Fish, docosahexaenoic acid and Alzheimer's disease

The association of dietary patterns with cognition through the lens of neuroimaging-a Systematic review

Despite the reported benefits of diet on cognition in older adults, randomized controlled trials (RCT) testing the impact of dietary interventions on cognitive scores have yielded less promising results when cognition was assessed via neuropsychological tests. More recently, neuroimaging has been used to identify more subtle brain-related changes associated to cognition. Hence, employing a combination of neuroimaging techniques with neuropsychological tests could clarify this controversy. To determine the effect of diet on cognitive performance, we conducted a systematic review of PubMed and Scopus databases for all studies, on middle-aged and older adults, combining neuroimaging, neuropsychological tests, and data on dietary patterns. The inclusion criteria were met by 14 observational studies and no RCTs. The range of brain measures assessed varied from volumes to white matter integrity, functional connectivity, brain glucose metabolism and beta-amyloid deposition. Given the variability of methods used in assessing cognitive performance, diet and brain correlates, conducting a meta-analysis was not possible. Here the evidence suggests that, in observational studies, dietary patterns may be associated with brain correlates that have been shown to precede cognitive decline. As such, neuroimaging should be included in future RCTs to identify any benefits of diet on brain measures linked with cognitive health.

Blood polyunsaturated omega-3 fatty acids, brain atrophy, cognitive decline, and dementia risk

INTRODUCTION

We searched for consistent associations of an omega-3 index in plasma (sum of eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) with several dementia-related outcomes in a large cohort of older adults.

METHODS

We included 1279 participants from the Three-City study, non-demented at the time of blood measurements at baseline, with face-to-face neuropsychological assessment and systematic detection of incident dementia over a 17-year follow-up. An ancillary study included 467 participants with up to three repeated brain imaging exams over 10 years.

RESULTS

In multivariable models, higher levels of plasma EPA+DHA were consistently associated with a lower risk of dementia (hazard ratio for 1 standard deviation = 0.87 [95% confidence interval, 0.76-0.98]), and a lower decline in global cognition (P = .04 for change over time), memory (P = .06), and medial temporal lobe volume (P = .02).

DISCUSSION

This prospective study provides compelling evidence for a relationship between long-chain omega-3 fatty acids levels and lower risks for dementia and related outcomes.

Acyl-CoA synthetases as regulators of brain phospholipid acyl-chain diversity

Each individual cell-type is defined by its distinct morphology, phenotype, molecular and lipidomic profile. The importance of maintaining cell-specific lipidomic profiles is exemplified by the numerous diseases, disorders, and dysfunctional outcomes that occur as a direct result of altered lipidome. Therefore, the mechanisms regulating cellular lipidome diversity play a role in maintaining essential biological functions. The brain is an organ particularly rich in phospholipids, the main constituents of cellular membranes. The phospholipid acyl-chain profile of membranes in the brain is rather diverse due in part to the high degree of cellular heterogeneity. These membranes and the acyl-chain composition of their phospholipids are highly regulated, but the mechanisms that confer this tight regulation are incompletely understood. A family of enzymes called acyl-CoA synthetases (ACSs) stands at a pinnacle step allowing influence over cellular acyl-chain selection and subsequent metabolic flux. ACSs perform the initial reaction for cellular fatty acid metabolism by ligating a Coenzyme A to a fatty acid which both traps a fatty acid within a cell and activates it for metabolism. The ACS family of enzymes is large and diverse consisting of 25-26 family members that are nonredundant, each with unique distribution across and within cell types, and differential fatty acid substrate preferences. Thus, ACSs confer a critical intracellular fatty acid selecting step in a cell-type dependent manner providing acyl-CoA moieties that serve as essential precursors for phospholipid synthesis and remodeling, and therefore serve as a key regulator of cellular membrane acyl-chain compositional diversity. Here we will discuss how the contribution of individual ACSs towards brain lipid metabolism has only just begun to be elucidated and discuss the possibilities for how ACSs may differentially regulate brain lipidomic diversity.

The chemical composition and lipid profile of the chub mackerel (Scomber colias) show a strong seasonal dependence: Contribution to a nutritional evaluation

The seasonal variation in chemical and lipid composition of chub mackerel (Scomber colias) was evaluated monthly over one year (proximate chemical composition and lipid profile: fatty acid (FA) and lipid classes distribution). Significant seasonal changes regarding fat content were noticed (1.3-10.3 g/100 g), with the lowest fat content obtained in February (during spawning period), and the highest in September. Regarding the FA profile, the main fluctuations were recorded in saturated (SFA) and polyunsaturated fatty acids (PUFA). The highest SFA content was registered between March and August (25.3-32.3%). PUFA (the most abundant group) reached its maximum percentual content between December and February (60.9 and 66.9%, respectively). In absolute terms, PUFA attained 5352.6 mg/100 g edible part in September, where 2473.8 mg/100 g of docosahexaenoic acid (DHA, C22:6n-3), representing 46.2% of total PUFA. DHA lowest level was 519.8 mg/100 g, registered in low-fat chub mackerel. Together DHA and EPA (eicosapentaenoic acid, C20:5n-3) represented 75% of the total PUFA and 84% of n-3 PUFA. Triacylglycerols (TAG) with 82.2-92.1% of total lipid content) and phospholipids (4.4-8.4%) were the main lipid classes. Polar lipid fraction (phospholipids), was predominantly constituted by PUFA (68.6-74.5%), mainly DHA (45.2-55.1%), with the highest percentage recorded in low-fat chub mackerel. High relative contents of PUFA (36.6-49.1%) were also found in TAG. Having into account the data obtained, chub mackerel is a privileged source of DHA even in a lean species whereby its consumption should be recommended as part a healthy dietary regime.

