Dementia and Alzheimer's disease in community-dwelling elders taking vitamin C and/or vitamin E

The role of nutrition in Alzheimer's disease: epidemiological evidence

The prevalence of Alzheimer's disease (AD) increases exponentially with age but there is limited knowledge of the modifiable risk factors for AD. However, there is growing evidence for possible dietary risk factors in the development of AD and cognitive decline with age, such as antioxidant nutrients, fish, dietary fats, and B-vitamins. Numerous animal and laboratory studies have shown that antioxidant nutrients can protect the brain from oxidative and inflammatory damage, but there are limited data available from epidemiological studies. There is more substantial epidemiological evidence from a number of recent studies that demonstrate a protective role of omega-3 fatty acids, such as docosahexaenoic acid, in AD and cognitive decline. This review will focus on epidemiological evidence investigating the relationship between nutrition and AD, focusing particularly on the roles of dietary fats and antioxidants.

Reversal of propoxur-induced impairment of step-down passive avoidance, transfer latency and oxidative stress by piracetam and ascorbic acid in rats

Propoxur, a carbamate pesticide has been shown to adversely affect memory and induce oxidative stress. The present study was designed to correlate the effect of propoxur, piracetam (a nootropic drug) and ascorbic acid (an antioxidant) on oxidative stress and cognitive function. Cognitive function was assessed using step-down latency (SDL) on a passive avoidance apparatus and transfer latency (TL) on elevated plus maze. Oxidative stress was assessed by examining brain malondialdehyde (MDA) and non-protein thiol (NP-SH) levels. A significant reduction in SDL and prolongation of TL was found for the propoxur-treated group at weeks 6 and 7 as compared with control (p<0.001). One week treatment by piracetam (400mg/kg/d, i.p.) or ascorbic acid (120mg/kg/d, i.p.) antagonized the effect of propoxur on SDL as well as TL. Both piracetam and ascorbic acid attenuated the propoxur-induced increase in brain MDA levels and decrease in brain NP-SH levels. Results of the present study show that ascorbic acid and piracetam have the potential to reverse cognitive dysfunction and oxidative stress induced by propoxur in the brain.

Biomarkers of oxidative and nitrosative damage in Alzheimer's disease and mild cognitive impairment

Alzheimer's disease (AD) is the most common type of dementia in the elderly. Products of oxidative and nitrosative stress (OS and NS, respectively) accumulate with aging, which is the main risk factor for AD. This provides the basis for the involvement of OS and NS in AD pathogenesis. OS and NS occur in biological systems due to the dysregulation of the redox balance, caused by a deficiency of antioxidants and/or the overproduction of free radicals. Free radical attack against lipids, proteins, sugars and nucleic acids leads to the formation of bioproducts whose detection in fluids and tissues represents the currently available method for assessing oxidative/nitrosative damage. Post-mortem and in-vivo studies have demonstrated an accumulation of products of free radical damage in the central nervous system and in the peripheral tissues of subjects with AD or mild cognitive impairment (MCI). In addition to their individual role, biomarkers for OS and NS in AD are associated with altered bioenergetics and amyloid-beta (Abeta) metabolism. In this review we discuss the main results obtained in the field of biomarkers of oxidative/nitrosative stress in AD and MCI in humans, in addition to their potential role as a tool for diagnosis, prognosis and treatment efficacy in AD.

Ingredients for Functional Drinks in Neurodegenerative Diseases: A Review

Several studies have indicated that oxidative stress is a major risk factor for the initiation and progression of neurological disorders like Parkinson's disease (PD) and Alzheimer's (AD). Therefore, reducing oxidative stress appears to be a rational choice for the prevention and reduction in the rate of progression of these neurological disorders. The brain utilizes about 25% of respired oxygen even though it represents only 5% of the body weight. Free radicals are generated during the normal intake of oxygen, during infection, and during normal oxidative metabolism of certain substrates. Although experimental data are consistent in demonstrating the neuroprotective effects of antioxidants in vitro and in animal models, the clinical evidence that antioxidant agents may prevent or slow the course of these diseases is still relatively unsatisfactory, and insufficient to strongly modify clinical practice.

In this paper, natural possible substances that could be added to a beverage to prevent or decrease the developing of neurodegenerative diseases are reviewed.

