length of the course of arterial hypertension did not have a significant adverse impact on cognitive functions and on the achieved MMSE result. Significant impact of age on the lowering of MMSE results and impairment of cognitive functions was shown.

Contributions of Modifiable Risk Factors to Dementia Incidence: A Bayesian Network Analysis

OBJECTIVE

To determine and compare the contributions of modifiable risk factors (RFs) with the prevention of dementia in older adults.

DESIGN

A systematic review and Bayesian network meta-analysis (NMA). The observational group was set as a reference to collect all existing RFs and compare them with each other.

SETTING AND PARTICIPANTS

An exhaustive and comprehensive literature search strategy was used to identify relevant prospective cohort studies from several online databases from their inception to May 1, 2019. Participants without dementia were adults aged greater than 50 years.

MEASURES

The required data were extracted from the eligible studies to facilitate the Bayesian NMA.

RESULTS

Forty-three cohort studies with 277,294 participants were included in this NMA. Using the observation group as the reference, all defined RFs, except for antioxidants, were associated with lower risks of all-cause dementia [no sleep disturbances (odds ratio, OR 0.43, 95% credible interval, CrI 0.24-0.62), a high level of education (OR 0.50, 95% CrI 0.34-0.66), no history of diabetes (OR 0.57, 95% CrI 0.36-0.78), nonobese patients (OR 0.61, 95% CrI 0.39-0.83), no smoking history (OR 0.62, 95% CrI 0.45-0.79), living with family members (OR 0.67, 95% CrI 0.45-0.89), participation in physical exercise (OR 0.73, 95% CrI 0.46-0.94), abstinence from drinking (OR 0.78, 95% CrI 0.56-0.99), and no history of hypertension (OR 0.80, 95% CrI 0.65-0.96)].

CONCLUSIONS/RELEVANCE

The findings provide reliable support for the hypothesis that modifiable somatic and lifestyle factors are strong predictors of all-cause dementia.

Taxonomic Distribution of Medicinal Plants for Alzheimer’s Disease: A Cue to Novel Drugs

Alzheimer’s disease (AD) is a neurodegenerative disorder manifested by decline in memory and mild cognitive impairment leading to dementia. Despite global occurrence of AD, the severity and hence onset of dementia vary among different regions, which was correlated with the customary use of medicinal herbs and exposure level to the causatives. In spite of execution of versatile therapeutic strategies to combat AD and other neurodegenerative diseases, success is only limited to symptomatic treatment. The role of natural remedies remained primitive and irreplaceable in all ages. In some examples, the extracted drugs failed to show comparable results due to lack of micro ingredients. Micro ingredients impart a peerless value to natural remedies which are difficult to isolate and/or determine their precise role during treatment. A variety of plants have been used for memory enhancement and other dementia-related complications since ages. Acetyl choline esterase inhibition, antioxidant potential, neuroprotection, mitochondrial energy restoration, and/or precipitated protein clearance put a vast taxonomic variety into a single group of anti-AD plants. Secondary metabolites derived from these medicinal plants have the potential to treat AD and other brain diseases of common pathology. This review summarizes the potential of taxonomically diverse medicinal plants in the treatment of AD serving as a guide to further exploration.

The Effects of Lower BP Goals on Cognitive Function in the Elderly

PURPOSE OF REVIEW

To review the research on the impact of blood pressure control on prevention of cognitive impairment and dementia.

RECENT FINDINGS

Observational evidence has shown an association between hypertension and cognitive impairment. However, clinical trial results of blood pressure lowering have been inconclusive, likely due to inadequate cognitive assessment, blood pressure difference between groups, and follow-up duration. SPRINT-MIND showed a 19% reduction in mild cognitive impairment (14.6 vs 18.3 per 1000 person-years; HR, 0.81; 95% CI, 0.67-0.95), the earliest manifestation of dementia, with intensive blood pressure control. There was a statistically non-significant 17% reduction in the risk of probable dementia (HR 0.83, 95% CI 0.67-1.04). The progress of clinical trials testing the impact of blood pressure reduction on cardiovascular disease incidence has helped inform large trial testing of this intervention's impact on cognitive decline and dementia. SPRINT MIND demonstrated a positive effect of intensive blood pressure control on risk for mild cognitive impairment (MCI), and though the effect size was similar to MCI, the result was statistically non-significant possibly due to early termination of the intervention. Extension of follow-up may increase the number of new cases of dementia, producing a more conclusive result for dementia.

