High-dose antioxidant supplements and cognitive function in community-dwelling elderly women

The Involvement of Antioxidants in Cognitive Decline and Neurodegeneration: Mens Sana in Corpore Sano

With neurodegenerative disorders being on the rise, a great deal of research from multiple fields is being conducted in order to further knowledge and propose novel therapeutic interventions. Among these investigations, research on the role of antioxidants in contrasting cognitive decline is putting forward interesting and promising results. In this review, we aim to collect evidence that focused on the role of a variety of antioxidants and antioxidant-rich foods in improving or stabilizing cognitive functions, memory, and Alzheimer's disease, the most common neurodegenerative disorder. Specifically, we considered evidence collected on humans, either through longitudinal studies or randomized, placebo-controlled ones, which evaluated cognitive performance, memory abilities, or the progression level of neurodegeneration. Overall, despite a great deal of variety between study protocols, cohorts of participants involved, neuropsychological tests used, and investigated antioxidants, there is a solid trend that suggests that the properties of antioxidants may be helpful in hampering cognitive decline in older people. Thus, the help of future research that will further elucidate the role of antioxidants in neuroprotection will lead to the development of novel interventions that will take into account such findings to provide a more global approach to treating neurodegenerative disorders.

Real-time imaging of mitochondrial redox reveals increased mitochondrial oxidative stress associated with amyloid β aggregates in vivo in a mouse model of Alzheimer's disease

BACKGROUND

Reactive oxidative stress is a critical player in the amyloid beta (Aβ) toxicity that contributes to neurodegeneration in Alzheimer's disease (AD). Damaged mitochondria are one of the main sources of reactive oxygen species and accumulate in Aβ plaque-associated dystrophic neurites in the AD brain. Although Aβ causes neuronal mitochondria reactive oxidative stress in vitro, this has never been directly observed in vivo in the living mouse brain. Here, we tested for the first time whether Aβ plaques and soluble Aβ oligomers induce mitochondrial oxidative stress in surrounding neurons in vivo, and whether this neurotoxic effect can be abrogated using mitochondrial-targeted antioxidants.

METHODS

We expressed a genetically encoded fluorescent ratiometric mitochondria-targeted reporter of oxidative stress in mouse models of the disease and performed intravital multiphoton microscopy of neuronal mitochondria and Aβ plaques.

RESULTS

For the first time, we demonstrated by direct observation in the living mouse brain exacerbated mitochondrial oxidative stress in neurons after both Aβ plaque deposition and direct application of soluble oligomeric Aβ onto the brain, and determined the most likely pathological sequence of events leading to oxidative stress in vivo. Oxidative stress could be inhibited by both blocking calcium influx into mitochondria and treating with the mitochondria-targeted antioxidant SS31. Remarkably, the latter ameliorated plaque-associated dystrophic neurites without impacting Aβ plaque burden.

CONCLUSIONS

Considering these results, combination of mitochondria-targeted compounds with other anti-amyloid beta or anti-tau therapies hold promise as neuroprotective drugs for the prevention and/or treatment of AD.

Potential neuroprotective effects of fermented foods and beverages in old age: a systematic review

Purpose

Numerous articles have recently studied the involvement of the gut microbiota in neurological diseases. Aging is associated with changes in the microbiome, which implies a reduction in microbial biodiversity among other changes. Considering that the consumption of a fermented-food diet improves intestinal permeability and barrier function, it seems of interest to study its participation in the prevention of neurodegenerative diseases. This article reviews existing studies to establish whether the consumption of fermented foods and fermented beverages prevents or ameliorates neurodegenerative decline in old age.

Methods

The protocol used was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Details of the protocol for this systematic review are registered on PROSPERO (CRD42021250921).

Results

Out of 465 articles identified in the Pubmed, Scopus, and Cochrane Library databases, a total of 29 that examined the relationship of the consumption of fermented products with cognitive impairment in old people were selected (22 cohort, 4 case-control, and 3 cross-sectional studies). The results suggest that low-to-moderate alcohol consumption and daily intake of coffee, soy products, and fermented-food diets in general are associated with a lower risk of dementia and Alzheimer's disease.

Conclusion

Daily consumption of fermented foods and beverages, either alone or as part of a diet, has neuroprotective effects and slows cognitive decline in old people.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=250921, identifier: CRD42021250921.

Effect of antioxidant intake patterns on risks of dementia and cognitive decline

BACKGROUND

Previous studies have suggested that increased antioxidant intakes might reduce risk of cognitive disorders including Alzheimer's disease (AD). Which avenue of antioxidant intake (vitamin E/C) is more effective for decreasing risk, however, is largely unknown.

OBJECTIVES

To quantitatively investigate the relationships between the pattern of antioxidant intakes and risks of dementia and cognitive decline.

METHODS

We searched all related prospective cohort studies reporting antioxidant intakes (diet and/or supplement) from patients with cognitive disorders. We conducted dose-response meta-analyses to assess potential linear and non-linear dose-response relationships. Summary RRs and 95% CIs were calculated using a random- or fixed-effects model.

RESULTS

73 eligible cohort studies totaling > 28,257 participants were included in the meta-analysis; the pooled relative risks of AD were 0.75 (95% CI 0.57-0.99; I² = 59.9%) for the dietary only intake of vitamin E, 0.73 (95% CI 0.54-1.00; I² = 0%) for the dietary plus supplemental intake of vitamin E, and 0.70 (95% CI 0.51-0.95; I² = 0%) for the dietary plus supplemental intake of vitamin C. Moreover, pooled RRs of AD and vitamin C intake per 20 mg/day increase were 0.98 (95% CI 0.97-0.99) via dietary plus supplemental intake, 0.98 (95% CI 0.96-1.00) in the dietary only intake and 0.98 (95% CI 0.98-0.99) in the overall intake. There were no significant associations of all-cause dementia or cognitive impairment no dementia with the antioxidant intake.

CONCLUSIONS

The risk of incident AD is significantly reduced by higher consumption of vitamin C by the intake avenue of diet plus supplement.

Association of Vitamin E and Cognitive Decline in Older Adults with and without the APOEɛ4 Allele: A Biracial Population-Based Community Study

BACKGROUND

The association of different types of tocopherols (vitamin E) with cognition might vary by the APOEɛ4 allele status.

OBJECTIVE

We examined the association of dietary tocopherols with cognitive decline among participants with and without the APOEɛ4 allele over a median of 12 years.

METHODS

2,193 participants from the Chicago Health and Aging Project were included in the analyses. Global cognition was assessed in three-year cycles. We used a 144-item FFQ to assess dietary intakes of tocopherols and hME Sequenom mass-array platform to assess APOE genotype. We used linear mixed effects models to examine the relationship between tocopherol from food sources and global cognitive decline.

RESULTS

The mean baseline age was 74.1 (SD = 5.9) years. Among APOEɛ4 carriers, participants in the highest quintile of intakes of dietary vitamin E had a slower cognitive decline of 0.022 SDU (95% CI: 0.000, 0.043) compared to those in the lowest quintile. A higher intake of dietary α-tocopherol from food sources only was associated with slower cognitive decline in APOEɛ4 carriers (p for trend 0.002) but not among the non-carriers (p for trend 0.937). Among APOEɛ4 carriers, those in the highest quintile of intake of α-tocopherol had a 16.4% slower rate of decline of global cognition compared to those in the lowest quintile (β= 0.034, 95% CI: 0.013, 0.054).

CONCLUSIONS

Individuals consuming high α-tocopherol from food sources had slower cognitive decline among APOEɛ4 carriers. In older adults, different forms of vitamin E might moderate the relationship of APOEɛ4 with global cognition.

Dietary Total Antioxidant Capacity and Cognitive Function in Older Adults in the United States: The NHANES 2011-2014

OBJECTIVES

Oxidative stress level takes part in the development of cognitive decline. However, the association between total antioxidant capacity (TAC) from diet and cognitive function is controversial. The aim of this study was to investigate the relationship between TAC and the cognitive function of older adults in the U.S.

DESIGN

A cross-sectional study.

SETTING

National Health and Nutrition Examination Surveys database.

PARTICIPANTS

2712 older adults aged over 60 years.

MEASUREMENTS

TAC was calculated from 8 antioxidative vitamins based on the reference values for vitamin C equivalent antioxidant capacity obtained from individuals' 24 h dietary recall. Four memory-related assessments were employed [Immediate Recall test (IRT), Delayed Recall test (DRT), Animal Fluency test (AFT), and Digit Symbol Substitution test (DSST)].

