Cardiac risk factors and potential treatments in Alzheimer's disease

Cerebral white matter rarefaction has both neurodegenerative and vascular causes and may primarily be a distal axonopathy

Cerebral white matter rarefaction (CWMR) was considered by Binswanger and Alzheimer to be due to cerebral arteriolosclerosis. Renewed attention came with CT and MR brain imaging, and neuropathological studies finding a high rate of CWMR in Alzheimer disease (AD). The relative contributions of cerebrovascular disease and AD to CWMR are still uncertain. In 1181 autopsies by the Arizona Study of Aging and Neurodegenerative Disorders (AZSAND), large-format brain sections were used to grade CWMR and determine its vascular and neurodegenerative correlates. Almost all neurodegenerative diseases had more severe CWMR than the normal control group. Multivariable logistic regression models indicated that Braak neurofibrillary stage was the strongest predictor of CWMR, with additional independently significant predictors including age, cortical and diencephalic lacunar and microinfarcts, body mass index, and female sex. It appears that while AD and cerebrovascular pathology may be additive in causing CWMR, both may be solely capable of this. The typical periventricular pattern suggests that CWMR is primarily a distal axonopathy caused by dysfunction of the cell bodies of long-association corticocortical projection neurons. A consequence of these findings is that CWMR should not be viewed simply as "small vessel disease" or as a pathognomonic indicator of vascular cognitive impairment or vascular dementia.

Pharmacotherapeutic Potential of Garlic in Age-Related Neurological Disorders

Age-related neurological disorders [ANDs] involve neurodegenerative diseases [NDDs] such as Alzheimer's disease [AD], the most frequent kind of dementia in elderly people, and Parkinson's disease [PD], and also other disorders like epilepsy and migraine. Although ANDs are multifactorial, Aging is a principal risk factor for them. The common and most main pathologic features among ANDs are inflammation, oxidative stress, and misfolded proteins accumulation. Since failing brains caused by ANDs impose a notable burden on public health and their incidence is increasing, a lot of works has been done to overcome them. Garlic, Allium sativum, has been used for different medical purposes globally and more than thousands of publications have reported its health benefits. Garlic and aged garlic extract are considered potent anti-inflammatory and antioxidants agents and can have remarkable neuroprotective effects. This review is aimed to summarize knowledge on the pharmacotherapeutic potential of garlic and its components in ANDs.

Chemical constituents and medicinal properties of Allium species

Allium species, belonging to Alliaceae family, are among the oldest cultivated vegetables used as food. Garlic, onions, leeks and chives, which belong to this family, have been reported to have medicinal properties. The Allium species constituents have been shown to have antibacterial and antioxidant activities, and, in addition, other biological properties. These activities are related to their rich organosulfur compounds. These organosulfur compounds are believed to prevent the development of cancer, cardiovascular, neurological, diabetes, liver diseases as well as allergy and arthritis. There have also been reports on toxicities of these compounds. The major active compounds of Allium species includes, diallyl disulfide, diallyl trisulfide, diallyl sulfide, dipropyl disulfide, dipropyl trisulfide, 1-propenylpropyl disulfide, allyl methyl disulfide and dimethyl disulfide. The aim of this review is to focus on a variety of experimental and clinical reports on the effectiveness, toxicities and possible mechanisms of actions of the active compounds of garlic, onions, leek and chives.

