Association between antioxidant nutritional indicators and the incidence of dementia: results from the PAQUID prospective cohort study

Neurotrophic function of phytochemicals for neuroprotection in aging and neurodegenerative disorders: modulation of intracellular signaling and gene expression

Bioactive compounds in food and beverages have been reported to promote health and prevent age-associated decline in cognitive, motor and sensory activities, and emotional function. Phytochemicals, a ubiquitous class of plant secondary metabolites, protect neuronal cells by interaction with cellular activities, in addition to the antioxidant and anti-inflammatory function. In aging and age-associated neurodegenerative disorders, phytochemicals protect neuronal cells by neurotrophic factor-mimic activity, in addition to suppression of apoptosis signaling in mitochondria. This review presents the cellular mechanisms underlying anti-apoptotic function and neurotrophic function of phytochemicals in the brain. Phytochemicals bind to receptors of neurotrophic factors, and also receptors for γ-aminobutyric acid, acetylcholine, serotonin, and glutamate and estrogen, and activate downstream signal pathways. Phytochemicals also directly intervene intracellular signaling molecules to modify the brain function. Finally, phytochemicals enhance the endogenous biosynthesis of genes coding anti-apoptotic Bcl-2 and neurotrophic factors, such as brain-derived and glial cell line-derived neurotrophic factor. The gene induction may play a major role in the neuroprotective function of dietary compounds shown by epidemiological studies. Quantitative measurement of neurotrophic factors induced by phytochemicals in the serum, cerebrospinal fluid, and other clinical samples is proposed as a surrogate assay method to evaluate the neuroprotective potency. Development of novel neuroprotective compounds is expected among compounds chemically synthesized from the brain-permeable basic structure of phytochemicals.

Nutritional management of older adults with cognitive decline and dementia

Age-related cognitive decline is a main predictor of disability among elderly people, and with the continued expansion of the aging population and the increase in life expectancy, the prevalence of mild cognitive impairment and dementia represented by Alzheimer's disease (AD), which is a multifactorial neurodegenerative disorder of older adults, have increased. Recent epidemiological and observational studies suggest a relationship exists between lifestyle factors, including nutrition and diet, and cognitive function in aging adults. It is also suggested that malnutrition and nutrient deficiencies are associated with cognitive decline in patients with dementia. There are a variety of nutritional factors, including nutritional status and dietary patterns, that might be associated with cognitive function, and specific micronutrients and dietary components have been suggested to have an association with cognitive function as well. Based on these findings and evidence, evaluation of nutritional state, as well as nutritional intervention, might be able to play a role in the management and prevention of dementia.

Early neuropsychological detection of Alzheimer's disease

Lifestyle modification offers a promising way of preventing or delaying Alzheimer's disease (AD). In particular, nutritional interventions can contribute to decrease the risk of dementia. The efficacy of such interventions should be assessed in individuals thought to be prone to AD. It is therefore necessary to identify markers that may help detecting AD as early as possible. This review will focus on subtle neuropsychological changes that may already exist in the predementia phase, and that could point to individuals at risk of dementia. Episodic memory decline appears consistently as the earliest sign of incipient typical AD. An episodic memory test that ensures deep encoding of information and assesses retrieval with free as well as cued recall appears as a useful tool to detect patients at an early stage of AD. Beyond the memory domain, category verbal fluency has been shown to decline early and to predict progression to AD. Moreover, in line with current diagnosis criteria for prodromal AD, combining neuropsychological scores and neuroimaging data allows a better discrimination of future AD patients than neuroimaging or neuropsychological data alone. Altogether, the detection of cognitive changes that are predictive of the typical form of probable AD already in the predementia stage points to at risk people who are the best target for therapeutic interventions, such as nutrition or physical exercise counseling or dietary interventions.