RESULTS

Among the 2712 participants, the median age was 68 years, and 50.4% were women. Participants in the group with higher TAC levels had relatively higher IRT, AFT and DSST scores (P=0.025, P=0.008, P<0.001, respectively). In adjusted weighted linear regression, log-transformed TAC was positively associated with AFT (β=1.10, 95%CI: 0.51, 1.70) and DSST (β=2.81, 95%CI: 1.16, 4.45). Compared with the first quartile, the participants in the second (Q2 vs. Q1, OR=0.66, 95%CI: 0.43,1.02) and fourth quartile (Q4 vs. Q1, OR=0.47, 95%CI:0.28, 0.78) of log-transformed TAC showed a decreased risk of impaired cognitive function (ICF) after adjusting for confounders. The dose-response analysis indicated a gradual descent in the risk of ICF as TAC increases. Diabetes mellitus (DM) mediated part of the effect of TAC on ICF. The relationship between TAC and ICF was more pronounced in subjects with DM (Q4 vs Q1, OR=0.36, 95%CI:0.17, 0.74).

CONCLUSION

Our findings support that higher dietary antioxidant potential was related to a decreased risk of cognitive dysfunction, particularly in the subjects with DM who may have oxidative injury. DM was one of the factors mediating the effect of TAC on ICF.

Association of 100% Fruit Juice Consumption with Cognitive Measures, Anxiety, and Depression in US Adults

Cognitive decline, anxiety, and depression are significant contributors to human ill health and decreased quality of life. Intake of fruits including 100% juice is associated with beneficial effects on several health outcomes. The current study explored the potential associations between consumption of 100% fruit juice and neurocognitive markers in adults. Twenty-four-hour dietary recall data from the National Health and Nutrition Examination Survey (NHANES) 1988-1994, 1999-2018 for adults 20+ years (N = 62,606) were used to assess 100% fruit juice intake, and NHANES questionnaire data were used for the assessment of neurocognition. Association of usual intake of 100% fruit juice with neurocognitive outcomes were assessed by regression analysis after adjusting for demographic, lifestyle, dietary, and health-related covariates. About 21% of adults were fruit juice consumers and the intake was a little over 2 oz per day. Consumers of 100% fruit juice had 16.3% fewer days per month of feeling anxious compared to non-consumers. There were no significant associations of 100% fruit juice usual intake with other neurocognitive measures. A large number of potential confounding variables have been identified to be associated with one or more neurocognitive measures suggesting that these may be important parameters to include in future studies.

Tea Consumption Is Associated with Reduced Cognitive Decline and Interacts with Iron Intake: A Population-Based Longitudinal Study on 4,820 Old Adults

Background: Previous studies suggest a positive effect of tea intake on cognition. Additional micronutrients that may moderate this association was not previously examined. Objective: To examine the association between tea consumption and cognition and explore the interaction between tea consumption and iron intake. Methods: Data from the China Health and Nutrition Survey between 1997 and 2011 was used. 4,820 individuals (≥55 years) were included in the analyses. Measurement of cognitive function was conducted in 1997, 2000, 2004, and 2006. Tea consumption was self-reported. Food intake was assessed by 24-hour dietary recalls of three consecutive days during home visits between 1997 and 2011. Multivariable mixed linear regression and logistic regression was used to assess the association. Results: Tea consumption was associated with reduced global cognitive function decline. In fully adjusted models, regression coefficients (95% CIs) for those who consumed 0 cups/day,<2 cups/day, 2–3.9 cups/day, and≥4 cups/day of tea were 0, –0.09 (–0.55–0.37), 0.05 (–0.34–0.45), and 0.87 (0.46–1.29), respectively. This effect was stronger in adults > 60 years. Tea consumption of≥4 cups/day was inversely associated with self-reported poor memory (OR 0.70 (95% CI 0.56–0.86)) and memory decline (OR, 0.73 (95% CI 0.62–0.87)). There was a significant interaction between tea consumption and iron intake in relation to cognition. High iron intake was inversely associated with cognition in non-consumers of tea but not in tea consumers. Conclusion: Higher tea intake is associated with reduced cognitive decline in adults and inhibits the adverse effect of high iron intake.

Effect of berry-based supplements and foods on cognitive function: a systematic review

In the current decade, a growing body of evidence has proposed the correlation between diet and cognitive function or dementia in the ageing population. This study was designed to appraise discoveries from the randomized controlled trials to confirm the effects of berry-based supplements or foods on cognitive function in older adults. PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, Scopus, EMBASE, Google Scholar, and ProQuest as well as SID, Magiran, and Iranmedex electronic databases were explored for human interventional studies up to March 2021. In total, eleven articles were identified using frozen blueberry (n = 4 studies), blueberry concentrate (n = 2), beverage (n = 3), capsule (n = 1), extract and powder (n = 1). These studies had been performed among older people with no recognized cognitive impairment or mild cognitive impairment (MCI). The primary outcomes included global cognitive function, psychomotor function, learning and memory, working memory capacity, executive functions, and brain perfusion/activity. To our knowledge, this is the first systematic review of available clinical trials on the effects of berry-based supplements and foods on cognitive performances as well as brain perfusion parameters among the elderly with normal cognition or MCI. Existing evidence concludes that berry-based supplements and foods have beneficial effects on resting brain perfusion, cognitive function, memory performance, executive functioning, processing speed, and attention indices.

Lead (Pb)-induced oxidative stress mediates sex-specific autistic-like behaviour in Drosophila melanogaster

Autism spectrum disorder (ASD) is a highly prevalent neurodevelopmental disorder characterised by three main behavioural symptoms: abnormal social interaction, verbal and non-verbal communication impairments, and repetitive and restricted activities or interests. Even though the exact aetiology of ASD remains unknown, studies have shown a link between genetics and environmental pollutants. Heavy metal lead (Pb), the environmental pollutant, is associated with ASD. Pb may also exhibit sex-specific ASD behaviour, as has been demonstrated in the global human populations. Drosophila melanogaster as a model has been used in the present study to understand the involvement of Pb-induced oxidative stress in developing ASD behaviour. The larval feeding technique has been employed to administer different Pb concentrations (0.2-0.8 mM) to Oregon-R (ORR), superoxide dismutase (Sod), or catalase (Cat) antioxidants overexpressed or knockdown flies. Adult Drosophila (5-day old) were used for Pb content, biochemical, and behavioural analysis.Pb accumulated in the Drosophila brain induces oxidative stress and exhibited a human autistic-like behaviour such as reduced climbing, increased grooming, increased social spacing, and decreased learning and memory in a sex-specific manner.Pb-induced autistic-like behaviour was intensified in Sod or Cat-knockdown flies, whereas Sod or Cat-overexpressed flies overcome that behavioural alterations. These results unequivocally proved that Pb-induced oxidative stress causes ASD behaviour of humans in Drosophila. Thus, Drosophila is used as a model organism to analyse ASD-like human behaviour and underlines the importance of using antioxidant therapy in alleviating ASD symptoms in children.

Effects of functional variants of vitamin C transporter genes on apolipoprotein E E4-associated risk of cognitive decline: The Nakajima study

Apolipoprotein E E4 (APOE4) is a risk factor for cognitive decline. A high blood vitamin C (VC) level reduces APOE4-associated risk of developing cognitive decline in women. In the present study, we aimed to examine the effects of functional variants of VC transporter genes expressed in the brain (SLC2A1, SLC2A3, and SLC23A2) on APOE4-associated risk of developing cognitive decline. This case–control study involved 393 Japanese subjects: 252 cognitively normal and 141 cognitively impaired individuals (87 mild cognitive impairment and 54 dementia). Database searches revealed that rs1279683 of SLC23A2, and rs710218 and rs841851 of SLC2A1 are functional variants that are significantly associated with the altered expression of the respective genes and genotyped as three single nucleotide variants (SNVs). When stratified by SNV genotype, we found a significant association between APOE4 and cognitive decline in minor allele carriers of rs1279683 (odds ratio [OR] 2.02, 95% CI, 1.05–3.87, p = 0.035) but not in the homozygote carriers of the major allele. Significant associations between APOE4 and cognitive decline were also observed in participants with major allele homozygotes of rs710218 (OR 2.35, 95% CI, 1.05–5.23, p = 0.037) and rs841851 (OR 3.2, 95% CI, 1.58–6.46, p = 0.0012), but not in minor allele carriers of the respective SNVs. In contrast, the three functional SNVs showed no significant effect on cognitive decline. Our results imply that functional SNVs of VC transporter genes can affect APOE4-associated risk of developing cognitive decline via altered VC levels in the brain.