Apolipoprotein E4 Mediates the Association Between Midlife Dyslipidemia and Cerebral Amyloid in Aging Women

Cerebral amyloid-β (Aβ) plaques are the hallmark biomarker of Alzheimer's disease (AD) and are detectable decades before clinical symptoms. Modifying risk factors associated with Aβ accrual offers an opportunity for AD prevention. While midlife vascular health is linked to AD; there is minimal longitudinal evidence regarding the effect of midlife lipids on Aβ. We examined the association between midlife lipids and Aβ 20 years later. One hundred and twenty-two women had serum lipid profiles in midlife (1992, 45-57 years), and cerebral imaging, genotyping, and cognition measured 20 years later (2012/13, 66-77 years). Imaging was performed in 2012/13 via F-18 Florbetaben positron emission tomography (PET) and standard uptake value ratios (SUVR) were calculated. Lipid profiles and other predictors of high PET-SUVR levels (>1.2) were evaluated using multivariable logistic regression. Increases in low-density lipoprotein (LDL) cholesterol in midlife were associated with Aβ, adjusting for age, education, cholesterol medication, and cognition (AdjOR1.81, 95% CI 1.08-3.01, p = 0.024), but attenuated on adjustment for apolipoprotein E4 (APOE ɛ4). Aβ risk increased in women with APOE ɛ4 and midlife cholesterol >6.2 mmol/L (AdjOR9.59, 95% CI 2.94-31.31, p < 0.001), APOE ɛ4 and LDL >3.3 mmol/L (AdjOR9.00, 95% CI 2.89-28.03, p < 0.001), and APOE ɛ4 and cholesterol to high-density lipoprotein ratio ≥3.25 (AdjOR8.32, 95% CI 2.32-29.89, p < 0.001). Presence of APOE ɛ4 and midlife dyslipidemia compounded the risk for Aβ deposition, although no independent effect of midlife lipids was found. Lipid-modifying treatment in midlife could mitigate the risk of Aβ in women with a genetic predisposition for AD. To better inform prevention, future consideration should be given toward managing dyslipidemia in women carrying the APOE ɛ4 allele.

High fat diet worsens Alzheimer's disease-related behavioral abnormalities and neuropathology in APP/PS1 mice, but not by synergistically decreasing cerebral blood flow

Obesity is linked to increased risk for and severity of Alzheimer's disease (AD). Cerebral blood flow (CBF) reductions are an early feature of AD and are also linked to obesity. We recently showed that non-flowing capillaries, caused by adhered neutrophils, contribute to CBF reduction in mouse models of AD. Because obesity could exacerbate the vascular inflammation likely underlying this neutrophil adhesion, we tested links between obesity and AD by feeding APP/PS1 mice a high fat diet (Hfd) and evaluating behavioral, physiological, and pathological changes. We found trends toward poorer memory performance in APP/PS1 mice fed a Hfd, impaired social interactions with either APP/PS1 genotype or a Hfd, and synergistic impairment of sensory-motor function in APP/PS1 mice fed a Hfd. The Hfd led to increases in amyloid-beta monomers and plaques in APP/PS1 mice, as well as increased brain inflammation. These results agree with previous reports showing obesity exacerbates AD-related pathology and symptoms in mice. We used a crowd-sourced, citizen science approach to analyze imaging data to determine the impact of the APP/PS1 genotype and a Hfd on capillary stalling and CBF. Surprisingly, we did not see an increase in the number of non-flowing capillaries or a worsening of the CBF deficit in APP/PS1 mice fed a Hfd as compared to controls, suggesting that capillary stalling is not a mechanistic link between a Hfd and increased severity of AD in mice. Reducing capillary stalling by blocking neutrophil adhesion improved CBF and short-term memory function in APP/PS1 mice, even when fed a Hfd.

Sensorineural Impairments, Cardiovascular Risk Factors, and 10-Year Incidence of Cognitive Impairment and Decline in Midlife: The Beaver Dam Offspring Study

BACKGROUND

Sensorineural impairments and cardiovascular risk factors (CVRF) and disease (CVD) in midlife may be important predictors of future cognitive health, but longitudinal studies that include multiple sensorineural measures in middle-aged adults are lacking.