Associations Between Midlife (but Not Late-Life) Elevated Coronary Heart Disease Risk and Lower Cognitive Performance: Results From the Framingham Offspring Study

It is unclear how coronary heart disease (CHD) risk across the adult life span affects late-life cognition. We estimated associations of midlife and late-life elevated CHD risk with cognitive trajectories (general cognitive performance, processing speed/executive function, memory) in later life (after age 55 years or age 70 years) among 2,892 Framingham Offspring Study participants who had completed CHD risk assessments approximately every 4 years since 1971 and had undergone neuropsychological testing between 1999 and 2014. We stratified analyses by apolipoprotein E gene (APOE) Ɛ4 allele carrier status. Using linear mixed-effects models, elevated CHD risk in midlife (age 55 years) was associated with lower levels of general cognitive performance (β = -0.560 standard deviation (SD) units, 95% confidence interval (CI): -0.874, -0.246), executive function (β = -0.624 SD units, 95% CI: -0.916, -0.332), and memory (β = -0.560 SD units, 95% CI: -0.907, -0.213) at age 70 years but not with rates of cognitive change. Late-life (age 70 years) elevated CHD risk, however, was associated with somewhat better levels of general cognitive performance and memory. There were associations between duration of elevated CHD risk during midlife and levels (but not trajectories) of later-life cognitive outcomes. Associations were not modified by APOE-ɛ4 status. These findings suggest that midlife elevated CHD risk is associated with lower cognition, independently of APOE-ɛ4 status, suggesting that risk of vascular disease may not contribute a "second hit" to AD risk.

Late-Life Vascular Risk Factors and Alzheimer Disease Neuropathology in Individuals with Normal Cognition

Vascular risk factors (VRFs) have been associated with clinically diagnosed Alzheimer disease (AD), but few studies have examined the association between VRF and AD neuropathology (ADNP) in cognitively normal individuals. We used longitudinal data from the National Alzheimer's Disease Center's Uniform Data Set and Neuropathology Data Set to examine the association between VRF and ADNP (moderate to frequent neuritic plaques; Braak stage III-VI) in those with normal cognition. Our sample included 53 participants with ADNP and 140 without ADNP. Body mass index (BMI), resting heart rate (HR), and pulse pressure (PP) were measured at each visit; values were averaged across participant visits and examined annual change in BMI, PP, and HR. Hypertension, diabetes, and hypercholesterolemia were self-reported. In the multivariable logistic regression analyses, average BMI and HR were associated with lower odds of ADNP, and annual increases in HR and BMI were associated with higher odds of ADNP. A previously experienced decline in BMI or HR in late-life (therefore, currently low BMI and low HR) as well as a late-life increase in BMI and HR may indicate underlying AD pathology. Additional clinicopathological research is needed to elucidate the role of changes in late-life VRF and AD pathogenesis.

Drug-induced cognitive impairment: Effect of cardiovascular agents

INTRODUCTION

Cardiovascular agents can be associated with a negative effect on cognition, especially in older adults, critically ill people, and those with baseline cognitive impairment. Negative effect on cognition is commonly reported as uncomplicated acute confusion and delirium and, less commonly, chronic cognitive changes due to drug-induced depression and/or dementia.

METHODS

A literature review of case reports, case series, prospective cohort studies, clinical trials, and literature reviews were included in this study. Articles were located using online databases PubMed and Medline using the following keywords: antiarrhythmic agents, anticholinergic burden, antihypertensive agents, beta-blockers, cardiovascular agents, cognitive impairment, delirium, cognition, dementia, depression, digoxin, diuretics, and drug-induced cognitive impairment.

RESULTS

In general, use of all antihypertensives, especially in the case of polypharmacy or inappropriate dosing, can lead to hypotension and/or bradycardia, and thus lead to mental/cognitive status change due to decreased cerebral perfusion. Use of diuretics can be associated with fluid/electrolyte and/or acid-base imbalance, resulting in the onset of confusion and delirium. In addition, cardiovascular agents with central bioavailability, such digoxin and select antiarrhythmics, and antihypertensives may carry a risk for cognitive impairment due to various mechanisms proposed, such as antagonism of central muscarinic acetylcholine receptors, neurotransmission imbalance in the brain, and disruption of physiologic function of sodium/potassium ATPase in the neuronal cells.

DISCUSSION

When dealing with an individual who presents with acute, subacute, and chronic changes in cognitive function, one should perform a thorough medication history as the first step in order to aid in the identification of drug-induced cognitive impairment.