Dietary total antioxidant capacity and late-life cognitive impairment: the Singapore Chinese Health Study

BACKGROUND

With the dramatically rapid rate of aging worldwide, the maintenance of cognitive function in old age is a major public health priority. The association between total antioxidant capacity (TAC) of midlife diet and cognitive function in late-life is still unclear.

METHODS

The study included 16 703 participants from a prospective cohort study in Singapore. Dietary intakes and selected supplementary use were assessed with a validated 165-item food frequency questionnaires at baseline (1993-1998). Two dietary TACs were calculated from the intake of antioxidant nutrients, the Comprehensive Dietary Antioxidant Index (CDAI) and the Vitamin C Equivalent Antioxidant Capacity (VCEAC). Cognitive function was assessed 20.2 years later using a Singapore-modified version of the Mini-Mental State Examination when subjects were 61-96 years old. Cognitive impairment was defined using education-specific cut-offs. Multivariable logistic regression models were utilized to estimate the associations between dietary TACs, component nutrients and cognitive impairment.

RESULTS

A total of 2392 participants (14.3%) were defined to have cognitive impairment. Both CDAI and VCEAC scores were inversely associated with odds of cognitive impairment in a dose-dependent manner. The odds ratio (95% confidence interval; p-trend) comparing the highest with the lowest quartile was 0.84 (0.73, 0.96; p-trend = .003) for the CDAI and 0.75 (0.66, 0.86; p-trend < .001) for the VCEAC. Higher intakes of vitamin C, vitamin E, carotenoids, and flavonoids were all inversely associated with cognitive impairment.

CONCLUSIONS

Higher dietary total antioxidant capacity was associated with lower odds of cognitive impairment in later life in a Chinese population in Singapore.

A Novel Galantamine-Curcumin Hybrid as a Potential Multi-Target Agent against Neurodegenerative Disorders

The acetylcholinesterase (AChE) inhibitors are the main drugs for symptomatic treatment of neurodegenerative disorders like Alzheimer’s disease. A recently designed, synthesized and tested hybrid compound between the AChE inhibitor galantamine (GAL) and the antioxidant polyphenol curcumin (CU) showed high AChE inhibition in vitro. Here, we describe tests for acute and short-term toxicity in mice as well as antioxidant tests on brain homogenates measured the levels of malondialdehide (MDA) and glutathione (GSH) and in vitro DPPH, ABTS, FRAP and LPO inhibition assays. Hematological and serum biochemical analyses were also performed. In the acute toxicity tests, the novel AChE inhibitor given orally in mice showed LD₅₀ of 49 mg/kg. The short-term administration of 2.5 and 5 mg/kg did not show toxicity. In the ex vivo tests, the GAL-CU hybrid performed better than GAL and CU themselves; in a dose of 5 mg/kg, it demonstrates 25% reduction in AChE activity, as well as a 28% and 73% increase in the levels of MDA and GSH, respectively. No significant changes in blood biochemical data were observed. The antioxidant activity of 4b measured ex vivo was proven in the in vitro tests. In the ABTS assay, 4b showed radical scavenging activity 10 times higher than the positive control butylhydroxy toluol (BHT). The GAL-CU hybrid is a novel non-toxic AChE inhibitor with high antioxidant activity which makes it a prospective multitarget drug candidate for treatment of neurodegenerative disorders.

Host-virus interaction and viral evasion

With each infectious pandemic or outbreak, the medical community feels the need to revisit basic concepts of immunology to understand and overcome the difficult times brought about by these infections. Regarding viruses, they have historically been responsible for many deaths, and such a peculiarity occurs because they are known to be obligate intracellular parasites that depend upon the host's cell machinery for their replication. Successful infection with the production of essential viral components requires constant viral evolution as a strategy to manipulate the cellular environment, including host internal factors, the host's nonspecific and adaptive immune responses to viruses, the metabolic and energetic state of the infected cell, and changes in the intracellular redox environment during the viral infection cycle. Based on this knowledge, it is fundamental to develop new therapeutic strategies for controlling viral dissemination, by means of antiviral therapies, vaccines, or antioxidants, or by targeting the inhibition or activation of cell signaling pathways or metabolic pathways that are altered during infection. The rapid recovery of altered cellular homeostasis during viral infection is still a major challenge. Here, we review the strategies by which viruses evade the host's immune response and potential tools used to develop more specific antiviral therapies to cure, control, or prevent viral diseases.

Improvement of Executive Function after Short-Term Administration of an Antioxidants Mix Containing Bacopa, Lycopene, Astaxanthin and Vitamin B12: The BLAtwelve Study

During the last few years increasing interest has been focused on antioxidants as potentially useful agents in the prevention of the onset and progression of cognitive dysfunction. In this randomized, double-blind, controlled, parallel arm study, the effects of daily consumption of an antioxidant mix on cognitive function in healthy older adults were evaluated. After a 1 week run-in period, 80 subjects aged 60 years or more, and with no evidence of cognitive dysfunction, were randomly allocated to a mix of four bioactive compounds (bacopa, lycopene, astaxanthin, and vitamin B12) or matched placebo, taken orally once a day for 8 weeks. The primary objective of the study was to evaluate the changes in trial making test (TMT) scores from baseline to 8 weeks of treatment, analyzed in the following hierarchical order: TMT-B, TMT-A, and TMT-B minus TMT-A. TMT-B increased in the control group (+3.46 s) and decreased in the active group (−17.63 s). The treatment difference was −21.01 s in favor of the active group (95% C.I. −26.80 to −15.2, p < 0.0001). The decrease in TMT-A was significantly higher in the active group (−6.86 s) than in the control group (−0.37 s). TMT-B minus TMT-A increased in the control group (+3.84 s) and decreased in the active group (−10.46 s). The increase in letter fluency in the verbal fluency test (VFT) was also significantly higher in the active group and statistically significant (+5.28 vs. +1.07 words; p < 0.001). Our findings provide encouraging evidence that regular dietary supplementation with bacopa, lycopene, astaxanthin, and vitamin B12 may be an effective dietary approach for counteracting cognitive changes associated with brain aging.

Table olives and health: a review

Table olives, a product of olive tree (Olea europaea L.), is an important fermented product of the Mediterranean Diet. Agronomical factors, particularly the cultivar, the ripening stage and the processing method employed are the main factors influencing the nutritional and non-nutritional composition of table olives and their organoleptic properties. The important nutritional value of this product is due to its richness in monounsaturated fat (MUFA), mainly oleic acid, fibre and vitamin E together with the presence of several phytochemicals. Among these, hydroxytyrosol (HT) is the major phenolic compound present in all types of table olives. There is a scarcity of in vitro, in vivo and human studies of table olives. This review focused comprehensively on the nutrients and bioactive compound content as well as the health benefits assigned to table olives. The possible health benefits associated with their consumption are thought to be primarily related to effects of MUFA on cardiovascular health, the antioxidant (AO) capacity of vitamin E and its role in protecting the body from oxidative damage and the anti-inflammatory and AO activities of HT. The influence of multiple factors on composition of the end product and the potential innovation in the production of table olives through the reduction of its final salt content was also discussed.

Can Healthy Diets, Regular Exercise, and Better Lifestyle Delay the Progression of Dementia in Elderly Individuals?

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by memory loss and multiple cognitive impairments. Current healthcare costs for over 50 million people afflicted with AD are about $818 million and are projected to be $2 billion by 2050. Unfortunately, there are no drugs currently available that can delay and/or prevent the progression of disease in elderly individuals and in AD patients. Loss of synapses and synaptic damage are largely correlated with cognitive decline in AD patients. Women are at a higher lifetime risk of developing AD encompassing two-thirds of the total AD afflicted population. Only about 1-2% of total AD patients can be explained by genetic mutations in APP, PS1, and PS2 genes. Several risk factors have been identified, such as Apolipoprotein E4 genotype, type 2 diabetes, traumatic brain injury, depression, and hormonal imbalance, are reported to be associated with late-onset AD. Strong evidence reveals that antioxidant enriched diets and regular exercise reduces toxic radicals, enhances mitochondrial function and synaptic activity, and improves cognitive function in elderly populations. Current available data on the use of antioxidants in mouse models of AD and antioxidant(s) supplements in diets of elderly individuals were investigated. The use of antioxidants in randomized clinical trials in AD patients was also critically assessed. Based on our survey of current literature and findings, we cautiously conclude that healthy diets, regular exercise, and improved lifestyle can delay dementia progression and reduce the risk of AD in elderly individuals and reverse subjects with mild cognitive impairment to a non-demented state.