METHODS

Hearing, vision, and olfaction, and CVRF and CVD were measured at the Beaver Dam Offspring Study baseline (2005-2008) examination. The Mini-Mental State Examination and Trail Making Tests A and B were administered at all phases and additional cognitive function measures were obtained at 5 (2010-2013) and 10 years (2015-2017). Cox proportional hazards models were used to evaluate associations between baseline sensorineural impairments, CVRF, CVD, and 10-year cumulative incidence of cognitive impairment and decline.

RESULTS

There were 2,556 participants (22-84 years) without cognitive impairment at baseline and data from at least one follow-up. In a multivariable model including age, sex, education, and head injury, visual impairment (hazard ratio = 2.59, 95% confidence interval = 1.34, 5.02), olfactory impairment (hazard ratio = 3.18, 95% confidence interval = 1.53, 6.59), CVD (hazard ratio = 2.37, 95% confidence interval = 1.24, 4.52), and not consuming alcohol in the past year (hazard ratio = 2.21, 95% confidence interval = 1.16, 4.19) were associated with the 10-year cumulative incidence of cognitive impairment. Current smoking and diabetes were associated with increased risk, and exercise with decreased risk, of 10-year decline in cognitive function.

CONCLUSIONS

Visual and olfactory impairments, CVRF, and CVD were associated with the 10-year cumulative incidence of cognitive impairment and decline in middle-aged adults. Identifying modifiable factors associated with cognitive decline and impairment in midlife may provide opportunities for prevention or treatment and improve cognitive health later in life.

Cholesterol and Alzheimer's Disease Risk: A Meta-Meta-Analysis

BACKGROUND

Alzheimer's disease (AD) is the most common subtype of dementia. In the last ten years, the relationship between cholesterol and AD has been investigated. Evidence suggests that cholesterol is associated with AD and represents promising targets for intervention. However, the causality of these associations is unclear. Therefore, we sought to conduct a meta-meta-analysis to determine the effect of cholesterol on the development AD. Then, we assessed the effect of serum levels of low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC) and triglycerides (TG), on AD risk.

METHODS

A systematic search of meta-analyses was conducted. Scopus, Web of Science, Science direct, PubMed and Google academic system databases were reviewed.

RESULTS

We found 100 primary studies and five meta-analyses to analyze the relationships between cholesterol and AD. The total effect of cholesterol on risk of AD was significant and heterogeneous. Subgroup analysis shows that LDL-C levels influence the development of AD. However, non-significant effects of HDL-C, TC and TG levels on AD were found.

CONCLUSIONS

These results strengthen the evidence that LDL-C cholesterol levels increase risk for AD. More initiatives to investigate the relationship between cholesterol and AD are needed.

Association of Early-Onset Alzheimer Disease With Elevated Low-Density Lipoprotein Cholesterol Levels and Rare Genetic Coding Variants of APOB

Importance

Early-onset Alzheimer disease (EOAD) is a rare form of Alzheimer disease (AD) with a large genetic basis that is only partially understood. In late-onset AD, elevated circulating cholesterol levels increase AD risk even after adjusting for the apolipoprotein E ε4 (APOE E4) allele, a major genetic factor for AD and elevated cholesterol levels; however, the role of circulating cholesterol levels in EOAD is unclear.

Objectives

To investigate the association between circulating cholesterol levels and EOAD and to identify genetic variants underlying this possible association.

Design, Setting, and Participants

In this case series, plasma cholesterol levels were directly measured in 267 samples from the AD research centers (ADRCs) of Emory University and University of California, San Francisco, collected from January 21, 2009, through August 21, 2014. The association between cholesterol and EOAD was examined using multiple linear regression. To determine the underlying genetic variants, APOB, APP, PSEN1, and PSEN2 were sequenced in samples from 2125 EOAD cases and controls recruited from 29 ADRCs from January 1, 1984, through December 31, 2015. Data were analyzed from November 23, 2016, through April 10, 2018.

Exposures

Clinical diagnosis, age at clinical diagnosis, plasma cholesterol measures (total cholesterol, low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol, triglycerides, and apolipoprotein B), and genetic variants in APOE, APP, PSEN1, PSEN2, and APOB.

Main Outcomes and Measures

The primary outcome was the association between EOAD and plasma cholesterol measures. The secondary outcome was the association between EOAD and the burden of genetic variants in APOB.

