Omega-3 fatty acids: potential role in the management of early Alzheimer's disease

Synthetic and Natural Bioactive Molecules in Balancing the Crosstalk among Common Signaling Pathways in Alzheimer's Disease: Understanding the Neurotoxic Mechanisms for Therapeutic Intervention

The structure and function of the brain greatly rely on different signaling pathways. The wide variety of biological processes, including neurogenesis, axonal remodeling, the development and maintenance of pre- and postsynaptic terminals, and excitatory synaptic transmission, depends on combined actions of these molecular pathways. From that point of view, it is important to investigate signaling pathways and their crosstalk in order to better understand the formation of toxic proteins during neurodegeneration. With recent discoveries, it is established that the modulation of several pathological events in Alzheimer's disease (AD) due to the mammalian target of rapamycin (mTOR), Wnt signaling, 5'-adenosine monophosphate activated protein kinase (AMPK), peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), and sirtuin 1 (Sirt1, silent mating-type information regulator 2 homologue 1) are central to the key findings. These include decreased amyloid formation and inflammation, mitochondrial dynamics control, and enhanced neural stability. This review intends to emphasize the importance of these signaling pathways, which collectively determine the fate of neurons in AD in several ways. This review will also focus on the role of novel synthetic and natural bioactive molecules in balancing the intricate crosstalk among different pathways in order to prolong the longevity of AD patients.

Rivastigmine-DHA ion-pair complex improved loading in hybrid nanoparticles for better amyloid inhibition and nose-to-brain targeting in Alzheimer's

Rivastigmine hydrogen tartrate (RIV-HT) is given orally for Alzheimer's disease. However, oral therapy shows low brain bioavailability, short half-life and gastrointestinal-mediated adverse effects. RIV-HT intranasal delivery can avoid these side effects, but its low brain bioavailability remains challenging. These issues could be solved with hybrid lipid nanoparticles with enough drug loading to enhance RIV-HT brain bioavailability while avoiding oral route side effects. The RIV-HT and docosahexaenoic acid (DHA) ion-pair complex (RIV:DHA) was prepared to improve drug loading into lipid-polymer hybrid (LPH) nanoparticles. Two types of LPH, i.e., cationic (RIV:DHA LPH(+ve)) and anionic LPH (RIV:DHA LPH(-ve)) were developed. The effect of LPH surface charge on in-vitro amyloid inhibition, in-vivo brain concentrations and nose-to-brain drug targeting efficiency were investigated. LPH nanoparticles showed concentration dependant amyloid inhibition. RIV:DHA LPH(+ve) demonstrated relatively enhanced Aβ1-42 peptide inhibition. The thermoresponsive gel embedded with LPH nanoparticles improved nasal drug retention. LPH nanoparticles gel significantly improved pharmacokinetic parameters compared to RIV-HT gel. RIV:DHA LPH(+ve) gel showed better brain concentrations than RIV:DHA LPH(-ve) gel. The histological examination of nasal mucosa treated with LPH nanoparticles gel showed that the delivery system was safe. In conclusion, the LPH nanoparticle gel was safe and efficient in improving the nose-to-brain targeting of RIV, which can potentially be utilized in managing Alzheimer's.

Potentiality Assessment of the Acetylcholinesterase-Inhibitory Activity of Olive Oil with an Additive Edible Insect Powder

Edible insects (Alphitobius diaperinus Panzer, Gryllus campestris, Tenebrio molitor, Chorthippus biguttulus) are rich in nutrients that potentially inhibit acetylcholinesterase (AChE), but also improve cognition. The aim of this study was to evaluate four varied species of freeze-dried edible insects (purchased from a store); their nutrient composition, including fat, total phenolic compounds, vitamins, and antioxidant properties; and the potential inhibitory effect of AChE. An additional goal was to obtain olive oil with the addition of edible insects. Such oil was characterized by high oxidizing properties and showed high affinity to AChE. The results showed that mealworms and grasshoppers had the highest content of fats (PUFA/SFA) and phenolic compounds. These insects also showed a high content of vitamins, which correlated with the highest affinity for AChE. Therefore, they were added as a functional additive to olive oil. Olive oil with the addition of edible insects showed a higher affinity for AChE and enriched the olive oil with vitamin C and B vitamins.

Efficacy and acceptability of anti-inflammatory eicosapentaenoic acid for cognitive function in Alzheimer's dementia: A network meta-analysis of randomized, placebo-controlled trials with omega-3 fatty acids and FDA-approved pharmacotherapy

Alzheimer's dementia (AD) is a major contributor to global disability, and effective therapies to modify disease progression are currently lacking. The neuro-inflammatory theory is a potential etiology underlying this neurodegenerative disease. Previous randomized, controlled trials (RCTs) have provided inconclusive results regarding efficacy of omega-3 polyunsaturated fatty acids (PUFAs) regimens, which might provide anti-inflammatory benefits in the management of AD, in improving cognitive function among participants with AD. The objective of this frequentist-model based network meta-analysis (NMA) was to evaluate the potential advantages of omega-3 PUFAs and currently FDA-approved medications for AD on overall cognitive function in AD individuals. The primary outcomes were: (1) changes in cognitive function, and (2) acceptability, which refers to all-cause discontinuation. Additionally, secondary outcomes included quality of life, behavioral disturbances and safety/tolerability, which was assessed through the frequency of any reported adverse event. This NMA included 52 RCTs (6 with omega-3 PUFAs and 46 with FDA-approved medications) involving 21,111 participants. The results showed that long-term high-dose (1500-2000 mg/day) of eicosapentaenoic acid (EPA)-dominant omega-3 PUFAs augmented with anti-oxidants had the highest potential for cognitive improvement among all investigated treatments [standardized mean difference = 3.00, 95% confidence intervals (95 %CIs) = 1.84-4.16]. Compared to placebo, omega-3 PUFAs had similar acceptability [odds ratio (OR) = 0.46, 95 %CIs = 0.04 to 5.87] and safety profiles (OR = 1.24, 95 %CIs = 0.66 to 2.33)o. These findings support the potential neurotherapeutic effects of high dosage EPA-dominant omega-3 PUFAs for the amelioration of cognitive decline in patients with AD. Future large-scale, long-term RCTs should focus on different dosages of EPA-dominant omega-3 PUFAs regimens on improving cognitive dysfunction in patients with AD at different levels of inflammatory status and psychopathology.

Aging decreases docosahexaenoic acid transport across the blood-brain barrier in C57BL/6J mice

Nutrients are actively taken up by the brain via various transporters at the blood-brain barrier (BBB). A lack of specific nutrients in the aged brain, including decreased levels of docosahexaenoic acid (DHA), is associated with memory and cognitive dysfunction. To compensate for decreased brain DHA, orally supplied DHA must be transported from the circulating blood to the brain across the BBB through transport carriers, including major facilitator superfamily domain-containing protein 2a (MFSD2A) and fatty acid-binding protein 5 (FABP5) that transport esterified and non-esterified DHA, respectively. Although it is known that the integrity of the BBB is altered during aging, the impact of aging on DHA transport across the BBB has not been fully elucidated. We used 2-, 8-, 12-, and 24-month-old male C57BL/6 mice to evaluate brain uptake of [14C]DHA, as the non-esterified form, using an in situ transcardiac brain perfusion technique. Primary culture of rat brain endothelial cells (RBECs) was used to evaluate the effect of siRNA-mediated MFSD2A knockdown on cellular uptake of [14C]DHA. We observed that the 12- and 24-month-old mice exhibited significant reductions in brain uptake of [14C]DHA and decreased MFSD2A protein expression in the brain microvasculature compared with that of the 2-month-old mice; nevertheless, FABP5 protein expression was up-regulated with age. Brain uptake of [14C]DHA was inhibited by excess unlabeled DHA in 2-month-old mice. Transfection of MFSD2A siRNA into RBECs decreased the MFSD2A protein expression levels by 30% and reduced cellular uptake of [14C]DHA by 20%. These results suggest that MFSD2A is involved in non-esterified DHA transport at the BBB. Therefore, the decreased DHA transport across the BBB that occurs with aging could be due to age-related down-regulation of MFSD2A rather than FABP5.