Hyperglycemia alters lipid metabolism and ultrastructural morphology of cerebellum in brains of diabetic rats: Therapeutic potential of raffia palm (Raphia hookeri G. Mann & H. Wendl) wine

The present study investigated the effect of raffia palm (Raphia hookeri) wine (RPW) on hyperglycemia-mediated lipid metabolites and pathways, functional chemistry and ultrastructural morphology of cerebellums in type 2 diabetes (T2D). T2D was induced in male Sprague-Dawley rats by feeding with 10% fructose ad libitum for 2 weeks before injecting intraperitoneally with 40 mg/kg bodyweight (bw) streptozotocin. Following confirmation of hyperglycemia at blood glucose >200 mg/dL, diabetic rats were treated with RPW at 150 and 300 mg/kg bw respectively. Metformin served as the standard drug. Negative and normal controls consisted of untreated diabetic and non-diabetic rats, respectively. After 5 weeks of treatment, the rats were humanely sacrificed, and their cerebellum excised from the harvested brains. GC-MS analysis revealed significant alterations in cerebellar lipid metabolites depicted by changes in unsaturated and saturated fatty acids, fatty - esters, alcohols, and amides, glycols and steroids on induction of T2D. Pathway enrichment analysis of the lipid metabolites revealed inactivation of arachidonic metabolic pathway following T2D induction. Treatment with both doses of RPW restored most of the metabolites, while reactivating arachidonic acid metabolism (high dose only). Low dose of RPW led to the activation of retinol metabolism. Both doses of RPW maintained cerebellar functional chemistry as revealed by FTIR analysis. TEM analysis revealed swollen mitochondria, depleted numbers of synaptic vesicles, and shrunk synaptic clefts following induction of T2D. These ultrastructural morphologies were improved in RPW-treated rats. These results portray the therapeutic potential of raffia palm wine in the management of neurodegenerative complications in T2D.

Risk Factors for Incident Dementia Among Older Cubans

Introduction: Little is known about risk factors of dementia in Latin American countries. We aimed to identify socio–demographic, health and lifestyle risk factors of incident dementia in Cuban older adults.

Methods: Data were from 1,846 participants in the Cuban cohort of the 10/66 Dementia Research Group. Participants completed questionnaires, health examinations, and cognitive tests at baseline (2003–2006) and 4.5 years later (2007–2010). Associations between risk factors (baseline) and incident dementia (follow-up) were examined using logistic regression.

Results: Just over 9% of participants developed dementia. Overall, older age and low physical activity were associated with incident dementia. In those 65–74 years of age, depression, stroke and low physical activity were associated with incident dementia. In those ≥75 years of age, low physical activity, never eating fish, and smoking were associated with incident dementia.

Conclusions: Modifiable lifestyle factors play an important role in developing dementia in Cuban older adults. This knowledge opens up opportunities for preventive strategies.

Plasma BDNF is a more reliable biomarker than erythrocyte omega-3 index for the omega-3 fatty acid enrichment of brain

Enriching brain DHA is believed to be beneficial for the prevention and treatment of several neurological diseases, including Alzheimer's disease. An impediment in assessing the effectiveness of the treatments is the lack of a reliable biomarker for brain DHA. The commonly used erythrocyte omega-3 index is not suitable for brain because of the involvement of unique transporter at the blood brain barrier (BBB). We recently showed that dietary lysophosphatidylcholine (LPC)-DHA significantly increases brain DHA, which results in increase of brain BDNF. Since there is bidirectional transport of BDNF through the BBB, we tested the hypothesis that plasma BDNF may be used as biomarker for brain DHA enrichment. We altered the brain DHA in rats and mice over a wide range using different dietary carriers of DHA, and the correlations between the increase in brain omega-3 index with the increases in plasma BDNF and the erythrocyte index were determined. Whereas the increase in brain omega-3 index positively correlated with the increase in plasma BDNF, it negatively correlated with the erythrocyte index. These results show that the plasma BDNF is more reliable than the erythrocyte index as biomarker for assessing the effectiveness of omega-3 supplements in improving brain function.

Dietary n-6/n-3 Ratio Influences Brain Fatty Acid Composition in Adult Rats

There is mounting evidence that diets supplemented with polyunsaturated fatty acids (PUFA) can impact brain biology and functions. This study investigated whether moderately high-fat diets differing in n-6/n-3 fatty acid ratio could impact fatty acid composition in regions of the brain linked to various psychopathologies. Adult male Sprague Dawley rats consumed isocaloric diets (35% kcal from fat) containing different ratios of linoleic acid (n-6) and alpha-linolenic acid (n-3) for 2 months. It was found that the profiles of PUFA in the prefrontal cortex, hippocampus, and hypothalamus reflected the fatty acid composition of the diet. In addition, region-specific changes in saturated fatty acids and monounsaturated fatty acids were detected in the hypothalamus, but not in the hippocampus or prefrontal cortex. This study in adult rats demonstrates that fatty acid remodeling in the brain by diet can occur within months and provides additional evidence for the suggestion that diet could impact mental health.

Evidence of the Role of Omega-3 Polyunsaturated Fatty Acids in Brain Glucose Metabolism

In mammals, brain function, particularly neuronal activity, has high energy needs. When glucose is supplemented by alternative oxidative substrates under different physiological conditions, these fuels do not fully replace the functions fulfilled by glucose. Thus, it is of major importance that the brain is almost continuously supplied with glucose from the circulation. Numerous studies describe the decrease in brain glucose metabolism during healthy or pathological ageing, but little is known about the mechanisms that cause such impairment. Although it appears difficult to determine the exact role of brain glucose hypometabolism during healthy ageing or during age-related neurodegenerative diseases such as Alzheimer’s disease, uninterrupted glucose supply to the brain is still of major importance for proper brain function. Interestingly, a body of evidence suggests that dietary n-3 polyunsaturated fatty acids (PUFAs) might play significant roles in brain glucose regulation. Thus, the goal of the present review is to summarize this evidence and address the role of n-3 PUFAs in brain energy metabolism. Taken together, these data suggest that ensuring an adequate dietary supply of n-3 PUFAs could constitute an essential aspect of a promising strategy to promote optimal brain function during both healthy and pathological ageing.

Outcomes of Perilla Seed Oil as an Additional Neuroprotective Therapy in Patients with Mild to Moderate Dementia: A Randomized Control Trial

BACKGROUND

Dementia is a common medical disorder in the elderly. Oxidative stress plays a major role in the process of cognitive decline in dementia. Perilla seed oil demonstrates its neuroprotective effects via anti-oxidative mechanisms against dementia. We investigate neuroprotective effects of perilla seed oil as an additional treatment in patients with mild to moderate dementia.

METHOD

A double-blind, randomized-control trial (perilla seed oil versus placebo) in patients with mild to moderate dementia was conducted. Perilla seed oil or placebo was added on with standard treatment for six months. Cognitive function was compared at nine months after enrollment.

RESULT

182 patients, with 94 in the experimental group and 88 in the placebo group, were able to complete the study. Cognitive function is not significantly different compared between groups. However, the total cholesterol and LDL cholesterol were significantly lower in the experimental group. Perilla seed oil had no adverse effect to kidney, liver, blood components or glucose metabolism.

