Poor cognitive ageing: Vulnerabilities, mechanisms and the impact of nutritional interventions

BACKGROUND

Ageing is a highly complex process marked by a temporal cascade of events, which promote alterations in the normal functioning of an individual organism. The triggers of normal brain ageing are not well understood, even less so the factors which initiate and steer the neuronal degeneration, which underpin disorders such as dementia. A wealth of data on how nutrients and diets may support cognitive function and preserve brain health are available, yet the molecular mechanisms underlying their biological action in both normal ageing, age-related cognitive decline, and in the development of neurodegenerative disorders have not been clearly elucidated.

OBJECTIVES

This review aims to summarise the current state of knowledge of vulnerabilities that predispose towards dysfunctional brain ageing, highlight potential protective mechanisms, and discuss dietary interventions that may be used as therapies. A special focus of this paper is on the impact of nutrition on neuroprotection and the underlying molecular mechanisms, and this focus reflects the discussions held during the 2nd workshop 'Nutrition for the Ageing Brain: Functional Aspects and Mechanisms' in Copenhagen in June 2016. The present review is the most recent in a series produced by the Nutrition and Mental Performance Task Force under the auspice of the International Life Sciences Institute Europe (ILSI Europe).

CONCLUSION

Coupling studies of cognitive ageing with studies investigating the effect of nutrition and dietary interventions as strategies targeting specific mechanisms, such as neurogenesis, protein clearance, inflammation, and non-coding and microRNAs is of high value. Future research on the impact of nutrition on cognitive ageing will need to adopt a longitudinal approach and multimodal nutritional interventions will likely need to be imposed in early-life to observe significant impact in older age.

Changes in Synaptic Plasticity and Glutamate Receptors in Type 2 Diabetic KK-Ay Mice

In the present study, the progressive alteration of cognition and the mechanisms of reduction in long-term potentiation (LTP) in spontaneous obese KK-Ay type 2 diabetic mice were investigated. In the study, 3-, 5-, and 7-month-old KK-Ay mice were used. The results indicated that KK-Ay mice showed cognitive deficits in the Morris water maze test beginning at the age of 3 months. LTP was significantly impaired in KK-Ay mice during whole study period (3 to 7 months). The above deficits were reversible at an early stage (3 to 5 months old) by diet intervention. Moreover, we found the underlying mechanisms of LTP impairment in KK-Ay mice might be attributed to abnormal phosphorylation or expression of postsynaptic glutamate receptor subunits instead of alteration of basal synaptic transmission. The expression levels of NR1, NR2A, and NR2B subunits of N-methyl-d-aspartate receptors (NMDARs) were unchanged while the Tyr-dependent phosphorylation of both NR2A and NR2B subunits were significantly reduced in KK-Ay mice. The level of p-Src expression mediating this process was decreased, and the level of αCaMKII autophosphorylation was also reduced. Meanwhile, the GluR1 of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) was decreased, and GluR2 was significantly increased. These data suggest that deficits in synaptic plasticity in KK-Ay mice may arise from the abnormal phosphorylation of the NR2 subunits and the alteration of subunit composition of AMPARs. Diet intervention at an early stage of diabetes might alleviate the cognitive deficits and LTP reduction in KK-Ay mice.

Nutrition for the ageing brain: Towards evidence for an optimal diet

As people age they become increasingly susceptible to chronic and extremely debilitating brain diseases. The precise cause of the neuronal degeneration underlying these disorders, and indeed normal brain ageing remains however elusive. Considering the limits of existing preventive methods, there is a desire to develop effective and safe strategies. Growing preclinical and clinical research in healthy individuals or at the early stage of cognitive decline has demonstrated the beneficial impact of nutrition on cognitive functions. The present review is the most recent in a series produced by the Nutrition and Mental Performance Task Force under the auspice of the International Life Sciences Institute Europe (ILSI Europe). The latest scientific advances specific to how dietary nutrients and non-nutrient may affect cognitive ageing are presented. Furthermore, several key points related to mechanisms contributing to brain ageing, pathological conditions affecting brain function, and brain biomarkers are also discussed. Overall, findings are inconsistent and fragmented and more research is warranted to determine the underlying mechanisms and to establish dose-response relationships for optimal brain maintenance in different population subgroups. Such approaches are likely to provide the necessary evidence to develop research portfolios that will inform about new dietary recommendations on how to prevent cognitive decline.

Intake of Fruit and Vegetables and the Incident Risk of Cognitive Disorders: A Systematic Review and Meta-Analysis of Cohort Studies

OBJECTIVES

No quantitative assessment has been performed to specifically link the consumption of fruit and vegetables with the incident risk of cognitive disorders.

METHODS

We searched the PubMed and the Embase databases (both from the inception to June 13th, 2016) for records that report the intake of fruit and vegetables and the risk of developing cognitive disorders (Alzheimer's disease, dementia, and cognitive decline/impairment). A generic inverse-variance method (random-effects model) was used to combine the relative risks (RRs) and 95% confidence intervals (CIs). To explore the potential sources of heterogeneity, we performed the subgroup and meta-regression analyses by pre-specified characteristics.

RESULTS

We identified 6 cohorts involving a total of 21,175 participants. The pooled analysis showed that consumption of fruit and vegetables was inversely associated with the incident risk of cognitive disorders, and the pooled RR (95% CI) was 0.74 (0.62, 0.88), with evidence of significant heterogeneity (I2 =68%). Furthermore, we found that the significant heterogeneity might be attributed to the ethnic difference.

CONCLUSION

Further large prospective studies should be performed to quantify the potential dose-response patterns of fruit and/or vegetables intake and to explore the role of fruit or vegetables consumption separately on cognitive disorders in different populations.

Clearing the fog: a review of the effects of dietary omega-3 fatty acids and added sugars on chemotherapy-induced cognitive deficits

Cancer treatments such as chemotherapy have been an important part of extending survival in women diagnosed with breast cancer. However, chemotherapy can cause potentially toxic side effects in the brain that impair memory, verbal fluency, and processing speed in up to 30% of women treated. Women report that post-chemotherapy cognitive deficits negatively impact quality of life and may last up to ten years after treatment. Mechanisms underlying these cognitive impairments are not fully understood, but emerging evidence suggests that chemotherapy induces structural changes in the brain, produces neuroinflammation, and reduces adult hippocampal neurogenesis. Dietary approaches that modify inflammation and neurogenesis are promising strategies for reducing chemotherapy-induced cognitive deficits in breast cancer survivors. In this review, we describe the cognitive and neuronal side effects associated with commonly used chemotherapy treatments for breast cancer, and we focus on the often opposing actions of omega-3 fatty acids and added sugars on cognitive function, neuroinflammation, and adult hippocampal neurogenesis. Omega-3 fatty acids administered concurrently with doxorubicin chemotherapy have been shown to prevent depressive-like behaviors and reduce neuroinflammation, oxidative stress, and neural apoptosis in rodent models. In contrast, diets high in added sugars may interact with n-3 FAs to diminish their anti-inflammatory activity or act independently to increase neuroinflammation, reduce adult hippocampal neurogenesis, and promote cognitive deficits. We propose that a diet rich in long-chain, marine-derived omega-3 fatty acids and low in added sugars may be an ideal pattern for preventing or alleviating neuroinflammation and oxidative stress, thereby protecting neurons from the toxic effects of chemotherapy. Research testing this hypothesis could lead to the identification of modifiable dietary choices to reduce the long-term impact of chemotherapy on the cognitive functions that are important to quality of life in breast cancer survivors.

