Eicosapentaenoic Acid Is Associated with Decreased Incidence of Alzheimer's Dementia in the Oldest Old

A Review of Recent Advances in the Management of Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative condition and a form of dementia encountered in medical practice. Despite many proposed and attempted treatments, this disease remains a major puzzle in the public health systems worldwide. The initial part of this article provides an overview and illustration of the primary mechanisms responsible for neuronal damage in AD. Subsequently, it offers a critical evaluation of the most noteworthy studies on pharmacological therapy for AD and outlines recent advancements and novel approaches to managing this condition. Main properties, categorization, Food and Drug Administration (FDA) status, mechanisms of action, benefits, and common side effects of the classical and the most recently proposed pharmacological treatments for AD are described. The conventional pharmacological agents revised comprise cholinesterase inhibitors, monoclonal antibodies, and other therapies, such as memantine, valproic acid, and rosiglitazone. The innovative reviewed pharmacological agents comprise the monoclonal antibodies: donanemab, gantenerumab, solanezumab, bapineuzumab, crenezumab, and semorinemab. Nutritional supplements such as alpha-tocopherol (vitamin E) and caprylidene are also revised. Tau and amyloid-targeting treatments include methylthioninium moiety (MT), leuco-methylthioninium bis (LMTM), an oxidized form of MT, and tramiprosate, which inhibits the beta-amyloid (Aβ) monomer aggregation into toxic oligomers. Antidiabetic and anti-neuroinflammation drugs recently proposed for AD treatment are discussed. The antidiabetic drugs include NE3107, an anti-inflammatory and insulin sensitizer, and the diabetes mainstream drug metformin. The anti-neuroinflammatory AD therapies include the use of sodium oligomannate (GV-971), infusions with intravenous immunoglobulin aiming to decrease plasma levels of the constituents of Aβ plaques, and masitinib, a tyrosine kinase inhibitor that impacts mast and microglia cells. Additional anti-inflammatory agents being currently tested in phase-2 clinical trials, such as atomoxetine (selective norepinephrine reuptake inhibitor), losartan (angiotensin 2 receptor agonist), genistein (anti-inflammatory isoflavone neuroprotective agent), trans-resveratrol (polyphenol antioxidant plant estrogen), and benfotiamine (synthetic thiamine precursor), were reviewed. Lastly, drugs targeting Alzheimer's-associated symptoms, such as brexpiprazole (serotonin dopamine activity modulator) and suvorexant (orexin receptor antagonist), respectively, used for agitation and insomnia in AD patients, are reviewed. As experimental investigations and clinical research progress, there is a possibility that a combination of newly tested medications and traditional ones may emerge as a promising treatment option for AD in the future.

Untargeted Metabolomic Profiling Reveals Differentially Expressed Serum Metabolites and Pathways in Type 2 Diabetes Patients with and without Cognitive Decline: A Cross-Sectional Study

Diabetes is recognized as a risk factor for cognitive decline, but the underlying mechanisms remain elusive. We aimed to identify the metabolic pathways altered in diabetes-associated cognitive decline (DACD) using untargeted metabolomics. We conducted liquid chromatography-mass spectrometry-based untargeted metabolomics to profile serum metabolite levels in 100 patients with type 2 diabetes (T2D) (54 without and 46 with DACD). Multivariate statistical tools were used to identify the differentially expressed metabolites (DEMs), and enrichment and pathways analyses were used to identify the signaling pathways associated with the DEMs. The receiver operating characteristic (ROC) analysis was employed to assess the diagnostic accuracy of a set of metabolites. We identified twenty DEMs, seven up- and thirteen downregulated in the DACD vs. DM group. Chemometric analysis revealed distinct clustering between the two groups. Metabolite set enrichment analysis found significant enrichment in various metabolite sets, including galactose metabolism, arginine and unsaturated fatty acid biosynthesis, citrate cycle, fructose and mannose, alanine, aspartate, and glutamate metabolism. Pathway analysis identified six significantly altered pathways, including arginine and unsaturated fatty acid biosynthesis, and the metabolism of the citrate cycle, alanine, aspartate, glutamate, a-linolenic acid, and glycerophospholipids. Classifier models with AUC-ROC > 90% were developed using individual metabolites or a combination of individual metabolites and metabolite ratios. Our study provides evidence of perturbations in multiple metabolic pathways in patients with DACD. The distinct DEMs identified in this study hold promise as diagnostic biomarkers for DACD patients.

