Omega-3 fatty acid docosahexaenoic acid increases SorLA/LR11, a sorting protein with reduced expression in sporadic Alzheimer's disease (AD): relevance to AD prevention

Unraveling the impact of Omega-3 polyunsaturated fatty acids on blood-brain barrier (BBB) integrity and glymphatic function

Alzheimer's disease (AD) and other forms of dementia represent major public health challenges but effective therapeutic options are limited. Pathological brain aging is associated with microvascular changes and impaired clearance systems. The application of omega-3 polyunsaturated fatty acids (n-3 or omega-3 PUFAs) is one of the most promising nutritional interventions in neurodegenerative disorders from epidemiological data, clinical and pre-clinical studies. As essential components of neuronal membranes, n-3 PUFAs have shown neuroprotection and anti-inflammatory effects, as well as modulatory effects through microvascular pathophysiology, amyloid-beta (Aβ) clearance and glymphatic pathways. This review meticulously explores these underlying mechanisms that contribute to the beneficial effects of n-3 PUFAs against AD and dementia, synthesizing evidence from both animal and interventional studies.

Gut microbiome-targeted therapies for Alzheimer's disease

The advent of high-throughput 'omics' technologies has improved our knowledge of gut microbiome in human health and disease, including Alzheimer's disease (AD), a neurodegenerative disorder. Frequent bidirectional communications and mutual regulation exist between the gastrointestinal tract and the central nervous system through the gut-brain axis. A large body of research has reported a close association between the gut microbiota and AD development, and restoring a healthy gut microbiota may curb or even improve AD symptoms and progression. Thus, modulation of the gut microbiota has become a novel paradigm for clinical management of AD, and emerging effort has focused on developing potential novel strategies for preventing and/or treating the disease. In this review, we provide an overview of the connection and causal relationship between gut dysbiosis and AD, the mechanisms of gut microbiota in driving AD progression, and the successes and challenges of implementing available gut microbiome-targeted therapies (including probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation) in preventive and/or therapeutic preclinical and clinical intervention studies of AD. Finally, we discuss the future directions in this field.

Potential Neuroprotective Effects of Dietary Omega-3 Fatty Acids on Stress in Alzheimer's Disease

BACKGROUND

A large number of individual potentially modifiable factors are associated with risk for Alzheimer's disease (AD). However, less is known about the interactions between the individual factors.

METHODS

In order to begin to examine the relationship between a pair of factors, we performed a pilot study, surveying patients with AD and controls for stress exposure and dietary omega-3 fatty acid intake to explore their relationship for risk of AD.

RESULTS

For individuals with the greatest stress exposure, omega-3 fatty acid intake was significantly greater in healthy controls than in AD patients. There was no difference among those with low stress exposure.

CONCLUSIONS

These initial results begin to suggest that omega-3 fatty acids may mitigate AD risk in the setting of greater stress exposure. This will need to be examined with larger populations and other pairs of risk factors to better understand these important relationships. Examining how individual risk factors interact will ultimately be important for learning how to optimally decrease the risk of AD.

Lipids and Secretory Vesicle Exocytosis

In recent years, the number of studies implicating lipids in the regulation of synaptic vesicle exocytosis has risen considerably. It has become increasingly clear that lipids such as phosphoinositides, lysophospholipids, cholesterol, arachidonic acid and myristic acid play critical regulatory roles in the processes leading up to exocytosis. Lipids may affect membrane fusion reactions by altering the physical properties of the membrane, recruiting key regulatory proteins, concentrating proteins into exocytic "hotspots" or by modulating protein functions allosterically. Discrete changes in phosphoinositides concentration are involved in multiple trafficking events including exocytosis and endocytosis. Lipid-modifying enzymes such as the DDHD2 isoform of phospholipase A1 were recently shown to contribute to memory acquisition via dynamic modifications of the brain lipid landscape. Considering the increasing reports on neurodegenerative disorders associated with aberrant intracellular trafficking, an improved understanding of the control of lipid pathways is physiologically and clinically significant and will afford unique insights into mechanisms and therapeutic methods for neurodegenerative diseases. Consequently, this chapter will discuss the different classes of lipids, phospholipase enzymes, the evidence linking them to synaptic neurotransmitter release and how they act to regulate key steps in the multi-step process leading to neuronal communication and memory acquisition.

Effects of Dietary Vitamin C on the Growth Performance, Biochemical Parameters, and Antioxidant Activity of Coho Salmon Oncorhynchus kisutch (Walbaum, 1792) Postsmolts

Vitamin C (VC) plays an essential role in fish physiological function and normal growth. However, its effects and requirement of coho salmon Oncorhynchus kisutch (Walbaum, 1792) are still unknown. Based on the influences on growth, serum biochemical parameters, and antioxidative ability, an assessment of dietary VC requirement for coho salmon postsmolts (183.19 ± 1.91 g) was conducted with a ten-week feeding trial. Seven isonitrogenous (45.66% protein) and isolipidic (10.76% lipid) diets were formulated to include graded VC concentrations of 1.8, 10.9, 50.8, 100.5, 197.3, 293.8, and 586.7 mg/kg, respectively. Results showed that VC markedly improved the growth performance indexes and liver VC concentration, enhanced the hepatic and serum antioxidant activities, and increased the contents of serum alkaline phosphatase (AKP) activity, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and total cholesterol (TC) whereas decreased the serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) activities, and triglyceride (TG) level. Polynomial analysis showed that the optimal VC levels in the diet of coho salmon postsmolts were 188.10, 190.68, 224.68, 132.83, 156.57, 170.12, 171.00, 185.50, 142.77, and 93.08 mg/kg on the basis of specific growth rate (SGR), feed conversion ratio (FCR), liver VC concentration, catalase (CAT), hepatic superoxide dismutase (SOD) activities, malondialdehyde (MDA) content, and serum total antioxidative capacity (T-AOC), AKP, AST, and ALT activities, respectively. The dietary VC requirement was in the range of 93.08-224.68 mg/kg for optimum growth performance, serum enzyme activities, and antioxidant capacity of coho salmon postsmolts.

Finding memo: versatile interactions of the VPS10p-Domain receptors in Alzheimer’s disease

The family of VPS10p-Domain (D) receptors comprises five members named SorLA, Sortilin, SorCS1, SorCS2 and SorCS3. While their physiological roles remain incompletely resolved, they have been recognized for their signaling engagements and trafficking abilities, navigating a number of molecules between endosome, Golgi compartments, and the cell surface. Strikingly, recent studies connected all the VPS10p-D receptors to Alzheimer’s disease (AD) development. In addition, they have been also associated with diseases comorbid with AD such as diabetes mellitus and major depressive disorder. This systematic review elaborates on genetic, functional, and mechanistic insights into how dysfunction in VPS10p-D receptors may contribute to AD etiology, AD onset diversity, and AD comorbidities. Starting with their functions in controlling cellular trafficking of amyloid precursor protein and the metabolism of the amyloid beta peptide, we present and exemplify how these receptors, despite being structurally similar, regulate various and distinct cellular events involved in AD. This includes a plethora of signaling crosstalks that impact on neuronal survival, neuronal wiring, neuronal polarity, and synaptic plasticity. Signaling activities of the VPS10p-D receptors are especially linked, but not limited to, the regulation of neuronal fitness and apoptosis via their physical interaction with pro- and mature neurotrophins and their receptors. By compiling the functional versatility of VPS10p-D receptors and their interactions with AD-related pathways, we aim to further propel the AD research towards VPS10p-D receptor family, knowledge that may lead to new diagnostic markers and therapeutic strategies for AD patients.