Feasibility Study: Comparison of Frontal Cortex Needle Core Versus Open Biopsy for Detection of Characteristic Proteinopathies of Neurodegenerative Diseases

The clinical diagnosis and classification of neurodegenerative diseases based on clinical examination or available biomarkers are currently insufficiently accurate. Although histologic examination is considered the gold standard for diagnosis, brain biopsies have been avoided because of the high risk-benefit ratio. However, brain biopsies have previously been performed with a craniotomy and excision of approximately 1 cm of cerebral cortex tissue, and it is possible that needle core brain biopsies would have a lower morbidity and mortality risk. Here, we compared the ability of simulated needle core biopsy versus simulated open biopsy to detect the frontal cortex histopathology associated with common neurodegenerative diseases in the elderly using 144 autopsy-proven cases. Simulated needle core biopsy, as compared with simulated open biopsy, gave close to 90% sensitivity and specificity for identifying graded densities of β-amyloid and neuritic plaques, neurofibrillary tangles, phosphorylated α-synuclein, and phosphorylated TDP-43 pathology. This study shows that the presence and densities of the most common molecular pathologies may be histopathologically assessed in simulated frontal cortex needle biopsies, with accuracy very close to that obtained by open cortical biopsy. An accurate estimation of the morbidity and mortality risk associated with cortical needle core biopsy will require specifically designed clinical trials in appropriate subjects.

Arizona Study of Aging and Neurodegenerative Disorders and Brain and Body Donation Program

The Brain and Body Donation Program (BBDP) at Banner Sun Health Research Institute (http://www.brainandbodydonationprogram.org) started in 1987 with brain-only donations and currently has banked more than 1600 brains. More than 430 whole-body donations have been received since this service was commenced in 2005. The collective academic output of the BBDP is now described as the Arizona Study of Aging and Neurodegenerative Disorders (AZSAND). Most BBDP subjects are enrolled as cognitively normal volunteers residing in the retirement communities of metropolitan Phoenix, Arizona. Specific recruitment efforts are also directed at subjects with Alzheimer's disease, Parkinson's disease and cancer. The median age at death is 82. Subjects receive standardized general medical, neurological, neuropsychological and movement disorders assessments during life and more than 90% receive full pathological examinations by medically licensed pathologists after death. The Program has been funded through a combination of internal, federal and state of Arizona grants as well as user fees and pharmaceutical industry collaborations. Subsets of the Program are utilized by the US National Institute on Aging Arizona Alzheimer's Disease Core Center and the US National Institute of Neurological Disorders and Stroke National Brain and Tissue Resource for Parkinson's Disease and Related Disorders. Substantial funding has also been received from the Michael J. Fox Foundation for Parkinson's Research. The Program has made rapid autopsy a priority, with a 3.0-hour median post-mortem interval for the entire collection. The median RNA Integrity Number (RIN) for frozen brain and body tissue is 8.9 and 7.4, respectively. More than 2500 tissue requests have been served and currently about 200 are served annually. These requests have been made by more than 400 investigators located in 32 US states and 15 countries. Tissue from the BBDP has contributed to more than 350 publications and more than 200 grant-funded projects.