Results

Of the 2125 samples that underwent genetic sequencing, 1276 were from women (60.0%) and 654 (30.8%) were from patients with EOAD (mean [SD] ages, 55.6 [4.3] years for cases and 72.0 [9.6] years for controls). APOE E4 explained 10.1% of the variance of EOAD. After controlling for APOE E4, EOAD cases had higher levels of total cholesterol (mean difference [SE], 21.9 [5.2] mg/dL; P = 2.9 × 10-5), LDL-C (mean difference [SE], 22.0 [4.5] mg/dL; P = 1.8 × 10-6), and ApoB (mean difference [SE], 12.0 [2.4] mg/dL; P = 2.0 × 10-6) than controls in 267 frozen samples. Approximately 3% of EOAD cases carried known AD-causing mutations. Gene-based rare variant burden testing in 2066 samples showed that rare APOB coding variants were significantly more abundant in EOAD cases after adjusting for sex, APOE E4, genetic principal components, ADRC center, and batch (effect size, 0.20; P = 4.20 × 10-4).

Conclusions and Relevance

Elevated LDL-C levels were associated with higher probability of having EOAD, and EOAD cases were enriched for rare coding variants in APOB, which codes for the major protein of LDL-C. Collectively, these novel findings highlight the important role of LDL-C in EOAD pathogenesis and suggest a direct link of APOB variants to AD risk.

Hemodynamic Instability in Heart Failure Intensifies Age-Dependent Cognitive Decline

This review attempts to examine two key elements in the evolution of cognitive impairment in the elderly who develop heart failure. First, major left side heart parts can structurally and functionally deteriorate from aging wear and tear to provoke hemodynamic instability where heart failure worsens or is initiated; second, heart failure is a major inducer of cognitive impairment and Alzheimer's disease in the elderly. In heart failure, when the left ventricular myocardium of an elderly person does not properly contract, it cannot pump out adequate blood to the brain, raising the risk of cognitive impairment due to the intensification of chronic brain hypoperfusion. Chronic brain hypoperfusion originates from chronically reduced cardiac output which progresses as heart failure worsens. Other left ventricular heart parts, including atrium, valves, myocardium, and aorta can contribute to the physiological shortfall of cardiac output. It follows that hemodynamic instability and perfusion changes occurring from the aging heart's blood pumping deficiency will, in time, damage vulnerable brain cells linked to specific cognitive regulatory sites, diminishing neuronal energy metabolism to a level where progressive cognitive impairment is the outcome. Could cognitive impairment progress be reversed with a heart transplant? Evidence is presented detailing the errant hemodynamic pathways leading to cognitive impairment during aging as an offshoot of inefficient structural and functional heart parts and their contribution to heart failure.

Tempe, Tofu, and Amyloid-β 1-40 Serum Levels in Ovariectomized Rats

BACKGROUND

Estrogens have been found to reduce amyloid-β (Aβ) levels, a risk factor associated with dementia. We hypothesized that phytoestrogenic soybean products such as tempe and tofu might show similar effects.

OBJECTIVE

The aim of this study were to analyze the effect of tempe and tofu flour on Aβ1-40 serum levels in ovariectomized rats.

METHODS

This research was conducted on female Sprague Dawley rats, aged 12 months. Before the intervention rats underwent ovariectomy (OVx) and were grouped into 5 intervention groups which were given tempe flour, tofu flour, estradiol, or casein as an active control. There was also a non-OVx control group which was fed a normal diet.

RESULTS

The intake of tempe and tofu flour decreased Aβ serum levels in all estrogen and phytoestrogenic treatment groups, offsetting effects of OVx (but not in the casein group, where Aβ levels rise).

CONCLUSION

The tempe flour group showed the strongest decrease in serum Aβ levels compared to the other groups. Future studies should investigate whether tempe can reduce Aβ levels in patients with dementia.

Association of Blood Pressure Lowering With Incident Dementia or Cognitive Impairment: A Systematic Review and Meta-analysis

IMPORTANCE

The benefit of blood pressure lowering for the prevention of dementia or cognitive impairment is unclear.

OBJECTIVE

To determine the association of blood pressure lowering with dementia or cognitive impairment.

DATA SOURCES AND STUDY SELECTION

Search of PubMed, EMBASE, and CENTRAL for randomized clinical trials published from database inception through December 31, 2019, that evaluated the association of blood pressure lowering on cognitive outcomes. The control groups consisted of either placebo, alternative antihypertensive agents, or higher blood pressure targets.