Plasma metabolic profiles predict future dementia and dementia subtypes: a prospective analysis of 274,160 participants

BACKGROUND

Blood-based biomarkers for dementia are gaining attention due to their non-invasive nature and feasibility in regular healthcare settings. Here, we explored the associations between 249 metabolites with all-cause dementia (ACD), Alzheimer's disease (AD), and vascular dementia (VaD) and assessed their predictive potential.

METHODS

This study included 274,160 participants from the UK Biobank. Cox proportional hazard models were employed to investigate longitudinal associations between metabolites and dementia. The importance of these metabolites was quantified using machine learning algorithms, and a metabolic risk score (MetRS) was subsequently developed for each dementia type. We further investigated how MetRS stratified the risk of dementia onset and assessed its predictive performance, both alone and in combination with demographic and cognitive predictors.

RESULTS

During a median follow-up of 14.01 years, 5274 participants developed dementia. Of the 249 metabolites examined, 143 were significantly associated with incident ACD, 130 with AD, and 140 with VaD. Among metabolites significantly associated with dementia, lipoprotein lipid concentrations, linoleic acid, sphingomyelin, glucose, and branched-chain amino acids ranked top in importance. Individuals within the top tertile of MetRS faced a significantly greater risk of developing dementia than those in the lowest tertile. When MetRS was combined with demographic and cognitive predictors, the model yielded the area under the receiver operating characteristic curve (AUC) values of 0.857 for ACD, 0.861 for AD, and 0.873 for VaD.

CONCLUSIONS

We conducted the largest metabolome investigation of dementia to date, for the first time revealed the metabolite importance ranking, and highlighted the contribution of plasma metabolites for dementia prediction.

Plasma Omega-3 Fatty Acids and Risk for Incident Dementia in the UK Biobank Study: A Closer Look

Dietary omega-3 fatty acids are promising nutrients in dementia. Several prospective cohort studies have examined the relationships between circulating omega-3 (an objective biomarker of dietary intake) and incident dementia, the largest to date being a report from the UK Biobank (n = 102,722). Given the recent release of new metabolomics data from baseline samples from the UK Biobank, we re-examined the association in a much larger sample (n = 267,312) and also focused on associations with total omega-3, docosahexaenoic acid (DHA), and non-DHA omega-3. Using Cox regression models, we observed that the total omega-3 status was inversely related to the risk of Alzheimer's (Q5 vs. Q1, hazard ratio [95% confidence interval] = 0.87 [0.76; 1.00]) and all-cause dementia (Q5 vs. Q1, 0.79 [0.72; 0.87]). The strongest associations were observed for total omega-3 (and non-DHA omega-3) and all-cause dementia. In prespecified strata, we found stronger associations in men, and in those aged ≥60 years at baseline (vs. those aged 50-59). Thus, in the largest study to date on this topic, we confirmed the favorable relationships between DHA and risk for dementia, and we also found evidence that non-DHA omega-3 may be beneficial. Finally, we have better defined the populations most likely to benefit from omega-3-based interventions.

Fungi under Modified Atmosphere-The Effects of CO2 Stress on Cell Membranes and Description of New Yeast Stenotrophomyces fumitolerans gen. nov., sp. nov

High levels of carbon dioxide are known to inhibit the growth of microorganisms. A total of twenty strains of filamentous fungi and yeasts were isolated from habitats with enriched carbon dioxide concentration. Most strains were derived from modified atmosphere packed (MAP) food products or mofettes and were cultivated under an atmosphere of 20% CO2 and 80% O2. The influence of CO2 on fungal cell membrane fatty acid profiles was examined in this study. Major changes were the increase in linolenic acid (C18:3 cis 9, 12, 15) and, additionally in most strains, linoleic acid (C18:2 cis 9, 12) with a maximum of 24.8%, at the expense of oleic (C18:1 cis 9), palmitic (C16:0), palmitoleic (C16:1 cis 9) and stearic acid (C18:0). The degree of fatty acid unsaturation increased for all of the strains in the study, which consequently led to lower melting temperatures of the cell membranes after incubation with elevated levels of CO2, indicating fluidization of the membrane and a potential membrane malfunction. Growth was reduced in 18 out of 20 strains in laboratory experiments and a change in pigmentation was observed in several strains. Two of the isolated strains, strain WT5 and strain WR1, were found to represent a hitherto undescribed yeast for which the new genus and species Stenotrophomyces fumitolerans (MB# 849906) is proposed.

