New perspectives on randomized controlled trials with omega-3 fatty acid supplements and cognition: A scoping review

An inverse association of cerebral amyloid-β deposition and serum docosahexaenoic acid levels in cognitively normal older adults in Japan

BackgroundAlzheimer's disease (AD) is driven by amyloid-β (Aβ) plaque accumulation, but the mechanisms behind this process remain unclear. Omega-3 fatty acids, particularly docosahexaenoic acid (DHA), may offer protective effects, though their relationship with Aβ accumulation is not fully understood.ObjectiveThis study investigated whether serum DHA and eicosapentaenoic acid (EPA) levels, measured 6-9 years before imaging, were inversely associated with cerebral Aβ deposition in cognitively normal older adults in Japan, a population known for high omega-3 intake. We focused on individuals identified as Aβ-positive based on positron emission tomography (PET) scans, as they are at higher risk for AD progression, to assess DHA's potential in mitigating early amyloid pathology.MethodsAn analytical sample of 97 older adults (75-89 years) from the Suita Study was analyzed. Serum DHA and EPA levels were assessed between 2008 and 2012, and amyloid PET was performed between 2016 and 2019. Multiple regression analyses were conducted, adjusting for age, sex, APOE4 status, and cardiometabolic disease.ResultsAmong 97 participants (49% males, 8.2% APOE4 carriers), 37.1% (n = 36) had cardiometabolic disease, and 29.8% (n = 29) were Aβ positive. In Aβ-positive individuals, higher serum DHA levels were significantly associated with lower Aβ deposition independent of age, sex and APOE4 status (standardized β = -0.423, p = 0.030). This became non-significant after additionally adjusting for cardiometabolic disease (β = -0.382, p = 0.059). No significant association was found between EPA and Aβ deposition.ConclusionsHigher long-term DHA levels may help reduce Aβ accumulation in those at risk for AD, supporting its potential role in early prevention.

Providing lysophosphatidylcholine-bound omega-3 fatty acids increased eicosapentaenoic acid, but not docosahexaenoic acid, in the cortex of mice with the apolipoprotein E3 or E4 allele

BACKGROUND

Several mechanisms have been proposed for the brain uptake of omega-3 fatty acids (n-3), including passive diffusion of the unesterified form and the use of Mfsd2a transporter for the lysophosphatidylcholine (LPC) form. We hypothesize that the accumulation of LPC n-3 in the brain is lower in mice carrying the apolipoprotein E ε4 allele (APOE4), a major genetic risk factor for developing sporadic Alzheimer's disease in humans.

OBJECTIVE

Determine whether two or four months of supplementation with LPC n-3 increases the levels of docosahexaenoic acids (DHA) and eicosapentaenoic acids (EPA) in the frontal cortex of APOE3 and APOE4 mice.

METHODS

APOE3 and APOE4 mice were administered LPC n-3 (9.6 mg DHA + 18.3 mg EPA) or sunflower oil (control) by oral gavage for two or four months (n = 5-8 per genotype, per treatment, and per treatment duration). At the end of the treatment period, frontal cortices were collected, and their FA profiles analyzed by gas chromatography with flame ionization detection.

RESULTS

After two months of gavage with LPC n-3, APOE3 mice showed increased levels of EPA in their cortex, but not DHA. In APOE4 mice, neither EPA nor DHA levels were significantly affected. After four months of LPC n-3, both APOE3 and APOE4 mice exhibited higher EPA levels, while changes in DHA levels were not statistically significant.

CONCLUSION

LPC n-3 supplementation increased EPA, but not DHA, levels in the frontal cortex of mice in a duration- and APOE genotype-dependent manner. Further research is needed to explore the implications for brain health.

Association between serum tricosanoic acid and cognitive function in older adults: findings from the NHANES and GEO databases

Introduction

With global aging, dementia prevalence rises. While long-chain saturated fatty acids show anti-cognitive decline potential, serum tricosanoic acid (C23:0)'s role in brain regions and cognition remains unclear.

