Nutrient biomarkers and vascular risk factors in subtypes of mild cognitive impairment: a cross-sectional study

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

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

Association Between Dietary Fish and PUFA Intake in Midlife and Dementia in Later Life: The JPHC Saku Mental Health Study

BACKGROUND

The relationship between midlife dietary habits and risk of dementia remains unclear.

OBJECTIVE

To investigate the association between dietary fish and n-3 polyunsaturated fatty acid (PUFA) consumption in midlife and risk of dementia in later life.

METHODS

This population-based cohort study assessed food frequency (average intake in 1995 and 2000) and cognition (2014-2015) in 1,127 participants (aged 45-64 in 1995). We used logistic regression analyses to calculate odds ratios (ORs) for dementia and mild cognitive impairment (MCI) diagnoses for consumption quartiles of fish, PUFA-rich fish, total n-3 PUFAs, total n-6 PUFAs, types of PUFAs, and n-3/n-6 PUFA ratio. Estimated ORs were adjusted for age; sex; education; smoking status; alcohol consumption frequency; physical activity; histories of cancer, myocardial infarction, and diabetes mellitus; and depression.

RESULTS

Significantly reduced risks of dementia over non-dementia (MCI plus cognitively normal) were observed in the second (OR = 0.43 (95% CI = 0.20-0.93)), third (OR = 0.22 (95% CI = 0.09-0.54)), and highest quartiles (OR = 0.39 (95% CI = 0.18-0.86)) for fish; the third (OR = 0.39 (95% CI = 0.16-0.92)) and highest quartiles (OR = 0.44 (95% CI = 0.19-0.98)) for eicosapentaenoic acid (EPA); the second (OR = 0.39 (95% CI = 0.18-0.84)), third (OR = 0.30 (95% CI = 0.13-0.70)), and highest quartiles (OR = 0.28 (95% CI = 0.12-0.66)) for docosahexaenoic acid (DHA); and the third (OR = 0.36 (95% CI = 0.16-0.85)) and highest quartiles (OR = 0.42 (95% CI = 0.19-0.95)) for docosapentaenoic acid (DPA).

CONCLUSION

High intake of fish in midlife might aid in preventing dementia.

The role of peripheral fatty acids as biomarkers for Alzheimer's disease and brain inflammation

Alzheimer's disease (AD) is a complex and heterogeneous neurodegenerative disease. A wide range of techniques have been proposed to facilitate early diagnosis of AD, including biomarkers from the cerebrospinal fluid and blood. Although phosphorylated tau and amyloid beta are amongst the most promising biomarkers of AD, other peripheral biomarkers have been identified and in this review we synthesize the current knowledge on circulating fatty acids. Fatty acids are involved in different biological process including neurotransmission and inflammation. Interestingly, some fatty acids appear to be modulated during disease progression, including long chain saturated fatty acids, and polyunsaturated fatty acids, such as docosahexaenoic acid . However, discrepant results have been reported in the literature and there is the need for further validation and method standardization. Nonetheless, our literature review suggests that fatty acid analyses could potentially provide a valuable source of data to further inform the pathology and progression of AD.

Blood fatty acids in Alzheimer's disease and mild cognitive impairment: A meta-analysis and systematic review

Plasma fatty acids have been reported to be dysregulated in mild cognitive impairment (MCI) and Alzheimer's disease (AD), though outcomes are not always consistent, and subject numbers often small. Our aim was to use a meta-analysis and systematic review approach to identify if plasma fatty acid dysregulation would be observed in case control studies of AD and MCI. Six databases were searched for studies reporting quantified levels of fatty acids in MCI and/or AD individuals, relative to cognitively normal controls. Docosahexaenoic (DHA) and vaccenic acids were significantly lower and higher respectively in MCI relative to controls. Total fatty acids were 27.2% lower in AD relative to controls, and this was reflected almost uniformly in all specific fatty acids in AD. Changes to plasma/serum fatty acids were identified in both MCI and AD relative to age and gender matched controls. Differences were greatest in AD, in both total number of fatty acids significantly altered, and the degree of change. Docosahexaenoic acid was lower in both MCI and AD, suggesting that it may be a driver of pathology.

