February 27, 2012 — New data from the Framingham Offspring Study cohort suggest that higher dietary intake of the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) may help protect the aging brain.
Dr. Zaldy S. Tan
Results showed that lower red blood cell (RBC) levels of DHA and EPA in late middle age were associated with smaller brain volumes and a "vascular" pattern of cognitive impairment, even in persons free of clinical dementia.
"People with lower blood levels of omega-3 fatty acids had lower brain volumes that were equivalent to about 2 years of structural brain aging," study author Zaldy S. Tan, MD, MPH, from the Easton Center for Alzheimer's Disease Research and the Division of Geriatrics, University of California, Los Angeles, comments in a written statement.
This study, Dr. Tan told Medscape Medical News, "adds to the current body of evidence on the beneficial health effects of omega-3 fatty acids." However, he said, it is premature to make clinical recommendations solely based on this study. "It needs to be validated in other populations and extended to clinical trials, which may be able to provide more specific recommendations."
"With that said, people who are already consuming fish as part of a balanced diet can take stock in the promising findings of this study that omega-3 fatty acid may benefit not only their heart but their brain as well," Dr. Tan said.
The findings were published in the February 28 issue of Neurology.
Building on Prior Studies
Some previous population-based studies have suggested an association between higher intake of fatty fish and a lower risk of dementia, as well as other health outcomes. As previously reported by Medscape Medical News, in the original Framingham Study cohort, individuals with the highest DHA levels had a 47% reduction in all-cause dementia and a 39% lower risk of developing Alzheimer's disease.
"We wanted to see whether RBC omega-3 fatty acid levels (which is more reflective of actual tissue exposure to these nutrients) [have] an effect on structural and cognitive brain aging in the late–middle age, nondemented offspring of the original Framingham Study cohort," Dr. Tan said. "To our knowledge, this is the first study that utilized RBC omega-3 fatty acid levels to markers of brain aging," he added.
The researchers related RBC DHA and EPA levels in 1575 dementia-free men and women (mean age, 67 years) to performance on standard cognitive tests and to volumetric brain magnetic resonance imaging scans.
After adjusting for age, sex, and time interval, those patients with RBC DHA levels in the lowest quartile (Q1, <3.9%) had significantly lower total brain volume (P = .009) and significantly greater white matter hyperintensity volume (P = .049) compared with those patients with higher RBC DHA levels (Q2 - Q4, >3.9%). The association persisted for total brain volume in the fully adjusted multivariable analysis (P = .019).
Participants with lower DHA and DHA+EPA levels (Q1 vs Q2 - Q4) also scored lower on tests of visual memory (P = .008), executive function (P = .004), and abstract thinking (P = .004) in the model, adjusting for age, sex, and time interval. The results remained significant in multivariable analysis.
Results Supportive Not Definitive
"These findings add some favorable data to the question regarding whether polyunsaturated fatty acids (PUFAs), like DHA and omega-3 fatty acids, could be related to better brain health," Rachelle S. Doody, MD, PhD, who was not involved in the study, told Medscape Medical News. Dr. Doody is Effie Marie Cain Chair in Alzheimer's Disease Research and director, Alzheimer's Disease and Memory Disorders Center, Baylor College of Medicine, Houston, Texas.
She said the key strengths of the study are a well-defined population and careful measurements of the PUFAs. "Key limitations are that this study does not investigate causality; you would have to follow people longitudinally to determine whether their levels of these PUFA's influence their brain health or their likelihood of developing dementia over time," Dr. Doody said.
"These findings cannot support definitive actions on the part of prescribing physicians or patients; that is, they do not provide proof that eating fish or taking supplements is beneficial, and they did not address safety," Dr. Doody added.
The study was supported by the Framingham Heart Study's National Heart, Lung, and Blood Institute contract and by the National Institute on Aging. Dr. Tan has received research support from the National Institutes of Health and the National Institute on Aging. A coinvestigator on the study is employed by Health Diagnostic Laboratory Inc, which offers blood omega-3 testing, and is the owner of OmegaQuant LLC, a company that offers blood fatty acid testing. A complete list of author disclosures can be found with the original article. Dr. Doody has disclosed no relevant financial relationships.
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