Methods

To confirm the association between C23:0 and cognition in the population, we analyzed gene expression data from the Alzheimer's disease (AD) brain gene chip data set (GSE118553) available in the Gene Expression Omnibus (GEO) database. Additionally, we examined data from 1,127 adults aged 60 years and older who participated in the National Health and Nutrition Examination Survey (NHANES) between 2011 and 2014. To explore potential metabolic pathways and mechanisms linking C23:0 to cognitive aging, the computational platform METAFlux was employed.

Results

Differential gene expression analysis identified 335 downregulated and 477 upregulated genes in AD frontal cortex. Metabolite analysis showed 20 upregulated and 37 downregulated nutrients (including C23:0) in AD vs. controls. Population-level analysis (NHANES, n = 1,127) confirmed higher serum C23:0 associated with better cognitive function.

Discussion

This study provides strong evidence for frontal cortex-specific reduced C23:0 in AD and highlights its potential as a serum cognitive marker.

Effects of a food supplement containing phosphatidylserine on cognitive function in Chinese older adults with mild cognitive impairment: A randomized double-blind, placebo-controlled trial

BACKGROUND

Phosphatidylserine (PS) and α-Linolenic acid (ALA), are positively associated with cognitive function, but their combination effects and possible mechanisms remain unclear. We aimed to explore the effects on cognition and potential mechanism of the supplements.

METHODS

This randomized, double-blind, placebo-controlled trial recruited 190 MCI patients in Tianjin, China, and randomly assigned in intervention group and placebo group. Each group consumed two capsules every day for 12 months. Each capsule for intervention group contains 144 mg ALA, 31.5 mg PS and 3.6 mg Ginkgo total flavonoids as main functional components, with 0.48 mg Vitamin B1 (as thiamine hydrochloride), 0.48 mg Vitamin B6 (as pyridoxine hydrochloride) and 90 μg folic acid as supplement. Capsules for placebo group were identical but contain no active ingredients. Cognitive function, serum n-3 polyunsaturated fatty acids (PUFAs) and neurotransmitters were assessed at baseline and 12 months. Linear mixed effects model and causal mediation analysis were conducted to explore the effects and potential mechanism of the intervention.

RESULTS

A total of 190 participants (mean [SD] age, 67.95 [5.62] years; 70 (36.8 %) male and 120 (63.2 %) female) were randomized to the placebo group (n = 95) and intervention group (n = 95). Compared with placebo group, the intervention group had statistically significant improvements in arithmetic testing (β, 0.688; 95 % CI, 0.103-1.274), the similarity test (β, 1.070; 95 % CI, 0.472-1.667) and short-term memory (β, 0.600; 95 % CI, 0.399-0.800). Besides, the intervention group had statistically significant increases in serum ALA (β, 1.620; 95 % CI, 0.967-2.265), DHA (β, 2.797; 95 % CI, 1.075-4.532), EPA (β, 1.472; 95 % CI, 0.296-2.643), acetylcholine (β, 0.441; 95 % CI, 0.415-0.468), GABA (β, 0.009; 95 % CI, 0.001-0.016) and 5-HT (β, 0.160; 95 % CI, 0.081-0.238) compared to the placebo group. And the intervention may improve short-term memory by increasing serum ALA levels (average causal mediation effect = 0.132, 95 % CI, 0.053-0.225) with 19.7 % mediation proportion.

CONCLUSIONS

This food supplement containing phosphatidylserine could improve different cognitive functions of MCI patients, especially short-term memory, and increase serum n-3 PUFAs and neurotransmitters levels. Serum ALA level might play a mediation role.