Mfsd2a Reverses Spatial Learning and Memory Impairment Caused by Chronic Cerebral Hypoperfusion via Protection of the Blood-Brain Barrier

Disruption of the blood–brain barrier (BBB) can lead to cognitive impairment. Major facilitator superfamily domain-containing protein 2a (Mfsd2a) is a newly discovered protein that is essential for maintaining BBB integrity. However, the role of Mfsd2a in vascular cognitive impairment has not been explored yet. In this study, a rat model of chronic cerebral hypoperfusion (CCH) was established by producing permanent bilateral common carotid artery occlusion (2VO) in rats. We found that after the 2VO procedure, the rats exhibited cognitive impairment, showed increased BBB leakage within the hippocampus, and had reduced expression of the Mfsd2a protein. The overexpression of Mfsd2a in the rat hippocampus reversed these changes. Further investigations using transmission electron microscopy revealed a significantly increased rate of vesicular transcytosis in the BBB of the hippocampus of the CCH rats; the rate reduced after overexpression of Mfsd2a. Moreover, Mfsd2a overexpression did not cause changes in the expression of tight junction-associated proteins and in the ultrastructures of the tight junctions. In conclusion, Mfsd2a attenuated BBB damage and ameliorated cognitive impairment in CCH rats, and its protective effect on the BBB was achieved via inhibition of vesicular transcytosis.

Protection of blood-brain barrier as a potential mechanism for enriched environments to improve cognitive impairment caused by chronic cerebral hypoperfusion

BACKGROUND

Chronic cerebral hypoperfusion (CCH) is a common pathophysiological basis for Alzheimer's Disease and vascular dementia in the early stages. It has been confirmed that blood-brain barrier (BBB) destruction is a key factor in CCH-related cognitive impairment. Here we explored the effects of an enriched environment (EE) intervention on CCH-induced BBB destruction and cognitive impairment, and the underlying mechanism.

METHODS

Rats in the EE group were exposed to an EE, while the standard environment (SE) group was maintained in a standard cage with bedding but no other objects. On day 14, CCH was induced via permanent bilateral common carotid artery occlusion (2VO). Next, Evans blue (EB) leakage in the hippocampus was measured by chemical colorimetry to dynamically evaluate BBB permeability. On day 28, the BBB ultrastructure was observed using transmission electron microscopy. The expression levels of BBB integrity-related proteins, matrix metalloproteinases-2/-9 (MMP-2/-9), and the classical Wnt/β-catenin signaling pathway-related proteins were detected using western-blotting techniques. On day 43, cognitive function was assessed using the Morris water maze.

RESULTS

After 2VO, CCH rats exposed to the SE developed obvious cognitive impairment and BBB destruction. BBB damage was manifested through increased EB leakage, ultrastructural destruction, degradation of BBB integrity-related proteins, and up-regulation of MMP-2/-9. These changes were significantly alleviated after the EE intervention. In addition, EEs activated the Wnt/β-catenin signaling pathway in the hippocampus of rats.

CONCLUSIONS

These results suggest that protection of the BBB may be a novel mechanism by which EEs ameliorate CCH-induced cognitive impairment, and this effect may be related to the activation of the Wnt/β-catenin pathway.

Vitamin D3 favorable outcome on recognition memory and prefrontal cortex expression of choline acetyltransferase and acetylcholinesterase in experimental model of chronic high-fat feeding

Aim of the study: High-fat diet (HFD) consumption and insufficient vitamin D levels are globally increasing phenomena. The present study assessed the effect of chronic HFD feeding with and without vitamin D supplementation on recognition memory and prefrontal cortex expression of choline acetyltransferase (CAT) and acetylcholinesterase (Achase).Materials and methods: Forty male Wistar rats were subjected to four dietary regimens (n = 10); control diet (10% fat), control + vitamin D3, high-fat diet (HFD 45% fat) and HFD + vitamin D3 for 6 months. Rats were tested for the novel object recognition test, and their prefrontal cortices were assessed for expression of CAT and Achase.Results: Recognition memory was impaired in HFD-fed rats compared to control rats as evidenced by significantly decreased discrimination index in the novel object recognition test. Moreover, CAT expression was significantly decreased while Achase expression was significantly increased in the prefrontal cortex of HFD-fed rats. Vitamin D3 supplementation with HFD significantly increased the exploration of the novel object and the discrimination index and attenuated the alterations in the prefrontal cortex CAT and Achase expression.Conclusions: The present findings support the potential effect of vitamin D on recognition memory and cholinergic transmission in the prefrontal cortex and add to the pathophysiology of HFD consumption.

Serum vitamin D in patients with mild cognitive impairment and Alzheimer's disease

OBJECTIVES

To determine the relevance of Mini-Mental State Examination (MMSE), serum 25-hydroxyvitamin D (25(OH)D3), and 1,25(OH)2D3 concentrations to mild cognitive impairment (MCI) and various stages of Alzheimer's disease (AD).

MATERIALS AND METHODS

The study included 230 participants (>74 years) allocated to three main groups: 1-healthy subjects (HS, n = 61), 2-patients with MCI (n = 61), and 3- patients with Alzheimer's disease (AD) subdivided into three stages: mild (n = 41), moderate (n = 35), and severe AD (n = 32). The cognitive status was evaluated using MMSE. Serum 25 (OH)D3 (ng/ml) and 1,25(OH)2D3 concentrations (pg/ml) were determined by competitive radioimmunoassay.