CONCLUSION

Perilla seed oil as additional neuroprotective therapy in patients with mild to moderate dementia does not improve cognitive function. Perilla seed oil significantly reduced total cholesterol and LDL cholesterol. A clinical trial is needed to prove the benefit of cholesterol-lowering effects with perilla seed oil in human.

Docosahexaenoic acid supplementation in age-related cognitive decline: a systematic review and meta-analysis

PURPOSE

To investigate the role of DHA supplementation in preventing age-related cognitive decline (ARCD) in individual cognitive domains by conducting systematic review and meta-analysis.

METHODS

Relevant clinical trials were systematically searched at Medline, PubMed, Scopus, Cochrane, ProQuest, and Embase databases since inception to June 2018. The PRISMA guidelines were adhered for data abstraction, quality assessment, and validation of included studies. Study details such as participant characteristics, DHA supplementation, and cognitive function outcome measures, i.e., memory, attention, working memory, and executive function, were extracted to perform meta-analysis according to the Cochrane guidelines. Additional meta-regression and subgroup analyses were performed to detect confounding variables and sensitivity of results, respectively.

RESULTS

Ten studies including 2327 elderly individuals were part of the final results. Study exhibited minimal or no pooled incremental effects on memory (0.22, 95%CI = - 0.17 to 0.61, I² = 94.36%), attention (0.1, 95%CI = - 0.04 to 0.25, I² = 32.25%), working memory (0.01, 95%CI = - 0.10 to 0.12, I² = 0%), and executive function (0.03, 95%CI = - 0.05 to 0.11, I² = 78.48%) among the DHA-supplemented group. The results from standard mean difference between the groups, on memory (0.08, 95%CI = - 0.12 to 0.28, I² = 76.82%), attention (0.04, 95%CI = - 0.09 to 0.23, I² = 42.63%), working memory (- 0.08, 95%CI = - 0.26 to 0.10, I² = 37.57%), and executive function (0.17, 95%CI = - 0.01 to 0.36, I² = 78.48%) were similar to the results of pooled incremental analysis. Lastly, results remained unaffected by sensitivity and sub-group analyses.

CONCLUSIONS

Current pieces of evidence do not support the role of DHA supplementation, in preventing/retarding ARCD of memory, executive function, attention, and working memory. Protocol registered at PROSPERO (ID: PROSPERO 2018 CRD42018099401).

Effect of APOE Genotype on Plasma Docosahexaenoic Acid (DHA), Eicosapentaenoic Acid, Arachidonic Acid, and Hippocampal Volume in the Alzheimer's Disease Cooperative Study-Sponsored DHA Clinical Trial

BACKGROUND

Docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (AA) play key roles in several metabolic processes relevant to Alzheimer's disease (AD) pathogenesis and neuroinflammation. Carrying the APOEɛ4 allele (APOE4) accelerates omega-3 polyunsaturated fatty acid (PUFA) oxidation. In a pre-planned subgroup analysis of the Alzheimer's Disease Cooperative Study-sponsored DHA clinical trial, APOE4 carriers with mild probable AD had no improvements in cognitive outcomes compared to placebo, while APOE 4 non-carriers showed a benefit from DHA supplementation.

OBJECTIVE

We sought to clarify the effect of APOEɛ4/ɛ4 on both the ratio of plasma DHA and EPA to AA, and on hippocampal volumes after DHA supplementation.

METHODS

Plasma fatty acids and APOE genotype were obtained in 275 participants randomized to 18 months of DHA supplementation or placebo. A subset of these participants completed brain MRI imaging (n = 86) and lumbar punctures (n = 53).

RESULTS

After the intervention, DHA-treated APOEɛ3/ɛ3 and APOEɛ2/ɛ3 carriers demonstrated significantly greater increase in plasma DHA/AA compared to ɛ4/ɛ4 carriers. APOEɛ2/ɛ3 had a greater increase in plasma EPA/AA and less decline in left and right hippocampal volumes compared to compared to ɛ4/ɛ4 carriers. The change in plasma and cerebrospinal fluid DHA/AA was strongly correlated. Greater baseline and increase in plasma EPA/AA was associated with a lower decrease in the right hippocampal volume, but only in APOE 4 non-carriers.

CONCLUSION

The lower increase in plasma DHA/AA and EPA/AA in APOEɛ4/ɛ4 carriers after DHA supplementation reduces brain delivery and affects the efficacy of DHA supplementation.

Omega-3 Polyunsaturated Fatty Acids and Their Health Benefits

Omega-3 polyunsaturated fatty acids (PUFAs) include α-linolenic acid (ALA; 18:3 ω-3), stearidonic acid (SDA; 18:4 ω-3), eicosapentaenoic acid (EPA; 20:5 ω-3), docosapentaenoic acid (DPA; 22:5 ω-3), and docosahexaenoic acid (DHA; 22:6 ω-3). In the past few decades, many epidemiological studies have been conducted on the myriad health benefits of omega-3 PUFAs. In this review, we summarized the structural features, properties, dietary sources, metabolism, and bioavailability of omega-3 PUFAs and their effects on cardiovascular disease, diabetes, cancer, Alzheimer's disease, dementia, depression, visual and neurological development, and maternal and child health. Even though many health benefits of omega-3 PUFAs have been reported in the literature, there are also some controversies about their efficacy and certain benefits to human health.

Association between improved adherence to the Japanese diet and incident functional disability in older people: The Ohsaki Cohort 2006 Study

BACKGROUND & AIMS

Although it has been reported that the Japanese dietary pattern is associated with a lower risk of incident functional disability among older people, the potential benefits of improving adherence to the Japanese diet remain unclear. The aim of the present study was to evaluate the association between 12-year change in adherence to the Japanese diet and the subsequent risk of incident functional disability in older people in Japan.

METHODS

We analyzed 10-year follow-up data from a cohort study of 2923 Japanese older adults (age ≥65 years) in 2006. We collected dietary information using a validated 39-item food frequency questionnaire at two time points (1994 and 2006). Adherence to the Japanese diet (high intake of rice, miso soup, seaweeds, pickles, green and yellow vegetables, fish, green tea; low intake of beef and pork, and coffee) was assessed using the Japanese Diet Index (JDI), which ranges from 0 to 9. Participants were categorized into five groups according to changes in the JDI score at these two time points. Data on incident functional disability from December 2006 to November 2016 were retrieved from the public long-term care insurance database. The Cox proportional hazards model was used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for incident functional disability.

RESULTS

During 22,466 person-years of follow-up, 1093 cases of incident functional disability were documented. Compared with participants in the group with the largest decrease in the JDI score (≤-2), the multivariate-adjusted HR (95% CI) of incident functional disability was 0.77 (0.61-0.98) for those in the largest increase group (≥+2).