Association of Antioxidant Vitamins A, C, E and Carotenoids with Cognitive Performance over Time: A Cohort Study of Middle-Aged Adults

Carotenoids may strengthen the association of antioxidant vitamins A, C, and E with favorable cognitive outcomes over time, though a few prospective studies have examined this hypothesis. We evaluated the longitudinal data from 1251 participants in the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study (Age at visit 1 in 2004–2009 (v₁): 30–65 years). Vitamins A, C, and E dietary intakes and total and individual dietary carotenoids were computed using two 24-h recalls at v₁. Cognitive tests, covering global mental status and domains of memory/learning, attention, psychomotor speed, visuo-spatial, language/verbal, and executive function were conducted at v₁ and/or v₂ (2009–2013); mean ± SD follow-up: 4.66 ± 0.93 years. Mixed-effects linear regression models detected an interaction between vitamin E and total (and individual) carotenoids for three of 11 cognitive tests at v₁, with only one meeting the statistical significance upon multiple testing correction whereby vitamin E was linked with greater verbal memory performance in the uppermost total carotenoid tertile (γ_0a = +0.26 ± 0.08, p = 0.002), a synergism largely driven by carotenoid lycopene. Vitamins A and C showed no consistent interactions with carotenoids. In conclusion, we provide partial evidence for synergism between vitamin E and carotenoids in relation to better baseline cognitive performance, pending further studies with time-dependent exposures and randomized trials directly examining this synergism.

Social participation is an important health behaviour for health and quality of life among chronically ill older Chinese people

BACKGROUND

Health behaviours (physical activity, maintenance of a healthy diet and not smoking) are known to be beneficial to the health and well-being of chronically ill people. With China's ageing population and increased prevalence of people with chronic diseases, the improvement of unhealthy behaviours in this population has become crucial. Although recent studies have highlighted the importance of social participation for health and quality of life (QoL) among older people, no study to date has included social participation along with more traditional health behaviours. Therefore, this study aimed to identify associations of multiple health behaviours (social participation, physical activity, maintenance of a healthy diet and not smoking) with health and QoL outcomes (including cognitive and physical function) among chronically ill older adults in China.

METHODS

For this nationally representative cross-sectional study, wave 1 data from the World Health Organization's Study on global AGEing and adult health (China) were examined. In total, 6629 community-dwelling older adults (mean age, 64.9 years) with at least one chronic disease were included. Multivariate linear regression analyses were used to evaluate associations of health behaviours with health and QoL outcomes while controlling for background characteristics.

RESULTS

Greater social participation was associated with better QoL [β = 0.127, standard error (SE) = 0.002, p < 0.001], cognitive function (β = 0.154, SE = 0.033, p < 0.001) and physical function (β = - 0.102, SE = 0.008, p < 0.001). Physical activity was associated with better QoL (β = 0.091, SE = 0.015, p < 0.001) and physical function (β = - 0.155, SE = 0.062, p < 0.001). Sufficient fruit and vegetable consumption was associated with better QoL (β = 0.087, SE = 0.015, p < 0.001).

CONCLUSIONS

Our findings suggest that social participation is an important health behaviour for quality of life and cognitive function among chronically ill older people in China. Health promotion programmes should expand their focus to include social participation as a health behaviour, in addition to physical activity, maintenance of a healthy diet and not smoking.

Vitamin E Intake Is Associated with Lower Brain Volume in Haptoglobin 1-1 Elderly with Type 2 Diabetes

BACKGROUNDS

The efficacy of vitamin E in prevention of diabetes-related complications differs by Haptoglobin (Hp) genotype.

OBJECTIVE

To examine the role of Hp genotype in the relationship of vitamin E intake with brain volume in cognitively normal elderly patients with type 2 diabetes.

METHODS

Brain volumes for the superior, middle, and inferior frontal gyri and for the middle temporal gyrus were generated from structural T1 MRI in 181 study participants (Hp 1-1: n = 24, Hp 2-1: n = 77, Hp 2-2: n = 80). Daily vitamin E intake was assessed using the Food Frequency Questionnaire. Analyses of covariance, controlling for demographic and cardiovascular variables was used to evaluate whether the association of daily vitamin E intake with brain volume was modified by Hp genotype.

RESULTS

Average age was 70.8 (SD = 4.2) with 40% females, and mean Mini-Mental State Examination score of 28.17 (SD = 1.90). A significant interaction was found between vitamin E intake and Hp genotype in inferior frontal gyrus' volume; p = 0.0108. For every 1 microgram increase in vitamin E intake, the volume of the inferior frontal gyrus decreased by 0.955% for Hp 1-1 (p = 0.0348), increased by 0.429% for Hp 2-1 (p = 0.0457), and by 0.077% for Hp 2-2 (p = 0.6318). There were no significant interactions between vitamin E intake and Hp genotype for the middle (p = 0.6011) and superior (p = 0.2025) frontal gyri or for the middle temporal gyrus (p = 0.503).

CONCLUSIONS

The effect of dietary vitamin E on the brain may differ by Hp genotype. Studies examining the impact of vitamin E on brain-related outcomes should consider Hp genotype.

The Major Source of Antioxidants Intake From Typical Diet Among Rural Farmers in North-eastern Japan in the 1990s

Background

Previous Japanese studies have led to the erroneous conclusion of antioxidant capacity (AOC) intakes of the overall Japanese diet due to limitations in the number and types of food measured, especially in rice and seafood intake. The aims of the study were to construct an AOC database of foods representative of the typical Japanese diet and to clarify the high contributors to AOC intake from the overall diet of the Japanese population.

Methods

Commonly consumed foods were estimated using 3-day dietary records (DRs) over the four seasons among 55 men and 58 women in Japan. To generate an AOC database suitable for the typical Japanese diet, hydrophilic (H-)/lipophilic (L-) oxygen radical absorbance capacity (ORAC) values of foods in each food group were measured via validated methods using the food intake rankings. Subsequently, we estimated the AOC intake and the AOC characteristics of a typical Japanese diet.

Results

Of 989 food items consumed by the participants, 189 food items were measured, which covered 78.8% of the total food intake. The most commonly consumed types of antioxidant-containing food were tea, soybean products, coffee, and rice according to H-ORAC, and soybean products, fish and shellfish, vegetables, and algae according to L-ORAC.

Conclusions

The characteristics of high AOC intake in rice and seafood more appropriately reflected the Japanese-style diet. Further studies are expected to clarify the association between food-derived AOC and its role in preventing or ameliorating lifestyle-related diseases.

A healthy diet and physical activity are important to promote healthy ageing among older Chinese people

Objective

To examine the associations between multiple health behaviours and health outcomes among older Chinese adults.

Methods

Data from the World Health Organization’s Study on global AGEing and adult health Wave 1 (2007–2010), collected among the older Chinese population, were included in this study. Smoking, diet, and physical activity were analysed by linear regression for any associations with depressive symptoms, quality of life (QoL), cognitive function, and physical function.

Results

A total of 13 367 participants aged >49 years were included in the analyses. After controlling for key socioeconomic factors, healthy diet was significantly associated with higher QoL (β = 0.099) and better cognitive function (β = 0.023). Physical activity was significantly associated with fewer depressive symptoms (β = –0.020), higher QoL (β = 0.086), better cognitive function (β = 0.072), and better physical function (β = –0.155 [higher scores = poorer physical function]). No relationship was found between smoking and any health-related outcome included in this study.

Conclusion

This study demonstrates the importance of healthy diet and physical activity for health outcomes in the older Chinese population.

Association of physical activity, vitamin E levels, and total antioxidant capacity with academic performance and executive functions of adolescents

BACKGROUND

Although various studies have shown the effect of vigorous physical activity on academic achievements, no studies have investigated the effect of vitamin E levels on academic performance. The present study aimed to assess the association between physical activity, vitamin E levels and total antioxidant capacity on the academic performance and executive functions of adolescents aged 15-18 years.

METHODS

The physical activity of participants was assessed according to the time spent engaging in moderate and intense exercise programs. Participants were classified into three groups representing mild, moderate, and high activity. Serum total antioxidant capacity was measured using a colorimetric assay kit. Vitamin E was estimated by the α- and γ-tocopherol levels in fasting serum samples using high-performance liquid chromatography paired with a diode array detector. School grades (ranging from 1.0, very poor; to 10.0, outstanding) were obtained at the end of the academic year to evaluate academic performance and executive functions.