Association of Circulating Caprylic Acid with Risk of Mild Cognitive Impairment and Alzheimer's Disease in the Alzheimer's Disease Neuroimaging Initiative (ADNI) Cohort

OBJECTIVE

Medium-chain fatty acids (MCFAs) can rapidly cross the blood-brain barrier and provide an alternative energy source for the brain. This study aims to determine 1) whether plasma caprylic acid (C8:0) is associated with risk of incident mild cognitive impairment (MCI) among baseline cognitively normal (CN) participants, and incident Alzheimer's Disease (AD) among baseline MCI participants; and 2) whether these associations differ by sex, comorbidity of cardiometabolic diseases, apolipoprotein E (APOE) ε4 alleles, and ADAS-Cog 13.

METHODS

Within the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort, plasma C8:0 was measured at baseline in 618 AD-free participants aged 55 to 91. Logistic regression models were used to estimate odds ratios (ORs) and 95% CIs with incident MCI and AD as dependent variables, separately.

RESULTS

The inverse association between circulating C8:0 and risk of incident MCI was of borderline significance. The inverse association between circulating levels of C8:0 and risk of incident MCI was significant among CN participants with ≥1 cardiometabolic diseases [OR (95% CI): 0.75 (0.58-0.98) (P=0.03)], those with one copy of APOE ε4 alleles [OR (95% CI): 0.43 (0.21-0.89) (P=0.02)], female [OR (95% CI): 0.60 (0.38-0.94) (P=0.02)], and ADAS-Cog 13 above the median [OR (95%CI): 0.69 (0.50-0.97)(P=0.03)] after adjusting for all covariates.

CONCLUSION

The inverse associations were present only among subgroups of CN participants, including female individuals, those with one or more cardiometabolic diseases, or one APOE ε4 allele, or higher ADAS-Cog 13 scores. If confirmed, this finding will facilitate precision prevention of MCI, in turn, AD among CN older adults.

A Systematic Review of Dietary Supplements in Alzheimer's Disease

Alzheimer's is the most common neurodegenerative disease among the aging population, which has been a major global challenge. The pathogenesis of the disease is still undetermined but postulated to be involved in various mechanisms including oxidative stress, excitotoxicity, inflammation, cell death, genetic factors, protein accumulation, and degradation. There are few Food and Drug Administration (FDA)-approved drugs available for the treatment of Alzheimer's disease (AD) that have limited benefits along with associated adverse effects. A retrospective review of randomized double-blind controlled trials of various supplements used in AD patients was performed on a PubMed search from January 1983 to March 2022. We found 10 articles that have shown positive outcomes in various cognitive domains. We conclude that there should be a global standard to endorse the quality and safety of these supplements.

Mechanisms of Mitochondrial Malfunction in Alzheimer’s Disease: New Therapeutic Hope

Mitochondria play a critical role in neuron viability or death as it regulates energy metabolism and cell death pathways. They are essential for cellular energy metabolism, reactive oxygen species production, apoptosis, Ca⁺⁺ homeostasis, aging, and regeneration. Mitophagy and mitochondrial dynamics are thus essential processes in the quality control of mitochondria. Improvements in several fundamental features of mitochondrial biology in susceptible neurons of AD brains and the putative underlying mechanisms of such changes have made significant progress. AD's etiology has been reported by mitochondrial malfunction and oxidative damage. According to several recent articles, a continual fusion and fission balance of mitochondria is vital in their normal function maintenance. As a result, the shape and function of mitochondria are inextricably linked. This study examines evidence suggesting that mitochondrial dysfunction plays a significant early impact on AD pathology. Furthermore, the dynamics and roles of mitochondria are discussed with the link between mitochondrial malfunction and autophagy in AD has also been explored. In addition, recent research on mitochondrial dynamics and mitophagy in AD is also discussed in this review. It also goes into how these flaws affect mitochondrial quality control. Furthermore, advanced therapy techniques and lifestyle adjustments that lead to improved management of the dynamics have been demonstrated, hence improving the conditions that contribute to mitochondrial dysfunction in AD.

Plasma and red blood cell n3 fatty acids correlate positively with the WISC-R verbal and full-scale intelligence quotients and inversely with Conner's parent-rated ADHD index t-scores in children with high functioning autism and Asperger's syndrome

Findings of the fatty acid status of people with autism spectrum disorders have been incongruent perhaps because of the diversity of the condition. A cross-sectional design study was used to  investigated fatty acid levels and relationships between fatty acids, and cognition and behaviour in a homogenous group of children with autism spectrum disorder. Children with Asperger's syndrome (AS) /high functioning autism (n = 44) and healthy siblings (n = 17) were recruited from the Diagnostic and Therapeutic Centre for Children with Autism, Warsaw, Poland. In the AS group, plasma phosphatidylcholine 22:5n3 correlated positively with verbal (r = 0.357, p = 0.019) and full scale (r = 0.402, p = 0.008) IQs, red blood cell phosphatidylcholine 22:5n3 with verbal (r = 0.308, p = 0.044), performance (r = 0.304, p = 0.047) and full scale (r = 0.388, p = 0.011) IQs and red blood cell phosphatidylethanolamine 22:5n3 with verbal (r = 0.390, p = 0.010) and full scale (r = 0.370, p = 0.016) IQs. Whilst, plasma phosphatidycholine 20:5n3 (r = -0.395, p = 0.009), 22:6n3 (r = -0.402, p = 0.007) and total n3 fatty acids (r = -425, p = 0.005), red blood cell phosphatidlycholine 20:5n3 (r = -0.321, p = 0.036) and red blood cell phosphatidylethanolamine 20:5n3 (r = -0.317, p = 0.038), 22:6n3 (r = -0.297, p = 0.05) and total n3 fatty acids (r = -0.306, p = 0.046) correlated inversly with ADHD index. Similarly, inattention was negatively related with plasma phosphatidylcholine 22:6n3 (r = -0.335, p = 0.028), and total n3 fatty acids (r = -0.340, p = 0.026), oppositional with plasma phosphatidylcholine 18:3n3 (r = -0.333, p = 0.029), 20:5n3 (r = -0.365, p = 0.016), total n3 fatty acids (r = -0.293, p < 0.05), red blood cell phosphatidylcholine 18:3n3 (r = -0.337, p = 0.027) and red blood cell ethanolamine 18:3n3 (r = - 0.333, p = 0.029), 20:5n3 (r = -0.328, p = 0.032), 22:6n3 (r = 0.362, p = 0.017) and total n-3 fatty acids (r = -0.298, p < 0.05) and hyperactivity with plasma phosphatidylcholine 22:6n3 (r = -0.320, p = 0.039). In contrast, there were inverse correlations between red blood cell phosphatidylcholine 18:2n6 and performance (r = -0.358, p = 0.019) and full scale (r = -0.320, p = 0.039) IQs, and direct correlations between red blood cell phosphatidylcholine 22:4n6 (r = 0.339, p = 0.026) and 22:5n6 (r = 0.298, p < 0.05) and ADHD index, between red blood cell phosphatidylcholine 22:4n6 (r = 0.308, p = 0.044) and inattention, between plasma phosphatidylcholine 22:4n6 (r = 0.341, p = 0.025), red blood cell phosphatidylcholine 20:4n6 (r = 0.314, p = 0.041) and total n6 fatty acids (r = 0.336, p = 0.028) and oppositional and plasma phosphatidylcholine 20:3n6 (r = 0.362, p = 0.018) and red blood cell phosphatidylcholine 20:3n6 (r = 0.401, p = 0.009) and hyperactivity. The findings of the ethnically homogenous children with Asperger's syndrome/high functioning autism study revealed positive associations between 22:5n3 and cognition, and negative relationships between 20:5n3 and 22:6n3 and behavioural problem. In contrast, cognitive ability and behavioural problems were negatively and positively associated with n6 fatty acids. Further investigation is required to establish whether there a cause and effect relationship. Regardless, it would be prudent to ensure that children with the conditions have optimum n3 PUFA intake.

