A gene-environment interplay between omega-3 supplementation and APOE ε4 provides insights for Alzheimer's disease precise prevention amongst high-genetic-risk population

Roles of ApoE4 on the Pathogenesis in Alzheimer's Disease and the Potential Therapeutic Approaches

The Apolipoprotein E ε4 (ApoE ε4) allele, encoding ApoE4, is the strongest genetic risk factor for late-onset Alzheimer's disease (LOAD). Emerging epidemiological evidence indicated that ApoE4 contributes to AD through influencing β-amyloid (Aβ) deposition and clearance. However, the molecular mechanisms of ApoE4 involved in AD pathogenesis remains unclear. Here, we introduced the structure and functions of ApoE isoforms, and then we reviewed the potential mechanisms of ApoE4 in the AD pathogenesis, including the effect of ApoE4 on Aβ pathology, and tau phosphorylation, oxidative stress; synaptic function, cholesterol transport, and mitochondrial dysfunction; sleep disturbances and cerebrovascular integrity in the AD brains. Furthermore, we discussed the available strategies for AD treatments that target to ApoE4. In general, this review overviews the potential roles of ApoE4 in the AD development and suggests some therapeutic approaches for AD. ApoE4 is genetic risk of AD. ApoE4 is involved in the AD pathogenesis. Aβ deposition, NFT, oxidative stress, abnormal cholesterol, mitochondrial dysfunction and neuroinflammation could be observed in the brains with ApoE4. Targeting the interaction of ApoE4 with the AD pathology is available strategy for AD treatments.

Potential Neuroprotective Effects of Dietary Omega-3 Fatty Acids on Stress in Alzheimer's Disease

BACKGROUND

A large number of individual potentially modifiable factors are associated with risk for Alzheimer's disease (AD). However, less is known about the interactions between the individual factors.

METHODS

In order to begin to examine the relationship between a pair of factors, we performed a pilot study, surveying patients with AD and controls for stress exposure and dietary omega-3 fatty acid intake to explore their relationship for risk of AD.

RESULTS

For individuals with the greatest stress exposure, omega-3 fatty acid intake was significantly greater in healthy controls than in AD patients. There was no difference among those with low stress exposure.

CONCLUSIONS

These initial results begin to suggest that omega-3 fatty acids may mitigate AD risk in the setting of greater stress exposure. This will need to be examined with larger populations and other pairs of risk factors to better understand these important relationships. Examining how individual risk factors interact will ultimately be important for learning how to optimally decrease the risk of AD.

The Relationship of Omega-3 Fatty Acids with Dementia and Cognitive Decline: Evidence from Prospective Cohort Studies of Supplementation, Dietary Intake, and Blood Markers

Previous data have linked omega-3 fatty acids with risk of dementia. We aimed to assess the longitudinal relationships of omega-3 polyunsaturated fatty acid intake as well as blood biomarkers with risk of Alzheimer's disease (AD), dementia, or cognitive decline. Longitudinal data were derived from 1135 participants without dementia (mean age = 73 y) in the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort to evaluate the associations of omega-3 fatty acid supplementation and blood biomarkers with incident AD during the 6-y follow-up. A meta-analysis of published cohort studies was further conducted to test the longitudinal relationships of dietary intake of omega-3 and its peripheral markers with all-cause dementia or cognitive decline. Causal dose-response analyses were conducted using the robust error meta-regression model. In the ADNI cohort, long-term users of omega-3 fatty acid supplements exhibited a 64% reduced risk of AD (hazard ratio: 0.36, 95% confidence interval: 0.18, 0.72; P = 0.004). After incorporating 48 longitudinal studies involving 103,651 participants, a moderate-to-high level of evidence suggested that dietary intake of omega-3 fatty acids could lower risk of all-cause dementia or cognitive decline by ∼20%, especially for docosahexaenoic acid (DHA) intake (relative risk [RR]: 0.82, I2 = 63.6%, P = 0.001) and for studies that were adjusted for apolipoprotein APOE ε4 status (RR: 0.83, I2 = 65%, P = 0.006). Each increment of 0.1 g/d of DHA or eicosapentaenoic acid (EPA) intake was associated with an 8% ∼ 9.9% (Plinear < 0.0005) lower risk of cognitive decline. Moderate-to-high levels of evidence indicated that elevated levels of plasma EPA (RR: 0.88, I2 = 38.1%) and erythrocyte membrane DHA (RR: 0.94, I2 = 0.4%) were associated with a lower risk of cognitive decline. Dietary intake or long-term supplementation of omega-3 fatty acids may help reduce risk of AD or cognitive decline.

Effect of nutrition in Alzheimer's disease: A systematic review

Background and objective

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by declining cognitive ability. Currently, there are no effective treatments for this condition. However, certain measures, such as nutritional interventions, can slow disease progression. Therefore, the objective of this systematic review was to identify and map the updates of the last 5 years regarding the nutritional status and nutritional interventions associated with AD patients.

Study design

A systematic review.

Methods

A search was conducted for randomized clinical trials, systematic reviews, and meta-analyses investigating the association between nutritional interventions and AD published between 2018 and 2022 in the PubMed, Web of Science, Scopus, and Cochrane Library databases. A total of 38 studies were identified, of which 17 were randomized clinical trials, and 21 were systematic reviews and/or meta-analyses.

Results

The results show that the western diet pattern is a risk factor for developing AD. In contrast, the Mediterranean diet, ketogenic diet, and supplementation with omega-3 fatty acids and probiotics are protective factors. This effect is significant only in cases of mild-to-moderate AD.

Conclusion

Certain nutritional interventions may slow the progression of AD and improve cognitive function and quality of life. Further research is required to draw more definitive conclusions.

Gene-environment interactions in Alzheimer disease: the emerging role of epigenetics

With the exception of a few monogenic forms, Alzheimer disease (AD) has a complex aetiology that is likely to involve multiple susceptibility genes and environmental factors. The role of environmental factors is difficult to determine and, until a few years ago, the molecular mechanisms underlying gene-environment (G × E) interactions in AD were largely unknown. Here, we review evidence that has emerged over the past two decades to explain how environmental factors, such as diet, lifestyle, alcohol, smoking and pollutants, might interact with the human genome. In particular, we discuss how various environmental AD risk factors can induce epigenetic modifications of key AD-related genes and pathways and consider how epigenetic mechanisms could contribute to the effects of oxidative stress on AD onset. Studies on early-life exposures are helping to uncover critical time windows of sensitivity to epigenetic influences from environmental factors, thereby laying the foundations for future primary preventative approaches. We conclude that epigenetic modifications need to be considered when assessing G × E interactions in AD.