Gluten-free and casein-free diets in the therapy of autism

PURPOSE OF REVIEW

The purpose of this study is to discuss the role of gluten-free and casein-free diets in the treatment of autism.

RECENT FINDINGS

In a recent UK survey, more than 80% of parents of children with autism spectrum disorder reported some kind of dietary intervention for their child (gluten-free and casein-free diet in 29%). When asked about the effects of the gluten-free and casein-free diet, 20-29% of the parents reported significant improvements on the autism spectrum disorder core dimensions. The findings of this study suggest additional effects of a gluten-free and casein-free diet on comorbid problems of autism such as gastrointestinal symptoms, concentration, and attention. The findings of another recent investigation suggested that age and certain urine compounds may predict the response of autism symptoms to a gluten-free and casein-free diet. Although these results need to be replicated, they highlight the importance of patient subgroup analysis. Intervention trials evaluating the effects of a gluten-free and casein-free diet on autistic symptoms have so far been contradictory and inconclusive.

SUMMARY

Most investigations assessing the efficacy of a gluten-free and casein-free diet in the treatment of autism are seriously flawed. The evidence to support the therapeutic value of this diet is limited and weak. A gluten-free and casein-free diet should only be administered if an allergy or intolerance to nutritional gluten or casein is diagnosed.

Nutrition, Frailty, Cognitive Frailty and Prevention of Disabilities with Aging

Older adults can be categorized into three subgroups to better design and develop personalized interventions: the disabled (those needing assistance in the accomplishment of basic activities of daily living), the 'frail' (those presenting limitations and impairments in the absence of disability) and the 'robust' (those without frailty or disability). However, despite evidence linking frailty with a poor outcome, frailty is not implemented clinically in most countries. Since many people are not identified as frail, their treatment is frequently inappropriate in health care settings. Assessing the frail and prefrail older adults can no longer be delayed, we should rather act preventively before the irreversible disabling cascade is in place. Clinical characteristics of frailty such as weakness, low energy, slow walking speed, low physical activity and weight loss underline the links between nutrition and frailty. Physical frailty is also associated with cognitive frailty. We need to better understand cognitive frailty, a syndrome which must be differentiated from Alzheimer's disease. At the Gérontopôle frailty clinics, we have found that almost 40% of the patients referred to our center by their primary care physicians to evaluate frailty had significant weight loss in the past 3 months, 83.9% of patients presented slow gait speed, 53.8% a sedentary lifestyle and 57.7% poor muscle strength. Moreover, 43% had a Mini-Nutritional Assessment less than 23.5 and 9% less than 17, which reflects protein-energy undernutrition. More than 60% had some cognitive impairment associated with physical frailty.

Focus on Pivotal Role of Dietary Intake (Diet and Supplement) and Blood Levels of Tocopherols and Tocotrienols in Obtaining Successful Aging

Numerous specific age-related morbidities have been correlated with low intake and serum levels of tocopherols and tocotrienols. We performed a review in order to evaluate the extant evidence regarding: (1) the association between intake and serum levels of tocopherols and tocotrienols and age-related pathologies (osteoporosis, sarcopenia and cognitive impairment); and (2) the optimum diet therapy or supplementation with tocopherols and tocotrienols for the treatment of these abnormalities. This review included 51 eligible studies. The recent literature underlines that, given the detrimental effect of low intake and serum levels of tocopherols and tocotrienols on bone, muscle mass, and cognitive function, a change in the lifestyle must be the cornerstone in the prevention of these specific age-related pathologies related to vitamin E-deficient status. The optimum diet therapy in the elderly for avoiding vitamin E deficiency and its negative correlates, such as high inflammation and oxidation, must aim at achieving specific nutritional goals. These goals must be reached through: accession of the elderly subjects to specific personalized dietary programs aimed at achieving and/or maintaining body weight (avoid malnutrition); increase their intake of food rich in vitamin E, such as derivatives of oily seeds (in particular wheat germ oil), olive oil, hazelnuts, walnuts, almonds, and cereals rich in vitamin E (such as specific rice cultivar rich in tocotrienols) or take vitamin E supplements. In this case, vitamin E can be correctly used in a personalized way either for the outcome from the pathology or to achieve healthy aging and longevity without any adverse effects.

ESPEN guidelines on nutrition in dementia

BACKGROUND

Older people suffering from dementia are at increased risk of malnutrition due to various nutritional problems, and the question arises which interventions are effective in maintaining adequate nutritional intake and nutritional status in the course of the disease. It is of further interest whether supplementation of energy and/or specific nutrients is able to prevent further cognitive decline or even correct cognitive impairment, and in which situations artificial nutritional support is justified.

OBJECTIVE

It is the purpose of these guidelines to cover these issues with evidence-based recommendations.

METHODS

The guidelines were developed by an international multidisciplinary working group in accordance with officially accepted standards. The GRADE system was used for assigning strength of evidence. Recommendations were discussed, submitted to Delphi rounds and accepted in an online survey among ESPEN members.

RESULTS

26 recommendations for nutritional care of older persons with dementia are given. In every person with dementia, screening for malnutrition and close monitoring of body weight are recommended. In all stages of the disease, oral nutrition may be supported by provision of adequate, attractive food in a pleasant environment, by adequate nursing support and elimination of potential causes of malnutrition. Supplementation of single nutrients is not recommended unless there is a sign of deficiency. Oral nutritional supplements are recommended to improve nutritional status but not to correct cognitive impairment or prevent cognitive decline. Artificial nutrition is suggested in patients with mild or moderate dementia for a limited period of time to overcome a crisis situation with markedly insufficient oral intake, if low nutritional intake is predominantly caused by a potentially reversible condition, but not in patients with severe dementia or in the terminal phase of life.

CONCLUSION

Nutritional care and support should be an integral part of dementia management. In all stages of the disease, the decision for or against nutritional interventions should be made on an individual basis after carefully balancing expected benefit and potential burden, taking the (assumed) patient will and general prognosis into account.

MIND diet slows cognitive decline with aging

INTRODUCTION

The Mediterranean and dash diets have been shown to slow cognitive decline; however, neither diet is specific to the nutrition literature on dementia prevention.

METHODS

We devised the Mediterranean-Dietary Approach to Systolic Hypertension (DASH) diet intervention for neurodegenerative delay (MIND) diet score that specifically captures dietary components shown to be neuroprotective and related it to change in cognition over an average 4.7 years among 960 participants of the Memory and Aging Project.

RESULTS

In adjusted mixed models, the MIND score was positively associated with slower decline in global cognitive score (β = 0.0092; P < .0001) and with each of five cognitive domains. The difference in decline rates for being in the top tertile of MIND diet scores versus the lowest was equivalent to being 7.5 years younger in age.