Cognition in non-demented diabetic older adults

Evidence links diabetes mellitus to cognitive impairment and increased risk of Alzheimer's disease (AD) and suggests that insulin therapy improves cognition. With an increasing percentage of the US elderly population at high risk for diabetes and AD, the evidence of an association between diabetes and poor cognition in non-demented elderly may have implications for diagnosis, prevention and treatment of cognitive decline including AD. In our study, we hypothesized that diabetic elders with normal cognition would demonstrate poorer cognitive outcomes than non-diabetic elders and that diabetic elders receiving diabetes treatment would demonstrate better outcomes than those not receiving treatment. Data were evaluated from the National Alzheimer's Coordinating Center's Uniform Data Set (UDS). The UDS consists of clinical and neuropsychological assessments of a sample of elderly research subjects recruited from thirty-one Alzheimer's Disease Centers nationwide. The UDS provides a unique opportunity to study cognition in a nationally recruited sample with structured neuropsychological tests. We examined the impact of diabetes and diabetes treatment on cognitive measures in 3421 elderly research subjects from 2005-2007 with normal cognition. We performed linear regression analyses to compare cognitive scores between diabetic subjects and non-diabetic subjects. Diabetic subjects had lower scores than non-diabetic subjects including attention, psychomotor function and executive function, but no differences in memory or semantic memory language. There was no association between diabetes treatment and cognitive scores. These subtle but significant cognitive deficits in diabetic subjects compared to non-diabetic subjects may contribute to difficulty with compliance with complex diabetes medication regimens. A specific role of diabetes as a risk for cognitive impairment will require longitudinal study.

Cardiovascular risk factors promote brain hypoperfusion leading to cognitive decline and dementia

Heart disease is the major leading cause of death and disability in the world. Mainly affecting the elderly population, heart disease and its main outcome, cardiovascular disease, have become an important risk factor in the development of cognitive decline and Alzheimer's disease (AD). This paper examines the evidence linking chronic brain hypoperfusion induced by a variety of cardiovascular deficits in the development of cognitive impairment preceding AD. The evidence indicates a strong association between AD and cardiovascular risk factors, including ApoE(4), atrial fibrillation, thrombotic events, hypertension, hypotension, heart failure, high serum markers of inflammation, coronary artery disease, low cardiac index, and valvular pathology. In elderly people whose cerebral perfusion is already diminished by their advanced age, additional reduction of cerebral blood flow stemming from abnormalities in the heart-brain vascular loop ostensibly increases the probability of developing AD. Evidence also suggests that a neuronal energy crisis brought on by relentless brain hypoperfusion may be responsible for protein synthesis abnormalities that later result in the classic neurodegenerative lesions involving the formation of amyloid-beta plaques and neurofibrillary tangles. Insight into how cardiovascular risk factors can induce progressive cognitive impairment offers an enhanced understanding of the multifactorial pathophysiology characterizing AD and ways at preventing or managing the cardiovascular precursors of this dementia.

Vascular factors and epigenetic modifications in the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is a debilitating illness with no known cure. Nowadays accumulating evidence suggested that the vascular endothelium and chronic hypoperfusion may play important role in pathobiology of AD. The vascular endothelium which regulates the passage of macromolecules and circulating cells from blood to tissue, is a major target of oxidative stress, playing a critical role in the pathophysiology of vascular diseases. Since the vascular endothelium, neurons and glia are all able to synthesize, store and release reactive oxygen species (ROS) and vascular active substances in response to certain stimuli, their contribution to the pathophysiology of AD can be very important. New evidence indicates that continuous formation of free ROS induces cellular damage and decreases antioxidant defenses. Specifically, oxidative stress increases vascular endothelial permeability and promotes leukocyte adhesion. We summarize the reports that sporadic, late-onset of AD results from vascular etiology. Recently an involvement of epigenetic alterations in the etiology of AD is also intensively investigated. Gaining a more complete understanding of the essential components and underlying mechanisms involved in epigenetic regulation could lead to novel treatments for a number of neurological and psychiatric conditions.

Hypertension is associated with cognitive decline in elderly people at high risk for dementia

Cardiovascular risk factors including hypertension (HTN) have been shown to increase the risk of Alzheimer disease. The current study investigated whether individuals with HTN are more susceptible to increased cognitive decline and whether the influence of HTN on cognitive decline varied as a function of dementia severity. A total of 224 nursing home and assisted living residents, with a mean age of 84.9 (±7.6) years, were assessed longitudinally with Mini Mental State Exams (MMSEs) and Clinical Dementia Ratings (CDR). Baseline dementia status was defined by the CDR score. As described in , MMSE scores in persons with HTN and questionable dementia (CDR = 0.5) declined significantly faster than nonhypertensive questionably demented persons. Hypertensive participants did not decline significantly faster than nonhypertensive participants in persons with intact cognition (CDR = 0) or frank dementia (CDR ≥ 1). These results suggest an increased risk of subsequent cognitive decline in hypertensive individuals who are especially vulnerable to developing dementia and raises the possibility that avoiding or controlling HTN might reduce the rate of cognitive decline in cognitively vulnerable individuals, potentially delaying their conversion to full-fledged dementia.