Insulin and Insulin Resistance in Alzheimer's Disease

Insulin plays a range of roles as an anabolic hormone in peripheral tissues. It regulates glucose metabolism, stimulates glucose transport into cells and suppresses hepatic glucose production. Insulin influences cell growth, differentiation and protein synthesis, and inhibits catabolic processes such as glycolysis, lipolysis and proteolysis. Insulin and insulin-like growth factor-1 receptors are expressed on all cell types in the central nervous system. Widespread distribution in the brain confirms that insulin signaling plays important and diverse roles in this organ. Insulin is known to regulate glucose metabolism, support cognition, enhance the outgrowth of neurons, modulate the release and uptake of catecholamine, and regulate the expression and localization of gamma-aminobutyric acid (GABA). Insulin is also able to freely cross the blood–brain barrier from the circulation. In addition, changes in insulin signaling, caused inter alia insulin resistance, may accelerate brain aging, and affect plasticity and possibly neurodegeneration. There are two significant insulin signal transduction pathways: the PBK/AKT pathway which is responsible for metabolic effects, and the MAPK pathway which influences cell growth, survival and gene expression. The aim of this study is to describe the role played by insulin in the CNS, in both healthy people and those with pathologies such as insulin resistance and Alzheimer’s disease.

Docosahexaenoic acid ameliorates autoimmune inflammation by activating GPR120 signaling pathway in dendritic cells

Although the phenomenon that omega-3 polyunsaturated fatty acids (n-3 PUFAs) shows to have a beneficial effect in patients suffering from multiple sclerosis (MS) and other autoimmune diseases has been empirically well-documented, the molecular mechanisms that underline the anti-inflammatory effects of n-3 PUFAs are yet to be understood. In experimental autoimmune encephalomyelitis (EAE), a model for MS, we show that one of the underlying mechanisms by which dietary docosahexaenoic acid (DHA) exerts its anti-inflammatory effect is regulating the functional activities of dendritic cells (DCs). In DHA-treated EAE mice, DCs acquire a regulatory phenotype characterized by low expression of co-stimulatory molecules, decreased production of pro-inflammatory cytokines, and enhanced capability of regulatory T-cell induction. The effect of DHA on DCs is mediated by the lipid-sensing receptor, G protein-coupled receptor 120 (GPR120). A GPR120-specific small-molecule agonist could ameliorate the autoimmune inflammation by regulating DCs, while silencing GPR120 in DCs strongly increased the immunogenicity of DCs. Stimulation of GPR120 induces suppressor of cytokine signaling 3 (SOCS3) expression and down-regulates signal transducer and activator of transcription 3 (STAT3) phosphorylation, explaining the molecular mechanism for regulatory DC induction.

Plasma fatty acid abnormality in Sudanese drug-resistant epileptic patients

Intervention studies have demonstrated that the n-3 fatty acids, docosahexaenoic and eicosapentaenoic acids, ameliorate seizure frequency in patients with drug-resistant epilepsy (DRE). There is a scarcity of fatty acid status of patients with epilepsy. We have investigated blood fatty acids of patients with DRE and assessed the indices of elongase and desaturase activities. DRE patients (n = 83) and healthy controls (n = 31) were recruited form Soba University Hospital Neurology Referral Clinic and Ibn-Auf paediatric Teaching Hospital Neurology Referral Clinic, Khartoum, Sudan. Fatty acid composition of plasma total lipids, phosphatidylcholine and neutral lipids were analysed. The patients compared with their healthy counterparts had higher levels of C14:0, C16:0, C18:0, C20:0, C22:0 (p<0.05) and C24:0, and total saturates (p<0.05). Similarly, the proportions of C16:1n-7, 18:1n-7, C18:1n-9, C20:1n-9, C24:1n-9 and total monounsaturated fatty acids; p<0.005) were higher in the drug-resistant patients. Conversely, the patients had lower levels of n-6 (C18:2n-6, C18:3n-6, C20:4n-6, n-6 metabolites and total n-6; p<0.005 and C20:2n-6 and C20:3n-6; p<0.05) and n-3 (C20:5n-3, C22:5n-3, C22:6n-3, ∑EPA and DHA, n-3 metabolites and total n-3; p<0.05) fatty acids. Indices of elongase and desaturase activities - The plasma total lipid ratios of C16:0/C14:0 (p = 0.001), C18:0/C16:0 (p = 0.001), C16:1n-7/C16:0 (p = 0.027), C18:1n-9/C18:0 (p = 0.022) and C22:4n-6/C20:4n-6 (p = 0.008) were higher and C18:3n-6/C18:2n-6 (p = 0.05), C20:4n-6/C20:3n-6 (p = 0.032) and C20:4n-6/C18:2n-6 (p>0.05) lower in the patients with drug-resistant epilepsy than in the healthy control subjects. DRE is associated with blood fatty acid perturbation and abnormal activities of long-chain fatty acid elongase (ELOVL-6), stearoyl-coenzyme A desaturase-1 (SCD-1), delta 6-fatty acid desaturase (D6D) and delta 5 fatty acid desaturase (D5D). N-3 fatty acids are known to ameliorate seizures frequency and dampen neuronal hyperexcitability. Therefore, patients with DRE should be regularly monitored and, if necessary, supplemented with n-3 fatty acids.

Consumption of Oleic Acid on the Preservation of Cognitive Functions in Japanese Elderly Individuals

We recruited 154 community-dwelling elderly individuals and conducted a cohort study to find out the nutrient intake that is suitable for maintaining cognitive function in Japanese elders. Cognitive function was evaluated by the two functional tests, the Montreal Cognitive Assessment (MoCA) and Wechsler Memory Scale-Delayed Recall (WMS-DR), and daily nutrient intake was estimated from a Brief-type Self-administered Diet History Questionnaire (BDHQ). By a multiple regression analysis, among the four major nutrients (protein, fat, carbohydrate and ash), we detected a significant correlation between the score of cognitive functions assessed by both MoCA and WMS-DR and daily consumption of fat (p = 0.0317 and p = 0.0111, respectively). Among categories of fatty acid, we found a significant correlation between the score of both MoCA and WMS-DR and consumption of monounsaturated fatty acid (MUFA) (p = 0.0157 and p = 0.0136, respectively). Finally, among MUFAs, we observed a significant correlation between the score of both MoCA and WMS-DR and consumption of oleic acid (p = 0.0405 and p = 0.0165, respectively). From these observations, we can propose that daily consumption of fat, especially in oleic acid, has a beneficial effect against cognitive decline in community-dwelling Japanese elderly individuals.

Dietary Fatty Acid Factors in Alzheimer's Disease: A Review

Alzheimer's disease (AD) is an irreversible neurodegenerative disease characterized by brain function disorder and chronic cognitive function impairment. The onset of AD is complex and is mostly attributed to interactions between genetic factors and environmental factors. Lifestyle, dietary habits, and food consumption are likely to play indispensable functions in aged-related neurodegenerative diseases in elderly people. An increasing number of epidemiological studies have linked dietary fatty acid factors to AD, raising the point of view that fatty acid metabolism plays an important role in AD initiation and progression as well as in other central nervous system disorders. In this paper, we review the effects of the consumption of various dietary fatty acids on AD onset and progression and discuss the detrimental and beneficial effects of some typical fatty acids derived from dietary patterns on the pathology of AD. We outline these recent advances, and we recommend that healthy dietary lifestyles may contribute to preventing the occurrence and decreasing the pathology of AD.

Targeting neuroinflammation: The therapeutic potential of ω-3 PUFAs in substance abuse

Substance abuse is a chronic relapsing disorder that results in serious health and socioeconomic issues worldwide. Addictive drugs induce long-lasting morphologic and functional changes in brain circuits and account for the formation of compulsive drug-seeking and drug-taking behaviors. Yet, there remains a lack of reliable therapy. In recent years, accumulating evidence indicated that neuroinflammation was implicated in the development of drug addiction. Findings from both our and other laboratories suggest that ω-3 polyunsaturated fatty acids (PUFAs) are effective in treating neuroinflammation-related mental diseases, and indicate that they could exert positive effects in treating drug addiction. Thus, in the present review, we summarized and evaluated recently published articles reporting the neuroinflammation mechanism in drug addiction and the immune regulatory ability of ω-3 PUFAs. We also sought to identify some of the challenges ahead in the translation of ω-3 PUFAs into addiction treatment.

