Dietary intake of fatty acids and fish in relation to cognitive performance at middle age

Fish intake of Swedish male adolescents is a predictor of cognitive performance

AIM

Fish intake is reported to positively influence cognitive performance in infants and the elderly. In a longitudinal cohort study, we evaluated how fish consumption related to later cognitive performance in healthy young male adolescents.

METHODS

In 2000, all 15-year-olds (n = 18 158; 9260 males) in the western region of Sweden were requested to complete an extensive questionnaire with items on diseases, fish consumption and socioeconomic status. Questionnaire data from the male responders (n = 4792, response rate 52%) were linked with records on subsequent intelligence test performance at age 18 from the Swedish Military Conscription Register (n = 3972). Multivariate linear models were used to estimate associations between fish intake and cognitive performance, adjusting for potential confounders.

RESULTS

There was a positive association between the number of times having fish meals per week at age 15 and cognitive performance measured 3 years later. Fish consumption of more than once per week compared to less than once per week was associated with higher stanine scores in combined intelligence (0.58 units; 95% confidence interval 0.39, 0.76), in verbal performance (0.45; 0.27, 0.63) and in visuospatial performance (0.50; 0.31, 0.69). The association between fish consumption and the 3 intelligence scores was the same in lowly and highly educated groups. This indicates that education did not influence the association between the frequency of fish meals consumed and cognitive performance.

CONCLUSION

Frequent fish intake at age 15 was associated with significantly higher cognitive performance 3 years later.

Education attenuates the association between dietary patterns and cognition

BACKGROUND/AIMS

Various foods have been shown to be associated with cognitive outcomes. As individual food items are not consumed in isolation, we examined the association between dietary patterns and cognitive function, with special attention to the role of education in this association.

METHODS

Analyses were carried out on 4,693 stroke-free white European participants of the Whitehall II study. Two dietary patterns were determined using principal component analysis: a 'whole food' and a 'processed food' pattern. Cognitive function was assessed using a battery of 5 tests.

RESULTS

After adjustment for demographic, behavioral and health measures, higher intake of 'whole food' diet was associated with lower and high consumption of 'processed food' with higher odds of cognitive deficit. However, adjustment for education significantly attenuated most of these associations.

CONCLUSIONS

Education, through its role as a powerful confounder, shapes the relationship between dietary patterns and cognitive deficit in a healthy middle-aged UK cohort.

Early intervention for cognitive decline: is there a role for multiple medical or behavioural interventions?

AIM

Early medical or behavioural intervention to slow cognitive decline might be a viable strategy for reducing disability and rates of institutional care in older persons. This paper details the published work supporting cross-sectional and longitudinal associations between vascular risk factors, depressive symptoms and progressive cognitive decline. Evidence for the beneficial effects of providing relevant interventions is assessed.

METHODS

Relevant published work from the areas of dementia research, 'vascular depression' and the cognitive benefits that might result from treating vascular risk factors, managing depression or promoting nutrition, cognitive or physical exercise was ascertained from electronic database searches and recent reviews of key areas.

RESULTS

The existing published work does not provide many examples of early intervention strategies that target vascular strategies or active treatment of depression to reduce the rate of cognitive decline. Most studies have major limitations including the evaluation of only single-risk-factor interventions, the observational designs and the inadequate measurement of cognition. An optimal early intervention strategy might be to target multiple risk factors within relevant experimental or health service frameworks.

CONCLUSIONS

Early identification and multifaceted reduction of vascular risk factors, active management of depression, engagement in cognitive activity and physical exercise and promotion of better nutrition might together help to slow some forms of cognitive decline or progression to dementia. This health services approach now requires systematic evaluation.

Increased selenium intake in elderly high fish consumers may account for health benefits previously ascribed to omega-3 fatty acids

OBJECTIVE

To examine relationships between fish consumption and plasma selenium (Se) and red blood-cell fatty acid (RBC FA) profile in aged subjects. We hypothesised that the importance of Se has been underestimated when interpreting the beneficial effect of fish consumption on health.

DESIGN

Cross-sectional analysis of data from a prospective cohort study.

SETTING

The EVA study in Nantes, France (1991-2002).

SUBJECTS

200 subjects aged > or = 69 y with information on RBC FAs, plasma Se and completed food frequency questionnaires.

METHODS

We examined correlations between the most abundant FAs, Se and number of fish meals per week. Linear regression models were used.

RESULTS

Plasma Se was negatively correlated with RBC omega6 poly-unsaturated FA (PUFAs) and positively with omega3 PUFAs. Plasma Se, RBC omega3 PUFAs, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) increased with fish consumption. Conversely, levels of omega6 PUFAs were lower in the highest fish consumption group. All associations between plasma Se and fish consumption remained significant when adjusting for omega6 PUFAs alone or additionally for age, sex, education, diabetes, hypertension, dyslipidemia, cardiovascular diseases, and broad food categories (meat, eggs, dairy products, cereals, fruit and vegetable). Associations between omega3 PUFAs and fish also remained significant in the same model independently of Se. In linear regression models adjusted for demographic indicators, fish consumption explained only 2.6% of the variance in RBC omega3 FAs (6.2% for omega6) but as much as 15% of the variance in plasma selenium.

CONCLUSIONS

The observed health benefits of fish consumption in the elderly could be related not only to the increase in omega3 FA intake but also to other nutrients such as selenium. It is important to consider this observation when interpreting associations between fish consumption and health status in the elderly, particularly with regard to brain function.

Effect of dietary n-3 polyunsaturated fatty acids on brain lipid fatty acid composition, learning ability, and memory of senescence-accelerated mouse

Animal studies have shown that a deficiency in brain of the n-3 polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) is associated with memory loss and diminished cognitive function. The senescence-accelerated prone 8 (SAMP8) mouse develops impairments in learning and memory at 8-12 months of age. The effect of diet supplemented with n-3 PUFA on brain phospholipid DHA status, learning, and memory ability in aged SAMP8 mice was investigated. At the age of 10 months, SAMP8 mice were fed either a low-DHA or a high-DHA diet for 8 weeks. In comparison to SAMP8 mice fed the low-DHA diet, those fed a high-DHA diet had improved acquisition and retention in a T-maze foot shock avoidance test and a higher proportion of DHA in hippocampal and amygdala phospholipids. This study demonstrates that, in mature animals, DHA is incorporated into brain phospholipids and that dietary n-3 PUFA is associated with delay in cognitive decline.

Synapse formation and cognitive brain development: effect of docosahexaenoic acid and other dietary constituents

The brain is unusual among organs in that the rates of many of its characteristic enzymatic reactions are controlled by the local concentrations of their substrates, which also happen to be nutrients that cross the blood-brain barrier. Thus, for example, brain levels of tryptophan, tyrosine, or choline can control the rates at which neurons synthesize serotonin, dopamine, or acetylcholine, respectively. The rates at which brain cells produce membrane phospholipids such as phosphatidylcholine (PC) are also under such control, both in adult animals and, especially, during early development. If pregnant rats are fed the 3 dietary constituents needed for PC synthesis- docosahexaenoic acid, uridine, and choline-starting 10 days before parturition and continuing for 20 days during nursing, brain levels of PC, and of the other membrane phosphatides (per cell or per mg protein), are increased by 50% or more. In adult animals, this treatment is also known to increase synaptic proteins (eg, synapsin-l, syntaxin-3, GluR-l, PSD-95) but not ubiquitous proteins like beta-tubulin and to increase (by 30% or more) the number of dendritic spines on hippocampal neurons. Docosahexaenoic acid currently is widely used, in human infants, to diminish the negative effects of prematurity on cognitive development. Moreover, docosahexaenoic acid, uridine (as uridine monophosphate), and choline are all found in mother's milk, and included in most infant formulas. It is proposed that these substances are part of a regulatory mechanism through which plasma composition influences brain development.