Roles of Omega-3 Polyunsaturated Fatty Acids in Managing Cognitive Impairment in Chronic Obstructive Pulmonary Disease: A Review

Chronic obstructive pulmonary disease (COPD) contributes significantly to the death of people worldwide, especially the elderly. An essential feature of COPD is pulmonary inflammation, which results from long-term exposure to noxious substances from cigarette smoking and other environmental pollutants. Pulmonary inflammatory mediators spill over to the blood, leading to systemic inflammation, which is believed to play a significant role in the onset of a host of comorbidities associated with COPD. A substantial comorbidity of concern in COPD patients that is often overlooked in COPD management is cognitive impairment. The exact pathophysiology of cognitive impairment in COPD patients remains a mystery; however, hypoxia, oxidative stress, systemic inflammation, and cerebral manifestations of these conditions are believed to play crucial roles. Furthermore, the use of medications to treat cognitive impairment symptomatology in COPD patients has been reported to be associated with life-threatening adverse effects, hence the need for alternative medications with reduced side effects. In this Review, we aim to discuss the impact of cognitive impairment in COPD management and the potential mechanisms associated with increased risk of cognitive impairment in COPD patients. The promising roles of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in improving cognitive deficits in COPD patients are also discussed. Interestingly, ω-3 PUFAs can potentially enhance the cognitive impairment symptomatology associated with COPD because they can modulate inflammatory processes, activate the antioxidant defence system, and promote amyloid-beta clearance from the brain. Thus, clinical studies are crucial to assess the efficacy of ω-3 PUFAs in managing cognitive impairment in COPD patients.

Effects of donepezil treatment on plasma and urine metabolites in amyloid beta-induced Alzheimer's disease rats

Accumulated clinical and biomedical evidence suggests that abnormalities in systemic metabolic processes such as fatty acid and amino acid metabolism can affect the brain function and behavior of various central nervous system diseases such as Alzheimer's disease (AD). In this study, metabolic profiling was used to investigate changes in plasma and urine metabolites following stereotactic injection of amyloid β (Aβ) and treatment with donepezil in rats. Aβ causes cognitive impairment, while donepezil treatment successfully improves memory impairment. Donepezil improves Aβ-induced plasma fatty acid and bile acid metabolism disorders, as well as Aβ-induced urine phenylalanine and tryptophan metabolism disorders in rats. More specifically, the plasma fatty acids improved by donepezil include alpha-linolenic acid, stearidonic acid, eicosapentaenoic acid, docosahexaenoic acid, linoleic acid, arachidonic acid, oleic acid, and palmitic acid, among others. Additionally, donepezil significantly restored the downregulation of bile acids such as ursodeoxycholic acid, cholic acid, and glycocholic acid caused by Aβ. As for urine metabolites, phenylacetylglycine, epinephrine, and other phenylalanine metabolites, as well as kynurenic acid, xanthurenic acid, and other tryptophan metabolites, were worsened by Aβ and improved by donepezil. These findings suggest that the cognitive impairment induced by Aβ and the improvement by donepezil are associated with changes in metabolic disorders in rats. This study provides basic data for the effects of Aβ and donepezil on plasma and urine metabolites in Aβ-induced AD rat models.

Circulating polyunsaturated fatty acids, fish oil supplementation, and risk of incident dementia: a prospective cohort study of 440,750 participants