Clinical use of omega-3 fatty acids in migraine: A narrative review

BACKGROUND

Omega-3 fatty acids (FAs) can produce several beneficial effects and are commonly used for the treatment of migraine symptoms. Although current therapeutic measures for migraine included pharmacological therapies, dietary supplements, and herbal ingredients, dietary patterns, acupuncture, relaxation techniques, biofeedback, and psychotherapy, omega-3 FAs therapeutic role seems to be obtained through the inhibition or reduction of the release of inflammatory cytokines. The present review aims to provide updated information about the effects of omega-3 FAs in migraine treatment, investigating their clinical effects alone or in combination with other substances.

METHODS

Bibliographic research was conducted by examining scientific literature from January 2000 until January 31, 2020. Ten clinical studies were included in the review. Quality assessment of randomized controlled trials was performed by using the JADAD scale.

RESULTS

Clinical studies methodology is not always of good quality and results show moderate evidence concerning the therapeutic role of omega-3 FAs in migraine.

CONCLUSION

Further clinical trials are necessary to implement the knowledge concerning the use of omega-3 fatty acids in the treatment of migraine.

Marine n-3 polyunsaturated fatty acids: Efficacy on inflammatory-based disorders

Inflammation is a physiological response to injury, stimulating tissue repair and regeneration. However, the presence of peculiar individual conditions can negatively perturb the resolution phase eventually leading to a state of low-grade systemic chronic inflammation, characterized by tissue and organ damages and increased susceptibility to non-communicable disease. Marine n-3 polyunsaturated fatty acids (n-3 PUFAs), mainly eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), are able to influence many aspects of this process. Experiments performed in various animal models of obesity, Alzheimer's disease and multiple sclerosis have demonstrated that n-3 PUFAs can modulate the basic mechanisms as well as the disease progression. This review describes the available data from experimental studies to the clinical trials.

Rodent Models of Amyloid-Beta Feature of Alzheimer's Disease: Development and Potential Treatment Implications

Alzheimer's disease (AD) is the most common neurodegenerative disorder worldwide and causes severe financial and social burdens. Despite much research on the pathogenesis of AD, the neuropathological mechanisms remain obscure and current treatments have proven ineffective. In the past decades, transgenic rodent models have been used to try to unravel this disease, which is crucial for early diagnosis and the assessment of disease-modifying compounds. In this review, we focus on transgenic rodent models used to study amyloid-beta pathology in AD. We also discuss their possible use as promising tools for AD research. There is still no effective treatment for AD and the development of potent therapeutics are urgently needed. Many molecular pathways are susceptible to AD, ranging from neuroinflammation, immune response, and neuroplasticity to neurotrophic factors. Studying these pathways may shed light on AD pathophysiology as well as provide potential targets for the development of more effective treatments. This review discusses the advantages and limitations of these models and their potential therapeutic implications for AD.

Role of nurses in addressing modifiable risk factors for early Alzheimer's disease and mild cognitive impairment

A multidisciplinary advisory group of health professionals involved in dementia care assessed the current evidence base regarding modifiable risk factors (MRFs) for early Alzheimer's disease and mild cognitive impairment. Based on evidence from the published literature and clinical experience, MRFs in four areas were identified where there is evidence to support interventions that may help delay cognitive decline or reduce the risk of developing Alzheimer's disease: medical (eg cardiovascular risk factors), psychosocial (eg depression, anxiety, social isolation), lifestyle (eg lack of physical activity, smoking) and nutrition (eg poor diet, lack of micronutrients). Practical guidance on how health professionals, but in particular nurses, may actively seek to address these MRFs in clinical practice was also developed. Nurses are at the forefront of patient care and, as such, are ideally placed to offer advice to patients that may proactively help mitigate the risks of cognitive decline and the development of Alzheimer's disease.

The LipiDiDiet trial: what does it add to the current evidence for Fortasyn Connect in early Alzheimer's disease?

Nutritional factors can influence the risk of developing Alzheimer’s disease (AD) and its rate of progression, and there is, therefore, increasing interest in nutrition as a modifiable risk factor for the disease. Synaptic loss is an important feature of early AD, and the formation of new synapses is dependent on key nutritional elements that are known to be deficient in patients with AD. The daily medical food, Souvenaid, contains Fortasyn Connect, a multinutrient combination developed to specifically address these deficiencies, comprising docosahexaenoic acid, eicosapentaenoic acid, uridine monophosphate, choline, phospholipids, selenium, folic acid, and vitamins B12, B6, C, and E. Although yielding heterogeneous findings, clinical studies of Fortasyn Connect provide preliminary evidence of clinically relevant benefits on cognitive outcomes in prodromal and early AD. The LipiDiDiet trial investigated the effects of Fortasyn Connect on cognition and related measures in prodromal AD, and is the first randomized, controlled, double-blind, multicenter trial study of a non-pharmacological intervention in this setting. The primary efficacy endpoint was change over 24 months in a composite score of cognitive performance using a neuropsychological test battery. Fortasyn Connect had no significant effect on this endpoint, but demonstrated a significant benefit on secondary endpoints, including domains of cognition affected by AD (attention, memory, executive function) and hippocampal atrophy, suggesting a potential benefit on disease progression. Other studies have demonstrated benefits for Fortasyn Connect on nutritional markers and levels of plasma homocysteine. Taken together, current evidence indicates that Fortasyn Connect may show benefit on domains of cognition affected by AD and nutritional measures that influence risk factors for its progression; that it has greater potential for benefit earlier rather than later in the disease; and that it is safe and well tolerated, alone or in combination with AD medications. Further research into its potential role in AD management is therefore warranted.

Small Molecule Natural Products and Alzheimer's Disease

Alzheimer's disease (AD) is a progressive and deadly neurodegenerative disease that is characterized by memory loss, cognitive impairment and dementia. Several hypotheses have been proposed for the pathogenesis based on the pathological changes in the brain of AD patients during the last few decades. Unfortunately, there is no effective agents/therapies to prevent or control AD at present. Currently, only a few drugs, which function as acetylcholinesterase (AChE) inhibitors or N-methyl-Daspartate (NMDA) receptor antagonists, are available to alleviate symptoms. Since many small molecule natural products have shown their functions as agonists or antagonists of receptors, as well as inhibitors of enzymes and proteins in the brain during the development of central nervous system (CNS) drugs, it is likely that natural products will play an important role in anti-AD drug development. We review recent papers on using small molecule natural products as drug candidates for the treatment of AD. These natural products possess antioxidant, anti-inflammatory, anticholinesterase, anti-amyloidogenic and neuroprotective activities. Moreover, bioactive natural products intended to be used for preventing AD, reducing the symptoms of AD and the new targets for treatment of AD are summarized.

Omega-3 decreases D1 and D2 receptors expression in the prefrontal cortex and prevents amphetamine-induced conditioned place preference in rats

Amphetamine (AMPH) abuse is a serious public health problem due to the high addictive potential of this drug, whose use is related to severe brain neurotoxicity and memory impairments. So far, therapies for psychostimulant addiction have had limited efficacy. Omega-3 polyunsaturated fatty acids (n-3 PUFA) have shown beneficial influences on the prevention and treatment of several diseases that affect the central nervous system. Here, we assessed the influence of fish oil (FO), which is rich in n-3 PUFA, on withdrawal and relapse symptoms following re-exposure to AMPH. Male Wistar rats received d,l-AMPH or vehicle in the conditioned place preference (CPP) paradigm for 14 days. Then, half of each experimental group was treated with FO (3 g/kg, p.o.) for 14 days. Subsequently, animals were re-exposed to AMPH-CPP for three additional days, in order to assess relapse behavior. Our findings have evidenced that FO prevented relapse induced by AMPH reconditioning. While FO prevented AMPH-induced oxidative damages in the prefrontal cortex, molecular assays allowed us to observe that it was also able to modulate dopaminergic cascade markers (DAT, TH, VMAT-2, D1R and D2R) in the same brain area, thus preventing AMPH-induced molecular changes. To the most of our knowledge, this is the first study to show a natural alternative tool which is able to prevent psychostimulant relapse following drug withdrawal. This non-invasive and healthy nutraceutical may be considered as an adjuvant treatment in detoxification clinics.