DHA Ameliorates Cognitive Ability, Reduces Amyloid Deposition, and Nerve Fiber Production in Alzheimer’s Disease

Background

The etiology of Alzheimer’s disease (AD) is very complex. Docosahexaenoic acid (DHA) is important in cognitive ability and nervous system development. A limited number of studies have evaluated the efficacy of DHA in the treatment of AD.

Introduction

We detected neurofibrillary tangles (NFT) in the hippocampus and cortex of transgenic mice brain through silver glycine staining. We determined the activity of neurons by staining Nissl bodies, used liquid NMR to detect metabolites in the brain, and functional magnetic resonance imaging results to observe the connection signal value between brain regions.

Materials and Methods

We fed 3-month-old APP/PS1 double transgenic mice with DHA mixed feeds for 4 months to assess the effects of DHA on cognitive ability in AD mice through the Morris water maze and open field tests. To evaluate its effects with AD pathology, continuous feeding was done until the mice reached 9 months of age.

Results

Compared to AD mice, escape latency significantly decreased on the fifth day while swimming speed, target quadrant stay time, and the crossing number of platforms increased by varying degrees after DHA treatment. Brain tissue section staining revealed that DHA significantly reduced Aβ and nerve fibers in the brain of AD mice.

Conclusion

DHA significantly reduced the deposition of Aβ in the brain and inhibited the production of nerve fibers, thereby increasing cognitive abilities in AD mice. In addition, DHA suppressed blood lipid levels, and restored uric acid and urea levels, implying that DHA is a potential therapeutic option for early AD.

The Potential Role of Gut Microbiota in Alzheimer’s Disease: from Diagnosis to Treatment

Gut microbiota is emerging as a key regulator of many disease conditions and its dysregulation is implicated in the pathogenesis of several gastrointestinal and extraintestinal disorders. More recently, gut microbiome alterations have been linked to neurodegeneration through the increasingly defined gut microbiota brain axis, opening the possibility for new microbiota-based therapeutic options. Although several studies have been conducted to unravel the possible relationship between Alzheimer’s Disease (AD) pathogenesis and progression, the diagnostic and therapeutic potential of approaches aiming at restoring gut microbiota eubiosis remain to be fully addressed. In this narrative review, we briefly summarize the role of gut microbiota homeostasis in brain health and disease, and we present evidence for its dysregulation in AD patients. Based on these observations, we then discuss how dysbiosis might be exploited as a new diagnostic tool in early and advanced disease stages, and we examine the potential of prebiotics, probiotics, fecal microbiota transplantation, and diets as complementary therapeutic interventions on disease pathogenesis and progression, thus offering new insights into the diagnosis and treatment of this devastating and progressive disease.

Unraveling metabolic alterations in transgenic mouse model of Alzheimer's disease using MALDI MS imaging with 4-aminocinnoline-3-carboxamide matrix

Revealing the metabolic abnormalities of central and peripheral systems in Alzheimer's disease (AD) mouse model is of paramount importance for understanding AD disease. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is a powerful label-free technique that has been extensively utilized for the interrogation of spatial changes of various metabolites in neurodegenerative disease. However, technical limitations still exist in MALDI MS, and there is a need to improve the performance of traditional MALDI for a deeper investigation of metabolic alterations in the AD mouse model. In this work, 4-aminocinnoline-3-carboxamide (4-AC) was developed into a novel dual-polarity MALDI matrix. Compared with traditionally used MALDI matrices such as 2,5-dihydroxybenzoic acid (DHB) and 9-aminoacridine (9-AA), 4-AC exhibited superior performance in UV absorption at 355 nm, ion yields, background interference, and vacuum stability, making it an ideal MALDI matrix for comprehensive evaluation of metabolic alteration in the brain and serum of APP/PS1 transgenic mouse model of AD. In total, 93 metabolites exhibited different levels of regional changes in the brain of AD mice as compared to the age-matched controls. Moreover, in the serum of AD mice, 81 altered metabolites distinguishing the AD group from the control were observed by using multivariate statistical analysis. It is expected that the application of the MALDI MSI method developed in this work to visualize the spatio-chemical change of various metabolites may improve our understanding of the etiopathogenesis of AD.

DHA and Its Metabolites Have a Protective Role against Methylmercury-Induced Neurotoxicity in Mouse Primary Neuron and SH-SY5Y Cells

The consumption of fish now involves a risk of methylmercury (MeHg) exposure but also provides the benefit of ω-3 polyunsaturated fatty acids (ω-3 PUFAs) such as docosahexaenoic acid (DHA). Some epidemiological studies have suggested that the intake of DHA can alleviate the neurotoxicity of MeHg, but the underlying mechanism is not known. Herein, we observed that pretreatment with 0.1–1 µM DHA suppressed MeHg-induced cytotoxicity in human neuroblastoma (SH-SY5Y) cells and mouse primary neuronal cells. These effects of DHA were canceled in the presence of the retinoid X receptor (RXR) antagonist UVI3003. An RXR agonist, bexarotene, suppressed the cytotoxicity of MeHg. DHA also suppressed the MeHg-induced production of reactive oxygen species (ROS) via an induction of antioxidant genes (catalase and SOD1). Pretreatment with DHA did not change the incorporation of MeHg. We showed previously that in the brain, the intake of DHA increased the level of 19,20-DHDP, which is the metabolite produced by cytochrome P450 and soluble epoxide hydrolase from DHA. In the present study, we observed that 19,20-DHDP also suppressed neurotoxicity from MeHg. These results indicate that DHA and its metabolites have a protective role in MeHg-induced neurotoxicity.

Effects of a Nutritional Formulation Containing Caprylic and Capric Acid, Phosphatidylserine, and Docosahexaenoic Acid in Streptozotocin-Lesioned Rats

Background

It has been studied that nutrition can influence Alzheimer's disease (AD) onset and progression. Some studies on rodents using intraventricular streptozotocin (STZ) injection showed that this toxin changes cerebral glucose metabolism and insulin signaling pathways.

Objective

The aim of the present study was to evaluate whether a nutritional formulation could reduce cognitive impairment in STZ-induced animals.

Methods

The rats were randomly divided into two groups: sham and STZ. The STZ group received a single bilateral STZ-ICV injection (1 mg/kg). The sham group received a bilateral ICV injection of 0.9% saline solution. The animals were treated with AZ1 formulation (Instanth^® NEO, Prodiet Medical Nutrition) (1 g/kg, PO) or its vehicle (saline solution) for 30 days, once a day starting one day after the stereotaxic surgery (n = 6-10). The rats were evaluated using the open field test to evaluate locomotor activity at day 27 after surgery. Cognitive performance was evaluated at day 28 using the object recognition test and the spatial version of the Y-maze test. At day 30, the rats were anesthetized with chloral hydrate (400 mg/kg, i.p) and euthanized in order to evaluate IBA1 in the hippocampus. The differences were analyzed using one-way ANOVA with Bonferroni's or Kruskal Wallis with Dunn's post-hoc test.