Diet, physical activity and cognitive impairment among elders: the EPIC–Greece cohort (European Prospective Investigation into Cancer and Nutrition)

Objectives

To identify dietary and lifestyle variables that may affect cognitive function in the elderly.

Design

Population-based prospective cohort study.

Setting

General community residing in Athens and the surrounding Attica region of Greece.

Subjects

A total of 732 men and women, 60 years or older, participating in the EPIC–Greece cohort (European Prospective Investigation into Cancer and Nutrition) and residing in the Attica region had sociodemographic, anthropometric, medical, dietary and lifestyle variables ascertained at enrolment (1993–1999). Six to 13 years later, cognitive function was evaluated through the Mini-Mental State Examination (MMSE) score and affective state through the Geriatric Depression Scale (GDS).

Results

MMSE score was positively associated with years of formal education, height and physical activity and inversely with age, diabetes mellitus and GDS score (P < 0·05 for all). Among dietary variables, intake of PUFA was inversely associated with cognitive function and this association was largely accounted for by a similar association with seed oils. Adherence to the Mediterranean diet, as well as intake of olive oil, MUFA and SFA exhibited weakly positive but not significant associations.

Conclusion

Physical activity and early life factors as reflected in height are significant predictors of cognitive function in the elderly. Seed oil consumption may adversely affect cognition, whereas other nutritional factors do not appear to have a quantitatively large effect.

Dietary omega 3 fatty acids and the developing brain

The omega-3 fatty acids are essential dietary nutrients and one of their important roles is providing the fatty acid with 22 carbons and 6 double bonds known as docosahexaenoic acid (DHA) for nervous tissue growth and function. Inadequate intakes of omega-3 fatty acids decrease DHA and increase omega-6 fatty acids in the brain. Decreased DHA in the developing brain leads to deficits in neurogenesis, neurotransmitter metabolism, and altered learning and visual function in animals. Western diets are low in omega-3 fatty acids, including the 18 carbon omega-3 fatty acid alpha linolenic acid found mainly in plant oils, and DHA, which is found mainly in fish. The DHA status of the newborn and breast-fed infant depends on the maternal intake of DHA and varies widely. Epidemiological studies have linked low maternal DHA to increased risk of poor child neural development. Intervention studies have shown improving maternal DHA nutrition decreases the risk of poor infant and child visual and neural development. Thus, sufficient evidence is available to conclude that maternal fatty acid nutrition is important to DHA transfer to the infant before and after birth, with short and long-term implications for neural function. However, genetic variation in genes encoding fatty acid desaturases also influence essential fatty acid metabolism, and may increase requirements in some individuals. Consideration of omega-3 fatty acid to include brain development, optimizing omega-3 and omega-6 fatty acids in gestation and lactation, and in fatty acid nutrition support for intravenous and formula-fed neonates is important.

Low plasma eicosapentaenoic acid and depressive symptomatology are independent predictors of dementia risk

BACKGROUND

The potential preventive role of polyunsaturated fatty acids (PUFAs) in Alzheimer disease has aroused increasing interest. Plasma n-3 PUFAs have been shown to be inversely related to the risk of dementia and to depression, which is frequently associated with dementia.

OBJECTIVE

The objective was to ascertain whether plasma PUFAs predict the risk of incident dementia in a cohort of older persons, independently of their depressive status.

DESIGN

Of 1214 nondemented participants in the Three-City Study from Bordeaux (France) who were followed up for 4 y, 65 developed dementia. The association between the proportion of plasma fatty acids at baseline and the risk of incident dementia was assessed by multivariate proportional hazard models, taking into account depressive status assessed on the basis of the Center for Epidemiologic Studies Depression scale.

RESULTS

A higher plasma eicosapentaenoic acid (EPA) concentration was associated with a lower incidence of dementia [hazard ratio (HR) for 1 SD = 0.69; 95% CI: 0.48, 0.98], independently of depressive status and after adjustment for age, education, apolipoprotein E epsilon4 allele, diabetes, and baseline plasma vitamin E and triacylglycerol. The relations between docosahexaenoic acid (DHA), total n-3 PUFAs, and incident dementia did not remain significant in multivariate models. Higher ratios of arachidonic acid (AA) to DHA and of n-6 to n-3 fatty acids were related to an increased risk of dementia, particularly in depressive subjects (n = 90): ratio of AA to DHA (HR: 2.65; 95% CI: 1.07, 6.56) and ratio of n-6 to n-3 (HR: 1.61; 95% CI: 1.04, 2.47).

CONCLUSIONS

A high plasma EPA concentration may decrease the risk of dementia, whereas high ratios of n-6 to n-3 fatty acids and of AA to DHA may increase the risk of dementia, especially in depressed older persons. The role of EPA in dementia warrants further research.

Effects of a saturated fat and high cholesterol diet on memory and hippocampal morphology in the middle-aged rat

Diets rich in cholesterol and/or saturated fats have been shown to be detrimental to cognitive performance. Therefore, we fed a cholesterol (2%) and saturated fat (hydrogenated coconut oil, Sat Fat 10%) diet to 16-month old rats for 8 weeks to explore the effects on the working memory performance of middle-aged rats. Lipid profiles revealed elevated plasma triglycerides, total cholesterol, HDL, and LDL for the Sat-Fat group as compared to an iso-caloric control diet (12% soybean oil). Weight gain and food consumption were similar in both groups. Sat-Fat treated rats committed more working memory errors in the water radial arm maze, especially at higher memory loads. Cholesterol, amyloid-beta peptide of 40 (Abeta40) or 42 (Abeta42) residues, and nerve growth factor in cortical regions was unaffected, but hippocampal Map-2 staining was reduced in rats fed a Sat-Fat diet, indicating a loss of dendritic integrity. Map-2 reduction correlated with memory errors. Microglial activation, indicating inflammation and/or gliosis, was also observed in the hippocampus of Sat-Fat fed rats. These data suggest that saturated fat, hydrogenated fat and cholesterol can profoundly impair memory and hippocampal morphology.

Strain-specific differences in cell proliferation and differentiation in the dentate gyrus of C57BL/6N and C3H/HeN mice fed a high fat diet

The authors investigated strain-specific cell proliferation and differentiation differences in the dentate gyri of C57BL/6N (susceptible strain to obesity) and C3H/HeN (resistant strain to obesity) mice. In addition, the influences of a high fat diet (HD) on neuronal differentiation in C57BL/6N and C3H/HeN mice fed a low-fat diet (LD) or HD for 4 or 12 weeks were investigated. Body weight and body weight gains were significantly higher in HD-fed C57BL/6N and C3H/HeN mice than in LD-fed C57BL/6N and C3H/HeN mice. In particular, body weight gains were significantly higher in C57BL/6N mice than in C3H/HeN mice. In both of HD- and LD-fed C57BL/6N and C3H/HeN mice for 4 weeks, some Ki67 and many DCX immunoreactive cells were detected in the subgranular zone of the dentate gyrus. In HD-fed C57BL/6N and C3H/HeN mice, the number of Ki67 immunoreactive cells and DCX immunoreactivities in the dentate gyri were significantly lower than in LD-fed C57BL/6N and C3H/HeN mice. However, the number of Ki67 immunoreactive cells and DCX immunoreactivities in HD-fed C57BL/6N mice were significantly lower than in HD-fed C3H/HeN mice. These results suggest that C57BL/6N mice are more vulnerable to HD induced obesity than C3H/HeN mice. In addition, the feeding of HD was found to exacerbate reduced cell proliferation and differentiation in the dentate gyri of C57BL/6N mice as compared with that in C3H/HeN mice.