RESULTS

A total of 120 school students (mean age 16.36 ± 0.77 years; 70 boys, 50 girls) participated in the study. Academic performance was higher for students classified as moderately or highly active compared with those in the mild activity group. Serum levels of vitamin E, total antioxidant capacity, and leisure-time physical activity were also higher in the moderate and high activity groups. There was a significant correlation between age, gender, body mind index, α- and γ-tocopherol, total antioxidant capacity, leisure-time physical activity and academic performance.

CONCLUSIONS

The academic performance and executive function scores were found to be positively correlated with age, gender, α- and γ-tocopherol, total antioxidant capacity, and physical activity; and were negatively correlated with body mind index. Our findings indicate that physical activity should be promoted during and after school hours, along with a healthy balanced diet including vitamin E.

Plasma Vitamin C Concentrations and Cognitive Function: A Cross-Sectional Study

Vitamin-C is a water soluble molecule that humans have lost the ability to produce. Vitamin-C plays a role in CNS functions such as neuronal differentiation, maturation, myelin formation and modulation of the catecholaminergic systems. A recent systematic review by our team indicated the need for further research into the relationship between plasma vitamin C and cognition in cognitively intact participants using plasma vitamin C concentrations instead of estimates derived from food-frequency-questionnaires (FFQ), and more sensitive cognitive assessments suitable for cognitive abilities vulnerable to aging. It was hypothesized that higher plasma vitamin C concentrations would be linked with higher cognitive performance. This cross-sectional trial was conducted on healthy adults (n = 80, Female = 52, Male = 28, 24-96 years) with a range of plasma Vitamin C concentrations. Cognitive assessments included The Swinburne-University-Computerized-Cognitive-Assessment-Battery (SUCCAB) and two pen and paper tests, the Symbol-Digits-Modalities-Test (SDMT) and Hopkins-Verbal-Learning-Test-Revised (HVLT-R). The pen and paper assessments were conducted to establish whether their scores would correlate with the computerized tasks. Plasma-Vitamin C concentrations were measured using two biochemical analyses. Participants were grouped into those with plasma vitamin-C concentrations of adequate level (≥28 μmol/L) and deficient level (<28 μmol/L). The SUCCAB identified a significantly higher performance ratio (accuracy/reaction-time) in the group with adequate vitamin-C levels vs. deficient vitamin-C on the choice reaction time (M = 188 ± 4 vs. 167 ± 9, p = 0.039), immediate recognition memory (M = 81 ± 3 vs. 68 ± 6, p = 0.03), congruent Stroop (M = 134 ± 3 vs. 116 ± 7, p = 0.024), and delayed recognition tasks (M = 72 ± 2 vs. 62 ± 4, p = 0.049), after adjusting for age (p < 0.05). Significantly higher scores in immediate recall on the HVLT-R (M = 10.64 ± 0.16 vs. 9.17 ± 0.37, p = 0.001), delayed recall (M = 9.74 ± 0.22 vs. 7.64 ± 0.51, p < 0.001), total recall (M = 27.93 ± 0.48 vs. 24.19 ± 1.11, p = 0.003) were shown in participants with adequate plasma Vitamin-C concentrations, after adjusting for vitamin-C supplementation dose (p < 0.05). Similarly, higher SDMT scores were observed in participants with adequate plasma Vitamin-C concentrations (M = 49.73 ± 10.34 vs. 41.38 ± 5.06, p = 0.039), after adjusting for age (p < 0.05). In conclusion there was a significant association between vitamin-C plasma concentrations and performance on tasks involving attention, focus, working memory, decision speed, delayed and total recall, and recognition. Plasma vitamin C concentrations obtained through vitamin C supplementation did not affect cognitive performance differently to adequate concentrations obtained through dietary intake. Clinicaltrials.gov Unique Identifier: ACTRN 12615001140549, URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=369440.

Health-Promoting Strategies for the Aging Brain

As the world's population ages and people live longer, the changes in the aging brain present substantial challenges to our health and society. With greater longevity come age-related diseases, many of which have direct and indirect influences on the health of the brain. Although there is some degree of predictable decline in brain functioning with aging, meaningful cognitive decline is not inevitable and is perhaps preventable. In this review, we present the case that the course of aging-related brain disease and dysfunction can be modified. We present the evidence for conditions and risk factors that may contribute to cognitive decline and dementia and for interventions that may mitigate their impact on cognitive functioning later in life, or even prevent them and their cognitive sequelae from developing. Although much work remains to be done to meet the challenges of the aging brain, strategies to promote its health have been demonstrated and offer much promise, which can only be realized if we mount a vigorous public health effort to implement these strategies.

Comprehensive review of mechanisms of pathogenesis involved in Alzheimer's disease and potential therapeutic strategies

AD is a progressive neurodegenerative disorder and a leading cause of dementia in an aging population worldwide. The enormous challenge which AD possesses to global healthcare makes it as urgent as ever for the researchers to develop innovative treatment strategies to fight this disease. An in-depth analysis of the extensive available data associated with the AD is needed for a more comprehensive understanding of underlying molecular mechanisms and pathophysiological pathways associated with the onset and progression of the AD. The currently understood pathological and biochemical manifestations include cholinergic, Aβ, tau, excitotoxicity, oxidative stress, ApoE, CREB signaling pathways, insulin resistance, etc. However, these hypotheses have been criticized with several conflicting reports for their involvement in the disease progression. Several issues need to be addressed such as benefits to cost ratio with cholinesterase therapy, the dilemma of AChE selectivity over BChE, BBB permeability of peptidic BACE-1 inhibitors, hurdles related to the implementation of vaccination and immunization therapy, and clinical failure of candidates related to newly available targets. The present review provides an insight to the different molecular mechanisms involved in the development and progression of the AD and potential therapeutic strategies, enlightening perceptions into structural information of conventional and novel targets along with the successful applications of computational approaches for the design of target-specific inhibitors.

Association between tea consumption and risk of cognitive disorders: A dose-response meta-analysis of observational studies

Background

The epidemiological evidence for a dose-response relationship between tea consumption and risk of cognitive disorders is sparse. The aim of the study was to summarize the evidence for the association of tea consumption with risk of cognitive disorders and assess the dose-response relationship.

Methods

We searched electronic databases of Pubmed, Embase, and Cochrane Library (from 1965 to Jan 19, 2017) for eligible studies that published in the international journals. A random-effects model was used to pool the most adjusted odds ratios (ORs) and the corresponding 95% confidence intervals (CIs).

Results

Seventeen studies involving 48,435 participants were included in our study. The meta-analysis showed that a higher tea consumption was associated with a significant reduction in the risk of cognitive disorders (OR=0.73, 95% CI: 0.65-0.82). When considering the specific types of tea consumption, the significantly inverse association is only found in green tea consumption (OR=0.64, 95% CI: 0.53-0.77) but not in black/oolong tea consumption (OR=0.75, 95% CI: 0.55-1.01). Dose-response meta-analysis indicated that tea consumption is linearly associated with a reduced risk of cognitive disorders. An increment of 100 ml/day, 300 ml/day, and 500 ml/day of tea consumption was associated with a 6% (OR=0.94, 95% CI: 0.92-0.96), 19% (OR=0.81, 95% CI: 0.74-0.88), and 29% (OR=0.71, 95% CI: 0.62-0.82) lower risk of cognitive disorders.

Conclusions

Tea consumption is inversely and linearly related to the risk of cognitive disorders. More studies are needed to further confirm our findings.

The Subcellular Distribution of Alpha-Tocopherol in the Adult Primate Brain and Its Relationship with Membrane Arachidonic Acid and Its Oxidation Products

The relationship between α-tocopherol, a known antioxidant, and polyunsaturated fatty acid (PUFA) oxidation, has not been directly investigated in the primate brain. This study characterized the membrane distribution of α-tocopherol in brain regions and investigated the association between membrane α-tocopherol and PUFA content, as well as brain PUFA oxidation products. Nuclear, myelin, mitochondrial, and neuronal membranes were isolated using a density gradient from the prefrontal cortex (PFC), cerebellum (CER), striatum (ST), and hippocampus (HC) of adult rhesus monkeys (n = 9), fed a stock diet containing vitamin E (α-, γ-tocopherol intake: ~0.7 µmol/kg body weight/day, ~5 µmol/kg body weight/day, respectively). α-tocopherol, PUFAs, and PUFA oxidation products were measured using high performance liquid chromatography (HPLC), gas chromatography (GC) and liquid chromatography-gas chromatography/mass spectrometry (LC-GC/MS) respectively. α-Tocopherol (ng/mg protein) was highest in nuclear membranes (p < 0.05) for all regions except HC. In PFC and ST, arachidonic acid (AA, µg/mg protein) had a similar membrane distribution to α-tocopherol. Total α-tocopherol concentrations were inversely associated with AA oxidation products (isoprostanes) (p < 0.05), but not docosahexaenoic acid oxidation products (neuroprostanes). This study reports novel data on α-tocopherol accumulation in primate brain regions and membranes and provides evidence that α-tocopherol and AA are similarly distributed in PFC and ST membranes, which may reflect a protective effect of α-tocopherol against AA oxidation.