CONCLUSIONS

Improved adherence to the Japanese diet was associated with a significantly lower risk of incident functional disability in older people in Japan.

Omega-3 PUFA metabolism and brain modifications during aging

In Canada, 5.5 million (16% of Canadians) adults are >65 years old and projections suggest this number will be approximately 20% of Canadians by 2024. A major concern regarding old age is a decline in health, especially if this entails a loss of self-sufficiency and independence caused by a decline in cognition. The brain contains 60% of fat and is one of the most concentrated organs in long chain omega-3 fatty acids such as docosahexaenoic acid (DHA). During aging, there are physiological modifications in the metabolism of lipids that could also have consequences on brain structure and levels of DHA. This review will hence discuss the physiological modifications in the metabolism of lipids during aging with a focus on long chain omega-3 and omega-6 fatty acids and also outline the structural and functional modifications of the brain during aging including brain lipid modifications and its relation to higher levels of DHA and cognition. Therefore, in this review, we outline the importance of collecting more data on the biology of aging since it might highly improve our understanding about what are «normal» modifications occurring during aging and what can become pathological.

Omega-3 Fatty Acids and Neurodegenerative Diseases: New Evidence in Clinical Trials

A nutritional approach could be a promising strategy to prevent or slow the progression of neurodegenerative diseases such as Parkinson's and Alzheimer's disease, since there is no effective therapy for these diseases so far. The beneficial effects of omega-3 fatty acids are now well established by a plethora of studies through their involvement in multiple biochemical functions, including synthesis of anti-inflammatory mediators, cell membrane fluidity, intracellular signaling, and gene expression. This systematic review will consider epidemiological studies and clinical trials that assessed the impact of supplementation or dietary intake of omega-3 polyunsaturated fatty acids on neurodegenerative diseases such as Parkinson's and Alzheimer's diseases. Indeed, treatment with omega-3 fatty acids, being safe and well tolerated, represents a valuable and biologically plausible tool in the management of neurodegenerative diseases in their early stages.

Molecular effects of dietary fatty acids on brain insulin action and mitochondrial function

The prevalence of obesity and its co-morbidities such as insulin resistance and type 2 diabetes are tightly linked to increased ingestion of palatable fat enriched food. Thus, it seems intuitive that the brain senses elevated amounts of fatty acids (FAs) and affects adaptive metabolic response, which is connected to mitochondrial function and insulin signaling. This review will address the effect of dietary FAs on brain insulin and mitochondrial function with a special emphasis on the impact of different FAs on brain function and metabolism.

Effect of Varying Concentrations of Docosahexaenoic Acid on Amyloid Beta (1⁻42) Aggregation: An Atomic Force Microscopy Study

Healthcare has advanced significantly, bringing with it longer life expectancies and a growing population of elders who suffer from dementia, specifically Alzheimer’s disease (AD). The amyloid beta (Aβ) peptide has been implicated in the cause of AD, where the peptides undergo a conformational change and form neurotoxic amyloid oligomers which cause neuronal cell death. While AD has no cure, preventative measures are being designed to either slow down or stop the progression of this neurodegenerative disease. One of these measures involves dietary supplements with polyunsaturated fatty acids such as docosahexaenoic acid (DHA). This omega-3 fatty acid is a key component of brain development and has been suggested to reduce the progression of cognitive decline. However, different studies have yielded different results as to whether DHA has positive, negative, or no effects on Aβ fibril formation. We believe that these discrepancies can be explained with varying concentrations of DHA. Here, we test the inhibitory effect of different concentrations of DHA on amyloid fibril formation using atomic force microscopy. Our results show that DHA has a strong inhibitory effect on Aβ_1–42 fibril formation at lower concentrations (50% reduction in fibril length) than higher concentrations above its critical micelle concentration (70% increase in fibril length and three times the length of those at lower concentrations). We provide evidence that various concentrations of DHA can play a role in the inhibitory effects of amyloid fibril formation in vitro and help explain the discrepancies observed in previous studies.

Apolipoprotein E genotype moderates the association between dietary polyunsaturated fat and brain function: an exploration of cerebral glutamate and cognitive performance

Objective: To investigate the effect of Apolipoprotein E (APOE) genotype on the association between dietary polyunsaturated fat (PUFA), cognitive function, and cerebral glutamate. Methods: A participant sample of 122 middle-aged adults were grouped according to APOE genotype (ϵ4 carrier or ϵ4 non-carrier) and asked to record dietary intake for three consecutive days. All participants also underwent neuropsychological testing and a proton magnetic resonance spectroscopy (¹H MRS) scan to assess glutamate in the posterior cingulate cortex. Results: Multiple regression analyses revealed a significant interaction between APOE genotype and PUFA intake on memory performance, F(1,113) = 6.749, p = .016. Greater PUFA intake was associated with better memory performance in healthy middle-aged adults who were APOE ϵ4 non-carriers, but not for ϵ4 carriers. Furthermore, there was a significant interaction between APOE genotype and PUFA intake on cerebral glutamate, in that dietary PUFA was associated with greater cerebral glutamate in APOE ϵ4 carriers, but not for ϵ4 non-carriers, F(1,114) = 5.173, p = .025. Conclusions: The findings suggest that PUFA action on the brain differs according to APOE polymorphism and points towards cerebral glutamate as a potential marker of genetic risk for Alzheimer's disease (AD). Early treatment consisting of PUFA supplementation that is tailored to APOE genotype may be an important intervention for the prevention of cognitive decline.

Moderating effect of PLIN4 genetic variant on impulsivity traits in 5-year-old-children born small for gestational age

Poor fetal growth is associated with long-term behavioral, metabolic and psychiatric alterations, including impulsivity, insulin resistance, and mood disorders. However, the consumption of omega-3 polyunsaturated fatty acid (n-3 PUFA) seems to be protective for this population, improving inhibitory control and behavioral reactivity. We investigated whether the presence of the A allele of rs8887 SNP (PLIN4 gene), known to be associated with increased sensitivity to the consumption of n-3 PUFAs, interacts with fetal growth influencing inhibitory control. 152 five-year-old children were genotyped and performed the Stop Signal Task (SSRT). There was a significant interaction between birth weight and the presence of the A allele on SSRT performance, in which lower birth weight associated with poorer inhibitory control only in non-carriers. These results suggest that a higher responsiveness to n-3 PUFAS protects small for gestational age children from developing poor response inhibition, highlighting that optimizing n-3 PUFA intake may benefit this population.

