Effect of a diet-induced n-3 PUFA depletion on cholinergic parameters in the rat hippocampus

The Conventional and Breakthrough Tool for the Study of L-Glutamate Transporters

In our recent report, we clarified the direct interaction between the excitatory amino acid transporter (EAAT) 1/2 and polyunsaturated fatty acids (PUFAs) by applying electrophysiological and molecular biological techniques to Xenopus oocytes. Xenopus oocytes have a long history of use in the scientific field, but they are still attractive experimental systems for neuropharmacological studies. We will therefore summarize the pharmacological significance, advantages (especially in the study of EAAT2), and experimental techniques that can be applied to Xenopus oocytes; our new findings concerning L-glutamate (L-Glu) transporters and PUFAs; and the significant outcomes of our data. The data obtained from electrophysiological and molecular biological studies of Xenopus oocytes have provided us with further important questions, such as whether or not some PUFAs can modulate EAATs as allosteric modulators and to what extent docosahexaenoic acid (DHA) affects neurotransmission and thereby affects brain functions. Xenopus oocytes have great advantages in the studies about the interactions between molecules and functional proteins, especially in the case when the expression levels of the proteins are small in cell culture systems without transfections. These are also proper to study the mechanisms underlying the interactions. Based on the data collected in Xenopus oocyte experiments, we can proceed to the next step, i.e., the physiological roles of the compounds and their significances. In the case of EAAT2, the effects on the neurotransmission should be examined by electrophysiological approach using acute brain slices. For new drug development, pharmacokinetics pharmacodynamics (PKPD) data and blood brain barrier (BBB) penetration data are also necessary. In order not to miss the promising candidate compounds at the primary stages of drug development, we should reconsider using Xenopus oocytes in the early phase of drug development.

n-3 Polyunsaturated Fatty Acids Modulate LPS-Induced ARDS and the Lung-Brain Axis of Communication in Wild-Type versus Fat-1 Mice Genetically Modified for Leukotriene B4 Receptor 1 or Chemerin Receptor 23 Knockout

Specialized pro-resolving mediators (SPMs) and especially Resolvin E1 (RvE1) can actively terminate inflammation and promote healing during lung diseases such as acute respiratory distress syndrome (ARDS). Although ARDS primarily affects the lung, many ARDS patients also develop neurocognitive impairments. To investigate the connection between the lung and brain during ARDS and the therapeutic potential of SPMs and its derivatives, fat-1 mice were crossbred with RvE1 receptor knockout mice. ARDS was induced in these mice by intratracheal application of lipopolysaccharide (LPS, 10 µg). Mice were sacrificed at 0 h, 4 h, 24 h, 72 h, and 120 h post inflammation, and effects on the lung, liver, and brain were assessed by RT-PCR, multiplex, immunohistochemistry, Western blot, and LC-MS/MS. Protein and mRNA analyses of the lung, liver, and hypothalamus revealed LPS-induced lung inflammation increased inflammatory signaling in the hypothalamus despite low signaling in the periphery. Neutrophil recruitment in different brain structures was determined by immunohistochemical staining. Overall, we showed that immune cell trafficking to the brain contributed to immune-to-brain communication during ARDS rather than cytokines. Deficiency in RvE1 receptors and enhanced omega-3 polyunsaturated fatty acid levels (fat-1 mice) affect lung-brain interaction during ARDS by altering profiles of several inflammatory and lipid mediators and glial activity markers.

New Perspectives on the Associations between Blood Fatty Acids, Growth Parameters, and Cognitive Development in Global Child Populations

Malnutrition is prevalent in low-middle-income countries (LMICs), but it is usually clinically diagnosed through abnormal anthropometric parameters characteristic of protein energy malnutrition (PEM). In doing so, other contributors or byproducts of malnutrition, notably essential fatty acid deficiency (EFAD), are overlooked. Previous research performed mainly in high-income countries (HICs) shows that deficiencies in essential fatty acids (EFAs) and their n-3 and n-6 polyunsaturated fatty acid (PUFA) byproducts (also known as highly unsaturated fatty acids or HUFAs) lead to both abnormal linear growth and impaired cognitive development. These adverse developmental outcomes remain an important public health issue in LMICs. To identify EFAD before severe malnutrition develops, clinicians should perform blood fatty acid panels to measure levels of fatty acids associated with EFAD, notably Mead acid and HUFAs. This review demonstrates the importance of measuring endogenous fatty acid levels for measuring fatty acid intake in various child populations in LMICs. Featured topics include a comparison of fatty acid levels between global child populations, the relationships between growth and cognition and PUFAs and the possible mechanisms driving these relationships, and the potential importance of EFAD and HUFA scores as biomarkers of overall health and normal development.

Complexity of understanding the role of dietary and erythrocyte docosahexaenoic acid (DHA) on the cognitive performance of school-age children

Background

Early childhood is a period of rapid brain development, with increases in synapses rich in the omega-3 (ω-3) fatty acid, DHA (22:6ω-3) continuing well beyond infancy. Despite the importance of DHA to neural phospholipids, the requirement of dietary DHA for neurodevelopment remains unclear.

Objectives

The aim was to assess the dietary DHA and DHA status of young children, and determine the association with cognitive performance.

Methods

This was a cross-sectional study of healthy children (5-6 y), some of whom were enrolled in a follow-up of a clinical trial (NCT00620672). Dietary intake data (n = 285) were assessed with a food-frequency questionnaire (FFQ) and three 24-h recalls. Family characteristics were collected by questionnaire, and anthropometric data measured. Venous blood was collected, cognitive performance assessed using several age-appropriate tools including the Kaufman Assessment Battery for Children. The relation between dietary DHA, RBC DHA, and child neurodevelopment test scores was determined using Pearson's correlation or Spearman's rho, and quintiles of test scores compared by Mann-Whitney U test.

Results

Child DHA intakes were highly variable, with a stronger association between RBC DHA and DHA intake assessed by FFQ (rho = 0.383, P < 0.001) compared with one or three 24-h recalls. Observed ethnic differences in DHA intake status as well as neurodevelopmental test scores led to analysis of the association between DHA intake and status with neurodevelopment test scores for White children only (n = 190). Child RBC DHA status was associated with neurodevelopment test scores, including language (rho = 0.211, P = 0.009) and short-term memory (rho = 0.187, P = 0.019), but only short-term memory was associated with dietary DHA (rho = 0.221, P = 0.003).