The hypoxic transcription factor KlMga2 mediates the response to oxidative stress and influences longevity in the yeast Kluyveromyces lactis

Hypoxia is defined as the decline of oxygen availability, depending on environmental supply and cellular consumption rate. The decrease in O2 results in reduction of available energy in facultative aerobes. The response and/or adaptation to hypoxia and other changing environmental conditions can influence the properties and functions of membranes by modifying lipid composition. In the yeast Kluyveromyces lactis, the KlMga2 gene is a hypoxic regulatory factor for lipid biosynthesis—fatty acids and sterols—and is also involved in glucose signaling, glucose catabolism and is generally important for cellular fitness.

In this work we show that, in addition to the above defects, the absence of the KlMGA2 gene caused increased resistance to oxidative stress and extended lifespan of the yeast, associated with increased expression levels of catalase and SOD genes. We propose that KlMga2 might also act as a mediator of the oxidative stress response/adaptation, thus revealing connections among hypoxia, glucose signaling, fatty acid biosynthesis and ROS metabolism in K. lactis.

Converging and Differential Brain Phospholipid Dysregulation in the Pathogenesis of Repetitive Mild Traumatic Brain Injury and Alzheimer's Disease

Repetitive mild traumatic brain injury (rmTBI) is a major epigenetic risk factor for Alzheimer’s disease (AD). The precise nature of how rmTBI leads to or precipitates AD pathology is currently unknown. Numerous neurological conditions have shown an important role for dysfunctional phospholipid metabolism as a driving factor for the pathogenesis of neurodegenerative diseases. However, the precise role in rmTBI and AD remains elusive. We hypothesized that a detailed phospholipid characterization would reveal profiles of response to injury in TBI that overlap with age-dependent changes in AD and thus provide insights into the TBI-AD relationship. We employed a lipidomic approach examining brain phospholipid profiles from mouse models of rmTBI and AD. Cortex and hippocampal tissue were collected at 24 h, 3, 6, 9, and 12 months post-rmTBI, and at ages representing ‘pre’, ‘peri’ and ‘post’ onset of amyloid pathology (i.e., 3, 9, 15 months-old). Total levels of phosphatidylcholine (PC), phosphatidylethanolamine (PE), LysoPE, and phosphatidylinositol (PI), including their monounsaturated, polyunsaturated and saturated fatty acid (FA) containing species were significantly increased at acute and/or chronic time points post-injury in both brain regions. However, levels of most phospholipid species in PS1/APP mice were nominal in the hippocampus, while in the cortex, levels were significantly decreased at ages post-onset of amyloid pathology. Sphingomyelin and LysoPC levels showed coincidental trends in our rmTBI and AD models within the hippocampus, an increase at acute and/or chronic time points examined. The ratio of arachidonic acid (omega-6 FA) to docosahexaenoic acid (omega-3 FA)-containing PE species was increased at early time points in the hippocampus of injured versus sham mice, and in PS1/APP mice there was a coincidental increase compared to wild type littermates at all time points. This study demonstrates some overlapping and diverse phospholipid profiles in rmTBI and AD models. Future studies are required to corroborate our findings in human post-mortem tissue. Investigation of secondary mechanisms triggered by aberrant downstream alterations in bioactive metabolites of these phospholipids, and their modulation at the appropriate time-windows of opportunity could help facilitate development of novel therapeutic strategies to ameliorate the neurodegenerative consequences of rmTBI or the potential triggering of AD pathogenesis by rmTBI.

Early Life Stress and Epigenetics in Late-onset Alzheimer's Dementia: A Systematic Review

Involvement of life stress in Late-Onset Alzheimer's Disease (LOAD) has been evinced in longitudinal cohort epidemiological studies, and endocrinologic evidence suggests involvements of catecholamine and corticosteroid systems in LOAD. Early Life Stress (ELS) rodent models have successfully demonstrated sequelae of maternal separation resulting in LOAD-analogous pathology, thereby supporting a role of insulin receptor signalling pertaining to GSK-3beta facilitated tau hyper-phosphorylation and amyloidogenic processing. Discussed are relevant ELS studies, and findings from three mitogen-activated protein kinase pathways (JNK/SAPK pathway, ERK pathway, p38/MAPK pathway) relevant for mediating environmental stresses. Further considered were the roles of autophagy impairment, neuroinflammation, and brain insulin resistance. For the meta-analytic evaluation, 224 candidate gene loci were extracted from reviews of animal studies of LOAD pathophysiological mechanisms, of which 60 had no positive results in human LOAD association studies. These loci were combined with 89 gene loci confirmed as LOAD risk genes in previous GWAS and WES. Of the 313 risk gene loci evaluated, there were 35 human reports on epigenomic modifications in terms of methylation or histone acetylation. 64 microRNA gene regulation mechanisms were published for the compiled loci. Genomic association studies support close relations of both noradrenergic and glucocorticoid systems with LOAD. For HPA involvement, a CRHR1 haplotype with MAPT was described, but further association of only HSD11B1 with LOAD found; however, association of FKBP1 and NC3R1 polymorphisms was documented in support of stress influence to LOAD. In the brain insulin system, IGF2R, INSR, INSRR, and plasticity regulator ARC, were associated with LOAD. Pertaining to compromised myelin stability in LOAD, relevant associations were found for BIN1, RELN, SORL1, SORCS1, CNP, MAG, and MOG. Regarding epigenetic modifications, both methylation variability and de-acetylation were reported for LOAD. The majority of up-to-date epigenomic findings include reported modifications in the well-known LOAD core pathology loci MAPT, BACE1, APP (with FOS, EGR1), PSEN1, PSEN2, and highlight a central role of BDNF. Pertaining to ELS, relevant loci are FKBP5, EGR1, GSK3B; critical roles of inflammation are indicated by CRP, TNFA, NFKB1 modifications; for cholesterol biosynthesis, DHCR24; for myelin stability BIN1, SORL1, CNP; pertaining to (epi)genetic mechanisms, hTERT, MBD2, DNMT1, MTHFR2. Findings on gene regulation were accumulated for BACE1, MAPK signalling, TLR4, BDNF, insulin signalling, with most reports for miR-132 and miR-27. Unclear in epigenomic studies remains the role of noradrenergic signalling, previously demonstrated by neuropathological findings of childhood nucleus caeruleus degeneration for LOAD tauopathy.

Serum Ethanolamine Plasmalogen and Urine Myo-Inositol as Cognitive Decline Markers

Recent studies have suggested that metabolic disorders, particularly type 2 diabetes mellitus (T2DM), and dementia, including Alzheimer's disease (AD), were linked at the clinical and molecular levels. Brain insulin deficiency and resistance may be key events in AD pathology mechanistically linking AD to T2DM. Ethanolamine plasmalogens (PlsEtns) are abundant in the brain and play essential roles in neuronal function and myelin formation. As such, PlsEtn deficiency may be pathologically relevant in some neurodegenerative disorders such as AD. Decreased brain PlsEtn associated with dementia may reflect serum PlsEtn deficiency. We hypothesized that myo-inositol plays a role in myelin formation through its facilitation of PlsEtn biosynthesis. Excessive urinary myo-inositol (UMI) loss would likely result in PlsEtn deficiency potentially leading to demyelinating diseases such as dementia. Accordingly, measurement of both serum PlsEtn and baseline UMI excretion could improve the detection of cognitive impairment (CI) in a more specific and reliable manner. To verify our hypothesis, we conducted a clinical observational study of memory clinic outpatients (MCO) and cognitively normal elderly (NE) for nearly 4.5years. We demonstrated that serum PlsEtn concentration associated with UMI excretion was useful for predicting advancing dementia in patients with mild CI. Because hyperglycemia and associated insulin resistance might be a leading cause of increased baseline UMI excretion, serum PlsEtn quantitation would be useful in detecting CI among the elderly with hyperglycemia. Our findings suggest that myo-inositol is a novel candidate molecule linking T2DM to AD.