Nutrition and Alzheimer Disease

We gathered some theoretic and practical concepts related to the importance of nutrition in the prevention and management of Alzheimer disease (AD). Besides the role of nutrients in brain development and functioning, some nutrients exert special control in the development of AD, due to their participation in neurotransmitter synthesis, their modulation in epigenetics mechanisms, and as antioxidants. In addition, some non-nutrient food-derived substances have shown potential in the control of neuroinflammation and consequently in the prevention of AD. Finally, it is important to be aware of the nutritional status and food intake patterns of the patient with AD.

Can inflammation be resolved in Alzheimer's disease?

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive memory loss and dementia. Accumulating evidence suggests that inflammation is involved in the pathogenesis of AD. Epidemiological studies suggest that use of anti-inflammatory drugs is associated with a lower incidence of AD. However, clinical trials with anti-inflammatory drugs have not been successful. Recent studies have shown that inflammation is resolved by a process that is mediated by a group of lipid mediators, so called specialized pro-resolving lipid mediators (SPMs). Unlike anti-inflammatory strategies, which usually involve inhibition of the synthesis of inflammatory mediators, stimulating the resolution of inflammation is aimed at ending inflammation in a similar fashion as under normal physiological conditions. We have previously shown that pathways of resolution are impaired in AD. Moreover, we found that SPMs can improve neuronal survival and increase microglial phagocytosis of amyloid beta (Aβ) in in vitro studies, indicating that stimulating resolution of inflammation may be a potential therapeutic target in AD. In this review, we summarize recent findings regarding resolution of inflammation in AD. We also discuss possible strategies to stimulate the resolution of inflammation in AD, specifically focusing on signaling pathways, including SPMs, their receptors and enzymes involved in their formation.

On the Neuroprotective Role of Astaxanthin: New Perspectives?

Astaxanthin is a carotenoid with powerful antioxidant and anti-inflammatory activity produced by several freshwater and marine microorganisms, including bacteria, yeast, fungi, and microalgae. Due to its deep red-orange color it confers a reddish hue to the flesh of salmon, shrimps, lobsters, and crayfish that feed on astaxanthin-producing organisms, which helps protect their immune system and increase their fertility. From the nutritional point of view, astaxanthin is considered one of the strongest antioxidants in nature, due to its high scavenging potential of free radicals in the human body. Recently, astaxanthin is also receiving attention for its effect on the prevention or co-treatment of neurological pathologies, including Alzheimer and Parkinson diseases. In this review, we focus on the neuroprotective properties of astaxanthin and explore the underlying mechanisms to counteract neurological diseases, mainly based on its capability to cross the blood-brain barrier and its oxidative, anti-inflammatory, and anti-apoptotic properties.

Precision Medicine for Alzheimer's Disease Prevention

Precision medicine is an approach to medical treatment and prevention that takes into account individual variability in genes, environment, and lifestyle and allows for personalization that is based on factors that may affect the response to treatment. Several genetic and epigenetic risk factors have been shown to increase susceptibility to late-onset Alzheimer's disease (AD). As such, it may be beneficial to integrate genetic risk factors into the AD prevention approach, which in the past has primarily been focused on universal risk-reduction strategies for the general population rather than individualized interventions in a targeted fashion. This review discusses examples of a "one-size-fits-all" versus clinical precision medicine AD prevention strategy, in which the precision medicine approach considers two genes that can be commercially sequenced for polymorphisms associated with AD, apolipoprotein E (APOE), and methylenetetrahydrofolate reductase (MTHFR). Comparing these two distinct approaches provides support for a clinical precision medicine prevention strategy, which may ultimately lead to more favorable patient outcomes as the interventions are targeted to address individualized risks.

Fish Intake, Genetic Predisposition to Alzheimer Disease, and Decline in Global Cognition and Memory in 5 Cohorts of Older Persons

Fish are a primary source of long-chain omega-3 fatty acids, which may help delay cognitive aging. We pooled participants from the French Three-City study and 4 US cohorts (Nurses' Health Study, Women's Health Study, Chicago Health and Aging Project, and Rush Memory and Aging Project) for whom diet and cognitive data were available (n = 23,688 white persons, aged ≥65 years, 88% female, baseline year range of 1992-1999, and median follow-up range of 3.9-9.1 years) to investigate the relationship of fish intake to cognitive decline and examine interactions with genes related to Alzheimer disease. We estimated cohort-specific associations between fish and change in composite scores of global cognition and episodic memory using linear mixed models, and we pooled results using inverse-variance weighted meta-analysis. In multivariate analyses, higher fish intake was associated with slower decline in both global cognition and memory (P for trend ≤ 0.031). Consuming ≥4 servings/week versus <1 serving/week of fish was associated with a lower rate of memory decline: 0.018 (95% confidence interval: 0.004, 0.032) standard units, an effect estimate equivalent to that found for 4 years of age. For global cognition, no comparisons of higher versus low fish intake reached statistical significance. In this meta-analysis, higher fish intake was associated with a lower rate of memory decline. We found no evidence of effect modification by genes associated with Alzheimer disease.

DHA supplementation improves cognitive function via enhancing Aβ-mediated autophagy in Chinese elderly with mild cognitive impairment: a randomised placebo-controlled trial

BACKGROUND

Higher docosahexaenoic acid (DHA) intake is inversely correlated with relative risk of Alzheimer's disease. The potential benefits of DHA supplementation in people with mild cognitive impairment (MCI) have not been fully examined.

OBJECTIVE

Our study aimed to assess the effect of a 24-month DHA supplementation on cognitive function and amyloid beta (Aβ)-mediated autophagy in elderly subjects with MCI.

METHODS

This was a randomised, double-blind, placebo-controlled trial in Tianjin, China. A total of 240 individuals with MCI were identified and randomly divided into intervention (DHA 2 g/day, n=120) and control (corn oil as placebo, n=120) groups. Cognitive function and blood Aβ-related biomarkers were measured at baseline, 6, 12, 18 and 24 months. Data were analysed using generalised estimating equation.

RESULTS

A total of 217 participants (DHA: 109, placebo: 108) completed the trial. During the follow-up, scores of full-scale IQ, verbal IQ and subdomains of information and digit span were significantly higher in the intervention group than the convention group (p<0.05). In the intervention group, blood Aβ-42 level and expression of Aβ protein precursor mRNA were decreased (p<0.05), while Beclin-1 and LC3-II levels and expression of LC3-II mRNA were increased (p<0.05).