Fish consumption and risk of subclinical brain abnormalities on MRI in older adults

OBJECTIVE

To investigate the association between fish consumption and subclinical brain abnormalities.

METHODS

In the population-based Cardiovascular Health Study, 3,660 participants age > or =65 underwent an MRI scan in 1992-1994. Five years later, 2,313 were scanned. Neuroradiologists assessed MRI scans in a standardized and blinded manner. Food frequency questionnaires were used to assess dietary intakes. Participants with known cerebrovascular disease were excluded from the analyses.

RESULTS

After adjustment for multiple risk factors, the risk of having one or more prevalent subclinical infarcts was lower among those consuming tuna/other fish > or =3 times/week, compared to <1/month (relative risk 0.74, 95% CI = 0.54-1.01, p = 0.06, p trend = 0.03). Tuna/other fish consumption was also associated with trends toward lower incidence of subclinical infarcts. Additionally, tuna/other fish intake was associated with better white matter grade, but not with sulcal and ventricular grades, markers of brain atrophy. No significant associations were found between fried fish consumption and any subclinical brain abnormalities.

CONCLUSIONS

Among older adults, modest consumption of tuna/other fish, but not fried fish, was associated with lower prevalence of subclinical infarcts and white matter abnormalities on MRI examinations. Our results add to prior evidence that suggest that dietary intake of fish with higher eicosapentaenoic acid and docosahexaenoic acid content, and not fried fish intake, may have clinically important health benefits.

Persistent, bioaccumulative and toxic substances in fish: human health considerations

Fish are important dietary items that provide essential nutrients. Fish however, bioaccumulate monomethyl mercury (MMHg) and organo-halogenated pollutants (OHP) that are persistent bioaccumulative and toxic substances (PBTS). Unlike man-made OHP, MMHg is mainly of natural origin but background concentrations of aquatic systems are determined by the environmental Hg-methylating potential. Industrial activities can modulate environmental discharges and fish bioaccumulation of PBTS. Fish and seafood consumption are associated with human body load of PBTS, but farming practices that utilize fishmeal increase the terrestrial food chain resulting in farm-animal accumulation of PBTS. These substances are neurotoxic and endocrine active that can impact humans and wild life, but chemical characteristics of MMHg and OHP modulate interactions with animal tissues. MMHg is protein reactive with a faster metabolism (months) than OHP that are stored and slowly (years) metabolized in fat tissues. Except for brain-Hg, neither Hg nor OHP in tissues are markers of toxic effects; however, deficits in neurobehavioral test-scores of children have been shown in some fish-eating populations. These deficits are transient and within normal range, and are not prodromes of neurological diseases. Although population studies show that consumption of fish at current levels of contamination do not explain neurological disorders, endocrine activity remains controversial. Understanding risk of hazard caused by fish-PBTS consumption requires a wide range of expertise. We discuss chemical, toxic, metabolic, and ecological characteristics associated with PBTS in fish. There are proven health outcome derived from fish consumption, while risk of exposure to avoidable PBTS is a chance that can be minimized by societal actions.

Neurological benefits of omega-3 fatty acids

The central nervous system is highly enriched in long-chain polyunsaturated fatty acid (PUFA) of the omega-6 and omega-3 series. The presence of these fatty acids as structural components of neuronal membranes influences cellular function both directly, through effects on membrane properties, and also by acting as a precursor pool for lipid-derived messengers. An adequate intake of omega-3 PUFA is essential for optimal visual function and neural development. Furthermore, there is increasing evidence that increased intake of the long-chain omega-3 PUFA, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may confer benefits in a variety of psychiatric and neurological disorders, and in particular neurodegenerative conditions. However, the mechanisms underlying these beneficial effects are still poorly understood. Recent evidence also indicates that in addition to the positive effects seen in chronic neurodegenerative conditions, omega-3 PUFA may also have significant neuroprotective potential in acute neurological injury. Thus, these compounds offer an intriguing prospect as potentially new therapeutic approaches in both chronic and acute conditions. The purpose of this article is to review the current evidence of the neurological benefits of omega-3 PUFA, looking specifically at neurodegenerative conditions and acute neurological injury.

Dietary fatty acids, age-related cognitive decline, and mild cognitive impairment

Currently available epidemiological evidence suggested that an increase of saturated fatty acids (SFA) could have negative effects on cognitive functions, while increased polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA) may be protective against cognitive decline. In a Southern Italian elderly population from the Italian Longitudinal Study on Aging (ILSA), a clear reduction of risk of age-related cognitive decline (ARCD) has been found with elevated intake of PUFA and MUFA. Furthermore, in the ILSA, while dietary fatty acids intakes were not associated with incident mild cognitive impairment (MCI), high PUFA intake appeared to have borderline non-significant trend for a protective effect against the development of MCI. These epidemiological findings on predementia syndromes, i.e. MCI or ARCD, together with a recent randomised controlled trial on a possible effect on cognitive and depressive symptoms of omega-3 PUFA supplementation in patients with very mild AD, suggested a possible role of fatty acids intake in maintaining adequate cognitive functioning and possibly in preventing or delaying the onset of dementia.

Different effect of high fat diet and physical exercise in the hippocampal signaling

Obesity is an epidemic disease that may affect brain function. The present study examined the effect of high fat diet (HF) and physical exercise on peripheral tissue and hippocampal signaling. CF-1 mice (n = 4, per cage) were divided into groups receiving high fat (HF) or control (CD) diets for 5 months, with or without voluntary exercise. Serum triacylglycerol, total cholesterol, HDLc, liver triacylglycerol and glycogen concentrations were evaluated (n = 6). Also, the phosphorylation state of the AKT --> ERK 1/2 --> CREB pathway (AKT, pAKTser473, ERK 1/2, pERK 1/2, CREB and pCREB, n = 4-6) was analyzed in the hippocampus. HF diet caused an increase in AKT phosphorylation at ser473 (P < 0.05), while exercise increased the phosphorylation of ERK 1/2 (P < 0.05) and CREB (P < 0.05). As expected, exercise reversed some of the harmful effects of HF, i.e., increased liver deposition of fat (P < 0.05) and fat gain in the abdominal region (P < 0.05). In conclusion, the effects of exercise and HF diet on brain signaling appear to affect the hippocampal AKT --> ERK 1/2 --> CREB pathway in independent ways: HF intake caused increased phosphorylation of AKTser473, while exercise increased ERK 1/2 --> CREB signaling. The physiological relevance of these findings in brain function remains to be elucidated.

The role of polyunsaturated fatty acids (PUFAs) in development, aging and substance abuse disorders: review and propositions

The polyunsaturated fatty acids (PUFAs), especially omega-3 and -6, play an important role in the functioning of membranes. Therefore, changes in their physical properties might entail impairment of the neurotransmission between cells. Studies emphasize the importance of omega-3 intakes, but they also highlight the need of a balance between omega-6 and -3, whose ideal ratio should be 4:1. The Western diet has very high amounts of saturated fat and omega-6, which might contribute, at least partially, to physiopathologies and high incidence as well as prevalence of psychiatric and neurodegenerative diseases. This narrow review aimed at systematizing the studies on the importance of PUFAs in some particular cases, that is, the extremes of life: pre- and post-natal development, and cognitive aging. Additionally, it aimed at studying the association between PUFAs and substance abuse disorders. We used the databases LILACs, MEDLINE and PUBMED.