Prospective Associations between Single Foods, Alzheimer's Dementia and Memory Decline in the Elderly

Background: Evidence whether single &ldquo;cognitive health&rdquo; foods could prevent cognitive decline is limited. We investigated whether dietary intake of red wine, white wine, coffee, green tea, olive oil, fresh fish, fruits and vegetables, red meat and sausages, assessed by a single-food-questionnaire, would be associated with either incident Alzheimer&rsquo;s dementia (AD) or verbal memory decline. Methods: Participants aged 75+ of the German Study on Aging, Cognition and Dementia in Primary Care Patients (AgeCoDe) cohort were regularly followed over 10 years (n = 2622; n = 418 incident AD cases). Multivariable-adjusted joint modeling of repeated-measures and survival analysis was used, taking gender and Apolipoprotein E4 (APOE &epsilon;4) genotype into account as possible effect modifiers. Results: Only higher red wine intake was associated with a lower incidence of AD (HR = 0.92; P = 0.045). Interestingly, this was true only for men (HR = 0.82; P < 0.001), while in women higher red wine intake was associated with a higher incidence of AD (HR = 1.15; P = 0.044), and higher white wine intake with a more pronounced memory decline over time (HR = &minus;0.13; P = 0.052). Conclusion: We found no evidence for these single foods to be protective against cognitive decline, with the exception of red wine, which reduced the risk for AD only in men. Women could be more susceptible to detrimental effects of alcohol.

Neuro-nutrients as anti-alzheimer's disease agents: A critical review

Alzheimer's disease (AD) is characterized by a massive neuronal death causing memory loss, cognitive impairment and behavioral alteration that ultimately lead to dementia and death. AD is a multi-factorial pathology controlled by molecular events such as oxidative stress, protein aggregation, mitochondrial dysfunction and neuro inflammation. Nowadays, there is no efficient disease-modifying treatment for AD and epidemiological studies have suggested that diet and nutrition have a significant impact on the development of this disorder. Indeed, some nutrients can protect all kind of cells, including neurons. As prevention is better than cure, life style improvement, with a special emphasis on diet, should seriously be considered as an anti-AD track and intake of nutrients promoting neuronal health is the need of the hour. Diets rich in unsaturated fatty acids, polyphenols and vitamins have been shown to protect against AD, whereas saturated fatty acids-containing diets deprived of polyphenols promote the development of the disease. Thus, Mediterranean diets, mainly composed of fruits, vegetables and omega-3 fatty acids, stand as valuable, mild and preventive anti-AD agents. This review focuses on our current knowledge in the field and how one can fight this devastating neurodegenerative disorder through the simple proper modification of our life style.

Deuterated polyunsaturated fatty acids reduce brain lipid peroxidation and hippocampal amyloid β-peptide levels, without discernable behavioral effects in an APP/PS1 mutant transgenic mouse model of Alzheimer's disease

Alzheimer's disease (AD) involves progressive deposition of amyloid β-peptide (Aβ), synapse loss, and neuronal death, which occur in brain regions critical for learning and memory. Considerable evidence suggests that lipid peroxidation contributes to synaptic dysfunction and neuronal degeneration, both upstream and downstream of Aβ pathology. Recent findings suggest that lipid peroxidation can be inhibited by replacement of polyunsaturated fatty acids (PUFA) with isotope-reinforced (deuterated) PUFA (D-PUFA), and that D-PUFA can protect neurons in experimental models of Parkinson's disease. Here, we determined whether dietary D-PUFA would ameliorate Aβ pathology and/or cognitive deficits in a mouse model of AD (amyloid precursor protein/presenilin 1 double mutant transgenic mice). The D-PUFA diet did not ameliorate spatial learning and memory deficits in the AD mice. Compared to mice fed an hydrogenated-PUFA control diet, those fed D-PUFA for 5 months exhibited high levels of incorporation of deuterium into arachidonic acid and docosahexaenoic acid, and reduced concentrations of lipid peroxidation products (F2 isoprostanes and neuroprostanes), in the brain tissues. Concentrations of Aβ40 and Aβ38 in the hippocampus were significantly lower, with a trend to reduced concentrations of Aβ42, in mice fed D-PUFA compared to those fed hydrogenated-PUFA. We conclude that a D-PUFA diet reduces the brain tissue concentrations of both arachidonic acid and docosahexaenoic acid oxidation products, as well as the concentration of Aβs.

Polyunsaturated fatty acids in marine bacteria and strategies to enhance their production

Polyunsaturated fatty acids (PUFAs) play an important role in human diet. Despite the wide-ranging importance and benefits from heart health to brain functions, humans and mammals cannot synthesize PUFAs de novo. The primary sources of PUFA are fish and plants. Due to the increasing concerns associated with food security as well as issues of environmental contaminants in fish oil, there has been considerable interest in the production of polyunsaturated fatty acids from alternative resources which are more sustainable, safer, and economical. For instance, marine bacteria, particularly the genus of Shewanella, Photobacterium, Colwellia, Moritella, Psychromonas, Vibrio, and Alteromonas, are found to be one among the major microbial producers of polyunsaturated fatty acids. Recent developments in the area with a focus on the production of polyunsaturated fatty acids from marine bacteria as well as the metabolic engineering strategies for the improvement of PUFA production are discussed.

Cerebrovascular β-amyloid deposition and associated microhemorrhages in a Tg2576 Alzheimer mouse model are reduced with a DHA-enriched diet

Cerebral amyloid angiopathy (CAA) is a major contributor to Alzheimer's disease (AD) pathogenesis. Like AD, CAA is often accompanied by marked inflammation, aggravating associated vasculopathies. No evidence-based prevention or treatment strategies are available. Here, we evaluate the possible beneficial effect of a diet enriched with docosahexaenoic acid (DHA), which is known to attenuate inflammation in CAA. Tg2576 mice, a transgenic model of AD/CAA, were fed a DHA-enriched diet starting at 2 mo of age and ending at 10, 14, or 18 mo of age. β-Amyloid (Aβ)-peptide deposition and bleeding were visualized by immunohistochemistry or histochemistry on coronal sections of the brain. DHA, arachidonic acid, and eicosanoid levels were measured by liquid chromatography/mass spectrometry or GC-MS. DHA-enriched diet throughout aging limits the accumulation of vascular Aβ peptide deposits as well as the likelihood of microhemorrhages. There is a strong correlation between systemic 12-hydroxyeicosatetraenoic acid (HETE) levels and the size of the area affected by both vascular amyloid deposits and hemorrhages. The lowest levels of 12-HETE, a lipid-derived proinflammatory product of 12-lipoxygenase (LOX), were found in DHA-fed mice. In vitro experiments performed on amyloid vascular smooth muscle cells showed that a 12-LOX inhibitor almost completely blocked the Aβ_1-40 peptide-induced apoptosis of these cells. This study yet again highlights the important role of inflammation in CAA pathogenesis and identifies potential new targets for preventive care.-Hur, J., Mateo, V., Amalric, N., Babiak, M., Béréziat, G., Kanony-Truc, C., Clerc, T., Blaise, R., Limon, I. Cerebrovascular β-amyloid deposition and associated microhemorrhages in a Tg2576 Alzheimer mouse model are reduced with a DHA-enriched diet.

A High-Fructose-High-Coconut Oil Diet Induces Dysregulating Expressions of Hippocampal Leptin and Stearoyl-CoA Desaturase, and Spatial Memory Deficits in Rats

We investigated the effects of high-fructose-high-fat diets with different fat compositions on metabolic parameters, hippocampal-dependent cognitive function, and brain leptin (as well as stearoyl-CoA desaturase (SCD1) mRNA expressions). Thirty-two male Wistar rats were divided into 3 groups, a control group (n = 8), a high-fructose soybean oil group (37.5% of fat calories, n = 12), and a high-fructose coconut oil group (37.5% of fat calories, n = 12) for 20 weeks. By the end of the study, the coconut oil group exhibited significantly higher serum fasting glucose, fructosamine, insulin, leptin, and triglyceride levels compared to those of the control and soybean oil groups. However, hippocampal leptin expression and leptin receptor mRNA levels were significantly lower, while SCD1 mRNA was significantly higher in rats fed the high-fructose-high-coconut oil diet than in rats fed the other experimental diets. In addition, the coconut oil group spent significantly less time in the target quadrant on the probe test in the Morris water maze (MWM) task. Rats fed the high-fructose-high-coconut oil diet for 20 weeks were prone to develop hyperglycemia, hyperinsulinemia, hyperleptinemia, and hypertriglyceridemia. These metabolic consequences may contribute to hippocampal-dependent memory impairment, accompanied by a lower central leptin level, and a higher SCD1 gene expression in the brain.