Cohort studies report inconsistent associations between omega-3 polyunsaturated fatty acids (n-3 PUFA) or fish oil and dementia risk. Furthermore, evidence relating omega-6 polyunsaturated fatty acids (n-6 PUFA) with dementia is scarce. Here, we included 440,750 dementia-free participants from UK Biobank to comprehensively investigate the associations between plasma levels of different types of PUFA, fish oil supplementation, and dementia risk. During a median follow-up of 9.25 years, 7768 incident dementia events occurred. Higher plasma levels of five PUFA measures showed consistent associations with lower dementia risk (hazard ratios [95% confidence intervals] for per standard deviation increment of plasma concentrations 0.85 [0.81-0.89] for total PUFAs; 0.90 [0.86-0.95] for omega-3 PUFAs; 0.92 [0.87-0.96] for docosahexaenoic acid (DHA); 0.86 [0.82-0.90] for omega-6 PUFAs; 0.86 [0.82-0.90] for linoleic acid (LA); all p < 0.001). Compared with non-users, fish oil supplement users had a 7% decreased risk of developing all-cause dementia (0.93 [0.89-0.97], p = 0.002), and the relationship was partially mediated by plasma n-3 PUFA levels (omega-3 PUFAs: proportion of mediation = 57.99%; DHA: proportion of mediation = 56.95%). Furthermore, we observed significant associations of plasma n-3 PUFA levels and fish oil supplementation with peripheral immune markers that were related to dementia risk, as well as the positive associations of plasma PUFA levels with brain gray matter volumes and white matter microstructural integrity, suggesting they may affect dementia risk by affecting peripheral immunity and brain structure. Taken together, higher plasma PUFA levels and fish oil supplementation were associated with lower risk of incident dementia. This study may support the value of interventions to target PUFAs (specifically n-3 PUFAs) to prevent dementia.

Destabilization of Aβ fibrils by omega-3 polyunsaturated fatty acids: a molecular dynamics study

The senile plaques of neurotoxic aggregates of Aβ protein, deposited extraneuronally, mark the pathological hallmark of Alzheimer's disease (AD). The natural compounds such as omega-3 (ω-3) polyunsaturated fatty acids (PUFAs), which can access blood-brain barrier, are believed to be potential disruptors of preformed Aβ fibrils to cure AD with unknown mechanism. Herein, we present the destabilization potential of three ω-3 PUFAs, viz. Eicosapentaenoic acid (EPA), Docosahexaenoic acid (HXA), and α-linolenic acid (LNL) by molecular dynamics simulation. After an initial testing of 300 ns, EPA and HXA have been considered further for extended production run time, 500 ns. The increased value of root mean square deviation (RMSD), radius of gyration, and solvent-accessible surface area (SASA), the reduced number of H-bonds and β-sheet content, and disruption of salt bridges and hydrophobic contacts establish the binding of these ligands to Aβ fibril leading to destabilization. The polar head was found to interact with positively charged lysine (K28) residue in the fibril. However, the hydrophobicity of the long aliphatic tail competes with the intrinsic hydrophobic interactions of Aβ fibril. This amphiphilic nature of EPA and HXA led to the breaking of inherent hydrophobic contacts and formation of new bonds between the tail of PUFA and hydrophobic residues of Aβ fibril, leading to the destabilization of fibril. The Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) results explain the binding of EPA and HXA to Aβ fibril by interacting with different residues. The destabilization potential of EPA and HXA establishes them as promising drug leads to cure AD, and encourages prospecting of other fatty acids for therapeutic intervention in AD.Communicated by Ramaswamy H. Sarma.

Suppression of Amyloid-β Adsorption on Endoplasmic Reticulum Stress-Mimicking Membranes by α-Tocopherol and α-Tocotrienol

Two forms of hydrophobic vitamin E (VE), α-tocopherol (Toc) and α-tocotrienol (Toc3), have been proposed to be effective against Alzheimer's disease (AD), the etiology of which is thought to involve endoplasmic reticulum (ER) stress. However, previous studies reported conflicting effects of Toc and Toc3 on the risk of AD. We prepared liposomes mimicking the phase separation of the ER membrane (solid-ordered/liquid-disordered phase separation) and studied how VE can influence the interaction between amyloid-β (Aβ) and the ER membrane. We found that Toc could inhibit the formation of the solid-ordered phase more significantly than Toc3. Furthermore, Aβ protofibril adsorption on ER stress-mimicking membranes was more strongly suppressed by Toc compared with Toc3. Therefore, we concluded that VE can relieve ER stress by destabilizing the solid-ordered phase of the ER membrane and subsequently reducing the amount of Aβ adsorbed on the membrane. Moreover, Toc exerted a stronger effect than Toc3.