The potential role of nutritional components in the management of Alzheimer's Disease

Epidemiological evidence linking nutrition to the incidence and risk of Alzheimer Disease is rapidly increasing. The specific nutritional deficiencies in Alzheimer patients may suggest a relative shortage of specific macro- and micronutrients. These include omega-3 fatty acids, several B-vitamins and antioxidants such as vitamins E and C. Recent mechanistic studies in cell systems and animal models also support the idea that nutritional components are able to counteract specific aspects of the neurodegenerative and pathological processes in the brain. In addition, it has been shown that several nutritional components can also effectively stimulate membrane formation and synapse formation as well as improve behavior and cerebrovascular health. The suggested synergy between nutritional components to improve neuronal plasticity and function is supported by epidemiological studies as well as experimental studies in animal models. The ability of nutritional compositions to stimulate synapse formation and effectively reduce Alzheimer Disease neuropathology in these preclinical models provides a solid basis to predict potential to modify the disease process, especially during the early phases of Alzheimer Disease.

Fatty acids, lipid metabolism and Alzheimer pathology

Alzheimer's disease is the most common form of dementia in the elderly. The cause of Alzheimer's disease is still unknown and there is no cure for the disease yet despite 100 years of extensive research. Cardiovascular risk factors such as high serum cholesterol, presence of the Apolipoprotein epsilon4 (APOE epsilon4) allele and hypertension, play important roles in the development of Alzheimer's disease. We postulate that a combination of diet, lifestyle, vascular, genetic, and amyloid related factors, which enhance each other's contribution in the onset and course of Alzheimer's disease, will be more likely the cause of the disease instead of one sole mechanism. The possibility that the risk for Alzheimer's disease can be reduced by diet or lifestyle is of great importance and suggests a preventative treatment in Alzheimer's disease. Because of the great importance of lipid diets and metabolism in preventative treatment against both Alzheimer's disease and cardiovascular disease, long-chain polyunsaturated fatty acids from fish oil, ApoE genotype and cholesterol metabolism in correlation with Alzheimer's disease will be reviewed.

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

Environmental and genetic factors, notably ApoE4, contribute to the etiology of late-onset Alzheimer's disease (LOAD). Reduced mRNA and protein for an apolipoprotein E (ApoE) receptor family member, SorLA (LR11) has been found in LOAD but not early-onset AD, suggesting that LR11 loss is not secondary to pathology. LR11 is a neuronal sorting protein that reduces amyloid precursor protein (APP) trafficking to secretases that generate beta-amyloid (Abeta). Genetic polymorphisms that reduce LR11 expression are associated with increased AD risk. However these polymorphisms account for only a fraction of cases with LR11 deficits, suggesting involvement of environmental factors. Because lipoprotein receptors are typically lipid-regulated, we postulated that LR11 is regulated by docosahexaenoic acid (DHA), an essential omega-3 fatty acid related to reduced AD risk and reduced Abeta accumulation. In this study, we report that DHA significantly increases LR11 in multiple systems, including primary rat neurons, aged non-Tg mice and an aged DHA-depleted APPsw AD mouse model. DHA also increased LR11 in a human neuronal line. In vivo elevation of LR11 was also observed with dietary fish oil in young rats with insulin resistance, a model for type II diabetes, another AD risk factor. These data argue that DHA induction of LR11 does not require DHA-depleting diets and is not age dependent. Because reduced LR11 is known to increase Abeta production and may be a significant genetic cause of LOAD, our results indicate that DHA increases in SorLA/LR11 levels may play an important role in preventing LOAD.

No effect ofn-3 long-chain polyunsaturated fatty acid (EPA and DHA) supplementation on depressed mood and cognitive function: a randomised controlled trial

Low dietary intakes of then-3 long-chain PUFA (LCPUFA) EPA and DHA are thought to be associated with increased risk for a variety of adverse outcomes, including some psychiatric disorders. Evidence from observational and intervention studies for a role ofn-3 LCPUFA in depression is mixed, with some support for a benefit of EPA and/or DHA in major depressive illness. The present study was a double-blind randomised controlled trial that evaluated the effects of EPA+DHA supplementation (1·5 g/d) on mood and cognitive function in mild to moderately depressed individuals. Of 218 participants who entered the trial, 190 completed the planned 12 weeks intervention. Compliance, confirmed by plasma fatty acid concentrations, was good, but there was no evidence of a difference between supplemented and placebo groups in the primary outcome – namely, the depression subscale of the Depression Anxiety and Stress Scales at 12 weeks. Mean depression score was 8·4 for the EPA+DHA group and 9·6 for the placebo group, with an adjusted difference of − 1·0 (95 % CI − 2·8, 0·8;P = 0·27). Other measures of mood, mental health and cognitive function, including Beck Depression Inventory score and attentional bias toward threat words, were similarly little affected by the intervention. In conclusion, substantially increasing EPA+DHA intake for 3 months was found not to have beneficial or harmful effects on mood in mild to moderate depression. Adding the present result to a meta-analysis of previous relevant randomised controlled trial results confirmed an overall negligible benefit ofn-3 LCPUFA supplementation for depressed mood.

Nutritional risk and cognitive impairment in the elderly

The purpose of this study was to determine the relationship between nutritional risk and cognitive impairment in the elderly living in the community. Data obtained from 2934 subjects (912 men and 2022 women) aged above 60 years was analyzed from the Gwangju Dementia and Mild Cognitive Impairment Study (GDEMCIS). The study questionnaire comprised demographic characteristics, history of current and past illnesses, drug history, Korean version-Mini Mental State Examination (K-MMSE), and Nutritional Screening Initiative (NSI) checklist. Additionally, we examined the blood pressure, fasting serum glucose level, lipid profile, body mass index, and ApoE genotype. Of the total, 1942 (66.2%) demonstrated good nutritional state (NSI checklist score< or =2) and 992 (33.8%) were at moderate or high nutritional risk (NSI checklist score>2). Multiple logistic regression analysis revealed that moderate or high nutritional risk subjects were associated with an increased risk of cognitive impairment (K-MMSE score< or =17) after adjustment for age, sex, educational level, and Korean version of Short form Geriatric Depression Scale (K-SGDS) score (Odds ratio=OR=1.71, 95%; confidence interval=CI=1.17-2.50). These results suggest that nutritional risk may be associated with cognitive impairment in the elderly.

Low plasma N-3 fatty acids and dementia in older persons: the InCHIANTI study

BACKGROUND

N-3 fatty acids (FA) have an important role in brain development and function. However, there is conflicting evidence concerning the relationship between n-3 FA and dementia in older persons.

METHODS

In the Invecchiare in Chianti (InCHIANTI) study, we measured plasma FA by gas chromatography in 935 community-dwelling older persons randomly extracted from the population of two towns near Florence, Italy. Cognitive impairment was measured using the Mini-Mental Status Examination. Participants who scored </=26 underwent a detailed clinical and neuropsychological evaluation. The diagnosis of dementia was based on Diagnostic and Statistical Manual of Mental Disorders, Third Revision (DSM-III-R) criteria. The population was divided in three groups: persons with normal cognitive function, persons with cognitive impairment not demented, and persons with dementia.

RESULTS

After adjustment for age, gender, education, body mass index, weight loss, smoking status, cholesterol and triglycerides levels, daily intake of alcohol, FA and total energy, cardiovascular disease, depression and other FA levels, participants with dementia had significantly lower n-3 FA levels (2.9% vs 3.2%; p <.05), particularly alpha-linolenic acid levels (0.34% vs 0.39%; p <.05), than did participants with normal cognitive function.