RESULTS

MMSE scores and 25(OH)D3 were decreased in MCI and all stages of the AD in both genders. MMSE variability was due to gender in HS (11%) and to 25(OH)D3 in MCI (15%) and AD (26%). ROC analysis revealed an outstanding property of MMSE in diagnosis of MCI (AUC, 0.906; CI 95%, 0.847-0.965; sensitivity 82%; specificity, 98%) and AD (AUC, 0.997; CI 95%, 0.992-1; sensitivity, 100%; specificity, 98%). 25(OH)D3 exhibited good property in MCI (AUC, 0.765; CI 95%, 0.681-0.849; sensitivity, 90%; specificity, 54%) and an excellent property in diagnosis of AD (AUC, 0.843; CI 95%, 0.782-0.904; sensitivity, 97%; specificity, 79%). Logistic analyses revealed that, in MCI, MMSE could predict (or classify correctly) with 97.6% accuracy (Wald, 15.22, β, -0.162; SE, 0.554; OR = 0.115:0.039-0.341; p = .0001), whereas 25(OH)D3 with 80% accuracy (Wald, 41,013; β, -0.213; SE, 0.033; OR = 0.808: 0.757-863; p = .0001). 25(OH)D3 was the only significant predictor for the severe AD and contributed to MMSE variability. Age and gender were significant predictors only in the moderate AD. In patients with MCI, 25(OH)D3 and 1,25(OH)2D3 were correlated men, but in case of the AD, they were correlated in women.

CONCLUSIONS

MMSE and serum 25(OH)D3 concentrations could be useful biomarkers for prediction and diagnosis of MCI and various stages of the AD. The results support the utility of vitamin D supplementation in AD therapy regimen.

Associations between Plasmatic Polyunsaturated Fatty Acids Concentrations and Cognitive Status and Decline in Neurocognitive Disorders

OBJECTIVE

To examine the association of plasmatic and erythrocyte concentrations polyunsaturated fatty acids (PUFA) with both cognitive status and decline.

DESIGN

Longitudinal observational cohort study.

SETTING

Memory Clinic of Lyon Sud university hospital.

PARTICIPANTS

140 patients, aged 60 and older, were referred to the memory clinic, and successively included in the cohort, between March 2010 and February 2014.

MEASUREMENTS

Concentration of ω-3 PUFA (eicosapentaenoic: EPA and docosahexaenoic: DHA) and ω-6 PUFA (arachidonic: AA), were measured at baseline in plasma and in the erythrocytes membrane. Cognitive status was assessed using the mini mental state examination (MMSE), at baseline and every six months during follow-up. The median follow-up period was of 11,5 months.

RESULTS

Compared to participants with minor neurocognitive disorders (MMSE≥24), participants with major neurocognitive disorders (NCD) had lower plasmatic concentrations of EPA and DHA (p<0.05) at baseline. Erythrocyte AA and DHA concentrations were significantly lower in patients with cognitive decline (defined as a ≥2 points loss of MMSE per year), while no difference in plasmatic concentrations was observed.

CONCLUSIONS

Our study suggests that ω-3 PUFA plasma concentrations (mainly EPA and DHA) could be associated with cognitive status in older people. Moreover, in this exploratory study, lower erythrocyte PUFA concentrations (AA and DHA) were associated with accelerated decline and could be proposed as a surrogate marker for prediction of cognitive decline.

Factors Influencing Serum-Hydroxivitamin D Levels and Other Bone Metabolism Parameters in Healthy Older Women

OBJECTIVE

Older women have frequently low serum 25-hydroxivitamin D (25[OH]D) concentrations, high parathormone (PTH) levels and low bone mineral density (BMD) values. Endogenous synthesis, dietary habits, sunlight exposure and fat-mass-mediated storage may influence 25(OH)D levels and bone metabolism, but the relevance of these factors in the elderly has yet to be fully elucidated. We aimed to investigate the influence of dietary vitamin D intake and fat mass on serum 25(OH)D levels and bone metabolism in older women.

DESIGN

Cross-sectional.

SETTING

Community.

PARTICIPANTS

218 fit older women attending a biweekly mild fitness program.

MEASUREMENTS

Dietary habits was investigated through a 3-day record questionnaire. Serum 25(OH)D and intact parathormone (PTH) concentrations were measured by radioimmunoassay and by a 2-step immunoradiometric assay, respectively. BMD and body composition were estimated using dual-energy X-ray absorptiometry with fan-beam technology.