The role of Omega-3 and Omega-9 fatty acids for the treatment of neuropathic pain after neurotrauma

Omega-3 polyunsaturated fatty acids (PUFAs), such as docosaexaenoic acid (DHA) and eicosapentaenoic acid (EPA), mediate neuroactive effects in experimental models of traumatic peripheral nerve and spinal cord injury. Cellular mechanisms of PUFAs include reduced neuroinflammation and oxidative stress, enhanced neurotrophic support, and activation of cell survival pathways. Bioactive Omega-9 monounsaturated fatty acids, such as oleic acid (OA) and 2-hydroxy oleic acid (2-OHOA), also show therapeutic effects in neurotrauma models. These FAs reduces noxious hyperreflexia and pain-related anxiety behavior following peripheral nerve injury and improves sensorimotor function following spinal cord injury (SCI), including facilitation of descending inhibitory antinociception. The relative safe profile of neuroactive fatty acids (FAs) holds promise for the future clinical development of these molecules as analgesic agents. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.

Modulation of innate immunity of patients with Alzheimer's disease by omega-3 fatty acids

The innate immune system of patients with Alzheimer's disease and mild cognitive impairment (MCI) is deregulated with highly increased or decreased transcription of inflammatory genes and consistently depressed phagocytosis of amyloid-β_1-42 (Aβ) by monocytes and macrophages. Current immune therapies target single mechanisms in the adaptive immune system but not innate immunity. Here, we summarize recent advances in therapy by ω-3, ω-6, and epoxy fatty acids; specialized proresolving mediators; and vitamin D₃ that have proven immune effects and emerging cognitive effects in patients with MCI. The hypothesis of this approach is that macrophages of normal participants, but not those of patients with Alzheimer's disease and MCI, possess effective phagocytosis for Aβ and protect homeostasis of the brain and, furthermore, that defective MCI macrophages recover phagocytic function via ω-3. Recent studies of fish-derived ω-3 supplementation in patients with MCI have shown polarization of Apoε3/ε3 patients' macrophages to an intermediate M1-M2 phenotype that is optimal for Aβ phagocytosis and the stabilization of cognitive decline. Therefore, accumulating preclinical and preliminary clinical evidence indicates that ω-3 supplementation should be tested in a randomized controlled clinical trial and that the analysis should involve the apolipoprotein E genotype and intervening conditions during trial.-Fiala, M., Kooij, G., Wagner, K., Hammock, B., Pellegrini, M. Modulation of innate immunity of patients with Alzheimer's disease by omega-3 fatty acids.

APP Function and Lipids: A Bidirectional Link

Extracellular neuritic plaques, composed of aggregated amyloid-β (Aβ) peptides, are one of the major histopathological hallmarks of Alzheimer's disease (AD), a progressive, irreversible neurodegenerative disorder and the most common cause of dementia in the elderly. One of the most prominent risk factor for sporadic AD, carrying one or two aberrant copies of the apolipoprotein E (ApoE) ε4 alleles, closely links AD to lipids. Further, several lipid classes and fatty acids have been reported to be changed in the brain of AD-affected individuals. Interestingly, the observed lipid changes in the brain seem not only to be a consequence of the disease but also modulate Aβ generation. In line with these observations, protective lipids being able to decrease Aβ generation and also potential negative lipids in respect to AD were identified. Mechanistically, Aβ peptides are generated by sequential proteolytic processing of the amyloid precursor protein (APP) by β- and γ-secretase. The α-secretase appears to compete with β-secretase for the initial cleavage of APP, preventing Aβ production. All APP-cleaving secretases as well as APP are transmembrane proteins, further illustrating the impact of lipids on Aβ generation. Beside the pathological impact of Aβ, accumulating evidence suggests that Aβ and the APP intracellular domain (AICD) play an important role in regulating lipid homeostasis, either by direct effects or by affecting gene expression or protein stability of enzymes involved in the de novo synthesis of different lipid classes. This review summarizes the current literature addressing the complex bidirectional link between lipids and AD and APP processing including lipid alterations found in AD post mortem brains, lipids that alter APP processing and the physiological functions of Aβ and AICD in the regulation of several lipid metabolism pathways.

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.

Contributions of polyunsaturated fatty acids (PUFA) on cerebral neurobiology: an integrated omics approach with epigenomic focus

The epigenetic landscape is vulnerable to diets. Here, we investigated the influence of different polyunsaturated fatty acids (PUFA) dietary supplements on rodents' nervous system development and functions and potential consequences to neurodegenerative disorders. Our previous nutrigenomics study showed significant impact of high n-3 PUFA-enriched diet (ERD) on synaptogenesis and various neuromodulators. The present study introduced a second equicaloric diet with n-6 PUFA balanced by n-3 PUFA (BLD). The typical lab diet with high n-6 PUFA was the baseline. Transcriptomic and epigenetic investigations, namely microRNA (miRNA) and DNA methylation assays, were carried out on the hemibrains of the C57BL/6j mice fed on any of these three diets from their neonatal age to midlife. Integrating the multiomics data, we focused on the genes encoding both hypermethylated CpG islands and suppressed transcripts. In addition, miRNA:mRNA pairs were screened to identify those overexpressed miRNAs that reduced transcriptional expressions. The majority of miRNAs overexpressed by BLD are associated with Alzheimer's and schizophrenia. BLD implicated long-term potentiation, memory, cognition and learning, primarily via hypermethylation of those genes that enrich the calcium-releasing neurotransmitters. ERD caused hypermethylation of those genes that enrich cytoskeletal development networks and promote the formation of neuronal precursors. We drew the present observations in light of our limited knowledge regarding the epigenetic influences on biofunctions. A more comprehensive study is essential to understand the broad influences of dietary supplements and to suggest optimal dietary solutions for neurological disorders.

Neuroprotective Effect of Several Phytochemicals and Its Potential Application in the Prevention of Neurodegenerative Diseases

The detrimental effects of oxidative stress and chronic neuroinflammation on neuronal cell death have been implicated in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). The nutritional neuroscience is quickly growing, and phytochemicals or phytobioactive compounds such as curcumin, resveratrol, propolis, ginsenoside, and ω-3 polyunsaturated fatty acids (PUFAs) have been extensively applied to potential therapeutic purposes for numerous neurodegenerative diseases for their anti-oxidative and anti-inflammatory effects. However, their administration as food supplements in the daily diet of the elderly is normally a voluntary and less-organized behavior, indicating the uncertainty of therapeutic effects in this sporadic population; specifically, the effective physiological dosages and the real positive effects in preserving brain health have not yet been fully elucidated. In this review, we collect several lines of evidence on these compounds, which constitute a major type of nutraceuticals and are widely integrated into the daily anti-aging caring of elderly patients, and discuss the underlying anti-oxidative and anti-inflammatory mechanisms of these phytochemicals. In conclusion, we highlight the implications of these compounds in the prevention and treatment of geriatric diseases, and of the potential supplementation procedures used as a dietary therapeutic program in clinical nursing services for patients with neurodegenerative diseases or for the elderly in certain communities, which we hope will lead to more beneficial health outcomes with respect to brain function, innate immunity, and gastrointestinal function, as well as more economic and social benefits.