Vitamin C function in the brain: vital role of the ascorbate transporter SVCT2

Ascorbate (vitamin C) is a vital antioxidant molecule in the brain. However, it also has a number of other important functions, participating as a cofactor in several enzyme reactions, including catecholamine synthesis, collagen production, and regulation of HIF-1 alpha. Ascorbate is transported into the brain and neurons via the sodium-dependent vitamin C transporter 2 (SVCT2), which causes accumulation of ascorbate within cells against a concentration gradient. Dehydroascorbic acid, the oxidized form of ascorbate, is transported via glucose transporters of the GLUT family. Once in cells, it is rapidly reduced to ascorbate. The highest concentrations of ascorbate in the body are found in the brain and in neuroendocrine tissues such as adrenal, although the brain is the most difficult organ to deplete of ascorbate. Combined with regional asymmetry in ascorbate distribution within different brain areas, these facts suggest an important role for ascorbate in the brain. Ascorbate is proposed as a neuromodulator of glutamatergic, dopaminergic, cholinergic, and GABAergic transmission and related behaviors. Neurodegenerative diseases typically involve high levels of oxidative stress and thus ascorbate has been posited to have potential therapeutic roles against ischemic stroke, Alzheimer's disease, Parkinson's disease, and Huntington's disease.

Dietary vitamin E, brain redox status and expression of Alzheimer's disease-relevant genes in rats

Oxidative stress is one of the major pathological features of Alzheimer's disease (AD). Here, we investigated whether dietary vitamin E (VE) depletion may induce adverse effects and supplementation with α-tocopherol (αT) may result in beneficial effects on redox status and the regulation of genes relevant in the pathogenesis of AD in healthy rats. Three groups of eight male rats each were fed diets with deficient ( < 1 mg αT equivalents/kg diet), marginal (9 mg αT equivalents/kg diet) or sufficient (18 mg αT equivalents/kg diet) concentrations of natural-source VE for 6 months; a fourth group was fed the VE-sufficient diet fortified with αT (total VE, 146 mg αT equivalents/kg diet). Feeding of the experimental diets dose dependently altered αT concentrations in the cortex and plasma. No significant changes in F2-isoprostane concentrations, activities of antioxidative enzymes (total superoxide dismutase, Se-dependent glutathione peroxidase) and concentrations of glutathione or the expression of AD-relevant genes were observed. In this non-AD model, depletion of VE did not induce adverse effects and supplementation of αT did not induce positive effects on the parameters related to the progression of AD.

Oxidative stress hypothesis in Alzheimer's disease: a reappraisal

Alzheimer's disease (AD) is the most common form of neurodegenerative disorder with dementia. In its sporadic form, AD results from the combination of genetic factors with different epigenetic events. Among them, oxidative metabolic reactions and their by-products have been consistently implicated in AD pathogenesis and represent the biological basis for the 'oxidative stress hypothesis' of AD. Numerous studies demonstrate that different biomarkers of oxidative-stress-mediated events are elevated in the AD brain. Studies in animal models of the disease with antioxidants report significant improvements of their AD-like phenotype. Although epidemiologic studies show that dietary intake of antioxidants reduces the risk of AD, clinical trials with antioxidants show only a marginal positive or no effect. These conflicting results have created a wave of criticism towards the oxidative stress hypothesis of AD. Here, I review the available data and discuss the necessary paths for a fair reappraisal of the hypothesis.

Oxidative damage and cognitive dysfunction: antioxidant treatments to promote healthy brain aging

Oxidative damage in the brain may lead to cognitive impairments in aged humans. Further, in age-associated neurodegenerative disease, oxidative damage may be exacerbated and associated with additional neuropathology. Epidemiological studies in humans show both positive and negative effects of the use of antioxidant supplements on healthy cognitive aging and on the risk of developing Alzheimer disease (AD). This contrasts with consistent behavioral improvements in aged rodent models. In a higher mammalian model system that naturally accumulates human-type pathology and cognitive decline (aged dogs), an antioxidant enriched diet leads to rapid learning improvements, memory improvements after prolonged treatment and cognitive maintenance. Cognitive benefits can be further enhanced by the addition of behavioral enrichment. In the brains of aged treated dogs, oxidative damage is reduced and there is some evidence of reduced AD-like neuropathology. In combination, antioxidants may be beneficial for promoting healthy brain aging and reducing the risk of neurodegenerative disease.