Role of Vitamin E in the Treatment of Alzheimer's Disease: Evidence from Animal Models

Alzheimer's disease (AD) is a neurodegenerative disorder representing the major cause of dementia. It is characterized by memory loss, and cognitive and behavioral decline. In particular, the hallmarks of the pathology are amyloid-β (Aβ) plaques and neurofibrillary tangles (NFTs), formed by aggregated hyperphosphorylated tau protein. Oxidative stress plays a main role in AD, and it is involved in initiation and progression of AD. It is well known that Aβ induced oxidative stress, promoting reactive oxygen species (ROS) production and consequently lipid peroxidation, protein oxidation, tau hyperphosphorylation, results in toxic effects on synapses and neurons. In turn, oxidative stress can increase Aβ production. For these reasons, the administration of an antioxidant therapy in AD patients was suggested. The term vitamin E includes different fat-soluble compounds, divided into tocopherols and tocotrienols, that possess antioxidant action. α-Tocopherol is the most studied, but some studies suggested that tocotrienols may have different health promoting capacities. In this review, we focused our attention on the effects of vitamin E supplementation in AD animal models and AD patients or older population. Experimental models showed that vitamin E supplementation, by decreasing oxidative stress, may be a good strategy to improve cognitive and memory deficits. Furthermore, the combination of vitamin E with other antioxidant or anti-inflammatory compounds may increase its efficacy. However, even if some trials have evidenced some benefits, the effects of vitamin E in AD patients are still under debate.

Vitamin C Status and Cognitive Function: A Systematic Review

Vitamin C plays a role in neuronal differentiation, maturation, myelin formation and modulation of the cholinergic, catecholinergic, and glutaminergic systems. This review evaluates the link between vitamin C status and cognitive performance, in both cognitively intact and impaired individuals. We searched the PUBMED, SCOPUS, SciSearch and the Cochrane Library from 1980 to January 2017, finding 50 studies, with randomised controlled trials (RCTs, n = 5), prospective (n = 24), cross-sectional (n = 17) and case-control (n = 4) studies. Of these, 36 studies were conducted in healthy participants and 14 on cognitively impaired individuals (including Alzheimer’s and dementia). Vitamin C status was measured using food frequency questionnaires or plasma vitamin C. Cognition was assessed using a variety of tests, mostly the Mini-Mental-State-Examination (MMSE). In summary, studies demonstrated higher mean vitamin C concentrations in the cognitively intact groups of participants compared to cognitively impaired groups. No correlation between vitamin C concentrations and MMSE cognitive function was apparent in the cognitively impaired individuals. The MMSE was not suitable to detect a variance in cognition in the healthy group. Analysis of the studies that used a variety of cognitive assessments in the cognitively intact was beyond the scope of this review; however, qualitative assessment revealed a potential association between plasma vitamin C concentrations and cognition. Due to a number of limitations in these studies, further research is needed, utilizing plasma vitamin C concentrations and sensitive cognitive assessments that are suitable for cognitively intact adults.

The effect of N-acetylcysteine (NAC) on human cognition - A systematic review

Oxidative stress, neuroinflammation and neurogenesis are commonly implicated as cognitive modulators across a range of disorders. N-acetylcysteine (NAC) is a glutathione precursor with potent antioxidant, pro-neurogenesis and anti-inflammatory properties and a favourable safety profile. A systematic review of the literature specifically examining the effect of NAC administration on human cognition revealed twelve suitable articles for inclusion: four examining Alzheimer's disease; three examining healthy participants; two examining physical trauma; one examining bipolar disorder, one examining schizophrenia, and one examining ketamine-induced psychosis. Heterogeneity of studies, insufficiently powered studies, infrequency of cognition as a primary outcome, heterogeneous methodologies, formulations, co-administered treatments, administration regimes, and assessment confounded the drawing of firm conclusions. The available data suggested statistically significant cognitive improvements following NAC treatment, though the paucity of NAC-specific research makes it difficult to determine if this effect is meaningful. While NAC may have a positive cognitive effect in a variety of contexts; larger, targeted studies are warranted, specifically evaluating its role in other clinical disorders with cognitive sequelae resulting from oxidative stress and neuroinflammation.

Mitochondria-Targeted Molecules as Potential Drugs to Treat Patients With Alzheimer's Disease

Alzheimer's disease (AD) is the most common multifactorial mental illness affecting the elderly population in the world. Its prevalence increases as person ages. There is no known drug or agent that can delay or prevent the AD and its progression. Extensive research has revealed that multiple cellular pathways involved, including amyloid beta production, mitochondrial structural and functional changes, hyperphosphorylation of Tau and NFT formation, inflammatory responses, and neuronal loss in AD pathogenesis. Amyloid beta-induced synaptic damage, mitochondrial abnormalities, and phosphorylated Tau are major areas of present research investigations. Synaptic pathology and mitochondrial oxidative damage are early events in disease process. In this chapter, a systematic literature survey has been conducted and presented a summary of antioxidants used in (1) AD mouse models, (2) elderly populations, and (3) randomized clinical trials in AD patients. This chapter highlights the recent progress in developing and testing mitochondria-targeted molecules using AD cell cultures and AD mouse models. This chapter also discusses recent research on AD pathogenesis and therapeutics, focusing on mitochondria-targeted molecules as potential therapeutic targets to delay or prevent AD progression.

Increased Consumption of Fruit and Vegetables Is Related to a Reduced Risk of Cognitive Impairment and Dementia: Meta-Analysis

Background: Increased consumption of fruit and vegetables has been shown to be associated with a reduced risk of cognitive impairment and dementia in many epidemiological studies. The purpose of this study was to assess the strength of this association in a meta-analysis.

Methods: We identified relevant studies by searching Medline, Embase, and Cochrane Library electronic databases (from 1970 to January 2016). Study were included if they reported relative risks and corresponding 95% confidence intervals (CIs) of cognitive impairment and dementia with respect to frequency of fruit and vegetable intake.

Results: Nine studies (five cohort studies and four cross-sectional studies) met the inclusion criteria and were included in the meta-analysis. There were a total of 31,104 participants and 4,583 incident cases of cognitive impairment and dementia. The meta-analysis showed that an increased consumption of fruit and vegetables was associated with a significant reduction in the risk of cognitive impairment and dementia (OR = 0.80, 95% CI 0.71–0.89). Subgroup analysis indicated this inverse association was only found among participants with mean age over 65 years and combined sexes. Dose–response meta-analysis showed that an increment of 100 g per day of fruit and vegetable consumption was related to an approximately 13% (OR = 0.87, 95% CI 0.77–0.99) reduction in cognitive impairment and dementia risk. There was no potential publication bias in the meta-analysis and the dose–response meta-analysis.

Conclusion: The increased consumption of fruit and vegetables is associated with a reduced risk of cognitive impairment and dementia.

Use of Vitamin E and C Supplements for the Prevention of Cognitive Decline

Background: There are few studies of the association between the use of antioxidant vitamin supplements and the risk of Alzheimer’s disease (AD). Cognitive decline is generally viewed as part of the continuum between normal aging and AD. Objective: To evaluate whether the use of vitamin E and C supplements is associated with reduced risks of cognitive impairment, not dementia (CIND), AD, or all-cause dementia in a representative sample of older persons ≥65 years old. Methods: Data from the Canadian Study of Health and Aging (1991-2002), a cohort study of dementia including 3 evaluation waves at 5-yearly intervals, were used. Exposure to vitamins E and C was self-reported at baseline in a risk factor questionnaire and/or in a clinical examination. Results: The data set included 5269 individuals. Compared with those not taking vitamin supplements, the age-, sex-, and education-adjusted hazard ratios of CIND, AD, and all-cause dementia were, respectively, 0.77 (95% CI = 0.60-0.98), 0.60 (95% CI = 0.42-0.86), and 0.62 (95% CI = 0.46-0.83) for those taking vitamin E and/or C supplements. Results remained significant in fully adjusted models except for CIND. Similar results were observed when vitamins were analyzed separately. Conclusions: This analysis suggests that the use of vitamin E and C supplements is associated with a reduced risk of cognitive decline. Further investigations are needed to determine their value as a primary prevention strategy.

