Abstract
Background:
Previous data have linked omega-3 fatty acid with risk of dementia.
Objectives:
To assess the longitudinal relationships of omega-3 polyunsaturated fatty acids intake as well as blood biomarkers with the risk of Alzheimer's disease (AD), dementia or cognitive decline.
Methods:
Longitudinal data were derived from 1,135 participants without dementia (mean age = 73 years) 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 6-year 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.
Results:
In the ADNI cohort, long-term users of omega-3 fatty acid supplements exhibited a 64% reduced risk of AD (adjusted hazard ratio = 0.36, 95% confidence interval [CI] = 0.54 to 0.96, p = 0.005). After incorporating 48 longitudinal studies involving 103,651 participants, moderate-to-high level of evidence suggested that dietary intake of omega-3 fatty acids could lower the risk of all-cause dementia or cognitive decline by ∼20% , especially for DHA intake (Relative risk [RR] = 0.82, I2 =63.6%, p = 0.001) and for studies that adjusted for APOE ε4 status (RR = 0.83, I2 =65%, p = 0.006). Each increment of 0.1 g per day of DHA or 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 = 0.86, I2 =38.9%) and erythrocyte membrane DHA (RR = 0.94, I2 =0.4%) was associated with a lower risk of cognitive decline.
Conclusions:
Dietary intake or long-term supplementation of omega-3 fatty acid may help reduce the risk of AD or cognitive decline.
Full text