Regulatory Compliance of Health Claims on Omega-3 Fatty Acid Food Supplements

Unlike the mandatory information that must be provided on a food supplement label, health claims are voluntary. This study assesses the regulatory compliance of omega-3 fatty acid (ω-3-FA) supplement label claims. Of the 97 supplements, 76 (78.4%) carried verbal claims referring to active substance, of which 68 (89.5%) were claims specific to ω-3-FA. According to the European Union Health Claims Registry, 107 claims listed on 59 supplements were authorized, as opposed to nine unauthorized claims on nine supplements. The degree to which claims aligned with regulatory standards, expressed in terms of scores scaled from 0 to 1, was the highest for supplements intended for pregnant women (1), while, in the case of adults, the mean score was 0.76 ± 0.35, and, in case of children, was 0.85 ± 0.27. Statistical analysis revealed a minor tendency for higher health claim scores to be associated with lower product prices. Furthermore, differences in compliance levels across groups of supplements formed according to the country of origin/sources of ω-3-FA/target populations were explored. The main differences were associated with products from Sweden and Italy/fish oil/supplements for pregnant women. A comparison of the daily intake of ω-3-FA provided by the supplement (based on labeled information) with the intake requirements for supplements with claims referring to ω-3-FA, supported 91 claims, five were unsubstantiated, and 11 were missing required data. Supplements also contained mineral- (19 approved) and vitamin-related claims (73, of which 9 were unauthorized). This study's findings reveal the extent of misuse of labelled information in markets that require pre-market supplement registration. Importantly, the non-compliance of health claims can significantly undermine consumer trust.

Differential impact of eicosapentaenoic acid and docosahexaenoic acid in an animal model of Alzheimer's disease

Dietary supplementation with n-3 polyunsaturated fatty acids improves cognitive performance in several animal models of Alzheimer's disease (AD), an effect often associated with reduced amyloid-beta and/or tau pathologies. However, it remains unclear to what extent eicosapentaenoic (EPA) provides additional benefits compared to docosahexaenoic acid (DHA). Here, male and female 3xTg-AD mice were fed for 3 months (13-16 months of age) the following diets: (1) control (no DHA/EPA), (2) DHA (1.1g/kg) and low EPA (0.4g/kg), or (3) DHA (0.9g/kg) with high EPA (9.2g/kg). The DHA and DHA + EPA diets respectively increased DHA by 19% and 8% in the frontal cortex of 3xTg-AD mice, compared to controls. Levels of EPA, which were below the detection limit after the control diet, reached 0.14% and 0.29% of total brain fatty acids after the DHA and DHA + EPA diet, respectively. DHA and DHA + EPA diets lowered brain arachidonic acid levels and the n-6:n-3 docosapentaenoic acid ratio. Brain uptake of free 14C-DHA measured through intracarotid brain perfusion, but not of 14C-EPA, was lower in 3xTg-AD than in NonTg mice. DHA and DHA + EPA diets in 3xTg-AD mice reduced cortical soluble phosphorylated tau (pS202) (-34% high-DHA, -34% DHA + EPA, P < 0.05) while increasing p21-activated kinase (+58% and +83%, P < 0.001; respectively). High EPA intake lowered insoluble phosphorylated tau (-31% vs. DHA, P < 0.05). No diet effect on amyloid-beta levels was observed. In conclusion, dietary intake of DHA and EPA leads to differential changes in brain PUFA while altering cerebral biomarkers consistent with beneficial effects against AD-like neuropathology.

Ethanolamine and Vinyl-Ether Moieties in Brain Phospholipids Modulate Behavior in Rats