Brain tocopherols related to Alzheimer's disease neuropathology in humans

Randomized trials of α-tocopherol supplements on cognitive decline are negative, whereas studies of dietary tocopherols have shown benefit. We investigated these inconsistencies by analyzing the relations of α- and γ-tocopherol brain concentrations to Alzheimer's disease (AD) neuropathology among 115 deceased participants of the prospective Rush Memory and Aging Project. Associations of amyloid load and neurofibrillary tangle severity with brain tocopherol concentrations were examined in separate adjusted linear regression models. γ-Tocopherol concentrations were associated with lower amyloid load (β = -2.10, P = .002) and lower neurofibrillary tangle severity (β = -1.16, P = .02). Concentrations of α-tocopherol were not associated with AD neuropathology, except as modified by γ-tocopherol: high α-tocopherol was associated with higher amyloid load when γ-tocopherol levels were low and with lower amyloid levels when γ-tocopherol levels were high (P for interaction = 0.03). Brain concentrations of γ- and α-tocopherols may be associated with AD neuropathology in interrelated, complex ways. Randomized trials should consider the contribution of γ-tocopherol.

Plasma and tissue concentrations of α-tocopherol and δ-tocopherol following high dose dietary supplementation in mice

Vitamin E isoforms are essential nutrients that are widely used as dietary supplements and therapeutic agents for a variety of diseases. However, their pharmacokinetic (PK) properties remain poorly characterized, and high dosage animal studies may provide further information on their in vivo functions and pharmacological effects. In this study, alpha-tocopherol (α-toc) and delta-tocopherol (δ-toc) levels were measured in mouse plasma and tissues following their high dosage dietary supplementation. Average α-toc levels at 5, 10 and 20 g α-toc/kg diet increased over baseline levels 6-fold in plasma, 1.6-fold in brain, and 4.9-fold in liver. These elevated α-toc concentrations remained constant from 5 to 20 g α-toc/kg diet, rather than showing further increases across these dosages. No α-toc-related toxicity occurred at these high dosages, and strain-specific differences in liver and brain α-toc levels between Balb/cJ and C57Bl/6J mice were observed. Relatively high-dosage administration of dietary δ-toc for 1 or 4 weeks resulted in 6-30-fold increases in plasma and liver levels between dosages of 0.33 and 1.67 g δ-toc/kg diet. Co-administration of sesamin with δ-toc further increased δ-toc levels between 1.3- and 14-fold in plasma, liver, and brain. These results provide valuable PK information on high dosage α-toc and δ-toc in mouse and show that supplementation of sesamin with δ-toc further increases δ-toc levels over those seen with δ-toc supplementation alone.

Vitamin E in aging, dementia, and Alzheimer's disease

Since its discovery, vitamin E has been extensively researched by a large number of investigators in an attempt to fully understand its role in a variety of pathophysiological contexts. The vast majority of published work has focused on vitamin E's antioxidant properties, which is why it is well known as a lipophilic antioxidant that protects membranes from being oxidatively damaged by free radicals. However, several lines of investigation have recently revealed that vitamin E has biological roles unrelated to its antioxidant properties. Among these roles, vitamin E has been described as: a regulator of signal transduction, gene expression, and redox sensor. In parallel with the discovery of novels cellular functions of vitamin E, the introduction of the free radical theory of brain aging has propelled a renewed interest in this vitamin. Most of the resulting work has been based on the postulate that, by preventing and/or minimizing the oxidative stress-dependent brain damage, vitamin E could be used as therapeutic approach. In this article, we will consider the existing literature regarding the biological properties of vitamin E and the potential therapeutic and/or preventative roles that this natural dietary factor plays in brain aging, cognition, and Alzheimer's dementia.