Cholesterol and LDL relate to neuritic plaques and to APOE4 presence but not to neurofibrillary tangles

Elevated serum total cholesterol (TC) has been considered a risk factor for Alzheimer's disease (AD), but conflicting results have confused understanding of the relationships of serum lipids to the presence of AD in the elderly.

METHODS

To clarify these issues, we evaluated correlations of admission TC, low-density (LDL) and high-density (HDL)cholesterol directly with the densities of Alzheimer hallmarks--neuritic plaques (NP) and neurofibrillary tangles (NFT)--in nursing home residents (n=281).

RESULTS

Significant positive associations of TC and LDL with NP densities were found in both the neocortex (TC: r=0.151, p=0.013 and LDL: r=0.190, p=0.005) and the hippocampal/entorhinal (allocortical)region (TC: r=0.182, p=0.002 and LDL: r=0.203, p=0.003). Associations of HDL with NP were less strong but also significant.In contrast, after adjustment for confounders, no correlations of NFT with any lipid were significant.When subjects with any non-AD neuropathology (largely vascular) were excluded, the TC-plaque and LDL-plaque associations for the remaining "Pure AD" subgroup were consistently stronger than for the full sample. The TC- and LDL-plaque correlations were also stronger for the subgroup of 87 subjects with an APOE ε4 allele.

CONCLUSIONS

The findings indicate that serum TC and LDL levels clearly relate to densities of NP, but not to densities of NFT. The stronger associations found in the subgroup that excluded all subjects with non-AD neuropathology suggest that cerebrovascular involvement does not explain these lipid-plaque relationships. Since the associations of TC/LDL with NP were particularly stronger in ε4 carriers, varying prevalence of this allele may explain some discrepancies among prior studies.

Reduced clinical and postmortem measures of cardiac pathology in subjects with advanced Alzheimer's Disease

BACKGROUND

Epidemiological studies indicate a statistical linkage between atherosclerotic vascular disease (ATH) and Alzheimer's disease (AD). Autopsy studies of cardiac disease in AD have been few and inconclusive. In this report, clinical and gross anatomic measures of cardiac disease were compared in deceased human subjects with and without AD.

METHODS

Clinically documented cardiovascular conditions from AD (n = 35) and elderly non-demented control subjects (n = 22) were obtained by review of medical records. Coronary artery stenosis and other gross anatomical measures, including heart weight, ventricular wall thickness, valvular circumferences, valvular calcifications and myocardial infarct number and volume were determined at autopsy.

RESULTS

Compared to non-demented age-similar control subjects, those with AD had significantly fewer total diagnosed clinical conditions (2.91 vs 4.18), decreased coronary artery stenosis (70.8 vs 74.8%), heart weight (402 vs 489 g for males; 319 vs 412 g for females) and valvular circumferences. Carriage of the Apolipoprotein E-ε4 allele did not influence the degree of coronary stenosis. Group differences in heart weight remained significant after adjustment for age, gender, body mass index and apolipoprotein E genotype while differences in coronary artery stenosis were significantly associated with body mass index alone.

CONCLUSIONS

The results are in agreement with an emerging understanding that, while midlife risk factors for ATH increase the risk for the later development of AD, once dementia begins, both risk factors and manifest disease diminish, possibly due to progressive weight loss with increasing dementia as well as disease involvement of the brain's vasomotor centers.