Plasmalogens are brain-enriched phospholipids with a vinyl-ether bond at the sn-1 position between the glycerol backbone and the alkyl chain. Previous studies have suggested that plasmalogens modulate locomotor activity, anxiety-like behavior, and cognitive functions in rodents; however, the specific moieties contributing to behavioral regulation are unknown. In this study, we examined the behavioral modulation induced by specific phospholipid moieties. To confirm the permeability of phospholipids in injected liposomes, we measured the fluorescence intensity following intravenous injection of liposomes containing ATTO 740-labeled dioleoylphosphatidylethanolamine. Then, we compared the behavioral effects following injection of liposomes composed of egg phosphatidylcholine (PC) and 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphoethanolamine (PE 18:0/22:6), PC 18:0/22:6, 1-(1Z-octadecenyl)-2-docosahexaenoyl-sn-glycero-3-phosphoethanolamine (PE P-18:0/22:6), or PC P-18:0/22:6, into the tail vein of male rats. The time spent in the central region of the open field was significantly reduced after injection of PE 18:0/22:6, harboring an ester bond at sn-1 compared to controls. Furthermore, the discrimination ratio in the novel object recognition test was significantly higher in PC 18:0/22:6 compared to PE 18:0/22:6, suggesting that the substitution of ethanolamine with choline can enhance recognition memory. We demonstrate that the structures of the sn-1 bond and the hydrophilic moiety in the phospholipids can modulate exploratory behaviors and recognition memory in rodents.

GPR40 agonist ameliorates neurodegeneration and motor impairment by regulating NLRP3 inflammasome in Parkinson's disease animal models

Parkinson's disease (PD) is characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra (SN) and accumulation of intracellular α-synuclein (ɑ-syn) aggregates known as Lewy bodies and Lewy neurites. Levels of polyunsaturated fatty acids (PUFAs) have previously been shown to be reduced in the SN of PD patients. G protein-coupled receptor 40 (GPR40) serves as a receptor for PUFAs, playing a role in neurodevelopment and neurogenesis. Additionally, GPR40 has been implicated in several neuropathological conditions, such as apoptosis and inflammation, suggesting its potential as a therapeutic target in PD. In this study, we investigated the neuroprotective effects of the GPR40 agonist, TUG469 in PD models. Our results demonstrated that TUG469 reduces the neurotoxicity induced by 6-OHDA in SH-SY5Y cells. In 6-OHDA-induced PD model mice, TUG469 treatment improved motor impairment, preserved dopaminergic fibers and cell bodies in the striatum (ST) or SN, and attenuated 6-OHDA-induced microgliosis and astrogliosis in the brain. Furthermore, in a PD model involving the injection of mouse ɑ-syn fibrils into the brain (mPFFs-PD model), TUG469 treatment reduced the levels of pSer129 ɑ-syn, and decreased microgliosis and astrogliosis. Our investigation also revealed that TUG469 modulates inflammasome activation, apoptosis, and autophagy in the 6-OHDA-PD model, as evidenced by the results of RNA-seq and western blotting analyses. In summary, our findings highlight the neuroprotective effects of GPR40 agonists on dopaminergic neurons and their potential as therapeutic agents for PD. These results underscore the importance of targeting GPR40 in PD treatment, particularly in mitigating neuroinflammation and preserving neuronal integrity.

Cognitive Function After Stopping Folic Acid and DHA Intervention: An Extended Follow-Up Results from the Randomized, Double Blind, Placebo-Controlled Trial in Older Adults with Mild Cognitive Impairment

Background

Our previously randomized controlled trial (RCT) showed daily oral folic acid (FA), docosahexaenoic acid (DHA) and their combined treatment for 6 months could significantly improve cognitive function in mild cognitive impairment (MCI) individuals.

Objective

This study aimed to evaluate whether this benefit seen in the treatment group would sustain after stopping intervention when patients returned to a real-world.

Methods

RCT (ChiCTR-IOR-16008351) was conducted in Tianjin, China. 160 MCI elders aged ≥60 years were randomly divided into four groups: FA + DHA, FA, DHA, and control. 138 MCI elders who completed the 6-month interventional trial underwent another 6-month follow-up without receiving nutritional therapy. Cognitive performance was measured at 6 and 12 months. Blood amyloid-β peptide (Aβ) and homocysteine (Hcy) related biomarkers were measured at baseline and 6 months.