CONCLUSION

Daily oral DHA supplementation (2 g/day) for 24 months may improve cognitive function and change blood biomarker-related Aβ-mediated autophagy in people with MCI. Larger longer-term confirmatory studies are warranted.

TRIAL REGISTRATION NUMBER

ChiCTR-IOR-15006058.

Cognitive response to fish oil, blueberry, and combined supplementation in older adults with subjective cognitive impairment

Given evidence that eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and anthocyanin-rich blueberries provide neurocognitive benefit, we investigated long-term supplementation in older adults with cognitive complaints. In a 24-week randomized, double-blind, placebo-controlled trial, elderly men and women received daily fish oil (FO) or blueberry (BB) or both. Diet records confirmed that participants reduced background consumption of EPA, DHA, and anthocyanins as prescribed. Erythrocyte EPA + DHA composition increased in the FO groups (p = 0.0001). Total urinary anthocyanins did not differ between the groups after supplementation but glycoside and native (food) forms increased only in the BB-supplemented groups. The FO (p = 0.03) and BB (p = 0.05) groups reported fewer cognitive symptoms, and the BB group showed improved memory discrimination (p = 0.04), indicating that supplementation improved cognition. Cognitive benefit in the BB group was associated with the presence of urinary anthocyanins reflecting recent BB intake but not with anthocyanin metabolites. However, combined FO + BB treatment was not associated with cognitive enhancement as expected.

Population-Based Approaches to Alzheimer's Disease Prevention

Progress in prevention and treatment of Alzheimer's disease (AD) and dementia is hampered by the restricted understanding of the biological and environmental causes underlying pathophysiology. It is widely accepted that certain genetic factors are associated with AD and a number of lifestyle and other environmental characteristics have also been linked to dementia risk. However, interactions between genes and the environment are not yet well understood, and coordinated global action is required to utilize existing cohorts and other resources effectively and efficiently to identify new avenues for dementia prevention. This chapter provides a brief summary of current research on risk and protective factors and opportunities and challenges in relation to population-based approaches are discussed.

Significance of long chain polyunsaturated fatty acids in human health

In the last decades, the development of new technologies applied to lipidomics has revitalized the analysis of lipid profile alterations and the understanding of the underlying molecular mechanisms of lipid metabolism, together with their involvement in the occurrence of human disease. Of particular interest is the study of omega-3 and omega-6 long chain polyunsaturated fatty acids (LC-PUFAs), notably EPA (eicosapentaenoic acid, 20:5n-3), DHA (docosahexaenoic acid, 22:6n-3), and ARA (arachidonic acid, 20:4n-6), and their transformation into bioactive lipid mediators. In this sense, new families of PUFA-derived lipid mediators, including resolvins derived from EPA and DHA, and protectins and maresins derived from DHA, are being increasingly investigated because of their active role in the "return to homeostasis" process and resolution of inflammation. Recent findings reviewed in the present study highlight that the omega-6 fatty acid ARA appears increased, and omega-3 EPA and DHA decreased in most cancer tissues compared to normal ones, and that increments in omega-3 LC-PUFAs consumption and an omega-6/omega-3 ratio of 2-4:1, are associated with a reduced risk of breast, prostate, colon and renal cancers. Along with their lipid-lowering properties, omega-3 LC-PUFAs also exert cardioprotective functions, such as reducing platelet aggregation and inflammation, and controlling the presence of DHA in our body, especially in our liver and brain, which is crucial for optimal brain functionality. Considering that DHA is the principal omega-3 FA in cortical gray matter, the importance of DHA intake and its derived lipid mediators have been recently reported in patients with major depressive and bipolar disorders, Alzheimer disease, Parkinson's disease, and amyotrophic lateral sclerosis. The present study reviews the relationships between major diseases occurring today in the Western world and LC-PUFAs. More specifically this review focuses on the dietary omega-3 LC-PUFAs and the omega-6/omega-3 balance, in a wide range of inflammation disorders, including autoimmune diseases. This review suggests that the current recommendations of consumption and/or supplementation of omega-3 FAs are specific to particular groups of age and physiological status, and still need more fine tuning for overall human health and well being.

Exploring the Association between Alzheimer's Disease, Oral Health, Microbial Endocrinology and Nutrition

Longitudinal monitoring of patients suggests a causal link between chronic periodontitis and the development of Alzheimer’s disease (AD). However, the explanation of how periodontitis can lead to dementia remains unclear. A working hypothesis links extrinsic inflammation as a secondary cause of AD. This hypothesis suggests a compromised oral hygiene leads to a dysbiotic oral microbiome whereby Porphyromonas gingivalis, a keystone periodontal pathogen, with its companion species, orchestrates immune subversion in the host. Brushing and chewing on teeth supported by already injured soft tissues leads to bacteremias. As a result, a persistent systemic inflammatory response develops to periodontal pathogens. The pathogens, and the host’s inflammatory response, subsequently lead to the initiation and progression of multiple metabolic and inflammatory co-morbidities, including AD. Insufficient levels of essential micronutrients can lead to microbial dysbiosis through the growth of periodontal pathogens such as demonstrated for P. gingivalis under low hemin bioavailability. An individual’s diet also defines the consortium of microbial communities that take up residency in the oral and gastrointestinal (GI) tract microbiomes. Their imbalance can lead to behavioral changes. For example, probiotics enriched in Lactobacillus genus of bacteria, when ingested, exert some anti-inflammatory influence through common host/bacterial neurochemicals, both locally, and through sensory signaling back to the brain. Early life dietary behaviors may cause an imbalance in the host/microbial endocrinology through a dietary intake incompatible with a healthy GI tract microbiome later in life. This imbalance in host/microbial endocrinology may have a lasting impact on mental health. This observation opens up an opportunity to explore the mechanisms, which may underlie the previously detected relationship between diet, oral/GI microbial communities, to anxiety, cognition and sleep patterns. This review suggests healthy diet based interventions that together with improved life style/behavioral changes may reduce and/or delay the incidence of AD.

Horseradish and radish peroxidases eaten with fish could help explain observed associations between fish consumption and protection from age-related dementia

A juxtaposition of regional cuisines and recent prospective studies of fish consumption in China and Japan points to fresh horseradish and/or radish (HRR) as possible contributors to delaying age-related dementia. The hypothesis is that the inverse association found sometimes between fish intake and cognitive decline is partially due to exposure of the oral cavity to active peroxidases from HRR served in conjunction with fish. This hypothesis can be tested by specifically looking at whether HRR is consumed with fish and whether such HRR is prepared in a way that preserves activity of HRR peroxidases. It is possible that by putting active HRR peroxidases in their mouths, elderly people supplement their age-diminished salivary antioxidant capacity and break down additional hydrogen peroxide (H₂O₂) in the oral cavity before it can migrate into the brain, thus decreasing the incidence of brain cell death induction by chronically-elevated H₂O₂. Intentional exposure of the oral cavity to active HRR peroxidases could be a prophylactic for delaying dementia. Because vegetable peroxidases are inactivated by gastric juices, it will be difficult to obtain benefit from HRR peroxidases' antioxidant effect via ingestion in encapsulated dietary supplements.