High dietary and plasma levels of the omega-3 fatty acid docosahexaenoic acid are associated with decreased dementia risk: the Rancho Bernardo study

OBJECTIVE

This study examined the association of plasma DHA, dietary DHA, and fish intake with dementia and Alzheimer's Disease (AD) in older adults.

DESIGN

Case-cohort study.

SETTING

Clinic visit in 1991-93.

PARTICIPANTS

266 community dwelling men and women aged 67-100 years (mean=80.2).

MEASUREMENTS

Participants had neurological and neuropsychological evaluations for dementia in 1991-93. Plasma DHA was measured in blood samples obtained at that visit. Dietary intakes of DHA and fish were obtained from an earlier (1988-91) visit. Three DHA exposure variables were used in separate analyses; plasma DHA, dietary DHA, and consumption of cold-water fish. All-cause dementia included AD and other types of possible or probable dementia.

RESULTS

Among these 266 participants, 42 had dementia and 30 had possible or probable AD. Plasma DHA in the highest tertile was associated with a 65% reduced odds of all-cause dementia (95% CI: 0.17, 0.92) and a 60% reduced odds of AD (95% CI: 0.15, 1.10). Dietary DHA in the highest tertile was associated with a 73% reduced odds of all-cause dementia (95% CI: 0.09, 0.79) and a 72% reduced odds of AD (95% CI: 0.09, 0.93). Fish intake had similar, though not significant, reduced odds of dementia (OR = 0.51; 95% CI: 0.20, 1.32) and AD (OR = 0.55; 95% CI: 0.20, 1.48).

CONCLUSIONS

Plasma and dietary DHA appear to protect against dementia. Increasing DHA intake from marine sources may be recommended for reducing dementia risk.

Cardiovascular dementia - a different perspective

The number of dementia patients has been growing in recent years and dementia represents a significant threat to aging people all over the world. Recent research has shown that the number of people affected by Alzheimer's disease (AD) and dementia is growing at an epidemic pace. The rapidly increasing financial and personal costs will affect the world's economies, health care systems, and many families. Researchers are now exploring a possible connection among AD, vascular dementia (VD), diabetes mellitus (type 2, T2DM) and cardiovascular diseases (CD). This correlation may be due to a strong association of cardiovascular risk factors with AD and VD, suggesting that these diseases share some biologic pathways. Since heart failure is associated with an increased risk of AD and VD, keeping the heart healthy may prove to keep the brain healthy as well. The risk for dementia is especially high when diabetes mellitus is comorbid with severe systolic hypertension or heart disease. In addition, the degree of coronary artery disease (CAD) is independently associated with cardinal neuropathological lesions of AD. Thus, the contribution of T2DM and CD to AD and VD implies that cardiovascular therapies may prove useful in preventing AD and dementia.

Vascular risk factors and cognitive functions in nondemented elderly individuals

BACKGROUND

The brain-at-risk stage is the earliest phase of the vascular cognitive impairment continuum and includes individuals with vascular risk factors (VRF). However, there is still no clear definition of this concept. The aim of the study is to characterize the neuropsychological profile of elderly individuals by 3 levels of VRF.

METHODS

This is a cross-sectional analysis of the Canadian Study of Health and Aging baseline data; 577 nondemented elderly individuals > or =65 years old were divided into 3 groups: reference group (0 VRF; n = 82); intermediate brain-at-risk group (1-2 VRF; n = 360); high brain-at-risk group (> or =3 VRF; n = 135). A principal component analysis (PCA) and univariate/multivariate analyses of variance were performed to examine the relationships between the groups and various cognitive measures.

MAIN FINDINGS

The PCA produced a 2-component solution (1) executive/psychomotor functions including measures of abstraction and (2) verbal memory. The high brain-at-risk group performed significantly worse than the reference group on the first component.

CONCLUSIONS

Elderly individuals presenting with > or =3 VRF are more impaired on measures of executive functions/ processing speed than participants without any VRF.