DISCUSSION

The study findings suggest that the MIND diet substantially slows cognitive decline with age. Replication of these findings in a dietary intervention trial would be required to verify its relevance to brain health.

Effects of a high protein diet on cognition and brain metabolism in cirrhotic rats

Hepatic encephalopathy (HE) is a neurological complication observed in patients with liver disease. Patients who suffer from HE present neuropsychiatric, neuromuscular and behavioral symptoms. Animal models proposed to study HE resulting from cirrhosis mimic the clinical characteristics of cirrhosis and portal hypertension, and require the administration of hepatotoxins such as thioacetamide (TAA). The aim of this study was to assess the effects of a high protein diet on motor function, anxiety and memory processes in a model of cirrhosis induced by TAA administration. In addition, we used cytochrome c-oxidase (COx) histochemistry to assess the metabolic activity of the limbic system regions. Male rats were distributed into groups: control, animals with cirrhosis, Control rats receiving a high protein diet, and animals with cirrhosis receiving a high protein diet. Results showed preserved motor function and normal anxiety levels in all the groups. The animals with cirrhosis showed an impairment in active avoidance behavior and spatial memory, regardless of the diet they received. However, the animals with cirrhosis and a high protein diet showed longer escape latencies on the spatial memory task. The model of cirrhosis presented an under-activation of the dentate gyrus and CA3 hippocampal subfields and the medial part of the medial mammillary nucleus. The results suggest that a high protein intake worsens spatial memory deficits shown by the TAA-induced model of cirrhosis. However, high protein ingestion has no influence on the COx hypoactivity associated with the model.

Neurocognitive and neuroimaging outcome of early treated young adult PKU patients: A longitudinal study

The aim of the study was to explore the outcome of neurocognitive deficits and neuroimaging correlates in young adult early treated phenylketonuric (PKU) patients. We conducted a longitudinal study of 14 PKU patients that were assessed for IQ and neuropsychological functioning including executive functions (EF) over 14 years of follow-up (age range at 1st and 2nd assessments were 7.8-13.5 and 22.2-27.7 years, respectively). The IQ of all 14 PKU patients was within the normal range. With respect to the 1st assessment, mean IQ at follow-up did not decrease significantly. Compared to control subjects (n = 14), mean IQ of patients was significantly lower (p = .0005). Throughout adolescence and early adulthood there was an improvement of neuropsychological functioning of PKU patients in spite of the relaxation of diet, however some deficits were still detectable when compared to controls. All patients that underwent a second MRI scan showed white matter alterations ranging from mild to severe which was correlated neither with IQ nor with EF scoring. Cognitive, neuropsychological and neuroimaging outcome was influenced from life-long and/or second decade of life metabolic control. Nevertheless patients' developmental trajectories were in some cases independent from metabolic control. Our results support the hypothesis of an individual vulnerability to phenylalanine. However, as long as individual factors that account for the vulnerability to Phe are not recognized, strict dietary control is recommended for all the patients also in the second decade of life.

MIND diet associated with reduced incidence of Alzheimer's disease

INTRODUCTION

In a previous study, higher concordance to the MIND diet, a hybrid Mediterranean-Dietary Approaches to Stop Hypertension diet, was associated with slower cognitive decline. In this study we related these three dietary patterns to incident Alzheimer's disease (AD).

METHODS

We investigated the diet-AD relations in a prospective study of 923 participants, ages 58 to 98 years, followed on average 4.5 years. Diet was assessed by a semiquantitative food frequency questionnaire.

RESULTS

In adjusted proportional hazards models, the second (hazards ratio or HR = 0.65, 95% confidence interval or CI 0.44, 0.98) and highest tertiles (HR = 0.47, 95% CI 0.26, 0.76) of MIND diet scores had lower rates of AD versus tertile 1, whereas only the third tertiles of the DASH (HR = 0.61, 95% CI 0.38, 0.97) and Mediterranean (HR = 0.46, 95% CI 0.26, 0.79) diets were associated with lower AD rates.

DISCUSSION

High adherence to all three diets may reduce AD risk. Moderate adherence to the MIND diet may also decrease AD risk.

The role for dietary omega-3 fatty acids supplementation in older adults

Optimal nutrition is one of the most important determinants of healthier ageing, reducing the risk of disability, maintaining mental and physical functions, and thus preserving and ensuring a better quality of life. Dietary intake and nutrient absorption decline with age, thus increasing the risk of malnutrition, morbidity and mortality. Specific nutrients, particularly long-chain omega-3 polyunsaturated fatty acids (PUFAs), might have the potential of preventing and reducing co-morbidities in older adults. Omega-3 PUFAs are able to modulate inflammation, hyperlipidemia, platelet aggregation, and hypertension. Different mechanisms contribute to these effects, including conditioning cell membrane function and composition, eicosanoid production, and gene expression. The present review analyzes the influence of omega-3 PUFAs status and intake on brain function, cardiovascular system, immune function, muscle performance and bone health in older adults. Omega-3 FAs may have substantial benefits in reducing the risk of cognitive decline in older people. The available data encourage higher intakes of omega-3 PUFAs in the diet or via specific supplements. More studies are needed to confirm the role of omega-3 FAs in maintaining bone health and preventing the loss of muscle mass and function associated with ageing. In summary, omega-3 PUFAs are now identified as potential key nutrients, safe and effective in the treatment and prevention of several negative consequences of ageing.

A low glycaemic load breakfast can attenuate cognitive impairments observed in middle aged obese females with impaired glucose tolerance

BACKGROUND AND AIMS

There has been no systematic investigation of the individual and combined effects of impaired glucose tolerance (IGT) and obesity on cognitive function in the absence of ageing. The aims were to examine the effects of IGT and increased waist circumference on cognitive function in ostensibly healthy adults, and to investigate whether a low glycaemic load (GL) breakfast can attenuate cognitive impairments in these populations.

METHODS AND RESULTS

Sixty five females aged 30-50 years were classified into one of four groups following waist circumference (WC) measurements and an oral glucose tolerance test: NGT/low WC (n = 25), NGT/high WC (n = 22), IGT/low WC (n = 9), IGT/high WC (n = 9). Memory, psychomotor and executive functions were examined 30 and 120 min after consuming low GL, high GL and water breakfasts according to a randomised, crossover, counterbalanced design. IGT was associated with impairment of verbal and spatial memory, and psychomotor function relative to females with NGT, independent of waist circumference. Increased waist circumference was associated with impairment of verbal memory and executive function relative to females with low WC, independent of IGT. Consumption of the LGL breakfast attenuated verbal memory impairment in the IGT/high WC group relative to the HGL breakfast and no energy control.

CONCLUSION

Increased central adiposity and abnormalities in glucose tolerance preceding type 2 diabetes can have demonstrable negative effects on cognitive function, even in ostensibly healthy, middle-aged females. The potential for GL manipulations to modulate glycaemic response and cognitive function in type 2 diabetes and obesity merits further investigation.