Vitamin E family: Role in the pathogenesis and treatment of Alzheimer's disease

Introduction

Vitamin E family, composed by tocopherols and tocotrienols, is a group of compounds with neuroprotective properties. The exact role in the pathogenesis and the benefit of vitamin E as treatment for Alzheimer's disease (AD) are still under debate.

Methods

A literature search in PubMed, Medline, and Cochrane databases has been carried out. All types of studies, from bench and animal models to clinical, were included.

Results

High plasma vitamin E levels are associated with better cognitive performance, even if clear evidence of their ability to prevent or delay cognitive decline in AD is still lacking. Each vitamin E form is functionally unique and shows specific biological functions. Tocotrienols seem to have superior antioxidant and anti-inflammatory properties compared with tocopherols.

Discussion

The benefit of vitamin E as a treatment for AD is still under debate, mainly because of the inconsistent findings from observational studies and the methodological limitations of clinical trials.

Hazelnut and neuroprotection: Improved memory and hindered anxiety in response to intra-hippocampal Aβ injection

OBJECTIVES

Corylus avellana L. (hazelnut) is known to be a delicious and nutritious food. This study was carried out to evaluate the use of hazelnut as a therapy for memory impairment because in Iranian traditional medicine, it is recommended for those suffering from a particular type of dementia, with symptoms of Alzheimer's disease.

METHODS

In this study, rats were fed with hazelnut kernel [(without skin) 800 mg/kg/day] during 1 week before stereotaxic surgery to 24 hours before behavioral testing (in general, for 16 consecutive days) and the effect of hazelnut eating on memory, anxiety, neuroinflammation and apoptosis was assessed in the amyloid beta-injected rat.

RESULTS

The results of this study showed that feeding with hazelnut improved memory, (which was examined by using Y-maze test and shuttle box apparatus), and reduced anxiety-related behavior, that was evaluated using elevated plus maze. Also, western blotting analysis of cyclooxygenase-2, interleukin-1β, tumor necrosis factor-α, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein, and caspase-3 showed that hazelnut has an ameliorating effect on the neuroinflammation and apoptosis caused by Aβ.

DISCUSSION

These findings suggest that hazelnut, as a dietary supplement, improves healthy aging and could be a beneficial diet for the treatment of AD.

Vitamin C Supplementation, APOE4 Genotype and Cognitive Functioning in a Rural-Dwelling Cohort

OBJECTIVE

Apolipoprotein E4 (APOE4) genotype has been implicated as a moderating factor in cognitive function studies. Although prior studies have suggested that vitamin C is associated with better cognitive function in elders, link between the two has been mixed. Limited data exist as to whether the APOE4 genotype influences these associations. Therefore, this study sought to determine whether the association between vitamin C and cognition in a rural community dwelling cohort differs by the APOE4 genotype.

DESIGN AND PARTICIPANTS

Data were analyzed on 582 participants (n=183 men; n=399 women) from a rural community-based cohort. Cognition was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status and The Executive Interview. APOE genotyping was ascertained by standard methods. The relation between vitamin C supplementation and cognition were analyzed first with ANOVA and then ANCOVA with age, gender, education as covariates. Analyses were initially run in the full sample and then split by APOE4 presence (yes/no).

RESULTS

Overall, Vitamin C supplementation was associated with significantly better immediate memory (p=0.04), visuospatial skills (p=0.002), language (p=0.01), and global cognitive functioning (p=0.006). Among APOE4 non-carriers, vitamin C supplementation was positively associated with immediate memory (F[1,392] =6.7, p=0.01), visuospatial skills (F[1,391]=10.6, p=0.001), language (F[1,392]=13.0, p<0.001), attention (F[1,386]=7.9, p=0.005, and global cognition (F[1,382]=11.0, p=0.001. However, there was no significant link between vitamin C supplementation and cognition among APOE4 carriers.

CONCLUSION

Vitamin C supplementation was found to be positively associated with cognition among this rural-dwelling community-based sample; however, the associations appeared to differ by APOE4 status. These data may suggest that targeted genotype-specific cognitive enhancement studies are needed to clarify the potential benefits of vitamin C supplementation.

Vitamin E Supplementation Delays Cellular Senescence In Vitro

Vitamin E is an important antioxidant that protects cells from oxidative stress-induced damage, which is an important contributor to the progression of ageing. Ageing can be studied in vitro using primary cells reaching a state of irreversible growth arrest called senescence after a limited number of cellular divisions. Generally, the most utilized biomarker of senescence is represented by the expression of the senescence associated β-galactosidase (SA-β-gal). We aimed here to study the possible effects of vitamin E supplementation in two different human primary cell types (HUVECs and fibroblasts) during the progression of cellular senescence. Utilizing an unbiased automated system, based on the detection of the SA-β-gal, we quantified cellular senescence in vitro and showed that vitamin E supplementation reduced the numbers of senescent cells during progression of ageing. Acute vitamin E supplementation did not affect cellular proliferation, whereas it was decreased after chronic treatment. Mechanistically, we show that vitamin E supplementation acts through downregulation of the expression of the cycline dependent kinase inhibitor P21. The data obtained from this study support the antiageing properties of vitamin E and identify possible mechanisms of action that warrant further investigation.

Effects of vitamin E on lead-induced impairments in hippocampal synaptic plasticity

Lead (Pb) exposure during development is associated with impaired cognitive function and long-term potentiation (LTP). Vitamin E (VE) is an antioxidant that could have protective effects against Pb intoxication. In this study, we examined the protective effects of vitamin E against Pb-induced LTP impairments. Forty-six adult male Wistar rats were randomly divided into 6 treatment groups: (1) control; (2) Pb exposure; (3) VE; (4) Pb +VE; (5) Pb exposure followed by VE 2 months after exposure; (6) VE followed by Pb exposure 1 month after treatment. Rats were exposed to Pb through daily consumption of Pb-contaminated distilled water; VE was administered by daily gavage for 3 months. After this period, the population spike (PS) amplitudes and the slopes of excitatory postsynaptic potentials (EPSPs) were measured in the dentate gyrus (DG) area of the hippocampus in adult rats in response to electrical stimulation applied to the perforant pathway in vivo. Blood samples were also collected to evaluate malondialdehyde (MDA) levels, total antioxidant capacity (TAC), and total oxidant status (TOS). Biochemical analyses demonstrated significant increases in plasma MDA and TOS levels in the Pb-exposed group compared to the control group. VE-protected groups revealed significant increases in TAC levels. Our results demonstrate that Pb decreased EPSP slopes and PS amplitudes compared to the control group, whereas VE increased these parameters compared to the control group. Co-administration of VE with Pb exposure inhibited Pb-induced effects. These findings suggest that VE via its antioxidant activity reverses Pb-induced impairments of synaptic plasticity in the DG.

Effect of Omega-3 Fatty Acids, Lutein/Zeaxanthin, or Other Nutrient Supplementation on Cognitive Function: The AREDS2 Randomized Clinical Trial

IMPORTANCE

Observational data have suggested that high dietary intake of saturated fat and low intake of vegetables may be associated with increased risk of Alzheimer disease.

OBJECTIVE

To test the effects of oral supplementation with nutrients on cognitive function.

DESIGN, SETTING, AND PARTICIPANTS

In a double-masked randomized clinical trial (the Age-Related Eye Disease Study 2 [AREDS2]), retinal specialists in 82 US academic and community medical centers enrolled and observed participants who were at risk for developing late age-related macular degeneration (AMD) from October 2006 to December 2012. In addition to annual eye examinations, several validated cognitive function tests were administered via telephone by trained personnel at baseline and every 2 years during the 5-year study.

INTERVENTIONS

Long-chain polyunsaturated fatty acids (LCPUFAs) (1 g) and/or lutein (10 mg)/zeaxanthin (2 mg) vs placebo were tested in a factorial design. All participants were also given varying combinations of vitamins C, E, beta carotene, and zinc.

MAIN OUTCOMES AND MEASURES

The main outcome was the yearly change in composite scores determined from a battery of cognitive function tests from baseline. The analyses, which were adjusted for baseline age, sex, race, history of hypertension, education, cognitive score, and depression score, evaluated the differences in the composite score between the treated vs untreated groups. The composite score provided an overall score for the battery, ranging from -22 to 17, with higher scores representing better function.