Results/Conclusion

STZ-lesioned rats present memory impairment besides the increased microglial activation. The treatment with AZ1 formulation reversed the memory impairment observed in the object recognition test and Y-maze and also reduced IBA1 in CA1 and DG.

Phospholipases in neuronal function: A role in learning and memory?

Despite the human brain being made of nearly 60% fat, the vast majority of studies on the mechanisms of neuronal communication which underpin cognition, memory and learning, primarily focus on proteins and/or (epi)genetic mechanisms. Phospholipids are the main component of all cellular membranes and function as substrates for numerous phospholipid-modifying enzymes, including phospholipases, which release free fatty acids (FFAs) and other lipid metabolites that can alter the intrinsic properties of the membranes, recruit and activate critical proteins, and act as lipid signalling molecules. Here, we will review brain specific phospholipases, their roles in membrane remodelling, neuronal function, learning and memory, as well as their disease implications. In particular, we will highlight key roles of unsaturated FFAs, particularly arachidonic acid, in neurotransmitter release, neuroinflammation and memory. In light of recent findings, we will also discuss the emerging role of phospholipase A₁ and the creation of saturated FFAs in the brain.

Omega-3 fatty acids as adjunctive therapeutics: prospective of nanoparticles in its formulation development

Omega-3 polyunsaturated fatty acids (ω-3-PUFAs) are dietary components that have been extensively recognized for their therapeutic value and have shown diverse therapeutic effects including anti-inflammatory, antiarrhythmic, antithrombotic, immunomodulatory and antineoplastic activities. Most of the ω-3-PUFAs are obtained through diet or supplements because the body does not synthesize them. The high instability of ω-3-PUFAs to oxidative deterioration, lower bioavailability at the target tissues and reduced bioactivity of ω-3-PUFAs is an impediment for achieving their therapeutic potential. The present review provides an overview of potential therapeutic activities of ω-3-PUFAs and different novel technical approaches based on nanotechnology, which have been emphasized to overcome instability problems as well as enhance the bioactivity of ω-3-PUFAs. Future prospects related to this area of research are also provided.

A blood-based nutritional risk index explains cognitive enhancement and decline in the multidomain Alzheimer prevention trial

Introduction

Multinutrient approaches may produce more robust effects on brain health through interactive qualities. We hypothesized that a blood-based nutritional risk index (NRI) including three biomarkers of diet quality can explain cognitive trajectories in the multidomain Alzheimer prevention trial (MAPT) over 3-years.

Methods

The NRI included erythrocyte n-3 polyunsaturated fatty acids (n-3 PUFA 22:6n-3 and 20:5n-3), serum 25-hydroxyvitamin D, and plasma homocysteine. The NRI scores reflect the number of nutritional risk factors (0–3). The primary outcome in MAPT was a cognitive composite Z score within each participant that was fit with linear mixed-effects models.

Results

Eighty percent had at lease one nutritional risk factor for cognitive decline (NRI ≥1: 573 of 712). Participants presenting without nutritional risk factors (NRI=0) exhibited cognitive enhancement (β = 0.03 standard units [SU]/y), whereas each NRI point increase corresponded to an incremental acceleration in rates of cognitive decline (NRI-1: β = −0.04 SU/y, P = .03; NRI-2: β = −0.08 SU/y, P < .0001; and NRI-3: β = −0.11 SU/y, P = .0008).

Discussion

Identifying and addressing these well-established nutritional risk factors may reduce age-related cognitive decline in older adults; an observation that warrants further study.

•

Multi-nutrient approaches may produce more robust effects through interactive properties

•

Nutritional risk index can objectively quantify nutrition-related cognitive changes

•

Optimum nutritional status associated with cognitive enhancement over 3-years

•

Suboptimum nutritional status associated with cognitive decline over 3-years

•

Optimizing this nutritional risk index may promote cognitive health in older adults

Docosahexaenoic Acid Increases the Potency of Soluble Epoxide Hydrolase Inhibitor in Alleviating Streptozotocin-Induced Alzheimer's Disease-Like Complications of Diabetes

Diabetes is a risk factor for Alzheimer's disease and it is associated with significant memory loss. In the present study, we hypothesized that the soluble epoxide hydrolase (sEH) inhibitor N-[1-(1-oxopropyl)-4-piperidinyl]-N'-[4-(trifluoromethoxy)phenyl)-urea (also known as TPPU) could alleviate diabetes-aggravated Alzheimer's disease-like symptoms by improving memory and cognition, and reducing the oxidative stress and inflammation associated with this condition. Also, we evaluated the effect of edaravone, an antioxidant on diabetes-induced Alzheimer's-like complications and the additive effect of docosahexaenoic acid (DHA) on the efficacy of TPPU. Diabetes was induced in male Sprague-Dawley rats by intraperitoneally administering streptozotocin (STZ). Six weeks after induction of diabetes, animals were either treated with vehicle, edaravone (3 or 10 mg/kg), TPPU (1 mg/kg) or TPPU (1 mg/kg) + DHA (100 mg/kg) for 2 weeks. The results demonstrate that the treatments increased the memory response of diabetic rats, in comparison to untreated diabetic rats. Indeed, DHA + TPPU were more effective than TPPU alone in reducing the symptoms monitored. All drug treatments reduced oxidative stress and minimized inflammation in the brain of diabetic rats. Expression of the amyloid precursor protein (APP) was increased in the brain of diabetic rats. Treatment with edaravone (10 mg/kg), TPPU or TPPU + DHA minimized the level of APP. The activity of acetylcholinesterase (AChE) which metabolizes acetylcholine was increased in the brain of diabetic rats. All the treatments except edaravone (3 mg/kg) were effective in decreasing the activity of AChE and TPPU + DHA was more efficacious than TPPU alone. Intriguingly, the histological changes in hippocampus after treatment with TPPU + DHA showed significant protection of neurons against STZ-induced neuronal damage. Overall, we found that DHA improved the efficacy of TPPU in increasing neuronal survival and memory, decreasing oxidative stress and inflammation possibly by stabilizing anti-inflammatory and neuroprotective epoxides of DHA. In the future, further evaluating the detailed mechanisms of action of sEH inhibitor and DHA could help to develop a strategy for the management of Alzheimer's-like complications in diabetes.