Green tea consumption affects cognitive dysfunction in the elderly: a pilot study

Green tea is known to have various health benefits for humans. However, the effect of green tea consumption on cognitive dysfunction remains to be clinically verified. We conducted a clinical study to investigate the effects of green tea consumption on cognitive dysfunction. Twelve elderly nursing home residents with cognitive dysfunction (Mini-Mental State Examination Japanese version (MMSE-J) score: <28) participated in the study (2 men, 10 women; mean age, 88 years). The participants consumed green tea powder 2 g/day for 3 months. After three months of green tea consumption, the participants’ MMSE-J scores were significantly improved (before, 15.3 ± 7.7; after, 17.0 ± 8.2; p = 0.03). This result suggests that green tea consumption may be effective in improving cognitive function or reducing the progression of cognitive dysfunction; however, long-term large-scale controlled studies are needed to further clarify the effect.

Current evidence for the use of coffee and caffeine to prevent age-related cognitive decline and Alzheimer's disease

Although nothing has been proven conclusively to protect against cognitive aging, Alzheimer's disease or related dementias, decades of research suggest that specific approaches including the consumption of coffee may be effective. While coffee and caffeine are known to enhance short-term memory and cognition, some limited research also suggests that long-term use may protect against cognitive decline or dementia. In vitro and pre-clinical animal models have identified plausible neuroprotective mechanisms of action of both caffeine and other bioactive components of coffee, though epidemiology has produced mixed results. Some studies suggest a protective association while others report no benefit. To our knowledge, no evidence has been gathered from randomized controlled trials. Although moderate consumption of caffeinated coffee is generally safe for healthy people, it may not be for everyone, since comorbidities and personal genetics influence potential benefits and risks. Future studies could include short-term clinical trials with biomarker outcomes to validate findings from pre-clinical models and improved epidemiological studies that incorporate more standardized methods of data collection and analysis. Given the enormous economic and emotional toll threatened by the current epidemic of Alzheimer's disease and other dementias, it is critically important to validate potential prevention strategies such as coffee and caffeine.

[Study on early intervention of compound nutrition for cognitive dysfunction in Alzheimer's disease]

OBJECTIVE

To observe the early prevention effect of the compound nutrients recipe for cognitive dysfunction of Alzheimer' s disease model-APP-PSN transgenic mouse.

METHODS

36 APP-PSN transgenic mice aged two months randomly were divided into the intervention group supplied with compound recipe in the diet and the control group fed based feed, the former had high dose and low dose, 12 APP-PSN transgenic negative mice aged two months as the negative control were fed based feed. After 3 months' intervention, four groups' cognitive functions were evaluated using the Morris water maze, active avoidance experiment and jumping stair experiment.

RESULTS

There was not statistically different between all the four groups for the weight and food intake. Compared with the control group, Morris water maze's incubation period of the intervention group was lower obviously, and jumping stair experiment's incubation period of the intervention group was higher obviously. In the active avoidance experiment, the high and low dose intervention group' s conditioned response accounted about 46.67% and 45.00% respectively, and the control group's conditioned response accounted about 20.83%. The differences of the three behavioral experiments between control group and intervention group had the statistical significance (P < 0.05), so the same as between control group and negative control group (P < 0.05). And there was no difference between intervention group and negative control group for the three behavioral experiments.

CONCLUSION

The early supplementation with compound nutrition could postpone the occurrence and development of Alzheimer' s disease mice model's cognitive dysfunction.

Rationale and clinical data supporting nutritional intervention in Alzheimer's disease

Adequate nutrition plays an important role in the maintenance of cognitive function, particularly during aging. Malnutrition is amongst the risk factors for developing mild cognitive impairment (MCI) and Alzheimer's disease (AD). Epidemiological studies have associated deficiencies in some nutrients with a higher risk of cognitive dysfunction and/or AD. Cognitive decline in AD is correlated with synaptic loss and many of the components required to maintain optimal synaptic function are derived from dietary sources. As synapses are part of the neuronal membrane and are continuously being remodelled, the availability of sufficient levels of nutritional precursors (mainly uridine monophosphate, choline and omega-3 fatty acids) to make the phospholipids required to build neuronal membranes may have beneficial effects on synaptic degeneration in AD. In addition, B-vitamins, phospholipids and other micronutrients act as cofactors to enhance the supply of precursors required to make neuronal membranes and synapses. Despite this, no randomized controlled trial has hitherto provided evidence that any single nutrient has a beneficial effect on cognition or lowers the risk for AD. However, a multi-target approach using combinations of (micro)nutrients might have beneficial effects on cognitive function in neurodegenerative brain disorders like AD leading to synaptic degeneration. Here we review the clinical evidence for supplementation, based on a multi-target approach with a focus on key nutrients with a proposed role in synaptic dysfunction. Based on preclinical evidence, a nutrient mixture, Souvenaid(®) (Nutricia N.V., Zoetermeer, The Netherlands) was developed. Clinical trials with Souvenaid(®) have shown improved memory performance in patients with mild AD. Further clinical trials to evaluate the effects of nutritional intervention in MCI and early dementia due to AD are on-going.

Dietary and plant polyphenols exert neuroprotective effects and improve cognitive function in cerebral ischemia

Cerebral ischemia is caused by an interruption of blood flow to the brain which generally leads to irreversible brain damage. Ischemic injury is associated with vascular leakage, inflammation, tissue injury, and cell death. Cellular changes associated with ischemia include impairment of metabolism, energy failure, free radical production, excitotoxicity, altered calcium homeostasis, and activation of proteases all of which affect brain functioning and also contribute to longterm disabilities including cognitive decline. Inflammation, mitochondrial dysfunction, increased oxidative/nitrosative stress, and intracellular calcium overload contribute to brain injury including cell death and brain edema. However, there is a paucity of agents that can effectively reduce cerebral damage and hence considerable attention has focused on developing newer agents with more efficacy and fewer side-effects. Polyphenols are natural compounds with variable phenolic structures and are rich in vegetables, fruits, grains, bark, roots, tea, and wine. Most polyphenols have antioxidant, anti-inflammatory, and anti-apoptotic properties and their protective effects on mitochondrial functioning, glutamate uptake, and regulating intracellular calcium levels in ischemic injury in vitro have been demonstrated. This review will assess the current status of the potential effects of polyphenols in reducing cerebral injury and improving cognitive function in ischemia in animal and human studies. In addition, the review will also examine available patents in nutrition and agriculture that relates to cerebral ischemic injury with an emphasis on plant polyphenols.

A ketone ester diet exhibits anxiolytic and cognition-sparing properties, and lessens amyloid and tau pathologies in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) involves progressive accumulation of amyloid β-peptide (Aβ) and neurofibrillary pathologies, and glucose hypometabolism in brain regions critical for memory. The 3xTgAD mouse model was used to test the hypothesis that a ketone ester-based diet can ameliorate AD pathogenesis. Beginning at a presymptomatic age, 2 groups of male 3xTgAD mice were fed a diet containing a physiological enantiomeric precursor of ketone bodies (KET) or an isocaloric carbohydrate diet. The results of behavioral tests performed at 4 and 7 months after diet initiation revealed that KET-fed mice exhibited significantly less anxiety in 2 different tests. 3xTgAD mice on the KET diet also exhibited significant, albeit relatively subtle, improvements in performance on learning and memory tests. Immunohistochemical analyses revealed that KET-fed mice exhibited decreased Aβ deposition in the subiculum, CA1 and CA3 regions of the hippocampus, and the amygdala. KET-fed mice exhibited reduced levels of hyperphosphorylated tau deposition in the same regions of the hippocampus, amygdala, and cortex. Thus, a novel ketone ester can ameliorate proteopathic and behavioral deficits in a mouse AD model.