Conclusions

Child RBC DHA but not dietary DHA was associated with multiple tests of cognitive performance. In addition, DHA intake was only moderately associated with RBC DHA, raising complex questions on the relation between diet, DHA transfer to membrane lipids, and neural function.

Dietary n-3 PUFA Deficiency Increases Vulnerability to Scopolamine-Induced Cognitive Impairment in Male C57BL/6 Mice

BACKGROUND

DHA (22:6n-3), a long-chain n-3 PUFA, is essential for normal brain development and function. Our previous study demonstrated that DHA significantly improves scopolamine-induced dementia. However, there are no reports on the relation between n-3 PUFA deficiency and scopolamine-induced cognitive impairment.

OBJECTIVES

The aim of this study was to evaluate whether n-3 PUFA deficiency increases vulnerability to scopolamine-induced cognitive impairment.

METHODS

Male and female C57BL/6 mice were mated and fed an n-3 PUFA-adequate [containing 2.88% α-linolenic acid (ALA; 18:3n-3)] or -deficient (containing 0.09% ALA) diet for 2 consecutive generations. The corresponding second-generation male offspring were kept on the same diet as their mothers after weaning, and were randomly assigned to 2 subgroups at 7 wk of age, in which they were intraperitoneally injected with saline [fed n-3 PUFA-adequate (Con) or -deficient (Def) diet] or scopolamine [5 mg/kg body weight; fed n-3 PUFA-adequate (Sco) or -deficient (Def + Sco) diet] once per day for 7 d before killing. Behavioral performance was analyzed using the Morris Water Maze test. Fatty acid composition, protein expression, and indicators of cholinergic and oxidative stress in the brain were measured.

RESULTS

The Def group showed lower brain DHA (-63.7%, P ≤ 0.01) and higher n-6 PUFA (+65.5%, P ≤ 0.05) concentrations than the Con group. The Def + Sco group and the Sco group showed poorer spatial learning and memory (escape latency on the sixth day: +60.3% and +36.8%; platform crossings: -43.9% and -28.2%, respectively) and more obvious cholinergic dysfunction (acetylcholine: -47.6% and -27.7%, respectively), oxidative stress (glutathione peroxidase: -64.2% and -32.5%, respectively), apoptosis [B-cell lymphoma 2 (BCL2)-associated X protein/BCL2: +230.8% and +153.8%; phosphorylated P38/P38: +232% and +130%, phosphorylated c-Jun N-terminal kinase (JNK)/JNK: +104.5% and +58.8%, respectively], neuroinflammation (IL-1β: +317.6% and +95%, respectively), and neurodevelopmental delay (brain-derived neurotrophic factor: -54.4% and -7.25%, respectively) than their corresponding saline-treated controls.

CONCLUSIONS

Dietary n-3 PUFA deficiency significantly decreases brain DHA concentrations and increases vulnerability to scopolamine-induced cognitive impairment in C57BL/6 male mice.

Fatty acids and evolving roles of their proteins in neurological, cardiovascular disorders and cancers

The dysregulation of fat metabolism is involved in various disorders, including neurodegenerative, cardiovascular, and cancers. The uptake of long-chain fatty acids (LCFAs) with 14 or more carbons plays a pivotal role in cellular metabolic homeostasis. Therefore, the uptake and metabolism of LCFAs must constantly be in tune with the cellular, metabolic, and structural requirements of cells. Many metabolic diseases are thought to be driven by the abnormal flow of fatty acids either from the dietary origin and/or released from adipose stores. Cellular uptake and intracellular trafficking of fatty acids are facilitated ubiquitously with unique combinations of fatty acid transport proteins and cytoplasmic fatty acid-binding proteins in every tissue. Extensive data are emerging on the defective transporters and metabolism of LCFAs and their clinical implications. Uptake and metabolism of LCFAs are crucial for the brain's functional development and cardiovascular health and maintenance. In addition, data suggest fatty acid metabolic transporter can normalize activated inflammatory response by reprogramming lipid metabolism in cancers. Here we review the current understanding of how LCFAs and their proteins contribute to the pathophysiology of three crucial diseases and the mechanisms involved in the processes.

Maternal Supply of Both Arachidonic and Docosahexaenoic Acids Is Required for Optimal Neurodevelopment

During the last trimester of gestation and for the first 18 months after birth, both docosahexaenoic acid,22:6n-3 (DHA) and arachidonic acid,20:4n-6 (ARA) are preferentially deposited within the cerebral cortex at a rapid rate. Although the structural and functional roles of DHA in brain development are well investigated, similar roles of ARA are not well documented. The mode of action of these two fatty acids and their derivatives at different structural-functional roles and their levels in the gene expression and signaling pathways of the brain have been continuously emanating. In addition to DHA, the importance of ARA has been much discussed in recent years for fetal and postnatal brain development and the maternal supply of ARA and DHA. These fatty acids are also involved in various brain developmental processes; however, their mechanistic cross talks are not clearly known yet. This review describes the importance of ARA, in addition to DHA, in supporting the optimal brain development and growth and functional roles in the brain.

Feeding Infants at the Breast or Feeding Expressed Human Milk: Long-Term Cognitive, Executive Function, and Eating Behavior Outcomes at Age 6 Years

OBJECTIVE

To examine how expressed milk feeding diverges from feeding at the breast in its association with neurodevelopment and behavior. We hypothesized that longer and exclusive feeding at the breast only (ie, no formula, no feeding expressed milk) would be associated with the optimal cognitive developmental, executive function, and eating behaviors and that expressed milk feeding would be associated with less-optimal outcomes.

STUDY DESIGN

The Moms2Moms cohort (Ohio, US) reported infant feeding practices at 12 months postpartum and children's global cognitive ability, executive function, and eating behaviors at 6 years. Linear and log-binomial regression models estimated associations with durations of feeding at the breast, expressed milk, human milk (modes combined), and formula.

RESULTS

Among 285 participants, each month of exclusive feeding at the breast only was associated with a decreased risk of clinically meaningful executive function (working memory) deficit (adjusted relative risk [RR] 0.78, 95% CI 0.63-0.96) but was unassociated with inhibition (adjusted RR 0.92, 95% CI 0.85-1.01). Feeding expressed milk was not clearly related to executive function outcomes. No associations with global cognitive ability were observed. Weak associations were observed with eating behaviors for some feeding practices.

CONCLUSIONS

Feeding at the breast may offer advantages to some aspects of executive function that expressed milk may not. Large, prospective studies exploring mechanisms could further distinguish the effect of feeding mode from that of nutrients.