Evaluating Cannabis sativa L.'s neuroprotection potential: From bench to bedside

BACKGROUND

Neurodegenerative diseases and dementia pose a global health challenge in an aging population, exemplified by the increasing incidence and prevalence of its most common form, Alzheimer's disease. Although several approved treatments exist for Alzheimer's disease, they only afford transient symptomatic improvements and are not considered disease-modifying. The psychoactive properties of Cannabis sativa L. have been recognized for thousands of years and now with burgeoning access to medicinal formulations globally, research has turned to re-evaluate cannabis and its myriad phytochemicals as a potential treatment and adjunctive agent for neurodegenerative diseases.

PURPOSE

This review evaluated the neuroprotective potential of C. sativa's active constituents for potential therapeutic use in dementia and Alzheimer's disease, based on published studies demonstrating efficacy in experimental preclinical settings associated with neurodegeneration.

STUDY DESIGN

Relevant information on the neuroprotective potential of the C. sativa's phytoconstituents in preclinical studies (in vitro, in vivo) were included. The collated information on C. sativa's component bioactivity was organized for therapeutic applications against neurodegenerative diseases.

METHODS

The therapeutic use of C. sativa related to Alzheimer's disease relative to known phytocannabinoids and other phytochemical constituents were derived from online databases, including PubMed, Elsevier, The Plant List (TPL, www.theplantlist.org), Science Direct, as well as relevant information on the known pharmacological actions of the listed phytochemicals.

RESULTS

Numerous C. sativa -prevalent phytochemicals were evidenced in the body of literature as having efficacy in the treatment of neurodegenerative conditions exemplified by Alzheimer's disease. Several phytocannabinoids, terpenes and select flavonoids demonstrated neuroprotection through a myriad of cellular and molecular pathways, including cannabinoid receptor-mediated, antioxidant and direct anti-aggregatory actions against the pathological toxic hallmark protein in Alzheimer's disease, amyloid β.

CONCLUSIONS

These findings provide strong evidence for a role of cannabis constituents, individually or in combination, as potential neuroprotectants timely to the emergent use of medicinal cannabis as a novel treatment for neurodegenerative diseases. Future randomized and controlled clinical studies are required to substantiate the bioactivities of phytocannabinoids and terpenes and their likely synergies.

Red Blood Cell DHA Is Inversely Associated with Risk of Incident Alzheimer's Disease and All-Cause Dementia: Framingham Offspring Study

Docosahexaenoic acid (DHA) might help prevent Alzheimer's disease (AD). Red blood cell (RBC) status of DHA is an objective measure of long-term dietary DHA intake. In this prospective observational study conducted within the Framingham Offspring Cohort (1490 dementia-free participants aged ≥65 years old), we examined the association of RBC DHA with incident AD, testing for an interaction with APOE-ε4 carriership. During the follow-up (median, 7.2 years), 131 cases of AD were documented. In fully adjusted models, risk for incident AD in the highest RBC DHA quintile (Q5) was 49% lower compared with the lowest quintile (Q1) (Hazard ratio [HR]: 0.51, 95% confidence interval [CI]: 0.27, 0.96). An increase in RBC DHA from Q1 to Q5 was predicted to provide an estimated 4.7 additional years of life free of AD. We observed an interaction DHA × APOE-ε4 carriership for AD. Borderline statistical significance for a lower risk of AD was observed per standard deviation increase in RBC DHA (HR: 0.71, 95% CI: 0.51, 1.00, p = 0.053) in APOE-ε4 carriers, but not in non-carriers (HR: 0.85, 95% CI: 0.65, 1.11, p = 0.240). These findings add to the increasing body of literature suggesting a robust association worth exploring dietary DHA as one strategy to prevent or delay AD.

Higher Serum DHA and Slower Cognitive Decline in Patients with Alzheimer's Disease: Two-Year Follow-Up