Tocopherols and tocotrienols plasma levels are associated with cognitive impairment

Vitamin E includes 8 natural compounds (4 tocopherols, 4 tocotrienols) with potential neuroprotective activity. α-Tocopherol has mainly been investigated in relation to cognitive impairment. We examined the relation of all plasma vitamin E forms and markers of vitamin E damage (α-tocopherylquinone, 5-nitro-γ-tocopherol) to mild cognitive impairment (MCI) and Alzheimer's disease (AD). Within the AddNeuroMed-Project, plasma tocopherols, tocotrienols, α-tocopherylquinone, and 5-nitro-γ-tocopherol were assessed in 168 AD cases, 166 MCI, and 187 cognitively normal (CN) people. Compared with cognitively normal subjects, AD and MCI had lower levels of total tocopherols, total tocotrienols, and total vitamin E. In multivariable-polytomous-logistic regression analysis, both MCI and AD cases had 85% lower odds to be in the highest tertile of total tocopherols and total vitamin E, and they were, respectively, 92% and 94% less likely to be in the highest tertile of total tocotrienols than the lowest tertile. Further, both disorders were associated with increased vitamin E damage. Low plasma tocopherols and tocotrienols levels are associated with increased odds of MCI and AD.

Nutritional determinants of cognitive aging and dementia

The objective of this review is to provide an overview of nutritional factors involved in cognitive aging and dementia with a focus on nutrients that are also important in neurocognitive development. Several dietary components were targeted, including antioxidant nutrients, dietary fats and B-vitamins. A critical review of the literature on each nutrient group is presented, beginning with laboratory and animal studies of the underlying biological mechanisms, followed by prospective epidemiological studies and randomised clinical trials. The evidence to date is fairly strong for protective associations of vitamin E from food sources, the n-3 fatty acid, DHA, found in fish, a high ratio of polyunsaturated to saturated fats, and vitamin B12 and folate. Attention to the level of nutrient intake is crucial for interpreting the literature and the inconsistencies across studies. Most of the epidemiological studies that observe associations have sufficient numbers of individuals who have both low and adequate nutrient status. Few of the randomised clinical trials are designed to target participants who have low baseline status before randomising to vitamin supplement treatments, and this may have resulted in negative findings. Post-hoc analyses by some of the trials reveal vitamin effects in individuals with low baseline intakes. The field of diet and dementia is a relatively young area of study. Much further work needs to be done to understand dietary determinants of cognitive aging and diseases. Further, these studies must be particularly focused on the levels of nutrient intake or status that confer optimum or suboptimal brain functioning.

Nutrition and age-related eye diseases: the Alienor (Antioxydants, Lipides Essentiels, Nutrition et maladies OculaiRes) Study

BACKGROUND

Worldwide, degenerative eye diseases (age-related maculopathy (ARM), cataract, glaucoma) are the main causes of visual impairment and blindness, which contribute to disability in the elderly. Mainly three types of nutritional factors are investigated for their potential protection against eye ageing: antioxidants; lutein and zeaxanthin (carotenoids which accumulate specifically in the eye); omega 3 polyunsaturated fatty acids. Few epidemiological studies have been conducted in this field, particularly in Europe.

OBJECTIVE

The Alienor (Antioxydants, Lipides Essentiels, Nutrition et maladies OculaiRes) Study aims at assessing the associations of eye diseases with nutritional factors, determined from plasma measurements and estimation of dietary intakes.

DESIGN, SETTING AND PARTICIPANTS

Subjects were recruited in Bordeaux (France) from the ongoing population-based 3C study. In 2006-2008, 963 subjects from the 3C Study, aged 73 years or more, had an eye examination and will have follow-up eye examinations every 2 years.

MEASUREMENTS

Vascular, genetic and nutritional factors were assessed at baseline (1999-2001) and follow-up examinations of the 3C Study. Eye diseases were classified according to international classifications.

RESULTS

Nutritional status and vascular disease and risk factors were similar between participants and non participants, except for a slight difference in plasma triglycerides and HDL-cholesterol. As expected, the prevalence of eye diseases was high: early and late ARM (28.4 % and 5.6 %, respectively), open-angle glaucoma and treated ocular hypertension (4.8 % and 10.0 %, respectively), cataract extraction (45.2 %), retinopathy (8.4 %), retinal vein occlusion (1.1 %), epiretinal membrane (3.9 %), current use of artificial tears (17.3 %).