Risk factors for dementia of the Alzheimer and vascular type

The current study was aimed at examining the risk factors in 30 patients with Alzheimer's dementia and 30 patients with vascular dementia. The reports of the caregivers and the medical documentation were used to estimate the risk factors. The condition for the patients to enter this study was the age above 60 years. The results showed that the average age in the patients with dementia of the Alzheimer type was statistically significantly higher than in the patients with vascular dementia (p<0.0043), which is the confirmation that the most potential risk factor for Alzheimer's disease is aging, and for vascular dementia it is an additional factor. The incomplete education is more common in patients with Alzheimer's disease than in the group with vascular dementia and the difference had statistical significance (p=0.0199). The patients with vascular dementia have higher rate of heart disease (p=0.0002), hypertension (p=0.0005) and diabetes mellitus (p=0.0228) than in the group with Alzheimer's disease with a statistically significant difference. In regard to marital status, head injury and smoking, the difference had no significance in either groups.

Cardiovascular risk and memory in non-demented elderly women

OBJECTIVE

To determine whether cardiovascular (CV) risk is associated with subtle memory deficits in non-demented, healthy older women with a family history of Alzheimer disease (AD).

METHODS

Baseline data of 375 participants from a randomized, double-blind placebo-controlled primary prevention trial to test the efficacy of hormone replacement therapy in delaying AD and cognitive decline were analyzed. All subjects were women over 65 with a family history of AD who had normal cognition and no active heart disease at baseline. A baseline memory composite score was calculated, consisting of immediate and delayed recall of verbal and nonverbal material. Multiple linear regression was performed to examine the association of relative CV risk with memory functioning; age, ethnicity and education level were included as covariates.

RESULTS

Mean baseline memory composite score was significantly higher in those with low relative CHD risk than those with high relative CHD risk.

CONCLUSION

These findings suggest that subtle elevation of CHD risk may negatively affect memory functioning even in otherwise healthy, non-demented older women without a history of heart disease.

Neuroprotective effects of garlic a review

Garlic has been investigated extensively for health benefits, resulting in more than one thousand publications over the last decade alone. It is considered one of the best disease preventive foods, based on its potent and varied effects. Midlife risk factors for cardiovascular diseases, such as high serum total cholesterol, raised LDL, increased LDL oxidation, increased platelet aggregation, impaired fibrinolysis, hypertension and homocystinemia are important risk factors for dementia in later years. These risk factors play a major role in the genesis of atherosclerosis of vital arteries causing both cardiovascular and cerebrovascular disease. Garlic is best known for its lipid lowering and anti-atherogenic effects. Possible mechanisms of action include inhibition of the hepatic activities of lipogenic and cholesterogenic enzymes that are thought to be the genesis for dyslipidemias, increased excretion of cholesterol and suppression of LDL-oxidation. Oxidative stress caused by increased accumulation of reactive oxygen species (ROS) in cells has been implicated in the pathophysiology of several neurodegenerative diseases including Alzheimer's disease (AD). Several studies have demonstrated the antioxidant properties of garlic and its different preparations including Aged Garlic Extract (AGE). AGE and S-allyl-cysteines (SAC), a bioactive and bioavailable component in garlic preparations have been shown in a number of in vitro studies to protect neuronal cells against beta-amyloid (A) toxicity and apoptosis. Thus the broad range of anti-atherogenic, antioxidant and anti-apoptotic protection afforded by garlic may be extended to its neuroprotective action, helping to reduce the risk of dementia, including vascular dementia and AD.