Polyunsaturated Fatty Acid Modulates Membrane-Bound Monomeric α-Synuclein by Modulating Membrane Microenvironment through Preferential Interactions

There is ample evidence that both native functions and pathogenic aggregation of α-synuclein are intimately dependent on lipid interactions and fatty acid type; the regulatory mechanism however remains unclear. In the present work, using extensive atomistic molecular dynamics simulations and enhanced-sampling, we have focused on exploring the mechanism of fatty acid dependent regulation of monomeric α-Syn₁₀₀ in a native synaptic vesicle-like membrane. Our results show that α-Syn₁₀₀ spontaneously binds to the membrane through its N-terminal region (residues 1-34), where the depth of membrane insertion, the structure, and orientation of the membrane-bound α-Syn₁₀₀ and its impact on membrane structure are modulated by docosahexaenoic acid (DHA). DHA is a polyunsaturated fatty acid abundantly found in the brain and known to promote the oligomerization of α-synuclein. We found that DHA exhibits marked propensity to interact with monomeric α-Syn₁₀₀ and modulates the microenvironment of the protein by preferentially sorting DHA-containing phospholipids, depleting other phospholipids and cholesterol as well as increasing the proportion of anionic to neutral lipids in the immediate vicinity of the protein. Owing to the unique conformational flexibility, DHA chains form more lipid-packing defects in the membrane and efficiently coat the membrane-embedded surface of the protein, compared to the saturated and monounsaturated fatty acids. DHA thus makes the bilayer more amiable to protein adsorption and less prone to α-synuclein-induced perturbation associated with cytotoxicity. Indeed, in the absence of DHA, we observed significant thinning of the local bilayer membrane induced by α-Syn₁₀₀. Though α-Syn₁₀₀ is predominantly α-helical in membranes studied here, in the presence of DHA we observe formation of β-sheet/β-strands in the C-terminal region (residues 35-100) of α-Syn₁₀₀, which is extended out from the membrane surface. Notably, DHA induces β structure in the NAC domain of α-Syn₁₀₀ and promotes extended conformations as well as large solvent exposure of this hydrophobic domain, properties that are known to facilitate self-assembly of α-synuclein. To the best of our knowledge, this study for the first time provides the atomistic insights into DHA-induced regulatory mechanism of monomeric α-synuclein, having implications in protein structure and its physiological/pathological functions.

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.

Relationship between the effect of polyunsaturated fatty acids (PUFAs) on brain plasticity and the improvement on cognition and behavior in individuals with autism spectrum disorder

Objective: This work aimed to compile information about the neuronal processes in which polyunsaturated fatty acids (PUFAs) could modulate brain plasticity, in order to analyze the role of nutritional intervention with the ω-3 and ω-6 fatty acids as a therapeutic strategy for the Autism Spectrum Disorder (ASD)-related signs and symptoms.Methods: We reviewed different articles reporting the effect of PUFAS on neurite elongation, membrane expansion, cytoskeleton rearrangement and neurotransmission, considering the ASD-related abnormalities in these processes.Results: In accordance to the reviewed studies, it is clear that ASD is one of the neurological conditions associated with an impairment in neuronal plasticity; therefore, PUFAs-rich diet improvements on cognition and behavioral deficits in individuals with autism, could be involved with the regulation of neuronal processes implicated in the atypical brain plasticity related with this neurodevelopmental disorder.Discussion: The behavioral and cognitive improvement observed in individuals with ASD after PUFAs treatment might underlie, at least in part, in the ability of ω-3 and ω-6 fatty acids to induce neurite outgrowth, probably, through the dynamic regulation of the neuronal cytoskeleton along with the expansion of neuronal membranes. Furthermore, it might also be associated with an enhancement of the efficacy of synaptic transmission and the modulation of neurotransmitters release.

PUFA and their derivatives in neurotransmission and synapses: a new hallmark of synaptopathies

PUFA of the n-3 and n-6 families are present in high concentration in the brain where they are major components of cell membranes. The main forms found in the brain are DHA (22 :6, n-3) and arachidonic acid (20:4, n-6). In the past century, several studies pinpointed that modifications of n-3 and n-6 PUFA levels in the brain through dietary supply or genetic means are linked to the alterations of synaptic function. Yet, synaptopathies emerge as a common characteristic of neurodevelopmental disorders, neuropsychiatric diseases and some neurodegenerative diseases. Understanding the mechanisms of action underlying the activity of PUFA at the level of synapses is thus of high interest. In this frame, dietary supplementation in PUFA aiming at restoring or promoting the optimal function of synapses appears as a promising strategy to treat synaptopathies. This paper reviews the link between dietary PUFA, synapse formation and the role of PUFA and their metabolites in synaptic functions.

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.

Degree of lipid saturation affects depressive-like behaviour and gut microbiota in mice

This study explored the effects of the degree of lipid saturation on depressive behaviour and gut microbiota in mice. Thirty-two mice were divided into normal (N), Prozac (NP), lard (L) and fish oil (F) groups. After a 12-week dietary intervention, the open field test (OFT) and the forced swim test (FST) were conducted before sacrifice. The mice in the L group exhibited anxiety-like behaviours in the OFT and depressive-like behaviours in the FST. A significant difference was observed in β-diversity indices between the L group and the F group. The abundance of Allobaculum and Bifidobacterium was significantly higher in the F group than in the L and N groups. The prefrontal cortex fatty acid composition was altered in various lipid-treated groups and was highly correlated with depressive-like behaviours. In conclusion, the degree of lipid saturation affects depressive-like behaviour, gut microbiota composition, and the prefrontal cortex fatty acid profile in mice.