CONCLUSIONS

This study confirms the high prevalence of eye diseases in the elderly. Its main strength is the combination of nutritional, vascular and genetic information, collected over a 7 year period of time before the first eye examination. It may help design future interventional studies, which might be common with other age-related disorders, because of common nutritional factors.

Neutrophils are immune cells preferentially targeted by retinoic acid in elderly subjects

Background

The immune system gradually deteriorates with age and nutritional status is a major factor in immunosenescence. Of the many nutritional factors implicated in age-related immune dysfunction, vitamin A may be a good candidate, since vitamin A concentrations classically decrease during aging whereas it may possess important immunomodulatory properties via its active metabolites, the retinoic acids. This prompted us to investigate the immune response induced by retinoids in adults and elderly healthy subjects. Before and after oral supplementation with 13cis retinoic acid (0.5 mg/kg/day during 28 days), whole blood cells were phenotyped, and functions of peripheral blood mononuclear cells (PBMC) and polymorphonuclear cells (PMN) were investigated by flow cytometry and ELISA tests.

Results

In both young adults (n = 20, 25 ± 4 years) and older subjects (n = 20, 65 ± 4 years), retinoic acid supplementation had no effect on the distribution of leukocyte subpopulations or on the functions of PBMC (Il-2 and sIl-2R production, membrane expression of CD25). Concerning PMN, retinoic acid induced an increase in both spontaneous migration and cell surface expression of CD11b in the two different age populations, whereas bactericidal activity and phagocytosis remained unchanged.

Conclusions

We demonstrated that retinoic acid induces the same intensity of immune response between adult and older subjects, and more specifically affects PMN functions, i.e. adhesion and migration, than PBMC functions.

Lower fluid and fruits/vegetable intake in questionable dementia among older Hong Kong Chinese

OBJECTIVE

Nutrition plays a role in the ageing process of the brain and suboptimal nutrient intake might precede clinical cognitive impairment. A diet high in fruits and vegetables has been recommended while little has been said about the influence of fluid intake in cognitive function. We examine the dietary pattern of community-dwelling older individuals with questionable dementia and compared that with normal individuals.

DESIGN

Cross-sectional.

SETTING

Community.

PARTICIPANTS

285 community-dwellers aged 60 or older.

MEASUREMENTS

Dietary habits were recorded using the Mini-Nutritional Assessment (MNA). Questionable dementia was diagnosed by psychogeriatricians and relevant demographic and dietary factors were examined using univariate then multivariate analyses.

RESULTS

146 questionable dementia and 139 cognitively normal subjects were interviewed. Both groups were not at risk of malnutrition (MNA score 26.1 vs. 26.7 respectively, p = 0.02). The former were older, had fewer years of education, lower MMSE and ADAS-cog as well as lower MNA scores. In univariate analysis, questionable dementia was associated with decline in food intake and appetite, eating less vegetables and fruits, and drinking less fluid. After adjustment for age, gender and education level, eating > 2 servings of vegetables / fruits per day (OR 0.26, 95% CI 0.067, 0.973) and taking > 5 cups of fluids per day (OR 0.4, 95% CI 0.204, 0.792) was associated with a lower prevalence of questionable dementia.

CONCLUSION

Older people with questionable dementia have lower intakes of vegetables, fruits and fluid than those who were cognitively normal. This may pose additional health risks, and increase their chance of progressing into dementia.

Moving forward with nutrition in Alzheimer's disease

Alzheimer's disease (AD) is the epidemic of the 21st century but still relatively little is known about the causes of the disease. Nutrient deficiencies, associated with loss of cognitive function, are frequently reported in patients with AD and currently available epidemiologic evidence suggests that an increased intake of certain nutrients may lower the risk of AD. Current treatment options offer only symptomatic relief, however, there is a growing body of evidence that nutrition in general and 'nutritional intervention' in a clinical setting may be able to play a key role in the management of the disease. However, randomized clinical trials are needed to test this approach. The Souvenir study is the first randomized, controlled, double-blind, multi-centre study designed to evaluate the efficacy of a multi-nutrient dietary approach on cognitive performance in drug-naïve early AD patients.