Immunophenotypes in the circulation of patients with mild cognitive impairment

Alterations in the peripheral immune system are associated with dementia and the neuropathology of Alzheimer's disease, but have yet to be studied early in the disease process. To test the hypothesis that the balance of immune cell phenotypes is disrupted in the early progression of memory deterioration, patients with mild cognitive impairment (MCI) and healthy elderly controls were examined for the distribution of subpopulations of leukocytes (lymphocytes, granulocytes, and monocytes) and lymphocyte subtypes (helper/inducer and suppressor/cytotoxic T lymphocytes and B lymphocytes) in blood. MCI subjects had a significantly higher percentage of total lymphocytes and a lower percentage of granulocytes compared to elderly controls. Furthermore, the expression of cell surface amyloid precursor protein (APP) and intracellular amyloid-beta peptide (Abeta) in lymphocytes and monocytes were determined. We found lymphocyte APP expression to be significantly increased in MCI subjects compared to controls. Our data indicate that changes in immunological parameters may be detected early in MCI, and an alteration of the immune response may precede clinical AD.

Drug discovery and the prevention of Alzheimer's disease

Progress in understanding the pathogenesis of Alzheimer's disease (AD) has advanced rapidly and has achieved parity in knowledge with other chronic degenerative diseases of the elderly. This knowledge has not yet been successfully translated into new and effective disease-modifying drugs. Many new clinical candidates are currently in clinical trials, and it is likely that some will be successful in achieving regulatory approval. Nevertheless, primary prevention of AD remains the ultimate and most important goal of research efforts because the unique clinical features of this dementing disease create a number of challenges for drug development, regulatory approval, and payment. Ultimately, the development of truly effective disease-modifying drugs through accelerated drug discovery is the only real pathway to primary prevention.

Cardiovascular risk factors for Alzheimer's disease

There is now sizable literature on the association between traditional cardiovascular risk factors and Alzheimer's disease (AD). Based on epidemiologic studies, both cross-sectional and longitudinal, there are statistically significant correlations between the prevalence of AD and diabetes, hypercholesterolemia, hypertension, hyperhomocysteinemia, dietary saturated fats, cholesterol, antioxidants, alcohol consumption, smoking, physical activity, the presence of atrial fibrillation, atherosclerotic disease, and the plasma concentration of some hemostatic factors. Most of the cardiovascular risk factors found to be associated with AD are age-dependent, and the prevalence of AD increases with age. Therefore, the association could simply be attributed to aging. On the other hand, the common pathogenetic mechanisms for the generation of both atherosclerotic disease and AD, such as inflammation and the generation of free radicals, suggest a causal link. If this is the case, the identification of modifiable risk factors for dementia becomes a research priority and early intervention aimed at reducing those cardiovascular risk factors a therapeutic imperative.

The impact of nutrition on cognition in the elderly

The possibility that nutritional manipulation may protect against cognitive decline and dementia is an inviting prospect. However data supporting a beneficial effect of a particular dietary pattern is limited. Although studies have demonstrated a health benefit to dietary plans that are high in fiber, whole grains, natural sugar and fish while maintaining lower intake in meat dairy and poultry, the ability to identify the most salient factors of these diets have been unsuccessful. Several aspects of diet have been studied in detail and provided support for potential mechanisms for improving cognition. Clinical trials have explored these mechanisms through supplementation studies with minimal benefits being observed. Continuing work to hone the mechanisms and refine our knowledge of dietary benefits is described.

NAD+ metabolism in health and disease

Nicotinamide adenine dinucleotide (NAD(+)) is both a coenzyme for hydride-transfer enzymes and a substrate for NAD(+)-consuming enzymes, which include ADP-ribose transferases, poly(ADP-ribose) polymerases, cADP-ribose synthases and sirtuins. Recent results establish protective roles for NAD(+) that might be applicable therapeutically to prevent neurodegenerative conditions and to fight Candida glabrata infection. In addition, the contribution that NAD(+) metabolism makes to lifespan extension in model systems indicates that therapies to boost NAD(+) might promote some of the beneficial effects of calorie restriction. Nicotinamide riboside, the recently discovered nucleoside precursor of NAD(+) in eukaryotic systems, might have advantages as a therapy to elevate NAD(+) without inhibiting sirtuins, which is associated with high-dose nicotinamide, or incurring the unpleasant side-effects of high-dose nicotinic acid.