Biochemical and cognitive effects of docosahexaenoic acid differ in a developmental and SorLA dependent manner

Beneficial effects of omega-3 fatty acid intake on cognition are under debate as some studies show beneficial effects while others show no effects of omega-3 supplementation. These inconsistencies may be a result of inter-individual response variations, potentially caused by gene and diet interactions. SorLA is a multifunctional receptor involved in ligand trafficking including lipoprotein lipase and amyloid precursor protein. Decreased SorLA levels have been correlated to Alzheimer's disease, and omega-3 fatty acid supplementation is known to increase SorLA expression in neuronal cell lines and mouse models. We therefore addressed potential correlations between Sorl1 and dietary omega-3 in SorLA deficient mice (Sorl1^-/-) and controls exposed to diets supplemented with or deprived of omega-3 during their entire development and lifespan (lifelong) or solely from the time of weaning (post weaning). Observed diet-induced effects were only evident when exposed to lifelong omega-3 supplementation or deprivation as opposed to post weaning exposure only. Lifelong exposure to omega-3 supplementation resulted in impaired spatial learning in Sorl1^-/- mice. The vitamin C antioxidant capacity in the brains of Sorl1^-/- mice was reduced, but reduced glutathione and vitamin E levels were increased, leaving the overall antioxidant capacity of the brain inconclusive. No gross morphological differences of hippocampal neurons were found to account for the altered behavior. We found a significant adverse effect in cognitive performance by combining SorLA deficiency with lifelong exposure to omega-3. Our results stress the need for investigations of the underlying molecular mechanisms to clarify the precise circumstances under which omega-3 supplementation may be beneficial.

Alzheimer's Disease Risk Genes and Lipid Regulators

Brain lipid homeostasis plays an important role in Alzheimer's disease (AD) and other neurodegenerative disorders. Aggregation of amyloid-β peptide is one of the major events in AD. The complex interplay between lipids and amyloid-β accumulation has been intensively investigated. The proportions of lipid components including phospholipids, sphingolipids, and cholesterol are roughly similar across different brain regions under physiological conditions. However, disruption of brain lipid homeostasis has been described in AD and implicated in disease pathogenesis. Moreover, studies suggest that analysis of lipid composition in plasma and cerebrospinal fluid could improve our understanding of the disease development and progression, which could potentially serve as disease biomarkers and prognostic indicators for AD therapies. Here, we summarize the functional roles of AD risk genes and lipid regulators that modulate brain lipid homeostasis including different lipid species, lipid complexes, and lipid transporters, particularly their effects on amyloid processing, clearance, and aggregation, as well as neuro-toxicities that contribute to AD pathogenesis.

Risk factor SORL1: from genetic association to functional validation in Alzheimer's disease

Alzheimer's disease (AD) represents one of the most dramatic threats to healthy aging and devising effective treatments for this devastating condition remains a major challenge in biomedical research. Much has been learned about the molecular concepts that govern proteolytic processing of the amyloid precursor protein to amyloid-β peptides (Aβ), and how accelerated accumulation of neurotoxic Aβ peptides underlies neuronal cell death in rare familial but also common sporadic forms of this disease. Out of a plethora of proposed modulators of amyloidogenic processing, one protein emerged as a key factor in AD pathology, a neuronal sorting receptor termed SORLA. Independent approaches using human genetics, clinical pathology, or exploratory studies in animal models all converge on this receptor that is now considered a central player in AD-related processes by many. This review will provide a comprehensive overview of the evidence implicating SORLA-mediated protein sorting in neurodegenerative processes, and how receptor gene variants in the human population impair functional receptor expression in sporadic but possibly also in autosomal-dominant forms of AD.

The Role of SORL1 in Alzheimer's Disease

Genetic variation in SORL1 gene, also known as LR11, has been identified to associate with Alzheimer's disease (AD) through replicated genetic studies. As a type I transmembrane protein, SORL1 is composed of several distinct domains and belongs to both the low-density lipoprotein receptor (LDLR) family and the vacuolar protein sorting 10 (VPS10) domain receptor family. The level of SORL1 was found to be decreased in the AD brain which positively correlated with β-amyloid (Aβ) accumulation. Emerging data suggests that SORL1 contributes to AD through various pathways, including emerging as a central regulator of the trafficking and processing of amyloid precursor protein (APP), involvement in Aβ destruction, and interaction with ApoE and tau protein. Primarily, SORL1 interacts with distinct sets of cytosolic adaptors for anterograde and retrograde movement of APP between the trans-Golgi network (TGN) and early endosomes, thereby restricting the delivery of the precursor to endocytic compartments that favor amyloidogenic breakdown. In this article, we review recent epidemiological and genetical findings of SORL1 that related with AD and speculate the possible roles of SORL1 in the progression of this disease. Finally, given the potential contributions of SORL1 to AD pathogenesis, targeting SORL1 might present novel opportunities for AD therapy.

Neuroprotective properties of the marine carotenoid astaxanthin and omega-3 fatty acids, and perspectives for the natural combination of both in krill oil

The consumption of marine fishes and general seafood has long been recommended by several medical authorities as a long-term nutritional intervention to preserve mental health, hinder neurodegenerative processes, and sustain cognitive capacities in humans. Most of the neurological benefits provided by frequent seafood consumption comes from adequate uptake of omega-3 and omega-6 polyunsaturated fatty acids, n-3/n-6 PUFAs, and antioxidants. Optimal n-3/n-6 PUFAs ratios allow efficient inflammatory responses that prevent the initiation and progression of many neurological disorders. Moreover, interesting in vivo and clinical studies with the marine antioxidant carotenoid astaxanthin (present in salmon, shrimp, and lobster) have shown promising results against free radical-promoted neurodegenerative processes and cognition loss. This review presents the state-of-the-art applications of n-3/n-6 PUFAs and astaxanthin as nutraceuticals against neurodegenerative diseases associated with exacerbated oxidative stress in CNS. The fundamental “neurohormesis” principle is discussed throughout this paper. Finally, new perspectives for the application of a natural combination of the aforementioned anti-inflammatory and antioxidant agents (found in krill oil) are also presented herewith.

The impact of cholesterol, DHA, and sphingolipids on Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disorder currently affecting over 35 million people worldwide. Pathological hallmarks of AD are massive amyloidosis, extracellular senile plaques, and intracellular neurofibrillary tangles accompanied by an excessive loss of synapses. Major constituents of senile plaques are 40–42 amino acid long peptides termed β-amyloid (Aβ). Aβ is produced by sequential proteolytic processing of the amyloid precursor protein (APP). APP processing and Aβ production have been one of the central scopes in AD research in the past. In the last years, lipids and lipid-related issues are more frequently discussed to contribute to the AD pathogenesis. This review summarizes lipid alterations found in AD postmortem brains, AD transgenic mouse models, and the current understanding of how lipids influence the molecular mechanisms leading to AD and Aβ generation, focusing especially on cholesterol, docosahexaenoic acid (DHA), and sphingolipids/glycosphingolipids.

Amide-type adduct of dopamine - plausible cause of Parkinson diseases

Dopamine is the endogenous neurotransmitter produced by nigral neurons. Dopamine loss can trigger not only prominent secondary morphological changes, but also changes in the density and sensitivity of dopamine receptors; therefore, it is a sign of PD development. The reasons for dopamine loss are attributed to dopamine's molecular instability due to it is a member of catecholamine family, whose catechol structure contributes to high oxidative stress through enzymatic and non-enzymatic oxidation. Oxidative stress in the brain easily leads to the lipid peroxidation reaction due to a high concentration of polyunsaturated fatty acids (PUFA), such as docosahexaenoic acid (DHA, C22:6/ω-3) and arachidonic acid (AA, C18:4/ω-6). Recent studies have shown that lipid hydroperoxides, the primary peroxidative products, could non-specifically react with primary amino groups to form N-acyl-type (amide-linkage) adducts. Therefore, based on the NH2-teminals in dopamine's structure, the aims of this chapter are to describes the possibility that reactive LOOH species derived from DHA/AA lipid peroxidation may modify dopamine to form amide-linkage dopamine adducts, which might be related to etiology of Parkinson's diseases.