DATA EXTRACTION AND SYNTHESIS

Data were screened and extracted independently by 2 authors. Random-effects meta-analysis models were used to report pooled treatment effects and CIs.

MAIN OUTCOMES AND MEASURES

The primary outcome was dementia or cognitive impairment. The secondary outcomes were cognitive decline and changes in cognitive test scores.

RESULTS

Fourteen randomized clinical trials were eligible for inclusion (96 158 participants), of which 12 reported the incidence of dementia (or composite of dementia and cognitive impairment [3 trials]) on follow-up and were included in the primary meta-analysis, 8 reported cognitive decline, and 8 reported changes in cognitive test scores. The mean (SD) age of trial participants was 69 (5.4) years and 40 617 (42.2%) were women. The mean systolic baseline blood pressure was 154 (14.9) mm Hg and the mean diastolic blood pressure was 83.3 (9.9) mm Hg. The mean duration of follow-up was 49.2 months. Blood pressure lowering with antihypertensive agents compared with control was significantly associated with a reduced risk of dementia or cognitive impairment (12 trials; 92 135 participants) (7.0% vs 7.5% of patients over a mean trial follow-up of 4.1 years; odds ratio [OR], 0.93 [95% CI, 0.88-0.98]; absolute risk reduction, 0.39% [95% CI, 0.09%-0.68%]; I2 = 0.0%) and cognitive decline (8 trials) (20.2% vs 21.1% of participants over a mean trial follow-up of 4.1 years; OR, 0.93 [95% CI, 0.88-0.99]; absolute risk reduction, 0.71% [95% CI, 0.19%-1.2%]; I2 = 36.1%). Blood pressure lowering was not significantly associated with a change in cognitive test scores.

CONCLUSIONS AND RELEVANCE

In this meta-analysis of randomized clinical trials, blood pressure lowering with antihypertensive agents compared with control was significantly associated with a lower risk of incident dementia or cognitive impairment.

Plasma cholesterol in Alzheimer's disease and frontotemporal dementia

Background

The relationship between the apolipoprotein E (APOE)-ε4 allele, triglyceride (TG) level, and cholesterol level and an increased risk of developing Alzheimer's disease (AD) has been well established, but their relationship with behavioral-variant frontotemporal dementia (bvFTD) is not well-known.

Methodology

The levels of TGs, total cholesterol (TC), low-density lipoprotein (LDL), and high-density lipoprotein were measured in bvFTD and AD patients and in normal controls (NCs). DNA was extracted, and APOE was genotyped.

Results

The APOE-ε4 allele frequency was higher in the AD group than in the NC group, but no difference was found between the AD and the bvFTD groups. The bvFTD group had higher LDL than the AD group, and significant differences were also found for the cholesterol level in the dementia groups compared with the NC group. Elevated LDL level was positively correlated with appetite and eating score in the bvFTD group. Compared with the AD patients and NCs without the APOE-ε4 allele, those with the APOE-ε4 allele had higher TC, but its correlation with the bvFTD group was absent.

Conclusions

The bvFTD and the AD groups had higher cholesterol levels. The APOE-ε4 allele and eating behavior might modify lipid metabolism in dementia. TG and cholesterol analyses may offer a new opportunity for targeted treatments.

Is psoriasis associated with dementia or cognitive impairment? A Critically Appraised Topic

CLINICAL QUESTION

Is psoriasis associated with dementia or cognitive impairment?

BACKGROUND

Psoriasis is a multisystemic inflammatory disorder that has an unclear association with cognitive dysfunction.

OBJECTIVES

To conduct a Critically Appraised Topic that synthesizes the results from relevant observational studies.

METHODS

A systematic literature search of PubMed and Embase was conducted on 12 July 2019 to identify case-control, cross-sectional or cohort studies that investigated the association between psoriasis and cognitive impairment or dementia. Risk of bias was assessed for each study, and the results presented in a narrative synthesis.

RESULTS

Eleven studies were included for critical appraisal. Of the 11 studies, 10 compared a total of 16 574 psoriasis cases with over 45 078 controls for risk of dementia or cognitive impairment. One of the 11 studies evaluated 7118 patients with dementia for odds of psoriasis compared with 21 354 controls. Six studies were assessed to have higher risk of bias. Nine of the 11 included studies found a significant positive association between the two diseases, one study a null association, and one study an inverse association.