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.

Plasma tocopherols and risk of cognitive impairment in an elderly Italian cohort

BACKGROUND

Evidence that vitamin E may preserve cognitive function in elderly subjects is conflicting. The most abundant and most investigated form of vitamin E in humans is alpha-tocopherol, but other antioxidant tocopherols (beta, gamma, and delta) exist in nature.

OBJECTIVE

We aimed to investigate plasma concentrations of the natural tocopherols and the tocopherol oxidation markers alpha-tocopherylquinone (alphaTQ) and 5-nitro-gamma-tocopherol (5NGT) in relation to cognitive function in the elderly.

DESIGN

Baseline plasma tocopherols and their oxidation markers were measured in 761 elderly Italian subjects from a population-based cohort assessed in 1999-2000 for mild cognitive impairment (MCI) and dementia. In 2003-2004, information about cognitive status was collected for 615 of the 666 subjects without baseline cognitive impairment. Tocopherols and oxidation markers were analyzed as plasma absolute values divided by serum total cholesterol because lipids affect their blood availability. Analyses were adjusted for sociodemographic, genetic, lifestyle, and medical confounders.

RESULTS

Compared with the corresponding lowest tertile, the risk of prevalent dementia was higher for the highest tertile of delta-tocopherol/cholesterol [odds ratio (OR): 3.87; 95% CI: 1.46, 10.27] and alphaTQ/cholesterol (4.02; 1.45, 11.14), but the risk of incident dementia was not directly associated with plasma vitamin E metabolites. A U-shaped association, with lower risk for intermediate tertiles, was found for prevalent MCI with 5NGT/cholesterol (0.39; 0.17, 0.91) and for incident dementia with gamma-tocopherol/cholesterol (hazard ratio: 0.42; 95% CI: 0.22, 0.84).

CONCLUSIONS

Plasma concentrations of some non-alpha-tocopherol forms of vitamin E are associated with cognitive impairment in elderly people. However, the associations depend on concurrent cholesterol concentration and need further investigation.

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.

Épidémiologie des démences

Dementia is a major public health problem and its burden will increase in the 30 years to come. Prevalence increases with age and incidence is slightly higher in women than men, especially after the age of 80 years. Survival after the onset of dementia is approximately 5 years. Lifestyle and health habits are a keystone for dementia: risk factors include physical, intellectual and social activity and nutritional habits. Data from well-conducted intervention studies are necessary to show whether better care for hypertension, diabetes, and dyslipidemia might decrease the incidence of dementia.

Nutritional status determinants and cognition in the elderly

It is possible to identify risks or protective factors against dementia. Increased levels of homocysteine (HCY) and vitamin B deficiency, obesity and central adiposity in midlife are independent risk factors for the development of dementia. High dietary intake of antioxidants and omega-3 fatty acids lower the risk of Alzheimer disease (AD). The supplementation with single nutrients, like vitamin B, omega-3-polyunsaturated fatty acids (PUFA) or antioxidants is generally not effective in lowering the risk of dementia or in slowing the progression of the disease. It is probably necessary that these nutrients are part of a healthy diet (with at least five portions of fruit and vegetables per day and one portion of fish per week) during the lite where other factors interact with them as it happens in the Mediterranean diet. Nutritional strategies for modifying the clinical course of cognitive failure should consider the use of nutritional screening tools in the multidimensional geriatric evaluation. Moreover, the diet, oral supplementation, caregiver education could be important factors to prevent or treat weight loss and its consequences in AD while the use of artificial nutrition in demented patients may have questionable benefits.

Associations of vegetable and fruit consumption with age-related cognitive change

OBJECTIVE

To examine the association between rates of cognitive change and dietary consumption of fruits and vegetables among older persons.