Docosahexaenoic acid,22:6n-3: Its roles in the structure and function of the brain

Docosahexaenoic acid,22:6n-3 (DHA) and its metabolites are vital for the structure and functional brain development of the fetus and infants, and also for maintenance of healthy brain function of adults. DHA is thought to be an essential nutrient required throughout the life cycle for the maintenance of overall brain health. The mode of actions of DHA and its derivatives at both cellular and molecular levels in the brain are emerging. DHA is the major prevalent fatty acid in the brain membrane. The brain maintains its fatty acid levels mainly via the uptake of plasma free fatty acids. Therefore, circulating plasma DHA is significantly related to cognitive abilities during ageing and is inversely associated with cognitive decline. The signaling pathways of DHA and its metabolites are involved in neurogenesis, antinociceptive effects, anti-apoptotic effect, synaptic plasticity, Ca²⁺ homeostasis in brain diseases, and the functioning of nigrostriatal activities. Mechanisms of action of DHA metabolites on various processes in the brain are not yet well known. Epidemiological studies support a link between low habitual intake of DHA and a higher risk of brain disorders. A diet characterized by higher intakes of foods containing high in n-3 fatty acids, and/or lower intake of n-6 fatty acids was strongly associated with a lower Alzheimer's Disease and other brain disorders. Supplementation of DHA improves some behaviors associated with attention deficit hyperactivity disorder, bipolar disorder, schizophrenia, and impulsive behavior, as well as cognition. Nevertheless, the outcomes of trials with DHA supplementation have been controversial. Many intervention studies with DHA have shown an apparent benefit in brain function. However, clinical trials are needed for definitive conclusions. Dietary deficiency of n-3 fatty acids during fetal development in utero and the postnatal state has detrimental effects on cognitive abilities. Further research in humans is required to assess a variety of clinical outcomes, including quality of life and mental status, by supplementation of DHA.

N-3 Polyunsaturated Fatty Acids and the Resolution of Neuroinflammation

In the past few decades, as a result of their anti-inflammatory properties, n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFAs), have gained greater importance in the regulation of inflammation, especially in the central nervous system (in this case known as neuroinflammation). If sustained, neuroinflammation is a common denominator of neurological disorders, including Alzheimer’s disease and major depression, and of aging. Hence, limiting neuroinflammation is a real strategy for neuroinflammatory disease therapy and treatment. Recent data show that n-3 LC-PUFAs exert anti-inflammatory properties in part through the synthesis of specialized pro-resolving mediators (SPMs) such as resolvins, maresins and protectins. These SPMs are crucially involved in the resolution of inflammation. They could be good candidates to resolve brain inflammation and to contribute to neuroprotective functions and could lead to novel therapeutics for brain inflammatory diseases. This review presents an overview 1) of brain n-3 LC-PUFAs as precursors of SPMs with an emphasis on the effect of n-3 PUFAs on neuroinflammation, 2) of the formation and action of SPMs in the brain and their biological roles, and the possible regulation of their synthesis by environmental factors such as inflammation and nutrition and, in particular, PUFA consumption.

Early α-linolenic acid exposure to embryo reduces pentylenetetrazol-induced seizures in zebrafish larva

Over the past few years, there has been a tremendous increase in interest of general population toward food-based therapies for management of chronic clinical conditions due to their lesser adverse effects with prolonged use over pharmacotherapies. Foods enriched with omega-3 fatty acids have shown some promising results in case of epilepsy. The present study was envisioned to investigate the effect of early exposure of α-linolenic acid (ALA), an essential omega-3 fatty acid in developing zebrafish (Danio rerio) embryos toward pentylenetetrazol (PTZ)-induced seizure susceptibility. The healthy wild-type zebrafish embryos were incubated in system water or system water containing different ALA concentrations (1-20 µM) till 7 dpf (days post fertilization). Each larva at 7 dpf was placed in 8 mM PTZ solution and seizure event was recorded. ALA incubation at 10 µM and 20 µM concentrations showed a dose-dependent reduction in PTZ-mediated hyperactive responses in larvae indicated by a marked decrease in total distance travelled and speed, as compared to vehicle control. Furthermore, both the treated groups showed increase in the latency to PTZ-induced clonus-like seizures in larvae, as compared to vehicle control. ALA incubated larvae at 10 µM and 20 µM concentrations also showed a significant reduction in c-fos mRNA level. A marked increase in the level of ALA and docosahexaenoic acid was also observed in the larvae incubated at highest effective concentration of ALA. The present study concluded that embryonic exposure of ALA reduced PTZ-induced seizures in zebrafish larva.

Omega-3 Polyunsaturated Fatty Acid Deficiency and Progressive Neuropathology in Psychiatric Disorders: A Review of Translational Evidence and Candidate Mechanisms

Meta-analytic evidence indicates that mood and psychotic disorders are associated with both omega-3 polyunsaturated fatty acid (omega-3 PUFA) deficits and progressive regional gray and white matter pathology. Although the association between omega-3 PUFA insufficiency and progressive neuropathological processes remains speculative, evidence from translational research suggests that omega-3 PUFA insufficiency may represent a plausible and modifiable risk factor not only for enduring neurodevelopmental abnormalities in brain structure and function, but also for increased vulnerability to neurodegenerative processes. Recent evidence from human neuroimaging studies suggests that lower omega-3 PUFA intake/status is associated with accelerated gray matter atrophy in healthy middle-aged and elderly adults, particularly in brain regions consistently implicated in mood and psychotic disorders, including the amygdala, anterior cingulate, hippocampus, prefrontal cortex, and temporal cortex. Human neuroimaging evidence also suggests that both low omega-3 PUFA intake/status and psychiatric disorders are associated with reductions in white matter microstructural integrity and increased rates of white matter hyperintensities. Preliminary evidence suggests that increasing omega-3 PUFA status is protective against gray matter atrophy and deficits in white matter microstructural integrity in patients with mood and psychotic disorders. Plausible mechanisms mediating this relationship include elevated pro-inflammatory signaling, increased synaptic regression, and reductions in cerebral perfusion. Together these associations encourage additional neuroimaging research to directly investigate whether increasing omega-3 PUFA status can mitigate neuropathological processes in patients with, or at high risk for, psychiatric disorders.

Effects of n-3 PUFA enriched and n-3 PUFA deficient diets in naïve and Aβ-treated female rats

Depression is one of the most common psychiatric diseases and the prevalence of depressive symptoms in women is almost twice compared to men, although the reasons of this gender difference are not fully understood yet. Recently, soluble Aβ_1-42 peptide has been receiving great importance in the development of depression, also since depression is highly comorbid with Alzheimer's disease and other neurodegenerative illnesses. Accordingly, we have previously shown that central Aβ injection is able to elicit depressive-like phenotype in male rats. In the present study, we reproduced for the first time the Aβ-induced depressive-like model in female rats, evaluating behavioural and neurochemical outcomes. Moreover, we studied the effect of lifelong exposure to either n-3 PUFA enriched or n-3 PUFA deficient diet, in female rats, both intact and after central Aβ administration. Our results confirmed the Aβ-induced depressive-like profile also in female rats. Moreover, chronic exposure to n-3 PUFA deficient diet led to highly negative alterations in behavioural and neurochemical parameters, while lifelong exposure to n-3 PUFA enriched diet was able to restore the Aβ-induced depressive-like profile in female rats. In conclusion, the Aβ-induced depressive-like profile was reversed by n-3 PUFA supplementation, indicating a possible therapeutic role of n-3 PUFA in the treatment of the burden of depressive disorders.