CONCLUSIONS

Dementia is associated with low plasma n-3 FA relative concentrations. The possibility that higher n-3 FA intake is associated with a lower risk of cognitive impairment should be further investigated in prospective studies.

n 3 fatty acid proportions in plasma and cognitive performance in older adults

BACKGROUND

Very-long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs) are suggested to be related to cognitive performance in older adults. However, limited data exist on the association between n-3 PUFAs and performance in specific cognitive domains.

OBJECTIVE

We evaluated the association between plasma n-3 PUFA proportions and cognitive performance in 5 cognitive domains and determined whether plasma n-3 PUFA proportions predict cognitive change over 3 y.

DESIGN

We used data from the FACIT trial, in which participants received folic acid or placebo capsules for 3 y. Fatty acid proportions in plasma cholesteryl esters at baseline were measured in 807 men and women aged 50-70 y. Cognitive performance for memory, sensorimotor speed, complex speed, information-processing speed, and word fluency was assessed at baseline and after 3 y. The cross-sectional analyses were based on all 807 participants; the longitudinal analyses were based only on 404 participants in the placebo group.

RESULTS

Higher plasma n-3 PUFA proportions predicted less decline in sensorimotor speed (multiple linear regression coefficient, z score = 0.31; 95% CI: 0.06, 0.57) and complex speed (0.40; 95% CI: 0.10, 0.70) over 3 y. Plasma n-3 PUFA proportions did not predict 3-y changes in memory, information-processing speed, or word fluency. The cross-sectional analyses showed no association between plasma n-3 PUFA proportions and performance in any of the 5 cognitive domains.

CONCLUSIONS

In this population, plasma n-3 PUFA proportions were associated with less decline in the speed-related cognitive domains over 3 y. These results need to be confirmed in randomized controlled trials.

Neuroprotective action of omega-3 polyunsaturated fatty acids against neurodegenerative diseases: evidence from animal studies

Studies in animals clearly show that oral intake of docosahexaenoic acid (DHA) can alter brain DHA concentrations and thereby modify brain functions. This provides us with an opportunity to use DHA as a nutraceutical or pharmaceutical tool in brain disorders such as Alzheimer disease (AD) and Parkinson disease (PD). Most of the published epidemiological studies are consistent with a positive association between high reported DHA consumption or high DHA blood levels and a lower risk of developing AD later in life. Such observations have prompted the investigation of DHA in three different transgenic models of AD. These analyses show that animal models of AD are more vulnerable to DHA depletion than controls and that DHA exerts a beneficial effect against pathological signs of AD, including A beta accumulation, cognitive impairment, synaptic marker loss, and hyperphosphorylation of tau. Multiple mechanisms of action can be associated with the neuroprotective effects of DHA and include antioxidant properties and activation of distinct cell signaling pathways. Although the first randomized clinical assays have yet failed to demonstrate convincing beneficial effects of DHA for AD patients, the knowledge gathered in recent years holds out a hope for prevention and suggests that the elderly and people bearing a genetic risk for AD should at least avoid DHA deficiency.

Cognitive performance among the elderly and dietary fish intake: the Hordaland Health Study

BACKGROUND

Increasing evidence suggests that cognitive impairment and dementia in older subjects might be influenced by a diet including seafood.

OBJECTIVE

The objective was to examine the cross-sectional relation between intake of different amounts of various seafood (fish and fish products) and cognitive performance.

DESIGN

The subjects (n = 2031 subjects; 55% women), aged 70-74 y, were recruited from the general population in Western Norway and underwent cognitive testing. A cognitive test battery included the Kendrick Object Learning Test, Trail Making Test (part A), modified versions of the Digit Symbol Test, Block Design, Mini-Mental State Examination, and Controlled Oral Word Association Test. Poor cognitive performance was defined as a score in the highest decile for the Trail Making Test and in the lowest decile for all other tests.

RESULTS

Subjects whose mean daily intake of fish and fish products was >/=10 g/d (n = 1951) had significantly better mean test scores and a lower prevalence of poor cognitive performance than did those whose intake was <10 g/d (n = 80). The associations between total intake of seafood and cognition were strongly dose-dependent; the maximum effect was observed at an intake of approximately 75 g/d. Most cognitive functions were influenced by fish intake. The effect was more pronounced for nonprocessed lean fish and fatty fish.

CONCLUSIONS

In the elderly, a diet high in fish and fish products is associated with better cognitive performance in a dose-dependent manner.

Towards a nutritional approach for prevention of Alzheimer's disease: Biochemical and cellular aspects

Alzheimer's disease (AD) is a major public health concern in all countries. Although the precise cause of AD is still unknown, a growing body of evidence supports the notion that soluble amyloid beta-peptide (Abeta) may be the proximate cause of synaptic injuries and neuronal death early in the disease. AD patients display lower levels of docosahexaenoic acid (DHA, C22:6 ; n-3) in plasma and brain tissues as compared to age-matched controls. Furthermore, epidemiological studies suggest that high DHA intake might have protective properties against neurodegenerative diseases. These observations are supported by in vivo studies showing that DHA-rich diets limits the synaptic loss and cognitive defects induced by Abeta peptide. Although the molecular basis of these neuroprotective effects remains unknown, several mechanisms have been proposed such as (i) regulation of the expression of potentially protective genes, (ii) activation of anti-inflammatory pathways, (iii) modulation of functional properties of the synaptic membranes along with changes in their physicochemical and structural features.

Docosahexaenoic acid stimulates non-amyloidogenic APP processing resulting in reduced Abeta levels in cellular models of Alzheimer's disease

Epidemiological studies suggest that a high intake of polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), is associated with a reduced risk of Alzheimer's disease. Here, we examined the effects of DHA on amyloid precursor protein (APP) processing in cellular models of Alzheimer's disease by analysing levels of different APP fragments, including amyloid-beta (Abeta). DHA administration stimulated non-amyloidogenic APP processing and reduced levels of Abeta, providing a mechanism for the reported beneficial effects of DHA in vivo. However, an increased level of APP intracellular domain was also observed, highlighting the need to increase our knowledge about the relevance of this fragment in Alzheimer's disease pathogenesis. In conclusion, our results suggest that the proposed protective role of DHA in Alzheimer's disease pathogenesis might be mediated by altered APP processing and Abeta production.

Comparison of biochemical effects of statins and fish oil in brain: the battle of the titans

Neural membranes are composed of glycerophospholipids, sphingolipids, cholesterol and proteins. The distribution of these lipids within the neural membrane is not random but organized. Neural membranes contain lipid rafts or microdomains that are enriched in sphingolipids and cholesterol. These rafts act as platforms for the generation of glycerophospholipid-, sphingolipid-, and cholesterol-derived second messengers, lipid mediators that are necessary for normal cellular function. Glycerophospholipid-derived lipid mediators include eicosanoids, docosanoids, lipoxins, and platelet-activating factor. Sphingolipid-derived lipid mediators include ceramides, ceramide 1-phosphates, and sphingosine 1-phosphate. Cholesterol-derived lipid mediators include 24-hydroxycholesterol, 25-hydroxycholesterol, and 7-ketocholesterol. Abnormal signal transduction processes and enhanced production of lipid mediators cause oxidative stress and inflammation. These processes are closely associated with the pathogenesis of acute neural trauma (stroke, spinal cord injury, and head injury) and neurodegenerative diseases such as Alzheimer disease. Statins, the HMG-CoA reductase inhibitors, are effective lipid lowering agents that significantly reduce risk for cardiovascular and cerebrovascular diseases. Beneficial effects of statins in neurological diseases are due to their anti-excitotoxic, antioxidant, and anti-inflammatory properties. Fish oil omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, have similar anti-excitotoxic, antioxidant and anti-inflammatory effects in brain tissue. Thus the lipid mediators, resolvins, protectins, and neuroprotectins, derived from eicosapentaenoic acid and docosahexaenoic acid retard neuroinflammation, oxidative stress, and apoptotic cell death in brain tissue. Like statins, ingredients of fish oil inhibit generation of beta-amyloid and provide protection from oxidative stress and inflammatory processes. Collective evidence suggests that antioxidant, anti-inflammatory, and anti-apoptotic properties of statins and fish oil contribute to the clinical efficacy of treating neurological disorders with statins and fish oil. We speculate that there is an overlap between neurochemical events associated with neural cell injury in stroke and neurodegenerative diseases. This commentary compares the neurochemical effects of statins with those of fish oil.