Results

In comparison to the end of nutritional therapy, all intervention groups had considerably lower full-scale IQ, arithmetic, and image completion scores during the follow-up period, while the combined intervention and DHA groups had significantly lower picture arrangement scores. Furthermore, after 6-month treatment with FA and FA + DHA, plasma Aβ40, Aβ42, and Hcy levels were significantly decreased. However, these biomarker levels at the start of follow-up were positively correlated with the degree of cognitive function change during follow-up period.

Conclusions

FA and DHA supplementation enhance cognitive performance in MCI elderly following a six-month intervention by reducing Hcy or Aβ levels. However, their effects on improving cognitive decline are likely to diminish when the intervention is discontinued.

Fish consumption, cognitive impairment and dementia: an updated dose-response meta-analysis of observational studies

BACKGROUND

Cognitive impairment is projected to affect a preponderant proportion of the aging population. Lifelong dietary habits have been hypothesized to play a role in preventing cognitive decline. Among the most studied dietary components, fish consumptionhas been extensively studied for its potential effects on the human brain.

AIMS

To perform a meta-analysis of observational studies exploring the association between fish intake and cognitive impairment/decline and all types of dementia.

METHODS

A systematic search of electronic databases was performed to identify observational studies providing quantitative data on fish consumption and outcomes of interest. Random effects models for meta-analyses using only extreme exposure categories, subgroup analyses, and dose-response analyses were performed to estimate cumulative risk ratios (RRs) and 95% confidence intervals (CIs).

RESULTS

The meta-analysis comprised 35 studies. Individuals reporting the highest vs. the lowest fish consumption were associated with a lower likelihood of cognitive impairment/decline (RR = 0.82, 95% CI: 0.75, 0.90, I2 = 61.1%), dementia (RR = 0.82, 95% CI: 0.73, 0.93, I2 = 38.7%), and Alzheimer's disease (RR = 0.80, 95% CI: 0.67, 0.96, I2 = 20.3%). The dose-response relation revealed a significantly decreased risk of cognitive impairment/decline and all cognitive outcomes across higher levels of fish intake up to 30% for 150 g/d (RR = 0.70, 95% CI: 0.52, 0.95). The results of this relation based on APOE ε4 allele status was mixed based on the outcome investigated.

CONCLUSIONS

Current findings suggest fish consumption is associated with a lower risk of cognitive impairment/decline in a dose-response manner, while for dementia and Alzheimer's disease there is a need for further studies to improve the strength of evidence.

Effects of APOE4 on omega-3 brain metabolism across the lifespan

Omega-3 (n-3) polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA), have important roles in human nutrition and brain health by promoting neuronal functions, maintaining inflammatory homeostasis, and providing structural integrity. As Alzheimer's disease (AD) pathology progresses, DHA metabolism in the brain becomes dysregulated, the timing and extent of which may be influenced by the apolipoprotein E ε4 (APOE4) allele. Here, we discuss how maintaining adequate DHA intake early in life may slow the progression to AD dementia in cognitively normal individuals with APOE4, how recent advances in DHA brain imaging could offer insights leading to more personalized preventive strategies, and how alternative strategies targeting PUFA metabolism pathways may be more effective in mitigating disease progression in patients with existing AD dementia.

Genetic association between FADS and ELOVL polymorphisms and the circulating levels of EPA/DHA in humans: a scoping review

BACKGROUND

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are two omega-3 fatty acids that can be synthesized out of their precursor alpha-linolenic acid (ALA). FADS and ELOVL genes encode the desaturase and elongase enzymes required for EPA and DHA synthesis from ALA; however, single nucleotide polymorphisms (SNPs) in FADS and ELOVL genes could modify the levels of EPA and DHA synthesized from ALA although there is no consensus in this area. This review aims to investigate EPA and DHA circulating levels in human blood and their association with FADS or ELOVL.

METHODS

PubMed, Cochrane, and Scopus databases were used to identify research articles. They were subsequently reviewed by two independent investigators.