RESULTS

A total of 89% (3741/4203) of AREDS2 participants consented to the ancillary cognitive function study and 93.6% (3501/3741) underwent cognitive function testing. The mean (SD) age of the participants was 72.7 (7.7) years and 57.5% were women. There were no statistically significant differences in change of scores for participants randomized to receive supplements vs those who were not. The yearly change in the composite cognitive function score was -0.19 (99% CI, -0.25 to -0.13) for participants randomized to receive LCPUFAs vs -0.18 (99% CI, -0.24 to -0.12) for those randomized to no LCPUFAs (difference in yearly change, -0.03 [99% CI, -0.20 to 0.13]; P = .63). Similarly, the yearly change in the composite cognitive function score was -0.18 (99% CI, -0.24 to -0.11) for participants randomized to receive lutein/zeaxanthin vs -0.19 (99% CI, -0.25 to -0.13) for those randomized to not receive lutein/zeaxanthin (difference in yearly change, 0.03 [99% CI, -0.14 to 0.19]; P = .66). Analyses were also conducted to assess for potential interactions between LCPUFAs and lutein/zeaxanthin and none were found to be significant.

CONCLUSIONS AND RELEVANCE

Among older persons with AMD, oral supplementation with LCPUFAs or lutein/zeaxanthin had no statistically significant effect on cognitive function.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00345176.

Oxidative Stress in Alzheimer's Disease: Should We Keep Trying Antioxidant Therapies?

The risk of chronic diseases such as Alzheimer's disease is growing as a result of the continuous increasing average life span of the world population, a syndrome characterized by the presence of intraneural neurofibrillary tangles and senile plaques composed mainly by beta-amyloid protein, changes that may cause a number of progressive disorders in the elderly, causing, in its most advanced stage, difficulty in performing normal daily activities, among other manifestations. Therefore, it is important to understand the underlying pathogenic mechanisms of this syndrome. Nevertheless, despite intensive effort to access the physiopathological pathways of the disease, it remains poorly understood. In that context, some hypotheses have arisen, including the recent oxidative stress hypothesis, theory supported by the involvement of oxidative stress in aging, and the vulnerability of neurons to oxidative attack. In the present revision, oxidative changes and redox mechanisms in Alzheimer's disease will be further stressed, as well as the grounds for antioxidant supplementation as adjuvant therapy for the disease will be addressed.

Effect of vitamin E on lead exposure-induced learning and memory impairment in rats

Chronic lead (Pb(2+)) exposure has been associated with learning and memory impairments, whereas vitamin E improves cognitive deficits. In this study, using a passive avoidance learning model in rats, we investigated the effects of vitamin E on Pb(2+) exposure-induced learning and memory impairments in rats. In the present study, 56 Wistar male rats (weighting 230-250g) were divided into eight groups (n=7). The Pb(2+) exposure involved gavages of lead acetate solution using three different doses (0.05%, 0.1%, and 0.2%) and the vitamin E consisted of three different doses (10, 25, 50μg/rat) for 30days. After the 30-day period, the rats were tested using a passive avoidance task (acquisition test). In a retrieval test conducted 48h after the training, step through latency (STL) and time in the dark compartment (TDC) were recorded. The statistical analysis of data was performed using ANOVA followed by Tukey's post hoc analysis. In all cases, differences were considered significant if p<0.05. The results of the present study showed that chronic exposure to high doses of Pb(2+) significantly increased both the number of trails required for learning and the TDC, whereas it decreased the STL in the passive avoidance test. Administration of vitamin E ameliorated the effects of Pb(2+) on animal behavior in the passive avoidance learning and memory task. Our results indicate that impairments of learning and memory in Pb(2+)-exposed rats are dose dependent and can be inhibited by antioxidants such as vitamin E.

Effects of vitamins E and C combined with β-carotene on cognitive function in the elderly

The aim of the present study was to investigate the effect of vitamins E (VE) and C (VC), combined with β-carotene (β-C), on cognitive function in the elderly. A total of 276 elderly subjects completed the prospective study following treatment with VE, VC and different doses of β-C or with VE only. Cognitive function was assessed by the Mini-Mental State Examination (MMSE) and Hasegawa Dementia Scale (HDS) tests. The plasma levels of amyloid-β (Aβ) and estradiol (E₂) were determined by radioimmunoassay (RIA). Results from the MMSE and HDS assessments indicated that the treatment strategy of VE and VC combined with β-C significantly improved cognitive function in the elderly subjects, particularly with higher doses of β-C. Furthermore, RIA suggested that treatment with these vitamins could markedly reduce plasma Aβ levels and elevate plasma E₂ levels. The present findings suggest that treatment with VE, VC and β-C results in promising improvements in cognitive function in the elderly.

Targeting the prodromal stage of Alzheimer's disease: bioenergetic and mitochondrial opportunities

Alzheimer's disease (AD) has a complex and progressive neurodegenerative phenotype, with hypometabolism and impaired mitochondrial bioenergetics among the earliest pathogenic events. Bioenergetic deficits are well documented in preclinical models of mammalian aging and AD, emerge early in the prodromal phase of AD, and in those at risk for AD. This review discusses the importance of early therapeutic intervention during the prodromal stage that precedes irreversible degeneration in AD. Mechanisms of action for current mitochondrial and bioenergetic therapeutics for AD broadly fall into the following categories: 1) glucose metabolism and substrate supply; 2) mitochondrial enhancers to potentiate energy production; 3) antioxidants to scavenge reactive oxygen species and reduce oxidative damage; 4) candidates that target apoptotic and mitophagy pathways to either remove damaged mitochondria or prevent neuronal death. Thus far, mitochondrial therapeutic strategies have shown promise at the preclinical stage but have had little-to-no success in clinical trials. Lessons learned from preclinical and clinical therapeutic studies are discussed. Understanding the bioenergetic adaptations that occur during aging and AD led us to focus on a systems biology approach that targets the bioenergetic system rather than a single component of this system. Bioenergetic system-level therapeutics personalized to bioenergetic phenotype would target bioenergetic deficits across the prodromal and clinical stages to prevent and delay progression of AD.

Dietary antioxidant intake and its association with cognitive function in an ethnically diverse sample of US adults

BACKGROUND

Dietary antioxidants can inhibit reactions accompanying neurodegeneration and thus prevent cognitive impairment. We describe associations of dietary antioxidants with cognitive function in a large biracial population, while testing moderation by sex, race, and age and mediation by depressive symptoms.

METHODS

This was a cross-sectional analysis of 1274 adults (541 men and 733 women) aged 30 to 64 years at baseline (mean [standard deviation] = 47.5 [9.3]) in the Healthy Aging in Neighborhoods of Diversity Across the Lifespan Study, Baltimore city, MD. Cognitive performance in the domains of memory, language/verbal, attention, spatial, psychomotor speed, executive function, and global mental status were assessed. The 20-item Center for Epidemiologic Studies Depression Scale was used to measure depressive symptoms. Dietary intake was assessed with two 24-hour recalls, estimating daily consumption of total carotenoids and vitamins A, C, and E per 1000 kcal.

RESULTS

Among key findings, 1 standard deviation (∼ 2.02 mg/1000 kcal) higher vitamin E was associated with a higher score on verbal memory, immediate recall (β = +0.64 [0.19], p = .001), and better language/verbal fluency performance (β = +0.53 [0.16], p = .001), particularly among the younger age group. Women with higher vitamin E intake (β = +0.68 [0.21], p = .001) had better performance on a psychomotor speed test. The vitamin E-verbal memory association was partially mediated by depressive symptoms (proportion mediated = 13%-16%).

CONCLUSIONS

In sum, future cohort studies and dietary interventions should focus on associations of dietary vitamin E with cognitive decline, specifically for domains of verbal memory, verbal fluency, and psychomotor speed.

Effects of vitamin E on cognitive performance during ageing and in Alzheimer's disease

Vitamin E is an important antioxidant that primarily protects cells from damage associated with oxidative stress caused by free radicals. The brain is highly susceptible to oxidative stress, which increases during ageing and is considered a major contributor to neurodegeneration. High plasma vitamin E levels were repeatedly associated with better cognitive performance. Due to its antioxidant properties, the ability of vitamin E to prevent or delay cognitive decline has been tested in clinical trials in both ageing population and Alzheimer’s disease (AD) patients. The difficulty in performing precise and uniform human studies is mostly responsible for the inconsistent outcomes reported in the literature. Therefore, the benefit of vitamin E as a treatment for neurodegenerative disorders is still under debate. In this review, we focus on those studies that mostly have contributed to clarifying the exclusive function of vitamin E in relation to brain ageing and AD.