Special lipid-based diets alleviate cognitive deficits in the APPswe/PS1dE9 transgenic mouse model of Alzheimer's disease independent of brain amyloid deposition

Dietary fish oil, providing n3 polyunsaturated fatty acids like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), associates with reduced dementia risk in epidemiological studies and reduced amyloid accumulation in Alzheimer mouse models. We now studied whether additional nutrients can improve the efficacy of fish oil in alleviating cognitive deficits and amyloid pathology in APPswe/PS1dE9 transgenic and wild-type mice. We compared four isocaloric (5% fat) diets. The fish oil diet differed from the control diet only by substituted fish oil. Besides fish oil, the plant sterol diet was supplemented with phytosterols, while the Fortasyn diet contained as supplements precursors and cofactors for membrane synthesis, viz. uridine-monophosphate; DHA and EPA; choline; folate; vitamins B6, B12, C and E; phospholipids and selenium. Mice began the special diets at 5 months and were sacrificed at 14 months after behavioral testing. Transgenic mice, fed with control chow, showed poor spatial learning, hyperactivity in exploring a novel cage and reduced preference to explore novel odors. All fish-oil-containing diets increased exploration of a novel odor over a familiar one. Only the Fortasyn diet alleviated the spatial learning deficit. None of the diets influenced hyperactivity in a new environment. Fish-oil-containing diets strongly inhibited β- and γ-secretase activity, and the plant sterol diet additionally reduced amyloid-β 1-42 levels. These data indicate that beneficial effects of fish oil on cognition in Alzheimer model mice can be enhanced by adding other specific nutrients, but this effect is not necessarily mediated via reduction of amyloid accumulation.

Sorting receptor SORLA – a trafficking path to avoid Alzheimer disease

Excessive proteolytic breakdown of the amyloid precursor protein (APP) to neurotoxic amyloid β peptides (Aβ) by secretases in the brain is a molecular cause of Alzheimer disease (AD). According to current concepts, the complex route whereby APP moves between the secretory compartment, the cell surface and endosomes to encounter the various secretases determines its processing fate. However, the molecular mechanisms that control the intracellular trafficking of APP in neurons and their contribution to AD remain poorly understood. Here, we describe the functional elucidation of a new sorting receptor SORLA that emerges as a central regulator of trafficking and processing of APP. SORLA interacts with distinct sets of cytosolic adaptors for anterograde and retrograde movement of APP between the trans-Golgi network and early endosomes, thereby restricting delivery of the precursor to endocytic compartments that favor amyloidogenic breakdown. Defects in SORLA and its interacting adaptors result in transport defects and enhanced amyloidogenic processing of APP, and represent important risk factors for AD in patients. As discussed here, these findings uncovered a unique regulatory pathway for the control of neuronal protein transport, and provide clues as to why defects in this pathway cause neurodegenerative disease.

Fat content, energy value and fatty acid profile of donkey milk during lactation and implications for human nutrition

Background and aims

Milk contains numerous nutrients. The content of n-3 fatty acids, the n-6/n-3 ratio, and short- and medium-chain fatty acids may promote positive health effects. In Western societies, cow’s milk fat is perceived as a risk factor for health because it is a source of a high fraction of saturated fatty acids. Recently, there has been increasing interest in donkey’s milk. In this work, the fat and energetic value and acidic composition of donkey’s milk, with reference to human nutrition, and their variations during lactation, were investigated. We also discuss the implications of the acidic profile of donkey’s milk on human nutrition.

Methods

Individual milk samples from lactating jennies were collected 15, 30, 45, 60, 90, 120, 150, 180 and 210days after foaling, for the analysis of fat, proteins and lactose, which was achieved using an infrared milk analyser, and fatty acids composition by gas chromatography.

Results

The donkey’s milk was characterised by low fat and energetic (1719.2kJ·kg^-1) values, a high polyunsaturated fatty acids (PUFA) content of mainly α-linolenic acid (ALA) and linoleic acid (LA), a low n-6 to n-3 FA ratio or LA/ALA ratio, and advantageous values of atherogenic and thrombogenic indices. Among the minor PUFA, docosahesaenoic (DHA), eicosapentanoic (EPA), and arachidonic (AA) acids were present in very small amounts (<1%). In addition, the AA/EPA ratio was low (0.18). The fat and energetic values decreased (P < 0.01) during lactation.

The fatty acid patterns were affected by the lactation stage and showed a decrease (P < 0.01) in saturated fatty acids content and an increase (P < 0.01) in the unsaturated fatty acids content. The n-6 to n-3 ratio and the LA/ALA ratio were approximately 2:1, with values <1 during the last period of lactation, suggesting the more optimal use of milk during this period.

Conclusions

The high level of unsaturated/saturated fatty acids and PUFA-n3 content and the low n-6/n-3 ratio suggest the use of donkey’s milk as a functional food for human nutrition and its potential utilisation for infant nutrition as well as adult diets, particular for the elderly.

Effects of DHA-rich n-3 fatty acid supplementation on gene expression in blood mononuclear leukocytes: the OmegAD study

BACKGROUND

Dietary fish oil, rich in n-3 fatty acids (n-3 FAs), e.g. docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), regulate inflammatory reactions by various mechanisms, e.g. gene activation. However, the effects of long-term treatment with DHA and EPA in humans, using genome wide techniques, are poorly described. Hence, our aim was to determine the effects of 6 mo of dietary supplementation with an n-3 FA preparation rich in DHA on global gene expression in peripheral blood mononuclear cells.

METHODS AND FINDINGS

In the present study, blood samples were obtained from a subgroup of 16 patients originating from the randomized double-blind, placebo-controlled OmegAD study, where 174 Alzheimer disease (AD) patients received daily either 1.7 g of DHA and 0.6 g EPA or placebo for 6 months. In blood samples obtained from 11 patients receiving n-3 FA and five placebo, expressions of approximately 8000 genes were assessed by gene array. Significant changes were confirmed by real-time PCR. At 6 months, the n-3 FAs group displayed significant rises of DHA and EPA plasma concentrations, as well as up- and down-regulation of nine and ten genes, respectively, was noticed. Many of these genes are involved in inflammation regulation and neurodegeneration, e.g. CD63, MAN2A1, CASP4, LOC399491, NAIP, and SORL1 and in ubiqutination processes, e.g. ANAPC5 and UBE2V1. Down-regulations of ANAPC5 and RHOB correlated to increases of plasma DHA and EPA levels.

CONCLUSIONS

We suggest that 6 months of dietary n-3 FA supplementation affected expression of genes that might influence inflammatory processes and could be of significance for AD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00211159.