DISCUSSION AND RECOMMENDATION

Most of the 11 included studies found a positive association between psoriasis and either mild cognitive impairment or dementia. Brief cognitive assessments have been suggested to screen older patients with psoriasis who present with subjective cognitive complaints.

The Effect of Blood Pressure on Cognitive Performance. An 8-Year Follow-Up of the Tromsø Study, Comprising People Aged 45-74 Years

Background

The relationship between blood pressure (BP) and cognition is complex were age appears to be an intervening variable. High and low BP have been associated with cognitive deficits as part of the aging process, but more studies are needed, especially in more recent birth cohorts.

Methods

The study sample comprised 4,465 participants, with BP measured at baseline in the Tromsø Study, Wave 6 in 2007–2008 (T0), and cognition assessed at follow-up 8 years later, in 2015–2016 in Tromsø Study 7 (T1). Age at T0 was 45–74 years, and at T1 it was 53–82 years. Cognition was assessed with three tests: The Mini Mental State Examination (MMSE), the Digit Symbol Test, and the Twelve-word Test. The associations between BP and cognition were examined specifically for age and sex using linear regression analysis adjusted for baseline BP medication use, education and body mass index (kg/m²).

Results

BP was associated with cognition at the 8-year follow-up, but the association differed according to age and sex. In men, higher systolic blood pressure (SBP) and diastolic blood pressure (DBP) at a young age (45–55 years of age) was associated with poorer cognition; the association was reversed at older ages, especially for those above 65 years of age. In women, the associations were generally weaker than for men, and sometimes in the opposite direction: For women, a higher SBP was associated with better cognition at a younger age and higher SBP poorer cognition at older ages – perhaps due to an age delay in women compared to men. Digit Symbol Test results correlated best with BP in a three-way interaction: BP by age by sex was significant for both SBP (p = 0.005) and DBP (p = 0.005).

Conclusion

Increased SBP and DBP at the younger age was clearly associated with poorer cognitive function in men 8 years later; in women the associations were weaker and sometimes in the opposite direction. Our findings clearly indicate that interactions between age and sex related to BP can predict cognitive performance over time. Men and women have different age trajectories regarding the influence of BP on cognition.

Multiple Causes of Dementia as Engineered Senescence

All traumas—cranial, cardiovascular, hormone, viral, bacterial, fungi, parasites, misfolded protein, genetic, behavior, environmental and medication—affect the brain. This paper itemizes studies showing the many different causes of dementia including Alzheimer’s disease. Causes interact with each other, act sequentially by preparing the optimal conditions for its successor, initiate other diseases, allow for other traumas to accumulate and degrade protective features of the brain. Since such age-related cognitive impairment is not exclusively a human attribute there might be support for an evolutionary theory of dementia. Relying on theories of antagonistic pleiotropy and polymorphism, the brain has been designed to sequester trauma. Because of increased longevity, the short-term tactic of sequestering trauma becomes a long-term liability. We are engineered to sequester these insults until a tipping point is reached. Dementia is an evolutionary trade-off for longevity. We cannot cure dementia without understanding the overall biology of aging.

The association between frailty and incidence of dementia in Beijing: findings from 10/66 dementia research group population-based cohort study

BACKGROUND

The relationship between frailty and dementia is unclear and there are very few population-based studies regarding this issue in China. The purpose of this study is to estimate the association between frailty and incident dementia in China, and to explore different effects of frailty established by three definitions of frailty on dementia incidence.

METHODS

A five-year prospective cohort study was carried out in 2022 participants aged 65 years and over in urban and rural sites in Beijing, China. The participants were interviewed by trained community primary health care workers from 2004 to 2009. Frailty was defined using modified Fried frailty phenotype, physical frailty definition, and multidimensional frailty definition. Dementia was diagnosed using the 10/66 dementia criterion for calculating cumulative incidence. Both competing risk regression models and Cox proportional hazards models were applied to examine the associations between frailty at baseline and five-year cumulative incidence of dementia.