Docosahexaenoic acid (DHA), a fundamental fatty acid for the brain: New dietary sources

Docosahexaenoic acid (C22: 6n-3, DHA) is a long-chain polyunsaturated fatty acid of marine origin fundamental for the formation and function of the nervous system, particularly the brain and the retina of humans. It has been proposed a remarkable role of DHA during human evolution, mainly on the growth and development of the brain. Currently, DHA is considered a critical nutrient during pregnancy and breastfeeding due their active participation in the development of the nervous system in early life. DHA and specifically one of its derivatives known as neuroprotectin D-1 (NPD-1), has neuroprotective properties against brain aging, neurodegenerative diseases and injury caused after brain ischemia-reperfusion episodes. This paper discusses the importance of DHA in the human brain given its relevance in the development of the tissue and as neuroprotective agent. It is also included a critical view about the ways to supply this noble fatty acid to the population.

Predictors of Memory in Healthy Aging: Polyunsaturated Fatty Acid Balance and Fornix White Matter Integrity

Recent evidence demonstrates that age and disease-related decline in cognition depends not only upon degeneration in brain structure and function, but also on dietary intake and nutritional status. Memory, a potential preclinical marker of Alzheimer's disease, is supported by white matter integrity in the brain and dietary patterns high in omega-3 and omega-6 polyunsaturated fatty acids. However, the extent to which memory is supported by specific omega-3 and omega-6 polyunsaturated fatty acids, and the degree to which this relationship is reliant upon microstructure of particular white matter regions is not known. This study therefore examined the cross-sectional relationship between empirically-derived patterns of omega-3 and omega-6 polyunsaturated fatty acids (represented by nutrient biomarker patterns), memory, and regional white matter microstructure in healthy, older adults. We measured thirteen plasma phospholipid omega-3 and omega-6 polyunsaturated fatty acids, memory, and regional white matter microstructure in 94 cognitively intact older adults (65 to 75 years old). A three-step mediation analysis was implemented using multivariate linear regressions, adjusted for age, gender, education, income, depression status, and body mass index. The mediation analysis revealed that a mixture of plasma phospholipid omega-3 and omega-6 polyunsaturated fatty acids is linked to memory and that white matter microstructure of the fornix fully mediates the relationship between this pattern of plasma phospholipid polyunsaturated fatty acids and memory. These results suggest that memory may be optimally supported by a balance of plasma phospholipid omega-3 and omega-6 polyunsaturated fatty acids through the preservation of fornix white matter microstructure in cognitively intact older adults. This report provides novel evidence for the benefits of plasma phospholipid omega-3 and omega-6 polyunsaturated fatty acid balance on memory and underlying white matter microstructure.

Docosahexaenoic acid prevents cognitive deficits in human apolipoprotein E epsilon 4-targeted replacement mice

At a population level, dietary consumption of fish rich in docosahexaenoic acid (DHA) is associated with prevention of cognitive decline but this association is not clear in carriers of the apolipoprotein E epsilon 4 allele (E4). Plasma and liver DHA concentrations show significant alterations in E4 carriers, in part corrected by DHA supplementation. However, whether DHA sufficiency in E4 carriers has consequences on cognition is unknown. Mice expressing human E4 or apolipoprotein E epsilon 3 allele (E3) were fed either a control diet or a diet containing DHA for 8 months and cognitive performance was tested using the object recognition test and the Barnes maze test. In E4 mice fed the control diet, impaired memory was detected and arachidonic acid concentrations were elevated in the hippocampus compared to E3 mice fed the control diet. DHA consumption prevented memory decline and restored arachidonic acid concentrations in the hippocampus of E4 mice. Our results suggest that long-term high-dose DHA intake may prevent cognitive decline in E4 carriers.

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.

n-3 Fatty acids, Mediterranean diet and cognitive function in normal aging: A systematic review

BACKGROUND

Intake of n-3 fatty acids and adherence to the Mediterranean diet (MedDiet) have been shown to slow the progression of age-related cognitive decline, but the results are mixed. We summarized and evaluated the effect of n-3 fatty acids and MedDiet on cognitive outcomes in a cognitively healthy aged population.

METHODS

Relevant published studies from January 2000 to May 2015 were identified by searching three electronic databases: Pubmed, Web of Science/MEDLINE, and CINHAL. Observational studies and randomized controlled trials (RCTs) were considered.

RESULTS

Twenty-four studies were included for the systematic review. n-3 fatty acids were associated with better global cognition and some specific cognitive domains though some results were conflicting. Adherence to the MedDiet was also significantly associated with better cognitive performance and less cognitive decline. Finally, better cognitive performance was observed in men compared to women and mixed results were also found for the influence of APOE4 genotype on the association between n-3 fatty acids or MedDiet and cognition.

CONCLUSIONS

Studies suggest that n-3 fatty acids in the diet and adherence to the MedDiet are beneficial in slowing age-related cognitive decline. However, more high-quality RCTs would be useful to clarify the effect of n-3 fatty acid supplements on cognition.

Functional and Structural Benefits Induced by Omega-3 Polyunsaturated Fatty Acids During Aging

BACKGROUND

Omega-3 polyunsaturated fatty acids (n-3 PUFA) are structural components of the brain and are indispensable for neuronal membrane synthesis. Along with decline in cognition, decreased synaptic density and neuronal loss, normal aging is accompanied by a reduction in n-3 PUFA concentration in the brain in both humans and rodents. Recently, many clinical and experimental studies have demonstrated the importance of n-3 PUFA in counteracting neurodegeneration and agerelated dysfunctions.

METHODS

This review will focus on the neuroprotective effects of n-3 PUFA on cognitive impairment, neuroinflammation and neurodegeneration during normal aging. Multiple pathways of n-3 PUFA preventive action will be examined.

RESULTS

Namely, n-3 PUFA have been shown to increase the levels of several signaling factors involved in synaptic plasticity, thus leading to the increase of dendritic spines and synapses as well as the enhancement of hippocampal neurogenesis even at old age. In elderly subjects n-3 PUFA exert anti-inflammatory effects associated with improved cognitive functions. Interestingly, growing evidence highlights n-3 PUFA efficacy in preventing the loss of both gray and white matter volume and integrity.