Modulation of Nrf2/ARE pathway by food polyphenols: a nutritional neuroprotective strategy for cognitive and neurodegenerative disorders

In recent years, there has been a growing interest, supported by a large number of experimental and epidemiological studies, for the beneficial effects of some phenolic substances, contained in commonly used spices and herbs, in preventing various age-related pathologic conditions, ranging from cancer to neurodegenerative diseases. Although the exact mechanisms by which polyphenols promote these effects remain to be elucidated, several reports have shown their ability to stimulate a general xenobiotic response in the target cells, activating multiple defense genes. Data from our and other laboratories have previously demonstrated that curcumin, the yellow pigment of curry, strongly induces heme-oxygenase-1 (HO-1) expression and activity in different brain cells via the activation of heterodimers of NF-E2-related factors 2 (Nrf2)/antioxidant responsive element (ARE) pathway. Many studies clearly demonstrate that activation ofNrf2 target genes, and particularly HO-1, in astrocytes and neurons is strongly protective against inflammation, oxidative damage, and cell death. In the central nervous system, the HO system has been reported to be very active, and its modulation seems to play a crucial role in the pathogenesis of neurodegenerative disorders. Recent and unpublished data from our group revealed that low concentrations of epigallocatechin-3-gallate, the major green tea catechin, induces HO-1 by ARE/Nrf2 pathway in hippocampal neurons, and by this induction, it is able to protect neurons against different models of oxidative damages. Furthermore, we have demonstrated that other phenolics, such as caffeic acid phenethyl ester and ethyl ferulate, are also able to protect neurons via HO-1 induction. These studies identify a novel class of compounds that could be used for therapeutic purposes as preventive agents against cognitive decline.

Diet intervention and cerebrospinal fluid biomarkers in amnestic mild cognitive impairment

OBJECTIVE

To compare the effects of a 4-week high-saturated fat/high-glycemic index (HIGH) diet with a low-saturated fat/low-glycemic index (LOW) diet on insulin and lipid metabolism, cerebrospinal fluid (CSF) markers of Alzheimer disease, and cognition for healthy adults and adults with amnestic mild cognitive impairment (aMCI).

DESIGN

Randomized controlled trial.

SETTING

Veterans Affairs Medical Center clinical research unit.

PARTICIPANTS

Forty-nine older adults (20 healthy adults with a mean [SD] age of 69.3 [7.4] years and 29 adults with aMCI with a mean [SD] age of 67.6 [6.8] years).

INTERVENTION

Participants received the HIGH diet (fat, 45% [saturated fat, > 25%]; carbohydrates, 35%-40% [glycemic index, > 70]; and protein, 15%-20%) or the LOW diet (fat, 25%; [saturated fat, < 7%]; carbohydrates, 55%-60% [glycemic index, < 55]; and protein, 15%-20%) for 4 weeks. Cognitive tests, an oral glucose tolerance test, and lumbar puncture were conducted at baseline and during the fourth week of the diet.

MAIN OUTCOME MEASURES

The CSF concentrations of β-amyloid (Aβ42 and Aβ40), tau protein, insulin, F2-isoprostanes, and apolipoprotein E, plasma lipids and insulin, and measures of cognition.

RESULTS

For the aMCI group, the LOW diet increased CSF Aβ42 concentrations, contrary to the pathologic pattern of lowered CSF Aβ42 typically observed in Alzheimer disease. The LOW diet had the opposite effect for healthy adults, ie, decreasing CSF Aβ42, whereas the HIGH diet increased CSF Aβ42. The CSF apolipoprotein E concentration was increased by the LOW diet and decreased by the HIGH diet for both groups. For the aMCI group, the CSF insulin concentration increased with the LOW diet, but the HIGH diet lowered the CSF insulin concentration for healthy adults. The HIGH diet increased and the LOW diet decreased plasma lipids, insulin, and CSF F2-isoprostane concentrations. Delayed visual memory improved for both groups after completion of 4 weeks of the LOW diet.

CONCLUSION

Our results suggest that diet may be a powerful environmental factor that modulates Alzheimer disease risk through its effects on central nervous system concentrations of Aβ42, lipoproteins, oxidative stress, and insulin.

Brain and spinal cord interaction: a dietary curcumin derivative counteracts locomotor and cognitive deficits after brain trauma

BACKGROUND

In addition to cognitive dysfunction, locomotor deficits are prevalent in traumatic brain injured (TBI) patients; however, it is unclear how a concussive injury can affect spinal cord centers. Moreover, there are no current efficient treatments that can counteract the broad pathology associated with TBI.

OBJECTIVE

The authors have investigated potential molecular basis for the disruptive effects of TBI on spinal cord and hippocampus and the neuroprotection of a curcumin derivative to reduce the effects of experimental TBI.

METHODS

The authors performed fluid percussion injury (FPI) and then rats were exposed to dietary supplementation of the curcumin derivative (CNB-001; 500 ppm). The curry spice curcumin has protective capacity in animal models of neurodegenerative diseases, and the curcumin derivative has enhanced brain absorption and biological activity.

RESULTS

The results show that FPI in rats, in addition to reducing learning ability, reduced locomotor performance. Behavioral deficits were accompanied by reductions in molecular systems important for synaptic plasticity underlying behavioral plasticity in the brain and spinal cord. The post-TBI dietary supplementation of the curcumin derivative normalized levels of BDNF, and its downstream effectors on synaptic plasticity (CREB, synapsin I) and neuronal signaling (CaMKII), as well as levels of oxidative stress-related molecules (SOD, Sir2).

CONCLUSIONS

These studies define a mechanism by which TBI can compromise centers related to cognitive processing and locomotion. The findings also show the influence of the curcumin derivative on synaptic plasticity events in the brain and spinal cord and emphasize the therapeutic potential of this noninvasive dietary intervention for TBI.

Morinda citrifolia fruit reduces stress-induced impairment of cognitive function accompanied by vasculature improvement in mice

The purpose of this study was to investigate effects of Morinda citrifolia fruit juice, which is locally called Noni, on stress-induced impairment of cognitive function. Male ICR mice were divided into four groups: Control (C mice), Restraint stress (RS mice), Restraint+Noni (Noni mice), and Restraint+vitamin E (VE mice). The RS, Noni, and VE mice were subjected to 8h of chronic restraint stress (CRS) 6days a week for 6weeks. During this period, the Noni and VE mice were given a diet supplemented with either Noni or vitamin E, respectively. At Week 5, the mice were subjected to the Morris water maze (MWM) test to measure cognitive function. At Week 7, mouse brains were isolated for immunohistochemical analysis with BrdU or CD31 antibody to assess the proliferation of new cells and blood vessel density in the dentate gyrus of the hippocampus. The time taken to reach the platform in the MWM test was shorter in the Noni mice than in the RS mice on Day 16. Malondialdehyde (MDA ) level of the Noni mice was significantly higher than that of the C mice; however no difference was found in MDA levels between the VE and C mice. Blood vessel area was significantly lower in the R and VE mice than in the C mice; no difference was found between the C and Noni mice. These findings suggest that the administration of Noni fruit juice protects brains from stress-induced impairment of cognitive function and that this protective effect may be related to improvement in stress-induced decreases in blood vessel density in the hippocampal dentate gyrus.