Omega-3 polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been associated with slower rates of cognitive decline. We investigated the association between omega-3 PUFAs and cognitive function in patients with Alzheimer’s disease (AD) receiving acetylcholinesterase inhibitors (AChEIs). This was a prospective cohort study using registered data. Patients with AD receiving AChEIs were recruited from 1 May 2016 to 30 April 2019 and were followed up for two years. Their daily diet record and blood concentration of omega-3 PUFAs were analyzed. Multiple linear and binary logistic regression was used to determine the factors associated with cognitive decline (continuous and dichotomized cognitive change). In the research, 129 patients with AD were identified with a mean age of 76.5 ± 6.6. Patients with AD with lower baseline omega-3 PUFAs levels were associated with a higher risk of cognitive decline than those with higher levels (odds ratio [OR] = 1.067, 95% confidence interval [CI]: 1.012, 1.125; p = 0.016) after adjustment. Patients with AD with a lower baseline DHA (OR = 1.131, 95% CI: 1.020, 1.254; p = 0.020), but not EPA, were associated with a higher risk of cognitive decline. We found that higher Mini-Nutritional Assessment scores (beta = −0.383, 95% CI = −0.182–−0.048, p = 0.001) and total fat (beta = −0.248, 95% CI = −0.067–−0.003, p = 0.031) were independently associated with slow cognitive decline in patients with AD receiving AChEIs. The baseline blood levels of omega-3 PUFAs were associated with cognitive decline in patients with AD receiving AChEIs. Future randomized controlled trials are needed to clarify whether this association is causal.

Impact of α-Linolenic Acid, the Vegetable ω-3 Fatty Acid, on Cardiovascular Disease and Cognition

Given the evidence of the health benefits of plant-based diets and long-chain n-3 (ω-3) fatty acids, there is keen interest in better understanding the role of α-linolenic acid (ALA), a plant-derived n-3 fatty acid, on cardiometabolic diseases and cognition. There is increasing evidence for ALA largely based on its major food sources (i.e., walnuts and flaxseed); however, this lags behind our understanding of long-chain n-3 fatty acids. Meta-analyses of observational studies have shown that increasing dietary ALA is associated with a 10% lower risk of total cardiovascular disease and a 20% reduced risk of fatal coronary heart disease. Three randomized controlled trials (RCTs) [AlphaOmega trial, Prevención con Dieta Mediterránea (PREDIMED) trial, and Lyon Diet Heart Study] all showed benefits of diets high in ALA on cardiovascular-related outcomes, but the AlphaOmega trial, designed to specifically evaluate ALA effects, only showed a trend for benefit. RCTs have shown that dietary ALA reduced total cholesterol, LDL cholesterol, triglycerides, and blood pressure, and epidemiologic studies and some trials also have shown an anti-inflammatory effect of ALA, which collectively account for, in part, the cardiovascular benefits of ALA. A meta-analysis reported a trend toward diabetes risk reduction with both dietary and biomarker ALA. For metabolic syndrome and obesity, the evidence for ALA benefits is inconclusive. The role of ALA in cognition is in the early stages but shows promising evidence of counteracting cognitive impairment. Much has been learned about the health benefits of ALA and with additional research we will be better positioned to make strong evidence-based dietary recommendations for the reduction of many chronic diseases.

Coronary microvascular dysfunction as a chronic inflammatory state: Is there a role for omega-3 fatty acid treatment?

Coronary microvascular dysfunction is a ubiquitous pathologic process that is operational in ischemia with no obstructive coronary artery disease and other cardiovascular disorders including heart failure with preserved ejection fraction. It may, in fact, be a manifestation of a multi-systemic condition of small vessel dysfunction that also affects the brain and kidneys. While the pathophysiology driving coronary microvascular dysfunction is multifactorial, chronic inflammation plays an important role. Resolution of inflammation is an active process mediated, in part, by a family of locally active mediators biosynthesized from omega-3 fatty acids, collectively referred to as specialized pro-resolving mediators. Omega-3 fatty acid treatment modulates inflammation and is associated with improved cardiovascular outcomes and attenuation of plaque progression on cardiovascular imaging. Whether omega-3 fatty acid treatment attenuates coronary microvascular dysfunction is unknown.

Nutrition, Gut Microbiota, and Alzheimer's Disease

Nutrition is known to play an important role in the pathogenesis of Alzheimer's disease. Evidence is obtained that the gut microbiota is a key player in these processes. Dietary changes (both adverse and beneficial) may influence the microbiome composition, thereby affecting the gut-brain axis and the subsequent risk for Alzheimer's disease progression. In this review, the research findings that support the role of intestinal microbiota in connection between nutritional factors and the risk for Alzheimer's disease onset and progression are summarized. The mechanisms potentially involved in these processes as well as the potential of probiotics and prebiotics in therapeutic modulation of contributed pathways are discussed.