RESULTS

At the end of follow-up the five-year cumulative incidence rates of dementia with frailty and without frailty defined by the modified Fried frailty were 21.0% and 9.6%, those defined by the physical frailty were 19.9% and 9.0%, and those defined by the multidimensional frailty were 22.8% and 8.9%, respectively. Compared with non-frail participants, frail people had a higher risk of incident dementia using multidimensional frailty definition after adjusting covariates based on competing risk regression model (HR = 1.47, 95% CI 1.01~2.17) and Cox proportional hazards model (HR = 1.56, 95% CI 1.07~2.26). The association between frailty and incident dementia was statistically significant in participants in the upper three quartiles of age (aged 68 years and over) using the multidimensional frailty definition based on the competing risk regression model (HR = 1.61, 95% CI 1.06~2.43) and Cox proportional hazard model (HR = 1.76, 95% CI 1.19~2.61).

CONCLUSIONS

Multidimensional frailty may play an inherent role in incident dementia, especially in the people aged over 68, which is significant for distinguishing high risk people and determining secondary prevention strategies for dementia patients.

Association of Heart Rate Variability With Cognitive Performance: The Multi-Ethnic Study of Atherosclerosis

Background Heart rate variability (HRV) is associated with vascular risk factors for dementia, but whether HRV is associated with specific domains of cognitive performance is unclear. Methods and Results In the Multi-Ethnic Study of Atherosclerosis (N=3018; mean age 59.3±9.2 years), we assessed the relationship of 10-second HRV to scores on tests of global cognitive performance (Cognitive Abilities Screening Instrument), processing speed (Digit Symbol Coding), and working memory (Digit Span). HRV was computed as the SD of normal-normal intervals (SDNN) and root mean square of successive differences (RMSSD) at Exam 1 (2000-2002) and Exam 5 (2010-2012). Cognitive tests were administered at Exam 5. We report regression coefficients (β [95% CI]) representing cognitive test score change per 2-fold increase in HRV. After adjustment for age, race/ethnicity, sex, education, apolipoprotein E genotype, and cardiovascular risk factors and incident disease, higher Exam 1 (β=0.37 [0.06, 0.67]) and Exam 5 (β=0.31 [0.04, 0.59]) SDNN were associated with better Cognitive Abilities Screening Instrument performance. Higher Exam 1 (β=0.80 [0.17, 1.43]) and Exam 5 (β=0.63 [0.06, 1.20]) SDNN, and Exam 5 RMSSD (β=0.54 [0.01, 1.08]) were associated with better Digit Symbol Coding performance. Finally, higher Exam 5 SDNN was associated with better Digit Span performance (β=0.17 [0.01, 0.33]). Associations were attenuated after adjustment for resting heart rate. Conclusions Higher HRV is generally associated with better cognitive performance in this multi-ethnic cohort of aging adults, and further study of the relationship of autonomic function to cognition is warranted.

Blood Pressure Control and Dementia Risk in Midlife Patients With Atrial Fibrillation

Atrial fibrillation (AF) is associated with increased risk of cognitive impairment and dementia, even with no overt stroke. Hypertension has been a potentially modifiable risk factor for dementia, especially in midlife (<70 years) individuals. We aimed to investigate the associations of blood pressure (BP) and hypertension burden with dementia risk among midlife AF patients. From the Korean National Health Insurance Service database, we enrolled 171 228 incident AF patients aged 50 to 69 years with no prior dementia from 2005 to 2016. During a mean of 6.6 years of follow-up, 9909 patients received a first-time diagnosis of dementia. U-shaped relationships were noted between systolic or diastolic BP and dementia risk: A 10 mm Hg increase or decrease in systolic BP starting from 120 mm Hg was associated with 4.4% (95% CI, 2.7%-6.0%) and 4.6% (95% CI, 0.1%-8.2%) higher dementia risk, respectively. An increase or decrease in diastolic BP starting from 80 mm Hg also increased dementia risk. In subtype analyses, Alzheimer disease increases with BP decrease whereas vascular dementia increases according to BP increase. When BP changes over time were accounted for in time-updated models, BP of 120 to 129/80 to 84 mm Hg was associated with the lowest dementia risk. Increasing hypertension burden (the proportion of days with increased BP during follow-up) was associated with higher dementia risk (hazard ratio, 1.10 per 10% increase [95% CI, 1.08-1.12]). Among midlife AF patients, there were a U-shaped association of BP and a log-linear association of hypertension burden with dementia risk. Minimizing the burden of hypertension in AF patients might help to prevent dementia.