RESULTS

Initially, 353 papers were identified. After removing duplicates and articles not meeting inclusion criteria, 98 full text papers were screened. Finally, this review included 40 studies investigating FADS and/or ELOVL polymorphisms. A total of 47 different SNPs in FADS genes were reported. FADS1 rs174537, rs174547, rs174556 and rs174561 were the most studied SNPs, with minor allele carriers having lower levels of EPA and DHA. SNPs in the FADS genes were in high linkage disequilibrium. SNPs in FADS were correlated with levels of EPA and DHA. No conclusion could be drawn with the ELOVL polymorphisms since the number of studies was too low.

CONCLUSION

Specific SNPs in FADS gene, such as rs174537, have strong associations with circulating levels of EPA and DHA. Continued investigation regarding the impact of genetic variants related to EPA and DHA synthesis is warranted.

Solitary and Synergistic Effects of Different Hydrophilic and Hydrophobic Phospholipid Moieties on Rat Behaviors

Glycerophospholipids have hydrophobic and hydrophilic moieties. Previous studies suggest that phospholipids with different moieties have different effects on rodent behavior; however, the relationship between chemical structures and behavioral effects remains unclear. To clarify the functions of phospholipid moieties, we injected male rats with phospholipids with different moieties and conducted behavioral tests. Exploratory activity was reduced by phosphatidylethanolamine (PE)(18:0/22:6) but not PE(18:0/18:0) or PE(18:0/20:4). Conversely, exploratory activity was increased by plasmanyl PE(16:0/22:6), which harbors an alkyl-ether linkage, but not by phosphatidylcholine (PC)(16:0/22:6) or plasmanyl PC(16:0/22:6). Docosahexaenoic acid (DHA)(22:6) and an alkyl-ether linkage in PE were thus postulated to be involved in exploratory activity. Anxiety-like behavior was reduced by plasmenyl PC(18:0/20:4), which harbors a vinyl-ether linkage, but not by PC(18:0/20:4) or plasmanyl PC(18:0/20:4), suggesting the anxiolytic effects of vinyl-ether linkage. The activation of social interaction was suppressed by PE(18:0/18:0), PE(18:0/22:6), PC(16:0/22:6), plasmanyl PE(16:0/22:6), and plasmanyl PC(16:0/22:6) but not by PE(18:0/20:4), plasmenyl PE(18:0/20:4), or plasmanyl PC(18:0/22:6). DHA may suppress social interaction, whereas arachidonic acid(20:4) or a combination of alkyl-ether linkage and stearic acid(18:0) may restore social deficits. Our findings indicate the characteristic effects of different phospholipid moieties on rat behavior, and may help to elucidate patterns between chemical structures and their effects.

ω-3 Polyunsaturated Fatty Acid Status Testing in Humans: A Narrative Review of Commercially Available Options

There is an increasing body of evidence supporting a link between low intakes of ω-3 long-chain polyunsaturated fatty acids (LCPUFA) and numerous diseases and health conditions. However, few people are achieving the levels of fish/seafood or eicosapentaenoic acid and docosahexaenoic acid intake recommended in national and international guidelines. Knowledge of a person's ω-3 LCPUFA status will benefit the interpretation of research results and could be expected to lead to an increased effort to increase intake. Dietary intake survey methods are often used as a surrogate for measuring ω-3 PUFA tissue status and its impact on health and functional outcomes. However, because individuals vary widely in their ability to digest and absorb ω-3 PUFA, analytical testing of biological samples is desirable to accurately evaluate ω-3 PUFA status. Adipose tissue is the reference biospecimen for measuring tissue fatty acids, but less-invasive methods, such as measurements in whole blood or its components (e.g., plasma, serum, red blood cell membranes) or breast milk are often used. Numerous commercial laboratories provide fatty acid testing of blood and breast milk samples by different methods and present their results in a variety of reports such as a full fatty acid profile, ω-3 and ω-6 fatty acid profiles, fatty acid ratios, as well as the Omega-3 Index, the Holman Omega-3 Test, OmegaScore, and OmegaCheck, among others. This narrative review provides information about the different ways to measure ω-3 LCPUFA status (including both dietary assessments and selected commercially available analytical tests of blood and breast milk samples) and discusses evidence linking increased ω-3 LCPUFA intake or status to improved health, focusing on cardiovascular, neurological, pregnancy, and eye health, in support of recommendations to increase ω-3 LCPUFA intake and testing.