RESULTS

Only fat mass showed a significant negative association with 25(OH)D (β=-3.76, p<0.001), and positive associations with whole body, lumbar, femoral neck and total hip BMD. Binary logistic analysis revealed a protective effect of adiposity on secondary hyperparathyroidism (OR=0.42, 95%CI:0.19-0.92, p=0.03). Dietary vitamin D intake was not associated to any of these outcomes.

CONCLUSION

Fat mass has a greater influence on serum 25(OH)D than dietary vitamin D intake.

Vitamin D Status and the Risk of Recurrent Stroke and Mortality in Ischemic Stroke Patients: Data from a 24-Month Follow-Up Study in China

PURPOSE

In this study, we determined serum 25-hydroxyvitamin D [25(OH) D] levels in serum, and investigated their associations with risk of recurrent stroke and mortality in a 24-month follow up study in Chinese patients with first-ever ischemic stroke.

METHODS

In this preplanned post hoc analysis, serum levels of 25(OH) D and NIH stroke scale (NIHSS) were measured at the time of admission in a cohort of patients with ischemic stroke. We used logistic regression model to assess the relationship between 25(OH) D levels and risk recurrent stroke or mortality.

RESULTS

The follow-up rate was 98.2% in 220 stroke patients. Of 216 patients, 18.5% (95%CI: 13.3%-23.7%) patients had a stroke recurrence, and 30.1% (95% CI: 24.0%-36.2%) died. After adjustment for traditional risk factors, serum 25(OH) D levels were negatively associated with the risk of stroke recurrence (odds ratio [OR], 0.77; 95% confidence interval [CI], 0.70-0.85; P < 0.001) and negatively associated with mortality during 24 months of follow-up (OR, 0.72; 95% CI, 0.64-0.80; P< 0.001). Compared with the first quartile of serum 25(OH) D levels, the ORs for stroke recurrence and mortality were as follows: second quartile, 0.80 (95% CI, 0.63-0.93) and 0.77 (95% CI, 0.65-0.89); third quartile, 0.42 (95% CI, 0.31-0.55) and 0.39 (95% CI, 0.30-0.52); fourth quartile, 0.12 (95% CI, 0.07-0.19) and 0.10 (95% CI, 0.06-0.15), respectively.

CONCLUSIONS

Lower serum levels of 25(OH) D are independently associated with the stroke recurrence and mortality at 24 months in ischemic stroke patients.

Docosahexaenoic Acid and Cognition throughout the Lifespan

Docosahexaenoic acid (DHA) is the predominant omega-3 (n-3) polyunsaturated fatty acid (PUFA) found in the brain and can affect neurological function by modulating signal transduction pathways, neurotransmission, neurogenesis, myelination, membrane receptor function, synaptic plasticity, neuroinflammation, membrane integrity and membrane organization. DHA is rapidly accumulated in the brain during gestation and early infancy, and the availability of DHA via transfer from maternal stores impacts the degree of DHA incorporation into neural tissues. The consumption of DHA leads to many positive physiological and behavioral effects, including those on cognition. Advanced cognitive function is uniquely human, and the optimal development and aging of cognitive abilities has profound impacts on quality of life, productivity, and advancement of society in general. However, the modern diet typically lacks appreciable amounts of DHA. Therefore, in modern populations, maintaining optimal levels of DHA in the brain throughout the lifespan likely requires obtaining preformed DHA via dietary or supplemental sources. In this review, we examine the role of DHA in optimal cognition during development, adulthood, and aging with a focus on human evidence and putative mechanisms of action.

Docosahexaenoic Acid and Cognition throughout the Lifespan

Docosahexaenoic acid (DHA) is the predominant omega-3 (n-3) polyunsaturated fatty acid (PUFA) found in the brain and can affect neurological function by modulating signal transduction pathways, neurotransmission, neurogenesis, myelination, membrane receptor function, synaptic plasticity, neuroinflammation, membrane integrity and membrane organization. DHA is rapidly accumulated in the brain during gestation and early infancy, and the availability of DHA via transfer from maternal stores impacts the degree of DHA incorporation into neural tissues. The consumption of DHA leads to many positive physiological and behavioral effects, including those on cognition. Advanced cognitive function is uniquely human, and the optimal development and aging of cognitive abilities has profound impacts on quality of life, productivity, and advancement of society in general. However, the modern diet typically lacks appreciable amounts of DHA. Therefore, in modern populations, maintaining optimal levels of DHA in the brain throughout the lifespan likely requires obtaining preformed DHA via dietary or supplemental sources. In this review, we examine the role of DHA in optimal cognition during development, adulthood, and aging with a focus on human evidence and putative mechanisms of action.