Free radical-mediated damage to brain in Alzheimer's disease and its transgenic mouse models

Advances in our understanding of the etiologies and pathogenesis of Alzheimer's disease (AD) highlight a role for free radical-mediated injury to brain regions from early stages of this illness. Here we will review the evidence from transgenic mouse models of AD, autopsy samples, and human biofluids obtained during life paying particular attention to the stage of disease. In addition, we will review the epidemiologic literature that addresses the potential of anti-oxidants to prevent incident dementia from AD, and the clinical trial literature that addresses anti-oxidant preventative or therapeutic strategies for different stage of AD. Future efforts in preclinical models and ultimately clinical trials are needed to define optimally effective agents and combinations, doses, and timing to suppress safely this facet of AD.

Disease-modifying therapies in Alzheimer's disease

Alzheimer's disease (AD) is a chronic, progressive, neurodegenerative disorder that places a substantial burden on patients, their families, and society. The disease affects approximately 5 million individuals in the United States, with an annual cost of care greater than $100 billion. During the past dozen years, several agents have been approved that enhance cognition and global function of AD patients, and recent advances in understanding AD pathogenesis has led to the development of numerous compounds that might modify the disease process. A wide array of antiamyloid and neuroprotective therapeutic approaches are under investigation on the basis of the hypothesis that amyloid beta (A beta) protein plays a pivotal role in disease onset and progression and that secondary consequences of A beta generation and deposition, including tau hyperphosphorylation and neurofibrillary tangle formation, oxidation, inflammation, and excitotoxicity, contribute to the disease process. Interventions in these processes with agents that reduce amyloid production, limit aggregation, or increase removal might block the cascade of events comprising AD pathogenesis. Reducing tau hyperphosphorylation, limiting oxidation and excitotoxicity, and controlling inflammation might be beneficial disease-modifying strategies. Potentially neuroprotective and restorative treatments such as neurotrophins, neurotrophic factor enhancers, and stem cell-related approaches are also under investigation.

Prevention of Alzheimer's disease

The already considerable public health burden of Alzheimer's disease will likely worsen as populations around the world age. As a result, there is considerable motivation to develop effective strategies for preventing the disease. A wide variety of such strategies are under investigation and include pharmaceuticals, nutriceuticals, diet, physical activity and cognitive activity. We review here the most promising candidates and the epidemiologic evidence for their efficacy. Although none of these have yet to be definitively shown to prevent Alzheimer's disease, further research should help to clarify what role they may play in reducing the burden of this disease.

Is antioxidant therapy a viable alternative for mild cognitive impairment? Examination of the evidence

Therapeutic interventions for the prodromal stages of dementia are currently being sought with a view to delaying if not preventing disease onset. Uncertainty as to whether cognitive disorder in a given individual will progress towards dementia and adverse drug side effects has led to hesitancy on the part of drug regulators to instigate preventive pharmacotherapies. In this context, antioxidant therapies may provide a low-risk alternative, targeting very early biological changes. While a growing body of knowledge demonstrates both the importance of oxidative stress in the aetiology of dementia and the efficacy of antioxidant treatment in animal and cellular models, studies in humans are presently inconclusive. While some antioxidants, notably flavonoid- or vitamin-rich diets, appear to lower the relative risk for Alzheimer's disease in humans in observational studies, these results must be interpreted in the light of the biological complexity of the relationship between oxidative stress and neurodegeneration, and the methodological and theoretical shortcomings of studies conducted to date. A clearer understanding of these factors will assist in the interpretation of the results of the intervention studies which are now being undertaken; these studies being the only current means of establishing efficacy for preventive drug treatment of Alzheimer's disease.

Application of classification tree and logistic regression for the management and health intervention plans in a community-based study

BACKGROUND

A community-based aboriginal study was conducted and analysed to explore the application of classification tree and logistic regression.

METHODS

A total of 1066 aboriginal residents in Yilan County were screened during 2003-2004. The independent variables include demographic characteristics, physical examinations, geographic location, health behaviours, dietary habits and family hereditary diseases history. Risk factors of cardiovascular diseases were selected as the dependent variables in further analysis.

RESULTS

The completion rate for heath interview is 88.9%. The classification tree results find that if body mass index is higher than 25.72 kg m(-2) and the age is above 51 years, the predicted probability for number of cardiovascular risk factors > or =3 is 73.6% and the population is 322. If body mass index is higher than 26.35 kg m(-2) and geographical latitude of the village is lower than 24 degrees 22.8', the predicted probability for number of cardiovascular risk factors > or =4 is 60.8% and the population is 74. As the logistic regression results indicate that body mass index, drinking habit and menopause are the top three significant independent variables.