Association between the circulating very long-chain saturated fatty acid and cognitive function in older adults: findings from the NHANES

BACKGROUND

Age-related cognitive decline has a significant impact on the health and longevity of older adults. Circulating very long-chain saturated fatty acids (VLSFAs) may actively contribute to the improvement of cognitive function. The objective of this study was to investigate the associations between arachidic acid (20:0), docosanoic acid (22:0), tricosanoic acid (23:0), and lignoceric acid (24:0) with cognitive function in older adults.

METHODS

This study used a dataset derived from the 2011-2014 National Health and Nutrition Examination Survey (NHANES). A total of 806 adults (≥ 60 years) were included who underwent comprehensive cognitive testing and plasma fatty acid measurements. Multivariable linear regression, restricted cubic spline (RCS), and interaction analyses were used to assess associations between VLSFAs and cognitive function. Partial Spearman' s correlation analysis was used to examine the correlations between VLSFAs and palmitic acid (16:0), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, total cholesterol, triglycerides, systemic inflammatory markers, and dietary nutrients.

RESULTS

Multivariable linear regression analysis, adjusting for sociodemographic, clinical conditions, and lifestyle factors, showed that 22:0 and 24:0 levels were positively associated with better global cognitive function (β = 0.37, 95% confidence interval [CI] = 0.01, 0.73; β = 0.73, 95% CI = 0.29, 1.2, respectively) as well as better CEARD-DR Z-score (β = 0.82, 95% CI = 0.36, 1.3 and β = 1.2, 95% CI = 0.63, 1.8, respectively). RCS analysis showed linear associations between higher 22:0 and 24:0 levels and better cognitive performance in both global cognitive function and CERAD-DR tests.

CONCLUSIONS

The study suggests that higher levels of 22:0 and 24:0 are associated with better global cognitive function in older adults. 22:0 and 24:0 may be important biomarkers for recognizing cognitive impairment, and supplementation with specific VLSFAs (22:0 and 24:0) may be an important intervention to improve cognitive function. Further studies are needed to elucidate the underlying biological mechanisms between VLSFAs and cognitive function.

Protective effect of unsaturated fatty acids on cognitive impairment in CKD patients: Results from the National Health and Nutrition Examination Survey (2011-2014)

BACKGROUND

It is still unknown whether unsaturated fatty acids (UFA) have the same effect on preventing cognitive impairment in chronic kidney disease (CKD) patients as in healthy people.

OBJECTIVE

To investigate the protective effect of dietary UFA intake and proportion on cognitive impairment in patients with CKD.

METHODS

We extracted data from the National Health and Nutrition Examination Survey (NHANES, 2011-2014) on participants with a previous diagnosis of CKD and at least one complete cognitive assessment (Consortium to Establish a Registry for Alzheimer's Disease test, Animal Fluency Test and Digit Symbol Substitution Test). We used the lower quartile of the total scores of these three tests as the cut-off point, and divided the participants into two groups of normal cognitive performance and low cognitive performance to extract participants' intake of various UFA from the NHANES dietary module. The data were weighted using weighting parameters included in NHANES, and logistics regression and restricted cubic spline were used to analyze the protective effect of UFA intake on cognitive impairment in CKD participants.