Mediterranean diet and cognitive function in older adults

PURPOSE OF REVIEW

The effectiveness of the Mediterranean diet in reducing the prevalence of cardiovascular and chronic diseases has been largely evidenced. Although nutrition constitutes an interesting approach in preventing age-related brain disorders, the association between the Mediterranean-style diet and cognitive functions has been very occasionally explored.

RECENT FINDINGS

Results are provided from only two recent prospective cohorts of older Americans and French individuals (> or =65 years) on the relationship of Mediterranean diet to cognitive functions. A high adherence to the Mediterranean diet has been associated with slower cognitive decline, with reduced risk of mild cognitive impairment conversion to Alzheimer's disease and with reduced risk of Alzheimer's disease.

SUMMARY

The possibility that the Mediterranean diet may affect not only the risk for Alzheimer's disease, but also the evolution of cognitive performances a long time before the clinical diagnosis of dementia and subsequent disease course constitutes major promising results. Replication of these results in other populations seems necessary to allow their generalization and to propose the Mediterranean diet as a potential preventive approach against cognitive decline or dementia in addition to its expected benefits against many other unfavorable outcomes in a public health perspective.

Validity of estimated dietary eicosapentaenoic acid and docosahexaenoic acid intakes determined by interviewer-administered food frequency questionnaire among older adults with mild-to-moderate cognitive impairment or dementia

Epidemiologic research is increasingly being focused on elderly persons, many of whom exhibit mild-to-moderate cognitive impairment. This presents a challenge for collection and interpretation of self-reported dietary data. There are few reports on the impact of cognitive function and dementia on the validity of self-reported dietary intakes. Using plasma phospholipid fatty acid profiles as a biomarker of intake, the authors assessed the validity of an interviewer-administered food frequency questionnaire (FFQ) to estimate intakes of 2 marine-based omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), among 273 community-dwelling adults aged > or =60 years participating in the Nutrition, Aging, and Memory in Elders Study (Boston, Massachusetts, 2002-2008). Age- and energy-adjusted Pearson correlation coefficients for correlations between dietary intakes and plasma phospholipids were consistent across categories of high and low cognitive function (r = 0.48), based on Mini-Mental State Examination score, and were similar across clinically diagnosed categories of normal functioning (r = 0.49), mild cognitive impairment (r = 0.45), and dementia (r = 0.52). The FFQ ranked 78% of subjects to within 1 quartile of their plasma phospholipid EPA + DHA quartile. This frequency was consistently high across all cognitive categories. With interviewer administration, this FFQ seems to be a valid method of assessing dietary EPA + DHA intake in older adults with mild-to-moderate cognitive impairment.

Creatine Supplementation and Cognitive Performance in Elderly Individuals

The purpose of this study was to examine the effect of creatine supplementation on the cognitive performance of elderly people. Participants were divided into two groups, which were tested on random number generation, forward and backward number and spatial recall, and long-term memory tasks to establish a baseline level. Group 1 (n = 15) were given 5 g four times a day of placebo for 1 week, followed by the same dosage of creatine for the second week. Group 2 (n = 17) were given placebo both weeks. Participants were retested at the end of each week. Results showed a significant effect of creatine supplementation on all tasks except backward number recall. It was concluded that creatine supplementation aids cognition in the elderly.

Physicians' attitudes about artificial feeding in older patients with severe cognitive impairment in Japan: a qualitative study

Background

The question of whether to withhold artificial nutrition and hydration (ANH) from severely cognitively impaired older adults has remained nearly unexplored in Japan, where provision of ANH is considered standard care. The objective of this study was to identify and analyze factors related to the decision to provide ANH through percutaneous endoscopic gastrostomy (PEG) in older Japanese adults with severe cognitive impairment.

Methods

Retrospective, in-depth interviews with thirty physicians experienced in the care of older, bed-ridden, non-communicative patients with severe cognitive impairment. Interview content included questions about factors influencing the decision to provide or withhold ANH, concerns and dilemmas concerning ANH and the choice of PEG feeding as an ANH method. The process of data collection and analysis followed the Grounded Theory approach.

Results

Data analysis identified five factors that influence Japanese physicians' decision to provide ANH through PEG tubes: (1) the national health insurance system that allows elderly patients to become long-term hospital in-patients; (2) legal barriers with regard to limiting treatment, including the risk of prosecution; (3) emotional barriers, especially abhorrence of death by 'starvation'; (4) cultural values that promote family-oriented end-of-life decision making; and (5) reimbursement-related factors involved in the choice of PEG. However, a small number of physicians did offer patients' families the option of withholding ANH. These physicians shared certain characteristics, such as a different perception of ANH and repeated communication with families concerning end-of-life care. These qualities were found to reduce some of the effects of the factors that favor provision of ANH.

Conclusion

The framework of Japan's medical-legal system unintentionally provides many physicians an incentive to routinely offer ANH for this patient group through PEG tubes. It seems apparent that end-of-life education should be provided to medical providers in Japan to change the automatic assumption that ANH must be provided.

Calorie restriction ameliorates neurodegenerative phenotypes in forebrain-specific presenilin-1 and presenilin-2 double knockout mice

Conditional double knockout of presenilin-1 and presenilin-2 (cDKO) in forebrain of mice led to brain atrophy, tau hyperphosphorylation, synaptic dysfunction and cognitive deficit. These brain changes recapitulated most of the neurodegenerative phenotypes of Alzheimer's disease (AD). In this report, we have investigated the effects of 4-month calorie restriction (CR) regimen on different phenotypes in cDKO mice. We found that CR improved novel object recognition and contextual fear conditioning memory in the cDKO mice. Histological and biochemical analysis showed that CR attenuated ventricle enlargement, caspase-3 activation and astrogliosis. In addition, the induction of tau hyperphosphorylation in the cDKO mice was reduced by CR, possibly through reduction of p25 accumulation and aberrant CDK5 activation. Finally, DNA microarray analysis demonstrated that CR could increase the expression of neurogenesis related genes and decrease the expression of inflammation related genes in the hippocampus of cDKO mice. The possible molecular mechanisms of the CR effects on alleviating AD pathogenesis have been discussed.

Folsäure – Freiwilliger Zusatz bei diversen Lebensmitteln oder obligate Anreicherung eines Grundnahrungsmittels?