Lipid metabolism and glial lipoproteins in the central nervous system

Lipoproteins in the central nervous system (CNS) are not incorporated from the blood but are formed mainly by glial cells within the CNS. In addition, cholesterol in the CNS is synthesized endogenously because the blood-brain barrier segregates the CNS from the peripheral circulation. Apolipoprotein (apo) E is a major apo in the CNS. In normal condition, apo E is secreted from glia, mainly from astrocytes, and forms cholesterol-rich lipoproteins by ATP-binding cassette transporters. Subsequently, apo E-containing glial lipoproteins supply cholesterol and other components to neurons via a receptor-mediated process. Recent findings demonstrated that receptors of the low density lipoprotein (LDL) receptor family not only internalize lipoproteins into the cells but also, like signaling receptors, transduce signals upon binding the ligands. In this review, the regulation of lipid homeostasis will be discussed as well as roles of lipoproteins and functions of receptors of LDL receptor family in the CNS. Furthermore, the relation between lipid metabolism and Alzheimer's disease (AD) is discussed.

Docosahexaenoic acid signalolipidomics in nutrition: significance in aging, neuroinflammation, macular degeneration, Alzheimer's, and other neurodegenerative diseases

Essential polyunsaturated fatty acids (PUFAs) are critical nutritional lipids that must be obtained from the diet to sustain homeostasis. Omega-3 and -6 PUFAs are key components of biomembranes and play important roles in cell integrity, development, maintenance, and function. The essential omega-3 fatty acid family member docosahexaenoic acid (DHA) is avidly retained and uniquely concentrated in the nervous system, particularly in photoreceptors and synaptic membranes. DHA plays a key role in vision, neuroprotection, successful aging, memory, and other functions. In addition, DHA displays anti-inflammatory and inflammatory resolving properties in contrast to the proinflammatory actions of several members of the omega-6 PUFAs family. This review discusses DHA signalolipidomics, comprising the cellular/tissue organization of DHA uptake, its distribution among cellular compartments, the organization and function of membrane domains rich in DHA-containing phospholipids, and the cellular and molecular events revealed by the uncovering of signaling pathways regulated by DHA and docosanoids, the DHA-derived bioactive lipids, which include neuroprotectin D1 (NPD1), a novel DHA-derived stereoselective mediator. NPD1 synthesis agonists include neurotrophins and oxidative stress; NPD1 elicits potent anti-inflammatory actions and prohomeostatic bioactivity, is anti-angiogenic, promotes corneal nerve regeneration, and induces cell survival. In the context of DHA signalolipidomics, this review highlights aging and the evolving studies on the significance of DHA in Alzheimer's disease, macular degeneration, Parkinson's disease, and other brain disorders. DHA signalolipidomics in the nervous system offers emerging targets for pharmaceutical intervention and clinical translation.

Dietary lipids and their oxidized products in Alzheimer's disease

Alzheimer's disease (AD) is the commonest form of dementia in the elderly, characterized by memory dysfunction, loss of lexical access, spatial and temporal disorientation, and impaired judgment. A growing body of scientific literature addresses the implication of dietary habits in the pathogenesis of AD. This review reports recent findings concerning the modulation of AD development by dietary lipids, in animals and humans, focusing on the pathogenetic role of lipid oxidation products. Oxidative breakdown products of ω-6 polyunsaturated fatty acids (ω-6 PUFAs), and cholesterol oxidation products (oxysterols), might play a role in favoring β-amyloid deposition, a hallmark of AD's onset and progression. Conversely, ω-3 PUFAs appear to contribute to preventing and treating AD. However, high concentrations of ω-3 PUFAs can also produce oxidized derivatives reacting with important functions of nervous cells. Thus, altered balances between cholesterol and oxysterols, and between ω-3 and ω-6 PUFAs must be considered in AD's pathophysiology. The use of a diet with an appropriate ω-3/ω-6 PUFA ratio, rich in healthy oils, fish and antioxidants, such as flavonoids, but low in cholesterol-containing foods, can be a beneficial component in the clinical strategies of prevention of AD.

Impacts of membrane biophysics in Alzheimer's disease: from amyloid precursor protein processing to aβ Peptide-induced membrane changes

An increasing amount of evidence supports the notion that cytotoxic effects of amyloid-β peptide (Aβ), the main constituent of senile plaques in Alzheimer's disease (AD), are strongly associated with its ability to interact with membranes of neurons and other cerebral cells. Aβ is derived from amyloidogenic cleavage of amyloid precursor protein (AβPP) by β- and γ-secretase. In the nonamyloidogenic pathway, AβPP is cleaved by α-secretases. These two pathways compete with each other, and enhancing the non-amyloidogenic pathway has been suggested as a potential pharmacological approach for the treatment of AD. Since AβPP, α-, β-, and γ-secretases are membrane-associated proteins, AβPP processing and Aβ production can be affected by the membrane composition and properties. There is evidence that membrane composition and properties, in turn, play a critical role in Aβ cytotoxicity associated with its conformational changes and aggregation into oligomers and fibrils. Understanding the mechanisms leading to changes in a membrane's biophysical properties and how they affect AβPP processing and Aβ toxicity should prove to provide new therapeutic strategies for prevention and treatment of AD.

Neuroprotectin D1 induces neuronal survival and downregulation of amyloidogenic processing in Alzheimer's disease cellular models

The mediator neuroprotectin D1 (NPD1) is an enzymatic derivative of the omega-3 essential fatty acid docosahexaenoic acid. NPD1 stereoselectively and specifically binds to human retinal pigment epithelium (RPE) cells and neutrophils. In turn, this lipid mediator induces dephosphorylation of Bcl-x(L) in a PP2A-dependent manner and induces PI3K/Akt and mTOR/p70S6K pathways leading to RPE cell survival during oxidative stress-induced apoptosis. As a proof of principle of its systemic in vivo bioactivity, NPD1 attenuates laser-induced choroidal neovascularization in mice. Using human neural cells transfected with amyloid precursor protein (APP)sw (Swedish double mutation APP695sw, K595N, M596L), NPD1 was shown to regulate secretase-mediated production of Aβ peptide, downregulates pro-inflammatory gene expression, and promotes cell survival. In human neural cells overexpressing beta-amyloid precursor protein (βAPP), the lipid mediator suppressed Aβ42 shedding by downregulating β-secretase (BACE1) while activating the α-secretase (ADAM10), thus shifting the βAPP cleavage from the noxious amyloidogenic pathway into a non-amyloidogenic, neurotrophic pathway. Furthermore, downregulation of Aβ42 peptide release by NPD1 may be dependent upon PPARγ activation. In conclusion, NPD1 exhibits anti-inflammatory, anti-amyloidogenic, and anti-apoptotic bioactivities in human neural cells in part via PPARγ signaling and through the targeting of α- and β-secretase systems.