RESULTS

We found that participants with low cognitive performance all had significantly lower intakes of total monounsaturated fatty acids, total polyunsaturated fatty acids, ω-3 UFA, ω-6 UFA and ω-9 UFA than participants with normal cognitive performance (p< 0.05), and the ω-6 UFA and ω-9 UFA had the most significant protective effects on cognitive impairment of participants. We also discovered that oleic and linoleic acids play important roles in protecting against cognitive impairment in CKD participants. The protective effect of oleic acid, but not linoleic acid, on cognitive impairment showed a nonlinear relationship. The changes in the proportion of monounsaturated fatty acids to polyunsaturated fatty acids, ω-6 UFA to ω-3 UFA, and oleic acid to linoleic acid did not affect the risk of cognitive impairment in CKD participants.

CONCLUSIONS

UFA can reduce the risk of cognitive impairment in CKD patients, especially oleic acid and linoleic acid have a more obvious protective effect on cognitive impairment in patients with CKD. Among them, the protective effect of linoleic acid on cognitive impairment was continuously enhanced with the increase of intake, indicating that linoleic acid may be the most important UFA to reduce cognitive impairment in CKD patients.

Measuring brain docosahexaenoic acid turnover as a marker of metabolic consumption

Docosahexaenoic acid (DHA, 22:6n-3) accretion in brain phospholipids is critical for maintaining the structural fluidity that permits proper assembly of protein complexes for signaling. Furthermore, membrane DHA can by released by phospholipase A₂ and act as substrate for synthesis of bioactive metabolites that regulate synaptogenesis, neurogenesis, inflammation, and oxidative stress. Thus, brain DHA is consumed through multiple pathways including mitochondrial β-oxidation, autoxidation to neuroprostanes, as well as enzymatic synthesis of bioactive metabolites including oxylipins, synaptamide, fatty-acid amides, and epoxides. By using models developed by Rapoport and colleagues, brain DHA loss has been estimated to be 0.07-0.26 μmol DHA/g brain/d. Since β-oxidation of DHA in the brain is relatively low, a large portion of brain DHA loss may be attributed to synthesis of autoxidative and bioactive metabolites. In recent years, we have developed a novel application of compound specific isotope analysis to trace DHA metabolism. By the use of natural abundance in ¹³C-DHA in food supply, we are able to trace brain phospholipid DHA loss in free-living mice with estimates ranging from 0.11 to 0.38 μmol DHA/g brain/d, in reasonable agreement with previous methods. This novel fatty acid metabolic tracing methodology should improve our understanding of the factors that regulate brain DHA metabolism.

Post-Prandial Cognitive and Blood Pressure Effects of a DHA-Rich Omega-3 Powder in Middle-Aged Males: A Pilot Study

The use of omega-3 polyunsaturated fatty acid (ω-3 PUFA) supplements is increasingly common among middle-aged and older adults. Users of ω-3 PUFA supplements often report using such supplements to support cognitive health, despite mixed findings reported within the ω-3 PUFA literature. To date, very few studies have explored cognitive effects in distinctly middle-aged (40 to 60 years) adults, and none have examined the acute effects (in the hours following a single dose) on cognitive performance. The current study evaluated whether a single dose of ω-3 PUFA (4020 mg docosahexaenoic acid and 720 mg eicosapentaenoic acid) influences cognitive performance and cardiovascular function in middle-aged males. Cognitive performance and cardiovascular function were assessed before and 3.5-4 h after consumption of a high dose of ω-3 PUFA (DHA + EPA) or placebo, incorporated into a standardized meal (i.e., single serve of Greek yogurt). In this study of middle-aged males, no significant differential treatment effects were observed for cognitive performance. However, a significant reduction in aortic systolic blood pressure (pre-dose to post-dose) was apparent following consumption of the ω-3 PUFA (DHA + EPA) treatment (mean difference = -4.11 mmHg, p = 0.004) but not placebo (mean difference = -1.39 mmHg, p = 0.122). Future replication in a sample comprising females, as well as patients with hypertension, is merited.