Increased intermediate M1-M2 macrophage polarization and improved cognition in mild cognitive impairment patients on ω-3 supplementation

Monocyte/macrophages of patients with mild cognitive impairment (MCI) and Alzheimer disease (AD) are defective in phagocytosis and degradation amyloid β_1–42 (Aβ_1–42), but are improved by ω-3 fatty acids (ω-3s). The hypothesis of this study was that active Aβ_1–42 phagocytosis by macrophages prevents brain amyloidosis and thus maintains cognition. We studied the effects of self-supplementation with a drink with ω-3s, antioxidants, and resveratrol on Mini-Mental State Examination (MMSE) scores, macrophage M1M2 phenotype [the ratio of inflammatory cluster of differentiation (CD)54+CD80 and proresolution markers CD163+CD206], and Aβ_1–42 phagocytosis in patients initially diagnosed as having MCI or subjective cognitive impairment (SCI). At baseline, the median MMSE score in patients in both the apolipoprotein E (ApoE) ε3/ε3 and ApoE ε3/ε4 groups was 26.0 and macrophage Aβ_1–42 phagocytosis was defective. The MMSE rate of change increased in the ApoE ε3/ε3 group a median 2.2 points per year (P = 0.015 compared to 0) but did not change in the ApoE ε3/ε4 group (P = 0.014 between groups). In the ApoE ε3/ε3 group, all patients remained cognitively stable or improved; in the ApoE ε3/ε4 group, 1 recovered from dementia, but 3 lapsed into dementia. The macrophage phenotype polarized in patients bearing ApoE ε3/ε3 to an intermediate (green zone) M1-M2 type at the rate of 0.226 U/yr, whereas in patients bearing ApoE ε3/ε4, polarization was negative (P = 0.08 between groups). The baseline M1M2 type in the extreme M1 (red zone) or M2 (white zone) was unfavorable for cognitive outcome. Aβ_1–42 phagocytosis increased in both ApoE groups (P = 0.03 in each groups). In vitro, the lipidic mediator resolvin D1 (RvD1) down regulated the M1 type in patients with ApoE ε3/ε3 but in some patients with ε3/ε4, paradoxically up-regulated the M1 type. Antioxidant/ω-3/resveratrol supplementation was associated with favorable immune and cognitive responses in ApoE ε3/ε3 and individual patients bearing ApoE ε3/ε4, and brings into personalized clinical practice the immune benefits expected from ω-3 mediators called resolvins. The validity of this study is limited by its small size and uncontrolled design.—Famenini, S., Rigali, E. A., Olivera-Perez, H. M., Dang, J., Chang, M T., Halder, R., Rao, R. V., Pellegrini, M., Porter, V., Bredesen, D., Fiala, M. Increased intermediate M1-M2 macrophage polarization and improved cognition in mild cognitive impairment patients on ω-3 supplementation.

Enriched endogenous n-3 polyunsaturated fatty acids alleviate cognitive and behavioral deficits in a mice model of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that accompanied by memory deficits and neuropsychiatric dysfunction. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have seemly therapeutic potential in AD, but the benefit of n-3 PUFAs is still in debates. Here, we employed a transgenic mice carry fat-1 gene to encode n-3 desaturase from Caenorhabditis elegans, which increase endogenous n-3 PUFAs by converting n-6 PUFAs to n-3 PUFAs crossed with amyloid precursor protein (APP) Tg mice to evaluate the protective effects of endogenous n-3 PUFAs on cognitive and behavioral deficits of APP Tg mice. We fed APP, APP/fat-1 and fat-1 mice with n-6 PUFAs rich diet. Brain tissues were collected at 3, 9 and 12 months for fatty acid and gene expression analysis, histology and protein assays. Morris Water Maze Test, open field test and elevated plus maze test were performed to measure the behavior capability. From the results, the expression of fat-1 transgene increased cortical n-3: n-6 PUFAs ratio and n-3 PUFAs concentrations, and sensorimotor dysfunction and cognitive deficits in AD were significantly less severe in APP/fat-1 mice with endogenous n-3 PUFAs than in APP mice controls. The protection against disturbance of spontaneous motor activity and cognitive deficits in AD was strongly correlated with increased n-3: n-6 PUFAs ratio and endogenous n-3 PUFAs, reduced APP generation, inhibited amyloid β peptide aggregation, suppressed nuclear factor-kappa B and astroglia activation, and reduced death of neurons in the cortex of APP/fat-1 mice compared with APP mice controls. In conclusion, our study demonstrates that an available medication with the maintenance of enriched n-3 PUFAs in the brain could slow down cognitive decline and prevent neuropsychological disorder in AD.

Global hypoxia induced impairment in learning and spatial memory is associated with precocious hippocampal aging

Both chronological aging and chronic hypoxia stress have been reported to cause degeneration of hippocampal CA3 neurons and spatial memory impairment through independent pathways. However, the possible occurrence of precocious biological aging on exposure to single episode of global hypoxia resulting in impairment of learning and memory remains to be established. The present study thus aimed at bridging this gap in existing literature on hypoxia induced biological aging. Male Sprague Dawley rats were exposed to simulated hypobaric hypoxia (25,000ft) for different durations and were compared with aged rats. Behavioral studies in Morris Water Maze showed decline in learning abilities of both chronologically aged as well as hypoxic rats as evident from increased latency and pathlength to reach target platform. These behavioral changes in rats exposed to global hypoxia were associated with deposition of lipofuscin and ultrastructural changes in the mitochondria of hippocampal neurons that serve as hallmarks of aging. A single episode of chronic hypobaric hypoxia exposure also resulted in the up-regulation of pro-aging protein, S100A9 and down regulation of Tau, SNAP25, APOE and Sod2 in the hippocampus similar to that in aged rats indicating hypoxia induced accelerated aging. The present study therefore provides evidence for role of biological aging of hippocampal neurons in hypoxia induced impairment of learning and memory.

Bacterial Long-Chain Polyunsaturated Fatty Acids: Their Biosynthetic Genes, Functions, and Practical Use

The nutritional and pharmaceutical values of long-chain polyunsaturated fatty acids (LC-PUFAs) such as arachidonic, eicosapentaenoic and docosahexaenoic acids have been well recognized. These LC-PUFAs are physiologically important compounds in bacteria and eukaryotes. Although little is known about the biosynthetic mechanisms and functions of LC-PUFAs in bacteria compared to those in higher organisms, a combination of genetic, bioinformatic, and molecular biological approaches to LC-PUFA-producing bacteria and some eukaryotes have revealed the notably diverse organization of the pfa genes encoding a polyunsaturated fatty acid synthase complex (PUFA synthase), the LC-PUFA biosynthetic processes, and tertiary structures of the domains of this enzyme. In bacteria, LC-PUFAs appear to take part in specific functions facilitating individual membrane proteins rather than in the adjustment of the physical fluidity of the whole cell membrane. Very long chain polyunsaturated hydrocarbons (LC-HCs) such as hentriacontanonaene are considered to be closely related to LC-PUFAs in their biosynthesis and function. The possible role of LC-HCs in strictly anaerobic bacteria under aerobic and anaerobic environments and the evolutionary relationships of anaerobic and aerobic bacteria carrying pfa-like genes are also discussed.

Eicosapentaenoic acid and docosahexaenoic acid increase the degradation of amyloid-β by affecting insulin-degrading enzyme

Omega-3 polyunsaturated fatty acids (PUFAs) have been proposed to be highly beneficial in Alzheimer's disease (AD). AD pathology is closely linked to an overproduction and accumulation of amyloid-β (Aβ) peptides as extracellular senile plaques in the brain. Total Aβ levels are not only dependent on its production by proteolytic processing of the amyloid precursor protein (APP), but also on Aβ-clearance mechanisms, including Aβ-degrading enzymes. Here we show that the omega-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) increase Aβ-degradation by affecting insulin-degrading enzyme (IDE), the major Aβ-degrading enzyme secreted into the extracellular space of neuronal and microglial cells. The identification of the molecular mechanisms revealed that EPA directly increases IDE enzyme activity and elevates gene expression of IDE. DHA also directly stimulates IDE enzyme activity and affects IDE sorting by increasing exosome release of IDE, resulting in enhanced Aβ-degradation in the extracellular milieu. Apart from the known positive effect of DHA in reducing Aβ production, EPA and DHA might ameliorate AD pathology by increasing Aβ turnover.