Docosahexaenoic acid-derived neuroprotectin D1 induces neuronal survival via secretase- and PPARγ-mediated mechanisms in Alzheimer's disease models

Neuroprotectin D1 (NPD1) is a stereoselective mediator derived from the omega-3 essential fatty acid docosahexaenoic acid (DHA) with potent inflammatory resolving and neuroprotective bioactivity. NPD1 reduces Aβ42 peptide release from aging human brain cells and is severely depleted in Alzheimer's disease (AD) brain. Here we further characterize the mechanism of NPD1's neurogenic actions using 3xTg-AD mouse models and human neuronal-glial (HNG) cells in primary culture, either challenged with Aβ42 oligomeric peptide, or transfected with beta amyloid precursor protein (βAPP)(sw) (Swedish double mutation APP695(sw), K595N-M596L). We also show that NPD1 downregulates Aβ42-triggered expression of the pro-inflammatory enzyme cyclooxygenase-2 (COX-2) and of B-94 (a TNF-α-inducible pro-inflammatory element) and apoptosis in HNG cells. Moreover, NPD1 suppresses Aβ42 peptide shedding by down-regulating β-secretase-1 (BACE1) while activating the α-secretase ADAM10 and up-regulating sAPPα, thus shifting the cleavage of βAPP holoenzyme from an amyloidogenic into the non-amyloidogenic pathway. Use of the thiazolidinedione peroxisome proliferator-activated receptor gamma (PPARγ) agonist rosiglitazone, the irreversible PPARγ antagonist GW9662, and overexpressing PPARγ suggests that the NPD1-mediated down-regulation of BACE1 and Aβ42 peptide release is PPARγ-dependent. In conclusion, NPD1 bioactivity potently down regulates inflammatory signaling, amyloidogenic APP cleavage and apoptosis, underscoring the potential of this lipid mediator to rescue human brain cells in early stages of neurodegenerations.

SORLA/SORL1, a neuronal sorting receptor implicated in Alzheimer's disease

The proteolytic breakdown of the amyloid precursor protein (APP) to neurotoxic amyloid-beta peptides in the brain has been recognized as a major pathological pathway in Alzheimer's disease (AD). Yet, the factors that control the processing of APP and their potential contribution to the common sporadic form of AD remain poorly understood. Here, we review recent findings from studies in patients and in animal models that led to the identification of a unique sorting receptor for APP in neurons, designated SORLA/SORL1, that emerges as a key player in amyloidogenic processing and as major genetic risk factor for AD.

Dietary fatty acids and the aging brain

Aging contributes to physiological decline and vulnerability to disease. In the brain, even with minimal neuronal loss, aging increases oxidative damage, inflammation, demyelination, impaired processing, and metabolic deficits, particularly during pathological brain aging. In this review, the possible role of docosahexaenoic acid (DHA) in the prevention of age-related disruption of brain function is discussed. High-fat diabetogenic diets, cholesterol, and the omega-6 fatty acid arachidonate and its prostaglandin metabolites have all been implicated in promoting the pathogenesis of Alzheimer's disease. Evidence presented here shows DHA acts to oppose this, exerting a plethora of pleiotropic activities to protect against the pathogenesis of Alzheimer's disease.

DHA diet reduces AD pathology in young APPswe/PS1 Delta E9 transgenic mice: possible gender effects

Epidemiological and clinical trial findings suggest that consumption of docosahexaenoic acid (DHA) lowers the risk of Alzheimer's disease (AD). We examined the effects of short-term (3 months) DHA enriched diet on plaque deposition and synaptic defects in forebrain of young APPswe/PS1 Delta E9 transgenic (tg) and non-transgenic (ntg) mice. Gas chromatography revealed a significant increase in DHA concomitant with a decrease of arachidonic acid in both brain and liver in mice fed with DHA. Female tg mice consumed relatively more food daily than ntg female mice, independent of diet. Plaque load was significantly reduced in the cortex, ventral hippocampus and striatum of female APPswe/PS1 Delta E9 tg mice on DHA diet compared to female tg mice on control diet. Immunoblot quantitation of the APOE receptor, LR11, which is involved in APP trafficking and A beta production, were unchanged in mice on DHA or control diets. Moreover drebrin levels were significantly increased in the hippocampus of tg mice on the DHA diet. Finally, in vitro DHA treatment prevented amyloid toxicity in cell cultures. Our findings support the concept that increased DHA consumption may play and important role in reducing brain insults in female AD patients.

Why pleiotropic interventions are needed for Alzheimer's disease

Alzheimer's disease (AD) involves a complex pathological cascade thought to be initially triggered by the accumulation of beta-amyloid (Abeta) peptide aggregates or aberrant amyloid precursor protein (APP) processing. Much is known of the factors initiating the disease process decades prior to the onset of cognitive deficits, but an unclear understanding of events immediately preceding and precipitating cognitive decline is a major factor limiting the rapid development of adequate prevention and treatment strategies. Multiple pathways are known to contribute to cognitive deficits by disruption of neuronal signal transduction pathways involved in memory. These pathways are altered by aberrant signaling, inflammation, oxidative damage, tau pathology, neuron loss, and synapse loss. We need to develop stage-specific interventions that not only block causal events in pathogenesis (aberrant tau phosphorylation, Abeta production and accumulation, and oxidative damage), but also address damage from these pathways that will not be reversed by targeting prodromal pathways. This approach would not only focus on blocking early events in pathogenesis, but also adequately correct for loss of synapses, substrates for neuroprotective pathways (e.g., docosahexaenoic acid), defects in energy metabolism, and adverse consequences of inappropriate compensatory responses (aberrant sprouting). Monotherapy targeting early single steps in this complicated cascade may explain disappointments in trials with agents inhibiting production, clearance, or aggregation of the initiating Abeta peptide or its aggregates. Both plaque and tangle pathogenesis have already reached AD levels in the more vulnerable brain regions during the "prodromal" period prior to conversion to "mild cognitive impairment (MCI)." Furthermore, many of the pathological events are no longer proceeding in series, but are going on in parallel. By the MCI stage, we stand a greater chance of success by considering pleiotropic drugs or cocktails that can independently limit the parallel steps of the AD cascade at all stages, but that do not completely inhibit the constitutive normal functions of these pathways. Based on this hypothesis, efforts in our laboratories have focused on the pleiotropic activities of omega-3 fatty acids and the anti-inflammatory, antioxidant, and anti-amyloid activity of curcumin in multiple models that cover many steps of the AD pathogenic cascade (Cole and Frautschy, Alzheimers Dement 2:284-286, 2006).