Assessing whether early attention of very preterm infants can be improved by an omega-3 long-chain polyunsaturated fatty acid intervention: a follow-up of a randomised controlled trial

INTRODUCTION

Docosahexaenoic acid (DHA) accumulates in the frontal lobes (responsible for higher-order cognitive skills) of the fetal brain during the last trimester of pregnancy. Infants born preterm miss some of this in utero provision of DHA, and have an increased risk of suboptimal neurodevelopment. It is thought that supplementing infants born preterm with DHA may improve developmental outcomes. The aim of this follow-up is to determine whether DHA supplementation in infants born preterm can improve areas of the brain associated with frontal lobe function, namely attention and distractibility.

METHODS AND ANALYSIS

We will assess a subset of children from the N-3 (omega-3) Fatty Acids for Improvement in Respiratory Outcomes (N3RO) multicentre double-blind randomised controlled trial of DHA supplementation. Infants born <29 weeks' completed gestation were randomised to receive an enteral emulsion containing 60 mg/kg/day of DHA or a control emulsion from within the first 3 days of enteral feeding until 36 weeks' postmenstrual age.Children will undergo multiple measures of attention at 18 months' corrected age. The primary outcome is the average time to be distracted when attention is focused on a toy. Secondary outcomes are other aspects of attention, and (where possible) an assessment of cognition, language and motor development with the Bayley Scales of Infant and Toddler Development, Third Edition.A minimum of 72 children will be assessed to ensure 85% power to detect an effect on the primary outcome. Families, and research personnel are blinded to group assignment. All analyses will be conducted according to the intention-to-treat principal.

ETHICS AND DISSEMINATION

All procedures were approved by the relevant institutional ethics committees prior to commencement of the study. Results will be disseminated in peer-reviewed journal publications and academic presentations.

TRIAL REGISTRATION NUMBER

ACTRN12612000503820; Pre-results.

Omega-6/omega-3 fatty acid intake of children and older adults in the U.S.: dietary intake in comparison to current dietary recommendations and the Healthy Eating Index

BACKGROUND

Omega-6 and omega-3 fatty acids (FAs) and their ratio have been shown to affect cognitive function in children and older adults. With these analyses, we aimed to describe omega-6 and omega-3 FA intake among children and older adults in light of FA intake recommendations and with consideration of overall diet.

METHODS

Data were merged from two cross-sectional studies with 219 children 7 to 12 years old and one longitudinal study with 133 adults 65 to 79 years old. Demographic data, anthropometric data, and Healthy Eating Index scores were used to study relations among the omega-6 to omega-3 FA ratio and age, education, body mass index, and diet quality. FA intake, demographic, and anthropometric data were examined using partial correlations, t-tests, and analysis of variance.

RESULTS

Most children and adults consumed at least the recommended amount of alpha-linolenic acid (LNA; omega-3) for their age and gender without consuming high amounts of linoleic acid (LA; omega-6), but did not consume sufficient eicosapentaenoic acid (EPA; omega-) and docosahexaenoic acid (DHA; omega-3). The average omega-6 to omega-3 ratios in both groups were lower than previously reported. Eating lower ratios was associated with healthier diets and consuming adequate amounts of several other nutrients. No demographic or anthropometric variables were related to FA intake in children. Adults with a college degree had significantly lower ratios than those without a college degree.

CONCLUSIONS

American children and older adults are able to consume more balanced omega-6 to omega-3 ratios than has been indicated by commodity data. However, very few American children met even the lowest recommendations for EPA and DHA intake. Research is needed to clarify recommendations for the optimal ratio across development, which may aid in increasing EPA and DHA intake and improving health outcomes in the United States.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02199808 13 July 2014, NCT01823419 (retrospectively registered) 20 March 2013, and NCT01515098 18 January 2012.

Docosahexaenoic Acid Helps to Lessen Extinction Memory in Rats

Abstract: Memory extinction is referred to as a learning process in which a conditioned response (CR) progressively reduces over time as an animal learns to uncouple a response from a stimulus. Extinction occurs when the rat is placed into a context without shock after training. Docosahexaenoic acid (DHA, C22:6, n-3) is implicated in memory formation in mammalian brains. In a two-way active shuttle-avoidance apparatus, we examined whether DHA affects the extinction memory and the expression of brain cognition-related proteins, including gastrin-releasing peptide receptor (GRPR), brain-derived neurotrophic factor receptor (BDNFR) tyrosine kinase receptor B (TrKB), and N-methyl-d-aspartate receptor (NMDAR) subunits NR2A and NR2B. Also, the protein levels of GRP, BDNF, postsynaptic density protein-95 (PSD-95), and vesicular acetylcholine transporter (VAChT), and the antioxidative potentials, in terms of lipid peroxide (LPO) and reactive oxygen species (ROS), were examined in the hippocampus. During the acquisition phase, the rats received a conditioned stimulus (CS-tone) paired with an unconditioned stimulus (UCS foot shock) for three consecutive days (Sessions S1, S2, and S3, each consisting of 30-trials) after 12 weeks of oral administration of DHA. After a three-day interval, the rats were re-subjected to two extinction sessions (S4, S5), each comprising 30 trials of CS alone. During the acquisition training in S1, the shock-related avoidance frequency (acquisition memory) was significantly higher in the DHA-administered rats compared with the control rats. The avoidance frequency, however, decreased with successive acquisition trainings in sessions S2 and S3. When the rats were subjected to the extinction sessions after a break for consolidation, the conditioned response (CR) was also significantly higher in the DHA-administered rats. Interestingly, the freezing responses (frequency and time) also significantly decreased in the DHA-administered rats, thus suggesting that a higher coping capacity was present during fear stress in the DHA-administered rats. DHA treatments increased the mRNA levels of GRPR, BDNF receptor TrKB, and NMDAR subunit NR2B. DHA also increased the protein levels of GRP, BDNF, PSD-95, and VAChT, and the antioxidative potentials in the hippocampus. These results suggest the usefulness of DHA for treating stress disorders.