Eine normale, landesübliche Mischkost reicht nicht aus, um den von wissenschaftlichen Gremien definierten Tagesbedarf von 400 μg Folsäure zu decken. Das Angebot diverser Folsäure-angereicherter Lebensmittel scheint deshalb berechtigt. Ob damit eine prophylaktische Wirkung auf die verschiedenen Homocystein-assoziierten Krankheiten der zweiten Lebenshälfte erwartet werden kann, ist allerdings nicht bewiesen, sondern nur fundierte Hypothese. Für die Verhütung von Neuralrohrdefekten und andern embryonalen Missbildungen und frühkindlichen Malignomen ist eine medikamentöse Prophylaxe mit 0,4–0,8 mg Folsäure notwendig, oder die generelle, d.h. obligate Anreicherung von Backmehl. Die Problematik dieser im Ausland erfolgreich erprobten Maßnahme wird diskutiert.

Dietary supplementation of arachidonic and docosahexaenoic acids improves cognitive dysfunction

Age-dependent increase of peroxidation of membrane fatty acids such as arachidonic acid (ARA) and docosahexaenoic acid (DHA) in neurons was reported to cause a decline of the hippocampal long-term potentiation (LTP) and cognitive dysfunction in rodents. Although supplementation of ARA and DHA can improve LTP and cognitive function in rodents, their effects in humans are unknown. The present work was undertaken to study whether ARA and DHA have beneficial effects in human amnesic patients. The subjects were 21 mild cognitive dysfunction (12 MCI-A with supplementation and 9 MIC-P with placebo), 10 organic brain lesions (organic), and 8 Alzheimer's disease (AD). The cognitive functions were evaluated using Japanese version of repeatable battery for assessment of neuropsychological status (RBANS) at two time points: before and 90 days after the supplementation of 240 mg/day ARA and DHA, or 240 mg/day of olive oil, respectively. MCI-A group showed a significant improvement of the immediate memory and attention score. In addition, organic group showed a significant improvement of immediate and delayed memories. However, there were no significant improvements of each score in AD and MCI-P groups. It is suggested from these data that ARA and DHA supplementation can improve the cognitive dysfunction due to organic brain damages or aging.

Long-term antioxidant supplementation attenuates oxidative stress markers and cognitive deficits in senescent-accelerated OXYS rats

Oxidative damage of biomolecules increases with age and is postulated to be a major causal factor of various neurodegenerative disorders. Consequently, the concept of neuroprotection by antioxidants has been developed. Recently we have shown that the behaviour of young senescent-accelerated OXYS rats is similar to the behaviour of old Wistar animals. To determine the role of oxidative stress in this phenomenon we investigated age-related changes in protein carbonyls (PrC), lipid peroxides (LP), reduced glutathione (GSH), alpha-tocopherol (TP) and SOD activity in the brain of OXYS and Wistar rats. We also studied the effect of long-term supplementation with bilberry extract (2g/kg of diet) and Vitamin E (140 mg/kg of diet) on oxidative stress markers and on learning in passive avoidance test. In both rat strains LP, PrC and TP increased with age and at 24 months PrC was significantly higher (p<0.0001) in OXYS rats. At 3 months GSH was higher and SOD activity was lower in OXYS rats than in Wistar rats. SOD activity decreased with age in OXYS whereas increased in Wistar rats. Cognitive impairments in OXYS rats were manifested earlier than significant differences in the level of brain oxidative stress markers between two strains. By contrast, differences in antioxidant systems of Wistar and OXYS rats were registered at 3 months. Antioxidants attenuated cognitive deficits in OXYS rats, providing evidence for therapeutic role of antioxidants. Nevertheless, the exact mechanisms of neuroprotective effects of antioxidants in vivo and the real impact of oxidative stress on the development of cognitive impairments in OXYS rats still needs to be further investigated.

Nutritional and cognitive relationships and long-term mortality in patients with various dementia disorders

BACKGROUND

Subjects with dementia are at risk for protein-energy malnutrition.

OBJECTIVE

To study the nutritional status, the short-term effects of adapted nutritional routines and the long-term mortality in subjects admitted for evaluation of cognitive dysfunction.

DESIGN

prospective observational study.

SETTING

University Hospital.

SUBJECTS

A total of 231 patients (80 +/- 7 years, 65% women).

METHODS

Body mass index (BMI, kg/m2), serum concentrations of albumin, ferritin, vitamin B12, folic acid and haemoglobin as well as Mini-Mental State Examination (MMSE, 0-30 p) results and co-morbidity were recorded at hospital admittance and before discharge. Seven years later, mortality was registered.

RESULTS

Mean BMI was in the normal range (23.3 +/- 4) as were the biochemical indices, and they did not vary among patients with Alzheimer's disease (AD), vascular dementia (VaD), mild cognitive impairment, mixed dementia and other diagnoses. A BMI of <23 was found in 108 (52%) subjects. Weight and MMSE score correlated weakly (r = 0.18, P < 0.01) at inclusion. During a median hospital stay of 3 weeks, an average weight gain of 0.5 +/- 1.8 kg (P < 0.001) and an increase in MMSE score of 0.9 +/- 3 (P < 0.001) was observed. However, these changes did not correlate. A BMI of <23 was associated with an increased risk for 7-year mortality (OR 3, 95% CI = 1.3-6.7), which was independent of age, male gender, dementia diagnosis and co-morbidity.

CONCLUSIONS

Nutritional status did not vary in patients with various dementia diagnoses. A BMI of <23 was related to reduced 7-year survival, but this result was independent of co-morbidity, male gender and age.

Roles of vitamins E and C on neurodegenerative diseases and cognitive performance

Demographic changes, together with improvements in nutrition, general health, and life expectancy, will greatly change the social and economic structures of most industrialized and developing countries in the next 50 years. Extended life expectancy has increased the number of chronic illnesses and disabilities, including cognitive impairments. Inflammatory processes and vascular dysfunctions appear to play important roles in the pathogenesis of age-associated pathologies including Alzheimer's and Parkinson's disease. A large body of evidence shows that both vitamins E and C are important for the central nervous system and that a decrease in their concentrations causes structural and functional damage to the cells. Several studies reveal a link between diets rich in fruits and vegetables containing generous amounts of vitamins E and C and lower incidence of certain chronic diseases.

Dietary enrichment counteracts age-associated cognitive dysfunction in canines

Advanced age is accompanied by cognitive decline indicative of central nervous system dysfunction. One possibly critical causal factor is oxidative stress. Accordingly, we studied the effects of dietary antioxidants and age in a canine model of aging that parallels the key features of cognitive decline and neuropathology in humans. Old and young animals were placed on either a standard control food, or a food enriched with a broad spectrum of antioxidants and mitochondrial enzymatic cofactors. After 6 months of treatment, the animals were tested on four increasingly difficult oddity discrimination learning problems. The old animals learned more slowly than the young, making significantly more errors. However, this age-associated decline was reduced in the animals fed the enriched food, particularly on the more difficult tasks. These results indicate that maintenance on foods fortified with complex mixtures of antioxidants can partially counteract the deleterious effects of aging on cognition.