CONCLUSIONS

The classification tree model specifically shows the discrimination paths and interactions between the risk groups. The logistic regression model presents and analyses the statistical independent factors of cardiovascular risks. Applying both models to specific situations will provide a different angle for the design and management of future health intervention plans after community-based study.

Oxidative stress: A bridge between Down's syndrome and Alzheimer's disease

Besides the genetic, biochemical and neuropathological analogies between Down's syndrome (DS) and Alzheimer's disease (AD), there is ample evidence of the involvement of oxidative stress (OS) in the pathogenesis of both disorders. The present paper reviews the publications on DS and AD in the past 10 years in light of the "gene dosage" and "two-hit" hypotheses, with regard to the alterations caused by OS in both the central nervous system and the periphery, and the main pipeline of antioxidant therapeutic strategies. OS occurs decades prior to the signature pathology and manifests as lipid, protein and DNA oxidation, and mitochondrial abnormalities. In clinical settings, the assessment of OS has traditionally been hampered by the use of assays that suffer from inherent problems related to specificity and/or sensitivity, which explains some of the conflicting results presented in this work. For DS, no scientifically proven diet or drug is yet available, and AD trials have not provided a satisfactory approach for the prevention of and therapy against OS, although most of them still need evidence-based confirmation. In the future, a balanced up-regulation of endogenous antioxidants, together with multiple exogenous antioxidant supplementation, may be expected to be one of the most promising treatment methods.

Alzheimer's disease: progress in the development of anti-amyloid disease-modifying therapies

The amyloid hypothesis--the leading mechanistic theory of Alzheimer's disease--states that an imbalance in production or clearance of amyloid beta (Abeta) results in accumulation of Abeta and triggers a cascade of events leading to neurodegeneration and dementia. The number of persons with Alzheimer's disease is expected to triple by mid-century. If steps are not taken to delay the onset or slow the progression of Alzheimer's disease, the economic and personal tolls will be immense. Different classes of potentially disease-modifying treatments that interrupt early pathological events (ie, decreasing production or aggregation of Abeta or increasing its clearance) and potentially prevent downstream events are in phase II or III clinical studies. These include immunotherapies; secretase inhibitors; selective Abeta42-lowering agents; statins; anti-Abeta aggregation agents; peroxisome proliferator-activated receptor-gamma agonists; and others. Safety and serious adverse events have been a concern with immunotherapy and gamma-secretase inhibitors, though both continue in clinical trials. Anti-amyloid disease-modifying drugs that seem promising and have reached phase III clinical trials include those that selectively target Abeta42 production (eg, tarenflurbil), enhance the activity of alpha-secretase (eg, statins), and block Abeta aggregation (eg, transiposate).

Antioxidant vitamins and Alzheimer’s disease: a review of the epidemiological literature

Identifying ways to prevent Alzheimer’s disease is becoming increasingly critical in our aging population. Antioxidant vitamins hold promise for lowering the risk of Alzheimer’s disease and cognitive decline in older persons. In animal models and cell lines, these vitamins, such as vitamins E and C, prevent neuronal damage caused by free radicals, delaying brain aging and, perhaps, memory loss. However, epidemiological data on antioxidant vitamins and cognition are conflicting and are not conclusive. This report reviews current research, in particular, the large, prospective, observational studies and randomized, controlled trials to assess the evidence regarding the relation of antioxidant vitamins to dementia or cognitive decline.

Vitamins for the elderly: from A to zinc

Nutritional status can be affected by a number of factors associated with increased age. Changes in appetite, taste, and swallowing can impact the eating habits of the elderly individual. In addition, the lower energy requirement of the elderly patient necessitates that these nutrients be consumed in greater density. Because many older adults have chronic diseases that may be affected by diet, providing optimal nutrition is especially important, and adequate stores of essential vitamins and minerals may play a key role in disease prevention and in modulating disease progression.

Systemic and brain metabolic dysfunction as a new paradigm for approaching Alzheimer's dementia

Since its definition Alzheimer's disease has been at the centre of consideration for neurologists, psychiatrists, and pathologists. With John P. Blass it has been disclosed a different approach Alzheimer's disease neurodegeneration understanding not only by the means of neurochemistry but also biochemistry opening new scenarios in the direction of a metabolic system degeneration. Nowadays, the understanding of the role of cholesterol, insulin, and adipokines among the others in Alzheimer's disease etiopathogenesis is clarifying approaches valuable not only in preventing the disease but also for its therapy.