N-3 PUFA diet enrichment prevents amyloid beta-induced depressive-like phenotype

Among neuropsychiatric diseases, depression is one of the most prevalent. Many pathologies have been indicated as comorbid with depression and in particular, neurodegenerative disorders such as Alzheimer's diseases (AD). In this regard, several evidences endorse a strong relationship between depression and AD, so much that this mental illness has been proposed either as a risk factor for AD or as a prodromic AD phase. Furthermore, amyloid beta (Aβ) peptide, the main constituent of amyloid plaques commonly considered the principal hallmark of AD brains, has been shown to be increased, in its soluble form, in depressed patients. Accordingly, we have previously found that Aβ, intracerebroventricularly (i.c.v.) injected, is able to evoke a depressive-like profile in rats accompanied by low cortical serotonin and reduced neurotrophin content. Taking into account the great increase in AD and depression prevalence, many environmental factors have been under study, particularly dietary factors, and the role of polyunsaturated fatty acids (PUFA) is becoming central in this field of research. Thus, aim of the present study was to evaluate the neurobehavioral effects of lifelong exposure to either n-3 PUFA rich or n-3 PUFA poor diet after Aβ central administration. Results showed that n-3 PUFA enriched diet prevented the Aβ- induced depressive-like behaviors, as reveled by the reduction in the immobility time in the FST test. Furthermore, n-3 PUFA rich diet exposure reverted also serotonin and neurotrophin level reduction in prefrontal cortex of Aβ treated rats. Taken together, our data support the concept that supplementation of diet with n-3 PUFA represents a valid approach to reduce the risk of developing depressive symptoms, as well as reducing the risk of Aβ-related pathologies, such as AD.

Omega – 3 fatty acids in schizophrenia – part I: importance in the pathophysiology of schizophrenia

Despite the increasing offer of antipsychotic drugs, the effectiveness of pharmacotherapy in schizophrenia is still unsatisfactory. Drug resistance, lack of complete remission and the increasing risk of metabolic complications are the reasons why the new forms of therapy in schizophrenia among which unsaturated essential fatty acids omega 3 (EFAs ω-3) affecting the proper functioning of nervous system, are mentioned, are being looked for.

Fatty acids represent 50-60% of the dry weight of the brain and diet is one of the factors that influence the value of each of the fat fractions in the neuron membranes. Patients with schizophrenia tend to have irregular nutritional status concerning essential fatty acids ω-3, which might result from metabolic disorders or irregular consumption of fatty acids.

Apart from being a review of the literature on this subject, this very paper characterizes essential fatty acids ω-3, their metabolism, the most important sources in the diet and the opinions of experts in the field about the recommended intake. It pays attention to the role of essential fatty acids in both the structure and functioning of the central nervous system is, as well as their role in the pathophysiology of schizophrenia, with particular emphasis on the membrane concept by David Horrobin. The assessment of the errors in consumption and metabolism of essential fatty acids are described as well.

The evidence was found both in epidemiological and modeling studies. It supports the participation of EFAs in etiopathogenesis and pathophysiology of schizophrenia. Further research is needed, both observational and interventional, as to the role of essential fatty acids ω-3 in the functioning of the CNS as well as the development and course of schizophrenia.

Neuroinflammation in Autism: Plausible Role of Maternal Inflammation, Dietary Omega 3, and Microbiota

Several genetic causes of autism spectrum disorder (ASD) have been identified. However, more recent work has highlighted that certain environmental exposures early in life may also account for some cases of autism. Environmental insults during pregnancy, such as infection or malnutrition, seem to dramatically impact brain development. Maternal viral or bacterial infections have been characterized as disruptors of brain shaping, even if their underlying mechanisms are not yet fully understood. Poor nutritional diversity, as well as nutrient deficiency, is strongly associated with neurodevelopmental disorders in children. For instance, imbalanced levels of essential fatty acids, and especially polyunsaturated fatty acids (PUFAs), are observed in patients with ASD and other neurodevelopmental disorders (e.g., attention deficit hyperactivity disorder (ADHD) and schizophrenia). Interestingly, PUFAs, and specifically n-3 PUFAs, are powerful immunomodulators that exert anti-inflammatory properties. These prenatal dietary and immunologic factors not only impact the fetal brain, but also affect the microbiota. Recent work suggests that the microbiota could be the missing link between environmental insults in prenatal life and future neurodevelopmental disorders. As both nutrition and inflammation can massively affect the microbiota, we discuss here how understanding the crosstalk between these three actors could provide a promising framework to better elucidate ASD etiology.

Lifelong Nutritional Omega-3 Deficiency Evokes Depressive-Like State Through Soluble Beta Amyloid

Recent evidence pointed out that the prevalence of depression has reached epidemic proportions in last decades. This increase has been linked to many environmental factors, among these the influence of dietary factors has gained great attention. In particular, it has been reported that low n-3 polyunsaturated fatty acid (n-3 PUFA) intake in diet is correlated to the development of depressive and anxiety-like symptoms. Furthermore, maternal malnutrition is a widely accepted risk factor for developing mental illness in later adulthood; among others, depression has been strongly associated to this event. On the other hand, we have previously found that acute intracerebral injection of the soluble beta amyloid 1–42 (Aβ_1–42) peptide induces a depressive-like behavior in rats, associated to altered hypothalamic–pituitary-adrenal (HPA) axis activation and reduced cortical serotonin and neurotrophin levels. The aim of the present work was to study the effect of pre- and post-natal (5 weeks post-weaning) exposure to diets differently enriched in n-3, n-6, as well as n-6/n-3 PUFA balanced, on immobility time displayed on the forced swimming test (FST), along with neuroendocrine quantification in offspring rats. Results showed that n-6 PUFA-enriched diet increased depressive- and anxiety-like behaviors, as shown by the elevation in the immobility time in the FST test and self-grooming in the open field test. Those effects were accompanied by reduced cortical serotonin, high plasmatic corticosterone and hypothalamic corticotropin-releasing factor levels. Finally, enhanced plasmatic Aβ_1–42 levels after n-6 PUFA diet and reduced plasmatic Aβ_1–42 levels after n-3 PUFA were found. Taken together, our data indicate that Aβ_1–42 might be crucially involved in behavioral alterations found after n-6 rich PUFA diet and strongly endorse the protective role of n-3 and the detrimental effect of improper n-6 PUFA diet consumption.