CONCLUSION

This review shows that n-3 PUFA are essential for a successful aging and appear as ideal cognitive enhancers to be implemented in nutritional interventions for the promotion of healthy aging.

Dietary DHA and health: cognitive function ageing

DHA is a key nutritional n-3 PUFA and needs to be supplied by the human diet. DHA is found in significant amounts in the retinal and neuronal cell membranes due to its high fluidity. Indeed, DHA is selectively concentrated in the synaptic and retinal membranes. DHA is deemed to display anti-inflammatory properties and to reduce the risk of CVD. Consumption of larger amounts of DHA appears to reduce the risk of depression, bipolar disorder, schizophrenia and mood disorders. Conversely, it has been shown that loss of DHA from the nerve cell membrane leads to dysfunction of the central nervous system in the form of anxiety, irritability, susceptibility to stress, dyslexia, impaired memory and cognitive functions, and extended reaction times. DHA plays an important role in ensuring a healthy ageing, by thwarting macular degeneration, Alzheimer's disease, and other brain disorders at the same time as enhancing memory and strengthening neuroprotection in general. A reduced level of DHA is associated with cognitive decline during ageing. Different mechanisms for this fundamental DHA role have been put forward. Namely, neuroprotectin D1, a DHA derivative, may support brain cell survival and repair through neurotrophic, anti-apoptotic, and anti-inflammatory signalling. Many of the effects of DHA on the neurological system may be related to signalling connections, thus leading to the study of the related signalolipidomics. Therefore, the present review will focus on the influence of DHA deficiency upon ageing, with specific emphasis upon neurological disorders related to cognitive function and mental health.

Neuron-astrocyte interactions in spinal cord dorsal horn in neuropathic pain development and docosahexaenoic acid therapy

The analgesic activity of docosahexaenoic acid (DHA, 22:6 n-3) was studied using a chronic constriction injury (CCI) rat model. Animals were subcutaneously injected with DHA emulsion at a dose of 4.5mg/kg (125mМ/kg) daily during 2weeks after surgery. We characterized the dynamics of GFAP-positive astrocyte, substance P (SP) and nNOS-positive neurons activity in the spinal cord dorsal horn (SCDH) superficial lamina. We found that DHA treatment decrease the intensity and duration of neurogenic pain syndrome, results in earlier stabilization of weight distribution, prevents the cold allodynia and dystrophic changings in denervated limb tissue. DHA treatment reduced the reactive astrocyte number, decrease SP-immunopositive fibers and nNOS-positive neurons number in the SCDH in neuropathic pain.

The effect of APOE genotype on the delivery of DHA to cerebrospinal fluid in Alzheimer's disease

Background

Apolipoprotein E (APOE) ɛ4 and low cerebrospinal fluid (CSF) amyloid-β42 (Aβ42) levels are predictors for developing Alzheimer’s disease (AD). The results of several studies indicate an interaction between docosahexaenoic acid (DHA) consumption and cognitive outcomes by APOE genotype. Our objective in the present study was to examine whether APOE ɛ4 genotype and low CSF Aβ42 levels were associated with reduced delivery of DHA to CSF in the Alzheimer’s Disease Cooperative Study-sponsored DHA clinical trial.

Methods

Phospholipid DHA was assayed in the plasma of 384 participants and CSF of 70 participants at baseline. Forty-four of the 70 participants completed the 18-month follow-up visit after allocation to placebo (n = 15) or DHA (n = 29). Plasma and CSF DHA levels, CSF Aβ42, Tau, and phosphorylated Tau were measured at baseline and after the 18-month intervention. Participants were divided into tertiles based on baseline Aβ42 CSF levels. To assess DHA delivery across the blood-brain barrier, the ratio of CSF to plasma DHA levels was calculated.

Results

At baseline, there were no significant differences between CSF or plasma phospholipid DHA levels by CSF Aβ42 tertiles or ɛ4 status. After 18 months of DHA supplementation, participants at the lowest Aβ42 tertile had significantly lower CSF DHA levels (p = 0.01) and lower CSF-to-plasma DHA ratios (p = 0.05) compared to the other tertiles. Baseline CSF Aβ42 levels were significantly lower in ɛ4 carriers than in ɛ4 noncarriers (p = 0.01). Participants carrying the ɛ4 allele (n = 25) demonstrated a less pronounced increase in CSF DHA level compared with noncarriers (n = 4), with a possible interaction effect between treatment and APOE genotype (p = 0.07).

Conclusions

APOE ɛ4 allele and lower CSF Aβ42 levels were associated with less transport of DHA to CSF. Brain amyloid pathology may limit the delivery of DHA to the brain in AD.

Trial Registration

Clinicaltrials.gov identifier: NCT00440050. Registered on 22 Feb 2007.

APOE ε4 and the associations of seafood and long-chain omega-3 fatty acids with cognitive decline

OBJECTIVE

To examine the association between consumption of seafood and long-chain n-3 fatty acids with change in 5 cognitive domains over an average of 4.9 years.

METHODS

From an ongoing longitudinal, community-based epidemiologic study of aging and dementia (the Rush Memory and Aging Project), we included 915 participants (age 81.4 ± 7.2 years, 25% men) who had completed at least one follow-up cognitive assessment and dietary data. Diet was assessed by semiquantitative food frequency questionnaire. Scores for global cognitive function and 5 cognitive domains (episodic, semantic, and working memory, perceptual speed, and visuospatial ability) were assessed using 19 cognitive tests. Mixed models adjusted for multiple risk factors of cognitive change were used to assess the associations.

RESULTS

Consumption of seafood was associated with slower decline in semantic memory (β = 0.024; p = 0.03) and perceptual speed (β = 0.020; p = 0.05) in separate models adjusted for age, sex, education, participation in cognitive activities, physical activity, alcohol consumption, smoking, and total energy intake. In secondary analyses, APOE ε4 carriers demonstrated slower rates of decline in global cognition and in multiple cognitive domains with weekly seafood consumption and with moderate to high long-chain n-3 fatty acid intake from food. These associations were not present in APOE ε4 noncarriers. Higher intake levels of α-linolenic acid were associated with slower global cognitive decline, but also only in APOE ε4 carriers.

CONCLUSIONS

These results suggest protective relations of one meal per week of seafood and long-chain n-3 fatty acids against decline in multiple cognitive domains. The role of APOE ε4 in this association needs further study.