A diet high in omega-3 fatty acids does not improve or protect cognitive performance in Alzheimer’s transgenic mice

Although a number of epidemiologic studies reported that higher intake of omega-3 fatty acids (largely associated with fish consumption) is protective against Alzheimer's disease (AD), other human studies reported no such effect. Because retrospective human studies are problematic and controlled longitudinal studies over decades are impractical, the present study utilized Alzheimer's transgenic mice (Tg) in a highly controlled study to determine whether a diet high in omega-3 fatty acid, equivalent to the 13% omega-3 fatty acid diet of Greenland Eskimos, can improve cognitive performance or protect against cognitive impairment. Amyloid precursor protein (APP)-sw+PS1 double transgenic mice, as well as nontransgenic (NT) normal littermates, were given a high omega-3 supplemented diet or a standard diet from 2 through 9 months of age, with a comprehensive behavioral test battery administered during the final 6 weeks. For both Tg and NT mice, long-term n-3 supplementation resulted in cognitive performance that was no better than that of mice fed a standard diet. In NT mice, the high omega-3 diet increased cortical levels of omega-3 fatty acids while decreasing omega-6 levels. However, the high omega-3 diet had no effect on cortical fatty acid levels in Tg mice. Irrespective of diet, no correlations existed between brain omega-3 levels and cognitive performance for individual NT or Tg mice. In contrast, brain levels of omega-6 fatty acids were strongly correlated with cognitive impairment for both genotypes. Thus, elevated brain levels of omega-3 fatty acids were not relevant to cognitive function, whereas high brain levels of omega-6 were associated with impaired cognitive function. In Tg mice, the omega-3 supplemental diet did not induce significant changes in soluble/insoluble Abeta within the hippocampus, although strong correlations were evident between hippocampal Abeta(1-40) levels and cognitive impairment. While these studies involved a genetically manipulated mouse model of AD, our results suggest that diets high in omega-3 fatty acids, or use of fish oil supplements (DHA+EPA), will not protect against AD, at least in high-risk individuals. However, normal individuals conceivably could derive cognitive benefits from high omega-3 intake if it corrects an elevation in the brain level of n-6 fatty acids as a result. Alternatively, dietary fish may contain nutrients, other than DHA and EPA, that could provide some protection against AD.

Measurement error adjustment in essential fatty acid intake from a food frequency questionnaire: alternative approaches and methods

Background

We aimed at assessing the degree of measurement error in essential fatty acid intakes from a food frequency questionnaire and the impact of correcting for such an error on precision and bias of odds ratios in logistic models. To assess these impacts, and for illustrative purposes, alternative approaches and methods were used with the binary outcome of cognitive decline in verbal fluency.

Methods

Using the Atherosclerosis Risk in Communities (ARIC) study, we conducted a sensitivity analysis. The error-prone exposure – visit 1 fatty acid intake (1987–89) – was available for 7,814 subjects 50 years or older at baseline with complete data on cognitive decline between visits 2 (1990–92) and 4 (1996–98). Our binary outcome of interest was clinically significant decline in verbal fluency. Point estimates and 95% confidence intervals were compared between naïve and measurement-error adjusted odds ratios of decline with every SD increase in fatty acid intake as % of energy. Two approaches were explored for adjustment: (A) External validation against biomarkers (plasma fatty acids in cholesteryl esters and phospholipids) and (B) Internal repeat measurements at visits 2 and 3. The main difference between the two is that Approach B makes a stronger assumption regarding lack of error correlations in the structural model. Additionally, we compared results from regression calibration (RCAL) to those from simulation extrapolation (SIMEX). Finally, using structural equations modeling, we estimated attenuation factors associated with each dietary exposure to assess degree of measurement error in a bivariate scenario for regression calibration of logistic regression model.

Results and conclusion

Attenuation factors for Approach A were smaller than B, suggesting a larger amount of measurement error in the dietary exposure. Replicate measures (Approach B) unlike concentration biomarkers (Approach A) may lead to imprecise odds ratios due to larger standard errors. Using SIMEX rather than RCAL models tends to preserve precision of odds ratios. We found in many cases that bias in naïve odds ratios was towards the null. RCAL tended to correct for a larger amount of effect bias than SIMEX, particularly for Approach A.

Low- and high-carbohydrate weight-loss diets have similar effects on mood but not cognitive performance

BACKGROUND

Low-carbohydrate diets are often used to promote weight loss, but their effects on psychological function are largely unknown.

OBJECTIVE

We compared the effects of a low-carbohydrate, high-fat (LCHF) diet with a conventional high-carbohydrate, low-fat (HCLF) diet on mood and cognitive function.

DESIGN

Ninety-three overweight or obese participants [x +/- SEM age: 50.2 +/- 0.8 y; body mass index (in kg/m2): 33.6 +/- 0.4] were randomly assigned to an energy-restricted ( approximately 6-7 MJ, 30% deficit), planned isocaloric LCHF diet or an HCLF diet for 8 wk. Body weight and psychological well-being were measured by using the Profile of Mood States, Beck Depression Inventory, and Spielberger State Anxiety Inventory instruments at baseline and fortnightly. Cognitive functioning (working memory and speed of processing) was assessed at baseline and week 8.

RESULTS

The LCHF diet resulted in significantly greater weight loss than did the HCLF diet (7.8 +/- 0.4 and 6.4 +/- 0.4 kg, respectively; P = 0.04). Both groups showed improvements in psychological well-being (P < 0.01 for time), with the greatest effect occurring during the first 2 wk, but there was no significant difference between groups. There were no significant between-group differences in working memory (P = 0.68), but there was a significant time x diet interaction for speed of processing (P = 0.04), so that this measure improved less in the LCHF than in the HCLF diet group.

CONCLUSIONS

Both dietary patterns significantly reduced body weight and were associated with improvements in mood. There was some evidence for a smaller improvement in cognitive functioning with the LCHF diet with respect to speed of processing, but further studies are required to determine the replicability of this finding.

n-3 Fatty acids, hypertension and risk of cognitive decline among older adults in the Atherosclerosis Risk in Communities (ARIC) study

OBJECTIVE

Recent research indicates that n-3 fatty acids can inhibit cognitive decline, perhaps differentially by hypertensive status.

DESIGN

We tested these hypotheses in a prospective cohort study (the Atherosclerosis Risk in Communities). Dietary assessment using a food-frequency questionnaire and plasma fatty acid exposure by gas chromatography were completed in 1987-1989 (visit 1), while cognitive assessment with three screening tools--the Delayed Word Recall Test, the Digit Symbol Substitution Test of the Wechsler Adult Intelligence Scale-Revised and the Word Fluency Test (WFT)--was completed in 1990-1992 (visit 2) and 1996-1998 (visit 4). Regression calibration and simulation extrapolation were used to control for measurement error in dietary exposures.

SETTING

Four US communities--Forsyth County (North Carolina), Jackson (Mississippi), suburbs of Minneapolis (Minnesota) and Washington County (Maryland).

