People who ranked highest in blood DHA levels were 49% less likely than those with the least amount of DHA in their blood to develop Alzheimer’s Disease (AD) in an observational study conducted on a population called the Framingham Offspring Cohort.
 
The study, conducted by the Fatty Acid Research Institute and published in the journal Nutrients, suggested that a diet rich in this omega-3 fatty acid may slow the development of AD, especially for carriers of the ApoE4 gene, which approximately doubles an individual’s susceptibility.
 
The study recruited 1,490 patients 65 years and older, who did not have dementia at baseline. Researchers examined the association of red blood cell (RBC) DHA with incident Alzheimer’s disease, while also testing for an interaction with carrying the ApoE4 gene.
 
The participants were broken into quintiles based on RBC DHA content, and it was noted that those in the highest quartile, averaging a DHA index of over 6.1%, had a 49% lower risk of developing AD compared with the lowest quintile, which had an average omega-3 DHA index of less than 3.8%. Additionally, an increase in DHA content from the lowest quintile to the highest quintile predicted to provide an estimated 4.7 additional years of life free of AD, according to the authors.
 
To put the public health burden into perspective: “Given that estimated health-care payments in 2021 for all patients with AD or other dementias amount to $355 billion in the US (not including caregiving by family members and other unpaid caregivers), any cost-effective strategy for delaying the onset of AD is of utmost public health interest,” the authors of the study said. “Delaying AD by 5 years leads to 2.7 additional years of life, and 4.8 additional AD-free years for an individual who would have acquired AD is worth over $500,000.”
 
The authors noted that these findings were in line with a previous clinical study appearing in Neurology, which found cross-sectional associations between red blood cell DHA on cognitive performance and brain volume measurements in the same cohort which participated in this study, according to William Harris, PhD, president of FARI, and senior author on the present study.
 
“More interestingly, 15 years ago similar findings were observed by Schaefer et al. in the parents of the individuals who were the focus of this present investigation, i.e. the original Framingham Heart Study cohort. “Schaefer et al. reported that participants in the top quartile of plasma phosphatidylcholine DHA experienced a significant 47% reduction in the risk of developing all-cause dementia compared with those with lower levels. Similar findings a generation apart in a similar genetic pool provide considerable confirmation of this DHA-dementia relationship.”