METHODS

The authors conducted a prospective cohort study of 3,718 participants, aged 65 years and older of the Chicago Health and Aging Project. Participants completed a food frequency questionnaire and were administered at least two of three cognitive assessments at baseline, 3-year, and 6-year follow-ups. Cognitive function was measured using the average z-score of four tests: the East Boston Tests of immediate memory and delayed recall, the Mini-Mental State Examination, and the Symbol Digit Modalities Test.

RESULTS

The mean cognitive score at baseline for the analyzed cohort was 0.18 (range: -3.5 to 1.6), and the overall mean change in score per year was a decline of 0.04 standardized units. In mixed effects models adjusted for age, sex, race, and education, compared with the rate of cognitive decline among persons in the lowest quintile of vegetable intake (median of 0.9 servings/day), the rate for persons in the fourth quintile (median, 2.8 servings/day) was slower by 0.019 standardized units per year (p = 0.01), a 40% decrease, and by 0.018 standardized units per year (p = 0.02) for the fifth quintile (median, 4.1 servings/day), or a 38% decrease in rates. The association remained significant (p for linear trend = 0.02) with further control of cardiovascular-related conditions and risk factors. Fruit consumption was not associated with cognitive change.

CONCLUSION

High vegetable but not fruit consumption may be associated with slower rate of cognitive decline with older age.

Deletion of vitamin E enhances phenotype of Alzheimer disease model mouse

Increased oxidative damage is a prominent and early feature in Alzheimer disease (AD). However, whether it is a primary cause or merely a downstream consequence in AD pathology is still unknown. We previously generated alpha-tocopherol transfer protein knockout (Ttpa-/-) mice, in which lipid peroxidation in the brain was significantly increased by complete depletion of alpha-tocopherol (alpha-Toc). Here we crossed AD transgenic (APPsw) model mice (Tg2576) with Ttpa-/- mice. The resulting double-mutant (Ttpa-/- APPsw) mice showed earlier and more severe cognitive dysfunction in the Morris water maze, novel-object recognition, and contextual fear conditioning tests. They also showed increased amyloid beta-peptide (Abeta) deposits in the brain by immunohistochemical analysis, which was ameliorated with alpha-Toc supplementation. In this report we provide clear evidence indicating that chronic lipid peroxidation due to alpha-Toc depletion enhances AD phenotype in a mouse model.

Hematologic risk factors of vascular disease and their relation to dementia

Multiple studies have implicated vascular-related conditions as risk factors for dementia. Clarification of these factors in dementia is important because most are modifiable, and may serve as the basis for preventive strategies. Several hematologic factors are associated with vascular diseases, but their relation to dementia is unclear. This review examines biological and epidemiological evidence concerning the role of these hematologic factors in dementia, and dementia subtypes. Reviewed factors include homocysteine, cholesterol, fatty acids, antioxidants, and C-reactive protein. The vast majority of studies reviewed are cross-sectional. Longitudinal studies with serial hematologic measures are needed to clarify the relationship between these factors and dementia over the lifespan. A necessary step is to examine multiple hematologic factors simultaneously, rather than in isolation, to determine how these factors are interrelated.

A life-course approach to the aetiology of late-onset dementias

Substantial progress has been made in the understanding of the neurobiology of dementias, but comprehensive causal models are not available. Genetic and environmental factors probably interact to determine vulnerability to the dementias. The life-course approach to age-related diseases, when systematically applied to the dementias, provides opportunities to identify the nature and timing of environmental contributions. We discuss the relevance of the fetal origins of adult disease hypothesis to the dementias. Associations between the dementias (most often described as Alzheimer's disease) and ischaemic heart disease, obesity, hypertension, hyperlipidaemia, and non-insulin-dependent diabetes mellitus are set against associations between dementias and childhood intelligence, low educational attainments, low socioeconomic status, occupation, and lifetime dietary history. Biological mechanisms that explain how fetal development might influence the risk of adult disease may be relevant to many age-related diseases including the dementias and, possibly, to the biology of ageing.