SUBJECTS

Men and women aged 50-65 years at visit 1 with complete dietary data (n = 7814); white men and women in same age group in the Minnesota field centre with complete plasma fatty acid data (n = 2251).

RESULTS

Findings indicated that an increase of one standard deviation in dietary long-chain n-3 fatty acids (% of energy intake) and balancing long-chain n-3/n-6 decreased the risk of 6-year cognitive decline in verbal fluency with an odds ratio (95% confidence interval) of 0.79 (0.66-0.95) and 0.81 (0.68-0.96), respectively, among hypertensives. An interaction with hypertensive status was found for dietary long-chain n-3 fatty acids (g day-1) and WFT decline (likelihood ratio test, P = 0.06). This exposure in plasma cholesteryl esters was also protective against WFT decline, particularly among hypertensives (OR = 0.51, P < 0.05).

CONCLUSION

One implication from our study is that diets rich in fatty acids of marine origin should be considered for middle-aged hypertensive subjects. To this end, randomised clinical trials are needed.

Spatial and visual discrimination reversals in adult and geriatric rats exposed during gestation to methylmercury and n-3 polyunsaturated fatty acids

Fish contain essential long chain polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid (DHA), an omega-3 (or n-3) PUFA, but are also the main source of exposure to methylmercury (MeHg), a potent developmental neurotoxicant. Since n-3 PUFAs support neural development and function, benefits deriving from a diet rich in n-3s have been hypothesized to protect against deleterious effects of gestational MeHg exposure. To determine whether protection occurs at the behavioral level, female Long-Evans rats were exposed, in utero, to 0, 0.5, or 5ppm of Hg as MeHg via drinking water, approximating exposures of 0, 40, and 400 microgHg/kg/day and producing 0, 0.29, and 5.50ppm of total Hg in the brains of siblings at birth. They also received pre- and postnatal exposure to one of two diets, both based on the AIN-93 semipurified formulation. A "fish-oil" diet was high in, and a "coconut-oil" diet was devoid of, DHA. Diets were approximately equal in alpha-linolenic acid and n-6 PUFAs. As adults, the rats were first assessed with a spatial discrimination reversal (SDR) procedure and later with a visual (nonspatial) discrimination reversal (VDR) procedure. MeHg increased the number of errors to criterion for both SDR and VDR during the first reversal, but effects were smaller or non-existent on the original discrimination and on later reversals. No such MeHg-related deficits were seen when the rats were retested on SDR after 2 years of age. These results are consistent with previous reports and hypotheses that gestational MeHg exposure produces perseverative responding. No interactions between diet and MeHg were found, suggesting that n-3 PUFAs do not guard against these behavioral effects. Brain Hg concentrations did not differ between the diets, either. In geriatric rats, failures to respond were less common and response latencies were shorter for rats fed the fish-oil diet, suggesting that exposure to a diet rich in n-3s may lessen the impact of age-related declines in response initiation.

Alcohol consumption and fatty acid intakes in the 2001-2002 National Health and Nutrition Examination Survey

BACKGROUND

Alcohol consumption has the potential to affect dietary intakes of nutrients; however, little is known about fatty acid intakes among alcohol consumers in the U.S. population.

METHOD

We examined the relation between self-reported alcohol consumption and dietary fatty acid intake in 4,168 adults in the cross-sectional National Health and Nutrition Examination Survey 2001-2002. Fatty acid intake was determined from a single, interviewer-administered 24-hour recall. The adjusted, weighted mean level of dietary fatty acid intakes, as characterized by nutrient density, was calculated as grams of fatty acid per 1,000 kcal of energy consumed according to average daily alcohol consumption and binge-drinking episodes.

RESULTS

Energy intake showed a significant increasing trend across alcohol consumption categories in both genders and binge-drinking categories in men. Women binge drinkers also showed a higher energy intake compared with nonbinge drinkers. Among men, decreased nutrient densities of saturated, monounsaturated, polyunsaturated, linoleic, and alpha-linolenic acids were associated with increasing alcohol consumption. Binge-drinking men but not women had significantly decreased intakes of total saturates, monounsaturates, polyunsaturates and linoleic, alpha-linolenic, eicosapentaenoic, and docosahexaenoic acid. When alcohol energy was excluded from calculation of nutrient densities, the results were similar to those with alcohol energy included, except that total saturated and monounsaturated fatty acid differences were no longer significant. In addition, there was an inverse relationship among men between binge-drinking frequency and total polyunsaturates, linoleic, alpha-linolenic, and eicosapentaenoic acids.

CONCLUSION

Our cross-sectional results suggest that alcohol consumption may impact the dietary intake of essential fatty acids (EFAs). Given the public health importance of both alcohol consumption and intakes of EFAs, prospective studies of the relation should be considered.

Dietary fat and plasma total homocysteine concentrations in 2 adult age groups: the Hordaland Homocysteine Study

BACKGROUND

The intake of n-3 (formerly called omega-3) fatty acids (FAs) may be inversely associated with plasma total homocysteine (tHcy) concentrations, but the epidemiologic data are sparse.

OBJECTIVE

We examined the association between dietary fat and tHcy in a Norwegian population.

DESIGN

A cross-sectional, population-based study of 5917 subjects in 2 age groups (47-49 and 71-74 y old) was conducted with the use of food-frequency questionnaires and measurement of plasma tHcy concentrations.

RESULTS

The intake of saturated FAs (SFAs) was positively and significantly (P for trend < 0.001) associated with tHcy concentrations; the difference in plasma tHcy concentrations between the highest and lowest quartiles of SFAs was 8.8%. The intake of marine very-long-chain n-3 FAs was inversely associated with tHcy concentrations; the difference in plasma tHcy concentrations between the lowest and the highest quartiles was -5.0% (P for trend < 0.001). Intakes of total and monounsaturated fat also were positively associated with plasma tHcy concentrations (P for trend < 0.001 and < 0.005, respectively), whereas the intake of polyunsaturated fat was positively associated with tHcy concentrations only in the younger subjects (P for trend = 0.03). The associations were weakened by additional adjustment for B vitamin intake but remained significant for SFA intake (P < 0.001). When stratified for total B vitamin intake, the inverse association between tHcy concentrations and very-long-chain n-3 FAs was significant only in the highest quartile of B vitamin intake (P for trend = 0.001), regardless of supplement use.

CONCLUSIONS

High intakes of SFAs are associated with high plasma concentrations of tHcy. The inverse association between dietary intakes of very-long-chain n-3 FAs and plasma tHcy concentrations is apparent only at high B vitamin intakes.

Possibilities for the prevention and treatment of cognitive impairment and dementia

The human brain has a remarkable capacity for plasticity, but does it have the capacity for repair and/or regeneration? On the basis of controversial new evidence we speculate that the answer may be ;yes', and suggest that clinicians should therefore approach cognitive impairment and dementia with a new, cautious optimism.

Fish consumption, n-3 fatty acids, and subsequent 5-y cognitive decline in elderly men: the Zutphen Elderly Study

BACKGROUND

Indications have been seen of a protective effect of fish consumption and the intake of n-3 fatty acids on cognitive decline. However, studies are scarce and results inconsistent.

OBJECTIVE

The objective of the study was to examine the associations between fish consumption, the intake of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish and other foods, and subsequent 5-y cognitive decline.

DESIGN

Data on fish consumption of 210 participants in the Zutphen Elderly Study, who were aged 70-89 y in 1990, and data on cognitive functioning collected in 1990 and 1995 were used in the study. The intake of EPA and DHA (EPA+DHA) was calculated for each participant. Multivariate linear regression analysis with multiple adjustments was used to assess associations.