DHA Supplementation Alone or in Combination with Other Nutrients Does not Modulate Cerebral Hemodynamics or Cognitive Function in Healthy Older Adults

A number of recent trials have demonstrated positive effects of dietary supplementation with the omega-3 polyunsaturated fatty acids (n-3 PUFAs), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on measures of cognitive function in healthy young and older adults. One potential mechanism by which EPA, and DHA in particular, may exert these effects is via modulation of cerebral hemodynamics. In order to investigate the effects of DHA alone or provided as one component of a multinutrient supplement (also including Gingko biloba, phosphatidylserine and vitamins B₉ and B₁₂) on measures of cerebral hemodynamics and cognitive function, 86 healthy older adults aged 50-70 years who reported subjective memory deficits were recruited to take part in a six month daily dietary supplementation trial. Relative changes in the concentration of oxygenated hemoglobin and deoxygenated hemoglobin were assessed using Near Infrared Spectroscopy (NIRS) during the performance of cognitive tasks prior to and following the intervention period. Performance on the cognitive tasks was also assessed. No effect of either active treatment was found for any of the NIRS measures or on the cognitive performance tasks, although the study was limited by a number of factors. Further work should continue to evaluate more holistic approaches to cognitive aging.

Is the Mediterranean diet a feasible approach to preserving cognitive function and reducing risk of dementia for older adults in Western countries? New insights and future directions

The rise in the ageing population has resulted in increased incident rates of cognitive impairment and dementia. The subsequent financial and societal burden placed on an already strained public health care system is of increasing concern. Evidence from recent studies has revealed modification of lifestyle and dietary behaviours is, at present, the best means of prevention. Some of the most important findings, in relation to the Mediterranean diet (MedDiet) and the contemporary Western diet, and potential molecular mechanisms underlying the effects of these two diets on age-related cognitive function, are discussed in this review. A major aim of this review was to discuss whether or not a MedDiet intervention would be a feasible preventative approach against cognitive decline for older adults living in Western countries. Critical appraisal of the literature does somewhat support this idea. Demonstrated evidence highlights the MedDiet as a potential strategy to reduce cognitive decline in older age, and suggests the Western diet may play a role in the aetiology of cognitive decline. However, strong intrinsic Western socio-cultural values, traditions and norms may impede on the feasibility of this notion.

Alpha-linolenic acid suppresses dopaminergic neurodegeneration induced by 6-OHDA in C. elegans

Parkinson's disease (PD) is the second most common neurodegenerative disorder characterized by the specific and massive loss of dopamine (DA) containing neurons in the substantia nigra pars compacta (SNpc) and aggregation of protein α-synuclein. There are a few animal studies, which indirectly implicate the neuroprotective action of omega-3 polyunsaturated fatty acids in neurodegenerative diseases. In this study, we exposed Caenorhabditis elegans (both wild type N2, and transgenic strain, UA44) to 6-hydroxydopamine (6-OHDA, the model neurotoxicant) and evaluated the extent of protection offered by alpha-linolenic acid (ALA). Larval stage worms (L1/L2) of N2 and transgenic strains were exposed to 6-OHDA (25 mM) with or without ALA (10, 50 and 100 μM) for 48 h at 20 °C. After 48 h, while the N2 worms were assessed for their responses in terms of locomotion, pharyngeal pumping, lifespan and AChE activity, the transgenic worms were monitored for dopaminergic neuronal degeneration. Worms exposed to 6-OHDA exhibited a significant reduction (48%) in the locomotion rate. Interestingly, supplementation with ALA increased the locomotion rate in 6-OHDA treated worms. A marked decrease (45%) in thrashing was evident in worms exposed to 6-OHDA while thrashing was slightly improved in worms co-exposed to 6-OHDA and higher concentrations of ALA. Interestingly, worms co-exposed to 6-OHDA with ALA (100 μM) exhibited a significant increase in thrashing (66 ± 1.80 thrashes/30s). The pharyngeal pumping rate declined significantly in the case of worms exposed to 6-OHDA (35%). However, the worms co-treated with ALA exhibited significant recovery in pharyngeal pumping. The mean survival for the control worms was 26 days, while the worms exposed to 6-OHDA, showed a marked reduction in survival (21 days). Worms co-exposed to 6-OHDA and ALA showed a concentration-dependent increase in lifespan compared to those exposed to 6-OHDA alone (23, 25 and 26 days respectively). Transgenic worms treated with 6-OHDA showed significant loss of processes of CEP and ADE neurons as evident from visibly marked reduction in GFP expression. Worms co-exposed to 6-OHDA and ALA showed visibly significant reduction in neuronal degeneration in both CEP and ADE. However, worms exposed to 6-OHDA together with ALA showed increased GFP expression within processes of CEP and ADE neurons. Overall, our results demonstrate that ALA significantly suppresses the dopaminergic neurodegeneration and movement disorder induced by 6-OHDA in C. elegans.

Antidepressant-like effects of Perilla frutescens seed oil during a forced swimming test

Unipolar depressive disorder may become one of the major leading causes of disease burden by 2030 according to the World Health Organization (WHO). Thus, the discovery of antidepressive foods is attractive and could have considerable impacts worldwide. We investigated the antidepressant-like effects of Perilla frutescens seed oil on adult male rats subjected to a forced swimming test (FST). Forty Sprague-Dawley rats were housed and fed various diets, including soybean oil-rich, eicosapentaenoic acid (EPA)-rich, and P. frutescens seed oil-rich diets for 6 weeks. After the dietary intervention, animals were tested using an FST and were sacrificed after the test. We analyzed the fatty acid profiles of red blood cells (RBCs) and the brain prefrontal cortex (PFC). Levels of brain-derived neurotrophic factor (BDNF), serotonin, and dopamine in the PFC were also determined. After the FST, the imipramine, EPA-rich, and P. frutescens seed oil-rich groups showed significant shorter immobility time and longer struggling time than the control group (p < 0.05). Levels of BDNF in the P. frutescens seed oil-rich group and levels of serotonin in the EPA-rich group were significantly (p < 0.05) higher than those of the control group. Moreover, the BDNF concentration in the PFC was significantly positively correlated with the struggling time. However, there were no significant differences in dopamine levels between the intervention groups and the control group. In conclusion, a P. frutescens seed oil-rich diet exhibited antidepressant-like properties through modulation of fatty acid profiles and BDNF expression in the brain during an FST.

Effects of docosahexaenoic Acid on neurotransmission

Docosahexaenoic acid (DHA) is the major polyunsaturated fatty acid (PUFA) in the brain and a structural component of neuronal membranes. Changes in DHA content of neuronal membranes lead to functional changes in the activity of receptors and other proteins which might be associated with synaptic function. Accumulating evidence suggests the beneficial effects of dietary DHA supplementation on neurotransmission. This article reviews the beneficial effects of DHA on the brain; uptake, incorporation and release of DHA at synapses, effects of DHA on synapses, effects of DHA on neurotransmitters, DHA metabolites, and changes in DHA with age. Further studies to better understand the metabolome of DHA could result in more effective use of this molecule for treatment of neurodegenerative or neuropsychiatric diseases.