Brain aging in the canine: a diet enriched in antioxidants reduces cognitive dysfunction

Animal models that simulate various aspects of human brain aging are an essential step in the development of interventions to manage cognitive dysfunction in the elderly. Over the past several years we have been studying cognition and neuropathology in the aged-canine (dog). Like humans, canines naturally accumulate deposits of beta-amyloid (Abeta) in the brain with age. Further, canines and humans share the same Abeta sequence and also first show deposits of the longer Abeta1-42 species followed by the deposition of Abeta1-40. Aged canines like humans also show increased oxidative damage. As a function of age, canines show impaired learning and memory on tasks similar to those used in aged primates and humans. The extent of Abeta deposition correlates with the severity of cognitive dysfunction in canines. To test the hypothesis that a cascade of mechanisms centered on oxidative damage and Abeta results in cognitive dysfunction we have evaluated the cognitive effects of an antioxidant diet in aged canines. The diet resulted in a significant improvement in the ability of aged but not young animals to acquire progressively more difficult learning tasks (e.g. oddity discrimination learning). The canine represent a higher animal model to study the earliest declines in the cognitive continuum that includes age associated memory impairments (AAMI) and mild cognitive impairment (MCI) observed in human aging. Thus, studies in the canine model suggest that oxidative damage impairs cognitive function and that antioxidant treatment can result in significant improvements, supporting the need for further human studies.

The effect of n-3 polyunsaturated fatty acid-rich diets on cognitive and cerebrovascular parameters in chronic cerebral hypoperfusion

Western diets consist to a large part of n-6 polyunsaturated fatty acids (PUFAs). These n-6 PUFAs and their conversion products favor immune and inflammatory reactions and compromise vasoregulation, which can contribute to the development of dementia. Recent epidemiological studies associated dementia, particularly the type accompanied by a vascular component, with high, saturated dietary fat intake. Conversely, high fish consumption (a source of long chain n-3 PUFAs) was related to a reduced risk for cognitive decline. Therefore we studied the effects of long chain n-3 PUFAs in rats with bilateral occlusion of the common carotid arteries (2VO), which mimics cerebral hypoperfusion, a risk factor for dementia. Male Wistar rats received experimental diets with a decreased (n-6)/(n-3) ratio from weaning on. At the age of 3 months, the animals underwent 2VO surgery. The rats were tested in the elevated plus maze, an active avoidance paradigm and the Morris water maze (at different survival times). Following behavioral testing, the animals were sacrificed at the age of 7 months. The frontoparietal cortex was analyzed for capillary ultrastructure with electron microscopy. No effects of cerebral hypoperfusion or diet were found on elevated plus maze and active avoidance, while spatial memory in the Morris maze was compromised due to cerebral hypoperfusion under placebo dietary conditions. n-3 PUFA supplementation in combination with extra additives improved the performance of the 2VO animals. The number of endothelial mitochondria, as well as the ratio of microvessels with degenerative pericytes appeared to be lower due to long chain n-3 PUFAs. These results may indicate an improved condition of the blood-brain barrier.

The influence of soy-derived phosphatidylserine on cognition in age-associated memory impairment

Phosphatidylserine (PS) is a phospholipid widely sold as a nutritional supplement. PS has been claimed to enhance neuronal membrane function and hence cognitive function, especially in the elderly. We report the results of a clinical trial of soybean-derived PS (S-PS) in aging subjects with memory complaints. Subjects were 120 elderly (> 57 years) of both sexes who fulfilled the more stringent criteria for age-associated memory impairment (AAMI); some also fulfilled the criteria for age-associated cognitive decline. Subjects were allocated at random to one of the three treatment groups: placebo, 300mg S-PS daily, or 600mg S-PS daily. Assessments were carried out at baseline, after 6 and 12 weeks of treatment, and after a wash-out period of 3 weeks. Tests of learning and memory, choice reaction time, planning and attentional functions were administered at each assessment. Delayed recall and recognition of a previously learned word list comprised the primary outcome measures. No significant differences were found in any of the outcome variables between the treatment groups. There were also no significant interactions between treatment and 'severity of memory complaints'. In conclusion, a daily supplement of S-PS does not affect memory or other cognitive functions in older individuals with memory complaints.

High monounsaturated fatty acids intake protects against age-related cognitive decline

OBJECTIVE

To study the relationships between dietary macronutrient intakes and age-related changes in cognitive functions.

METHODS

We investigated these associations in the prevalence survey (1992 through 1993) of the Italian Longitudinal Study on Aging (ILSA). The population-based sample of 5,632 subjects of the ILSA, age 65 to 84 years, was identified from the electoral rolls of eight Italian municipalities. In this study, standardized test batteries assessing global cognitive functions (Mini-Mental State Examination [MMSE]), selective attention (Digit Cancellation Test [DCT]), and episodic memory (Babcock Story Recall Test), and a semi-quantitative food frequency questionnaire evaluating macronutrient energy intakes, were performed on 278 nondemented elderly subjects from the randomized cohort of Casamassima, Bari (n = 704).

RESULTS

There was an inverse relationship between monounsaturated fatty acids (MUFAs) energy intake and cognitive decline (MMSE < 24). The effect of education on the odds of having a MMSE score <24 decreased exponentially with the increase of MUFA intakes (over 2,400 kJ; odds ratio, 0.69). Moreover, a significant inverse association was observed between MUFA intakes and DCT score (odds ratio, 0.99). No association was found between nutritional variables and episodic memory.

CONCLUSIONS

In an elderly population of Southern Italy with a typical Mediterranean diet, high MUFA intakes appeared to be protective against age-related cognitive decline. Prospective clinical trials are needed to evaluate the impact of specific dietary macronutrient intakes on the age-related changes of cognitive functions.

Long-term dietary strawberry, spinach, or vitamin E supplementation retards the onset of age-related neuronal signal-transduction and cognitive behavioral deficits

Recent research has indicated that increased vulnerability to oxidative stress may be the major factor involved in CNS functional declines in aging and age-related neurodegenerative diseases, and that antioxidants, e.g., vitamin E, may ameliorate or prevent these declines. Present studies examined whether long-term feeding of Fischer 344 rats, beginning when the rats were 6 months of age and continuing for 8 months, with diets supplemented with a fruit or vegetable extract identified as being high in antioxidant activity, could prevent the age-related induction of receptor-mediated signal transduction deficits that might have a behavioral component. Thus, the following parameters were examined: (1) oxotremorine-enhanced striatal dopamine release (OX-K+-ERDA), (2) cerebellar beta receptor augmentation of GABA responding, (3) striatal synaptosomal 45Ca2+ clearance, (4) carbachol-stimulated GTPase activity, and (5) Morris water maze performance. The rats were given control diets or those supplemented with strawberry extracts (SE), 9.5 gm/kg dried aqueous extract (DAE), spinach (SPN 6.4 gm/kg DAE), or vitamin E (500 IU/kg). Results indicated that SPN-fed rats demonstrated the greatest retardation of age-effects on all parameters except GTPase activity, on which SE had the greatest effect, whereas SE and vitamin E showed significant but equal protection against these age-induced deficits on the other parameters. For example, OX-K+-ERDA enhancement was four times greater in the SPN group than in controls. Thus, phytochemicals present in antioxidant-rich foods such as spinach may be beneficial in retarding functional age-related CNS and cognitive behavioral deficits and, perhaps, may have some benefit in neurodegenerative disease.