RESULTS

Fish consumers had significantly (P = 0.01) less 5-y subsequent cognitive decline than did nonconsumers. A linear trend was observed for the relation between the intake of EPA+DHA and cognitive decline (P = 0.01). An average difference of approximately 380 mg/d in EPA+DHA intake was associated with a 1.1-point difference in cognitive decline (P = 0.01).

CONCLUSIONS

A moderate intake of EPA+DHA may postpone cognitive decline in elderly men. Results from other studies are needed before definite conclusions about this association can be drawn.

Plasma n-3 fatty acids and the risk of cognitive decline in older adults: the Atherosclerosis Risk in Communities Study

BACKGROUND

Plasma fatty acids may affect the risk of cognitive decline in older adults.

OBJECTIVES

We prospectively studied the association between plasma fatty acids and cognitive decline in adults aged 50-65 y at baseline and conducted a subgroup analysis.

DESIGN

From 1987 through 1989, the Atherosclerosis Risk in Communities (ARIC) Study analyzed plasma fatty acids in cholesteryl esters and phospholipids in whites residing in Minneapolis, MN. From 1990 through 1992 and from 1996 through 1998, 3 neuropsychological tests in the domains of delayed word recall, psychomotor speed, and verbal fluency were administered. We selected cutoffs for statistically reliable cognitive decline in each of these domains and a measure of global cognitive change computed by principal-components analysis. Multivariate logistic regression was conducted. Focusing on n-3 highly unsaturated fatty acids (HUFAs), a subgroup analysis assessed differential association across potential effect modifiers implicated in oxidative stress and increased risk of neurodegenerative disease.

RESULTS

In the 2251 study subjects, the risk of global cognitive decline increased with elevated palmitic acid in both fractions and with high arachidonic acid and low linoleic acid in cholesteryl esters. Higher n-3 HUFAs reduced the risk of decline in verbal fluency, particularly in hypertensive and dyslipidemic subjects. No significant findings were shown for psychomotor speed or delayed word recall.

CONCLUSIONS

Promoting higher intakes of n-3 HUFAs in the diet of hypertensive and dyslipidemic persons may have substantial benefits in reducing their risk of cognitive decline in the area of verbal fluency. However, clinical trials are needed to confirm this finding.

Nutrition challenges for the twenty-first century

Although progress has been made towards international goals for the eradication of hunger and malnutrition, considerable work is still required to achieve them and to respond to emerging public health nutrition challenges. The present paper outlines sixteen major inter-linked nutrition challenges recently identified by the UN Standing Committee on Nutrition. While many of the challenges relate to the nutritional needs of children and mothers, an increased emphasis on nutrition-related chronic diseases that affect later life is also evident. Promoting healthy ageing and the maintenance of physical and mental function in older age are undoubtedly major challenges for the future, and the present paper also informs on the role of nutrition, specifically n-3 essential fatty acids, in the prevention of cognitive decline. The importance of determining the cost-effectiveness of nutrition interventions is advocated, in order that the nutrition community can respond appropriately to global nutrition challenges.

Exploratory study into the relation between plasma phospholipid fatty acid status and cognitive performance

Previous research found a negative association between DHA status and selective attention in pregnant women. Goal of the present exploratory study is to investigate the potential relationship between essential fatty acid status and cognitive performance in a healthy non-pregnant population. Cognitive performance of 54 non-pregnant women was determined at baseline, 3, 15, and 22 weeks later with an objective neurocognitive test battery covering different brain domains. Plasma phospholipid fatty acid status was determined at baseline and at 22 weeks. The fatty acids of primary interest (arachidonic acid, adrenic acid, Osbond acid, eicosapentaenoic acid, and docosahexaenoic acid) were no significant predictors of cognitive performance at baseline or 22 weeks later. However, they attributed significantly (26.3%) to the amount of explained variance of the learning effect on the Stroop task, measuring general speed of information processing. Higher docosahexaenoic acid levels were associated with a slower learning curve. For arachidonic acid the opposite was found. In conclusion, this study provides a preliminary indication that a higher DHA status might be associated with slower learning curves. However, additional studies are necessary.

Cognitive performance is associated with macronutrient intake in healthy young and middle-aged adults

PRIMARY OBJECTIVE

The objective was to examine whether dietary intakes of macronutrients are associated with neuropsychological performance.

RESEARCH DESIGN AND METHOD

Study participants were 3960 adults aged 20-59 years, who completed three neuropsychological tests and a 24-hour dietary recall as a part of the Third National Health and Nutrition Examination Survey, 1988-1994. Poor performance was defined as the test score below gender-specific 15th percentile.

MAIN OUTCOMES AND RESULTS

While holding the energy percentages from different macronutrients, additional 100 kcal intake of energy was associated with a reduced odds of poor performance on serial digital learning test (OR = 0.98, 95% CI = 0.96, 0.99) and symbol digital substitution test (OR = 0.97, 95% CI = 0.96, 0.99). Compared with equivalent energy from carbohydrates, each 5% of energy from poly-unsaturated fatty acids (PUFA) or total fat was associated with a reduced OR of poor performance on simple reaction time test (PUFA: OR = 0.77, 95% CI = 0.63-0.95 and total fat: OR = 0.93, 95% CI = 0.87, 0.99). Poor global cognition was associated with an additional intake of 100 mg cholesterol (OR = 1.14, 95% CI = 1.05, 1.23). These associations were more salient in men.

CONCLUSION

Habitual intake of macronutrients is weakly but significantly associated with cognitive functioning. These relationships are more evident in men.

Modulation of inflammation in brain: a matter of fat

Neuroinflammation is a host defense mechanism associated with neutralization of an insult and restoration of normal structure and function of brain. Neuroinflammation is a hallmark of all major CNS diseases. The main mediators of neuroinflammation are microglial cells. These cells are activated during a CNS injury. Microglial cells initiate a rapid response that involves cell migration, proliferation, release of cytokines/chemokines and trophic and/or toxic effects. Cytokines/chemokines stimulate phospholipases A2 and cyclooxygenases. This results in breakdown of membrane glycerophospholipids with the release of arachidonic acid (AA) and docosahexaenoic acid (DHA). Oxidation of AA produces pro-inflammatory prostaglandins, leukotrienes, and thromboxanes. One of the lyso-glycerophospholipids, the other products of reactions catalyzed by phospholipase A2, is used for the synthesis of pro-inflammatory platelet-activating factor. These pro-inflammatory mediators intensify neuroinflammation. Lipoxin, an oxidized product of AA through 5-lipoxygenase, is involved in the resolution of inflammation and is anti-inflammatory. Docosahexaenoic acid is metabolized to resolvins and neuroprotectins. These lipid mediators inhibit the generation of prostaglandins, leukotrienes, and thromboxanes. Levels of prostaglandins, leukotrienes, and thromboxanes are markedly increased in acute neural trauma and neurodegenerative diseases. Docosahexaenoic acid and its lipid mediators prevent neuroinflammation by inhibiting transcription factor NFkappaB, preventing cytokine secretion, blocking the synthesis of prostaglandins, leukotrienes, and thromboxanes, and modulating leukocyte trafficking. Depending on its timing and magnitude in brain tissue, inflammation serves multiple purposes. It is involved in the protection of uninjured neurons and removal of degenerating neuronal debris and also in assisting repair and recovery processes. The dietary ratio of AA to DHA may affect neurodegeneration associated with acute neural trauma and neurodegenerative diseases. The dietary intake of docosahexaenoic acid offers the possibility of counter-balancing the harmful effects of high levels of AA-derived pro-inflammatory lipid mediators.