Mary S. Easton Center of Alzheimer's Disease Research at UCLA: advancing the therapeutic imperative

The Mary S. Easton Center for Alzheimer's Disease Research (UCLA-Easton Alzheimer's Center) is committed to the "therapeutic imperative" and is devoted to finding new treatments for Alzheimer's disease (AD) and to developing technologies (biomarkers) to advance that goal. The UCLA-Easton Alzheimer's Center has a continuum of research and research-related activities including basic/foundational studies of peptide interactions; translational studies in transgenic animals and other animal models of AD; clinical research to define the phenotype of AD, characterize familial AD, develop biomarkers, and advance clinical trials; health services and outcomes research; and active education, dissemination, and recruitment activities. The UCLAEaston Alzheimer's Center is supported by the National Institutes on Aging, the State of California, and generous donors who share our commitment to developing new therapies for AD. The naming donor (Jim Easton) provided substantial funds to endow the center and to support projects in AD drug discovery and biomarker development. The Sidell-Kagan Foundation supports the Katherine and Benjamin Kagan Alzheimer's Treatment Development Program, and the Deane F. Johnson Alzheimer's Research Foundation supports the Deane F. Johnson Center for Neurotherapeutics at UCLA. The John Douglas French Alzheimer's Research Foundation provides grants to junior investigators in critical periods of their academic development. The UCLA-Easton Alzheimer's Center partners with community organizations including the Alzheimer's Association California Southland Chapter and the Leeza Gibbons memory Foundation. Collaboration with pharmaceutical companies, biotechnology companies, and device companies is critical to developing new therapeutics for AD and these collaborations are embraced in the mission of the UCLA-Easton Alzheimer's Center. The Center supports excellent senior 3 investigators and serves as an incubator for new scientists, agents, models, technologies and concepts that will significantly influence the future of AD treatment and AD research.

DHA may prevent age-related dementia

The risk for dementia, a major contributor to incapacitation and institutionalization, rises rapidly as we age, doubling every 5 y after age 65. Tens of millions of new Alzheimer's disease (AD) and other dementia cases are projected as elderly populations increase around the world, creating a projected dementia epidemic for which most nations are not prepared. Thus, there is an urgent need for prevention approaches that are safe, effective, and affordable. This review addresses the potential of one promising candidate, the (n-3) fatty acid docosahexaenoic acid (DHA), which appears to slow pathogenesis of AD and possibly vascular dementia. DHA is pleiotropic, acting at multiple steps to reduce the production of the beta-amyloid peptide, widely believed to initiate AD. DHA moderates some of the kinases that hyperphosphorylate the tau-protein, a component of the neurofibrillary tangle. DHA may help suppress insulin/neurotrophic factor signaling deficits, neuroinflammation, and oxidative damage that contribute to synaptic loss and neuronal dysfunction in dementia. Finally, DHA increases brain levels of neuroprotective brain-derived neurotrophic factor and reduces the (n-6) fatty acid arachidonate and its prostaglandin metabolites that have been implicated in promoting AD. Clinical trials suggest that DHA or fish oil alone can slow early stages of progression, but these effects may be apolipoprotein E genotype specific, and larger trials with very early stages are required to prove efficacy. We advocate early intervention in a prodromal period with nutrigenomically defined subjects with an appropriately designed nutritional supplement, including DHA and antioxidants.

Are omega-3 fatty acids options for prevention and treatment of cognitive decline and dementia?

PURPOSE OF REVIEW

To report recent data on the potential role of omega-3 fatty acids (n-3 FA) found in oily fish, especially docosahexaenoic acid (DHA), to prevent and treat cognitive decline and Alzheimer's disease.

RECENT FINDINGS

Observational studies still provide conflicting results, in which the majority indicate beneficial effects on cognition, both when assessed as a continuous variable or as incident dementia, mainly Alzheimer's disease. Experimental studies have demonstrated potentially ameliorating effects of eicosapentaenoic acid (EPA) and DHA on amyloid fragment formation, signal transduction including upregulation of the apolipoprotein receptor SorLA, as well as on angiogenesis. The role of EPA and DHA metabolites on Alzheimer's disease pathology is under investigation. Recently, three randomized intervention studies, with duration up to 6 months have been reported. In contrast to a small study from Taiwan, no positive overall effects were reported from the Swedish OmegAD Study or from a Dutch study, although post hoc analyses indicate that selected individuals with mild forms of Alzheimer's disease or cognitive decline may respond to treatment.

SUMMARY

No firm conclusions can be drawn. Based on epidemiological data, fish including oily fish could be advised as part of a balanced diet for public health purpose, although the evidence for better cognition is only fairly consistent. It is unlikely that n-3 FA will emerge as a treatment option in general for improving cognitive function in patients with Alzheimer's disease. n-3 FA, especially DHA, may turn out as an adjuvant therapy in selected cases. Further long-term intervention studies on individuals with mild cognitive reductions are awaited.

Amyloid-Beta Peptide, Oxidative Stress and Inflammation in Alzheimer's Disease: Potential Neuroprotective Effects of Omega-3 Polyunsaturated Fatty Acids

Alzheimer's disease is the most common form of dementia in the elderly and is a progressive neurodegenerative disorder characterised by a decline in cognitive function and also profound alterations in mood and behaviour. The pathology of the disease is characterised by the presence of extracellular amyloid peptide deposits and intracellular neurofibrillary tangles in the brain. Although many hypotheses have been put forward for the aetiology of the disease, increased inflammation and oxidative stress appear key to be features contributing to the pathology. The omega-3 polyunsaturated fats, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) have well-characterised effects on inflammation and may have neuroprotective effects in a number of neurodegenerative conditions including Alzheimer's disease. The aims of this paper are to review the neuroprotective effects of EPA and DHA in Alzheimer's disease, with special emphasis on their role in modulating oxidative stress and inflammation and also examine their potential as therapeutic agents.

Nutrition, brain aging, and neurodegeneration

The onset of age-related neurodegenerative diseases superimposed on a declining nervous system could enhance the motor and cognitive behavioral deficits that normally occur in senescence. It is likely that, in cases of severe deficits in memory or motor function, hospitalization and/or custodial care would be a likely outcome. This means that unless some way is found to reduce these age-related decrements in neuronal function, health care costs will continue to rise exponentially. Applying molecular biological approaches to slow aging in the human condition may be years away. So, it is important to determine what methods can be used today to increase healthy aging, forestall the onset of these diseases, and create conditions favorable to obtaining a "longevity dividend" in both financial and human terms. Recent studies suggest that consumption of diets rich in antioxidants and anti-inflammatory components such as those found in fruits, nuts, vegetables, and spices, or even reduced caloric intake, may lower age-related cognitive declines and the risk of developing neurodegenerative disease.

Single and repeated oral dose toxicity study of fucoxanthin (FX), a marine carotenoid, in mice

Fucoxanthin (FX), a xanthophyll derivative, is an orange-colored pigment present in edible brown algae. As a part of safety evaluation, single and repeated oral dose toxicity study of FX was conducted. In a single dose study, FX purified from seaweed was orally administered to male and female ICR mice at doses of 1,000 and 2,000 mg/kg. In a repeated doses study, FX at doses of 500 and 1,000 mg/kg was orally administered for 30 days. In both studies, no mortality and no abnormalities in gross appearance were observed. In the repeated doses study, histological observation revealed no abnormal changes in liver, kidney, spleen and gonadal tissues of any of the FX-treated groups. However, significantly increased total cholesterol concentrations were shown by plasma biochemical analyses in all FX-treated groups. Although total bilirubin concentrations were increased by FX, it was established that presence of fucoxanthinol, a major metabolite of FX, interfered with bilirubin determination in plasma. To further ascertain the safety of FX, the mechanism by which FX induces hypercholesterolemia in mice and species differences in the induction of hypercholesterolemia should be elucidated.