Anti-inflammatory and hypoglycemic efficacy of Poria cocos and Dioscorea opposita in prediabetes mellitus rats

Poria cocos (Fu Ling) and Dioscorea opposita (Chinese Yam) were suggested to have potential benefits in blood sugar control.

Dietary omega-3 deficiency reduces BDNF content and activation NMDA receptor and Fyn in dorsal hippocampus: implications on persistence of long-term memory in rats

Omega-3 (n-3) fatty acids are important for adequate brain function and cognition. The aim of the present study was to evaluate how n-3 fatty acids influence the persistence of long-term memory (LTM) in an aversive memory task and to explore the putative mechanism involved. Female rats received isocaloric diets that included n-3 (n-3 group) or not (D group). The adult litters were subjected to an inhibitory avoidance task (0.7 mA, 1.0 seconds foot shock) to elicit persistent LTM. Twelve hours after the training session, the fatty acid profile and the brain derived neurotrophic factor (BDNF) content of the dorsal hippocampus were assessed. In addition, we measured the activation of the NR2B subunit of the N-methyl-d-aspartate (NMDA) receptor and the SRC family protein Fyn. Despite pronounced learning in both groups, the persistence of LTM was abolished in the D group 7 days after the training session. We also observed that the D group presented reductions in hippocampal DHA (22:6 n-3) and BDNF content. Twelve hours after the training session, the D group showed decreased NR2B and Fyn phosphorylation in the dorsal hippocampus, with no change in the total content of these proteins. Further, there was a decrease in the interaction of Fyn with NR2B in the D group, as observed by co-immunoprecipitation. Taken together, these data suggest that n-3 fatty acids influence the persistence of LTM by maintaining adequate levels of DHA and BDNF as well as by influencing the activation of NR2B and Fyn during the period of memory formation.

Neurochemical and behavioural impact of C18 fatty acids in male mice postweaning

Dietary components, particularly essential fatty acids, affect the expression and maintenance of normal physiological phenotypes. However, the influence of C18 fatty acids that are abundantly present in the normal diet is unclear. We focused on the behavioural and neurochemical effects of C18 fatty acids during postweaning development in male mice. An AIN-93G diet supplemented with 8% stearic acid (C18:0), 3% oleic acid (C18:1), 3% linoleic acid (C18:2) or 3% α-linolenic acid (C18:3) was provided from four weeks of age for eight weeks. At 12 weeks of age, novel exploratory behaviour and social interaction tests were carried out. One week after the last behavioural test, the brain of each mouse was removed. The frequency of social interactive behaviour was decreased by approximately 70% in the C18:0 group compared to the basal diet group, but there was no difference in cumulative time. The frequency of social interaction showed a positive correlation to cumulative time in mice fed with the experimental diets except for C18:0. Dietary C18 fatty acids following weaning had no impact on brain fatty acid composition except for the C18:3 diet. Furthermore, the neurochemical properties to be especially noted were that choline acetyltransferase activity was absolutely higher in C18:0 diet-fed mice than in the other groups, especially in the frontal cortex where it was 1.7-fold higher than in the basal diet-fed group. The present results reveal a significant possibility of neurochemical and behavioural effects of dietary fatty acids, and saturated fatty acids are of special importance during the postweaning period.

Omega-3 fatty acids and brain resistance to ageing and stress: body of evidence and possible mechanisms

The increasing life expectancy in the populations of rich countries raises the pressing question of how the elderly can maintain their cognitive function. Cognitive decline is characterised by the loss of short-term memory due to a progressive impairment of the underlying brain cell processes. Age-related brain damage has many causes, some of which may be influenced by diet. An optimal diet may therefore be a practical way of delaying the onset of age-related cognitive decline. Nutritional investigations indicate that the ω-3 poyunsaturated fatty acid (PUFA) content of western diets is too low to provide the brain with an optimal supply of docosahexaenoic acid (DHA), the main ω-3 PUFA in cell membranes. Insufficient brain DHA has been associated with memory impairment, emotional disturbances and altered brain processes in rodents. Human studies suggest that an adequate dietary intake of ω-3 PUFA can slow the age-related cognitive decline and may also protect against the risk of senile dementia. However, despite the many studies in this domain, the beneficial impact of ω-3 PUFA on brain function has only recently been linked to specific mechanisms. This review examines the hypothesis that an optimal brain DHA status, conferred by an adequate ω-3 PUFA intake, limits age-related brain damage by optimizing endogenous brain repair mechanisms. Our analysis of the abundant literature indicates that an adequate amount of DHA in the brain may limit the impact of stress, an important age-aggravating factor, and influences the neuronal and astroglial functions that govern and protect synaptic transmission. This transmission, particularly glutamatergic neurotransmission in the hippocampus, underlies memory formation. The brain DHA status also influences neurogenesis, nested in the hippocampus, which helps maintain cognitive function throughout life. Although there are still gaps in our knowledge of the way ω-3 PUFA act, the mechanistic studies reviewed here indicate that ω-3 PUFA may be a promising tool for preventing age-related brain deterioration.

Deciphering the role of docosahexaenoic acid in brain maturation and pathology with magnetic resonance imaging

Animal studies have found that deficits in brain docosahexaenoic acid (DHA, 22:6n-3) accrual during perinatal development leads to transient and enduring abnormalities in brain development and function. Determining the relevance of this evidence to brain disorders in humans has been hampered by an inability to determine antimortem brain DHA levels and limitations associated with a postmortem approach. Accordingly, there is a need for alternate or complementary approaches to better understand the role of DHA in cortical function and pathology, and conventional magnetic resonance imaging (MRI) techniques may be ideally suited for this application. A major advantage of neuroimaging is that it permits prospective evaluation of the effects of manipulating DHA status on both clinical and neuroimaging variables. Emerging evidence from MRI studies suggest that greater DHA status is associated with cortical structural and functional integrity, and suggest that reduced DHA status and abnormalities in cortical function observed in psychiatric disorders may be interrelated phenomenon. Preliminary evidence from animal MRI studies support a critical role of DHA in normal brain development. Neuroimaging research in both human and animals therefore holds tremendous promise for developing a better understanding of the role of DHA status in cortical function, as well as for elucidating the impact of DHA deficiency on neuropathological processes implicated in the etiology and progression of neurodevelopmental and psychiatric disorders.