Omega-3 fatty acids and their importance for the prevention of Alzheimer's and dementia

Abstract: Long-term study on the role of DHA

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

Docosahexaenoic acid (DHA) may help prevent Alzheimer's disease (AD). Red blood cell (RBC) DHA status 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), the association of RBC DHA with the occurrence of AD was investigated, also testing an interaction with the APOE ε4 gene. During the follow-up period (median: 7.2 years), 131 cases of AD were documented. In fully adjusted models, the risk of AD occurrence was 49% lower in the highest RBC DHA quintile (Q5) than in 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 could provide an estimated 4.7 additional years of AD-free life. An interaction between DHA and APOE ε4 carriership for AD was observed. Borderline statistical significance for a lower risk of AD was found per standard deviation increase in RBC DHA in APOE ε4 carriers (HR: 0.71, 95% CI: 0.51, 1.00, p = 0.053), but not in non-carriers (HR: 0.85, 95% CI: 0.65, 1.11, p = 0.240). These results add to the growing literature suggesting a robust association and worthy of investigating dietary DHA as a strategy to prevent or delay AD ​ ( MDPI ) ​.

Abstract: Meta-analysis on the relationship between omega-3 fatty acids and dementia and cognitive decline

Title of the study: "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 to the risk of dementia. The aim of this study was to evaluate the longitudinal relationships of omega-3 polyunsaturated fatty acid intake as well as blood biomarkers with the risk of Alzheimer's disease (AD), dementia, or cognitive decline. Longitudinal data were used from 1135 dementia-free participants (mean age = 73 years) of the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort to evaluate the associations of omega-3 fatty acid supplementation and blood biomarkers with the occurrence of AD during 6 years of follow-up. A meta-analysis of published cohort studies was conducted to test the longitudinal relationships of dietary omega-3 intake and its peripheral markers with dementia or cognitive decline. Causal dose-response analyses were performed using the robust error meta-regression model. In the ADNI cohort, long-term users of omega-3 fatty acid supplements showed a 64% reduced risk of AD (hazard ratio: 0.36, 95% CI: 0.18, 0.72; P = 0.004). After including 48 longitudinal studies with 103,651 participants, a moderate-high level of evidence was found that dietary intake of omega-3 fatty acids can reduce the risk of dementia or cognitive decline by about 20%, especially for DHA intake (relative risk [RR]: 0.82, I2 = 63.6%, P = 0.001) and for studies adjusted for apolipoprotein APOE ε4 status (RR: 0.83, I2 = 65%, P = 0.006). Each increase in intake of 0.1 g/day of DHA or eicosapentaenoic acid (EPA) was associated with an 8% to 9.9% (Plinear < 0.0005) lower risk of cognitive decline. Moderate-high levels of evidence suggested that increased plasma levels of EPA (RR: 0.88, I2 = 38.1%) and DHA in red blood cell membranes (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 the risk of AD or cognitive decline ​ ( SciTechDaily ) ​.

W-questions on the role of omega-3 fatty acids in Alzheimer's and dementia

What are omega-3 fatty acids and why are they important?

Omega-3 fatty acids are essential, polyunsaturated fatty acids that are important for many bodily functions, especially for brain and cardiovascular health. Since the human body cannot produce them itself, they must be obtained through food or supplements. The most important omega-3 fatty acids include docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and alpha-linolenic acid (ALA)​ ( Alzheimer Germany ) ​.

What is docosahexaenoic acid (DHA) and what role does it play in preventing Alzheimer's?

DHA is an omega-3 fatty acid that plays a central role in the functionality of the central nervous system. It is particularly important for cognitive functions, learning ability and many other neurological processes. Studies have shown that higher levels of DHA in the blood are associated with a lower risk of developing Alzheimer's and other dementias​ ( MDPI ) ​.

How was the long-term study on the role of DHA conducted and what were the results?

The long-term study of the role of DHA was conducted within the Framingham Offspring Cohort and included 1490 dementia-free participants aged 65 years and older. Participants were followed for a median of 7.2 years, and 131 cases of Alzheimer's were documented. The study found that the risk of developing Alzheimer's was 49% lower among participants in the highest quintile of RBC DHA levels than among those in the lowest quintile​ ( MDPI ) ​.

What results did the meta-analysis show on the relationship between omega-3 fatty acids and dementia and cognitive decline?

The meta-analysis included 48 long-term studies with a total of 103,651 participants. It found that long-term supplementation with omega-3 fatty acids can reduce the risk of Alzheimer's disease by 64%. The analysis also showed that DHA and EPA intake can reduce the risk of cognitive decline by about 20%. Each increase in intake of 0.1 g/day of DHA or EPA was associated with an 8% to 9.9% lower risk of cognitive decline​ ( SciTechDaily ) ​.


The results of the studies underline the important role of DHA and other omega-3 fatty acids in the prevention of Alzheimer's disease and dementia. Regular intake of these essential fatty acids, either through eating fatty fish or through dietary supplements, could be an effective strategy to reduce the risk of dementia and support cognitive health.


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