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

BACKGROUND

Since increased oxidative stress may impair cognition and be a risk factor for dementia, there has been interest in determining whether use of antioxidants could protect against such events.

OBJECTIVE

To determine whether supplement use of vitamins C and/or E in a community-based sample of older African American and white individuals delayed incident dementia or Alzheimer's disease (AD).

METHODS

We selected a subgroup from the Duke Established Populations for Epidemiologic Studies of the Elderly, a longitudinal study of community-representative persons aged 65-105 years living in 5 adjacent counties in North Carolina, and followed them for dementia (1986-1987 through June 2000). Information gathered during in-home interviews included sociodemographic characteristics, health status, health service use, and vitamin use. Diagnosis of dementia and AD was based on evaluations using the clinical and neuropsychological batteries of the Consortium to Establish a Registry for Alzheimer's Disease, with final determination by consensus agreement of specialists using Diagnostic and Statistical Manual of Mental Disorders, third revision, and National Institute for Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders criteria.

RESULTS

Of 616 persons initially dementia-free (mean age 73 y; 62% female; 62% African American), 141 developed dementia, of whom 93 developed AD. Increased age and mobility problems were risk factors for dementia (only age for AD), while an increased number of outpatient visits reduced the likelihood of developing dementia. Neither use of any vitamins C and/or E (used by 8% of subjects at baseline) nor high-dose use reduced the time to dementia or AD.

CONCLUSIONS

In this community in the southeastern US where vitamin supplement use is low, use of vitamins C and/or E did not delay the incidence of dementia or AD.

A review of antioxidants and Alzheimer's disease

BACKGROUND

In this article, we review a diverse body of research and draw conclusions about the usefulness, or lack there-of, of specific antioxidants in the prevention of Alzheimer's disease (AD).

METHODS

The National Library of Medicine's database was searched for the years 1996-2004 using the search terms "Alzheimer's, anti-oxidants, antioxidants."

RESULTS

Over 300 articles were identified and 187 articles were selected for inclusion based on relevance to the topic. Agents that show promise in helping prevent AD include: 1) aged garlic extract, 2) curcumin, 3) melatonin, 4) resveratrol, 5) Ginkgo biloba extract, 6) green tea, 7) vitamin C and 8) vitamin E.

CONCLUSIONS

While the clinical value of antioxidants for the prevention of AD is often ambiguous, some can be recommended based upon: 1) epidemiological evidence, 2) known benefits for prevention of other maladies, and 3) benign nature of the substance. Long-term, prospective studies are recommended.

Assessment of nutritional interventions for modification of age-associated cognitive decline using a canine model of human aging

The present review focuses on the utility of a canine model in evaluating nutritional interventions for age-related cognitive dysfunction. Aged dogs demonstrate progressive cognitive decline with concurrent amyloid-beta pathology that parallels the pathology observed in aging humans. Dogs, therefore, provide a natural model of human pathological aging. We have and are in the process of evaluating several nutritional-based interventions aimed at preventing cognitive decline and brain aging. In a three-year longitudinal study, we examined the effects of a diet enriched with antioxidants and mitochondrial cofactors on several measures of cognition and brain aging. Compared to controls, aged dogs on the enriched diet demonstrated both short- and long-term cognitive benefits, as well decreased deposition of amyloid-beta protein. The diet also reduced behavioral signs associated with canine Cognitive Dysfunction Syndrome when assessed in veterinary clinical trials. We also have preliminary evidence suggesting a beneficial effect of a proprietary blend of docosahexaenoic acid and phospholipids on both cognitive and physiological measures. Collectively, our data indicate (1) that the dog, either in the laboratory or in the clinic, provides an important tool for assessing nutritional interventions and (2) that combination interventions aimed at several mechanisms of pathological aging may prove more effective than single nutritive components in human trials.