Omega-3 Levels Enhance B Vitamins’ Ability to Slow Cognitive Decline in Mild Cognitive Impairment
New analysis from an international research team suggests that higher blood levels of Omega-3 fatty acids strengthen the protective effect of B vitamin supplements against cognitive decline in older adults with mild cognitive impairment (MCI).
Researchers from the Universities of Cape Town, Oslo, Oxford and the UAE examined more than 250 people with MCI in Oxford. MCI describes a level of cognitive decline greater than expected for age but not severe enough to interfere with daily life. While not as advanced as dementia, MCI often progresses to dementia if left untreated.
Dr. Celeste de Jager explained that earlier work showed B vitamin supplementation can slow brain atrophy and memory loss in people with MCI, particularly in those with elevated homocysteine, a marker tied to B vitamin status that may be harmful to the brain. “Scientists in our group initially observed a relationship among Omega-3 levels, homocysteine, and brain atrophy rates. This led us to investigate whether Omega-3 fatty acids and B vitamins interact to prevent cognitive decline,” she said.
At baseline, participants completed cognitive tests and provided blood samples to measure two common long-chain Omega-3 fatty acids found in oily fish: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The study randomly assigned participants to receive either a B-vitamin supplement (folic acid, vitamin B6 and vitamin B12) or a placebo for two years. Cognitive performance was reassessed at the end of the intervention and compared with the initial measurements.
Dr. Abderrahim Oulhaj reported a clear interaction between Omega-3 status and the effect of B vitamins: “For people with low Omega-3 levels, the vitamin supplements had little to no benefit. But among those with higher baseline Omega-3 concentrations, B vitamins were effective in reducing cognitive decline compared with placebo. This finding complements our previous observation that B vitamins slow brain atrophy in MCI only when Omega-3 levels are adequate at the start.”
The investigators also noted that DHA appeared to be a stronger predictor of benefit than EPA, although they caution that additional research is needed to confirm this distinction.
Professor David Smith emphasized the next steps: “We now need a clinical trial testing a combined intervention of B vitamins plus Omega-3 supplements to determine whether this approach can slow the conversion from MCI to Alzheimer’s disease. Demonstrating that a combined nutritional strategy reduces progression to Alzheimer’s would be a major advance in prevention, but securing funding for such trials remains challenging.”
Dr. Doug Brown, Director of Research and Development at the Alzheimer’s Society, commented on the clinical implications: “These results help identify who might benefit from B vitamin therapy, suggesting improvement in cognition may occur mainly in people who already have higher circulating levels of Omega-3 oils. Encouragingly, the findings indicate that a combination of fish oil and B vitamins could help some older adults preserve thinking and memory.”
He added: “The relationship between nutrition and brain health is complex. These findings highlight the need for more research to clarify how diet and specific nutrients affect dementia risk and cognitive aging.”
Source: Oxford University
Image credit: Image adapted from the Oxford University press release
Original research: Abstract for “Omega-3 Fatty Acid Status Enhances the Prevention of Cognitive Decline by B Vitamins in Mild Cognitive Impairment” by Oulhaj A., Jernerén F., Refsum H., Smith A. D., and de Jager C. A., published in the Journal of Alzheimer’s Disease. Published online January 6, 2016. DOI: 10.3233/JAD-150777
Abstract
A randomized trial (VITACOG) in people with mild cognitive impairment (MCI) previously showed that B vitamin treatment designed to lower homocysteine slowed cognitive and clinical decline. Using data from that trial, researchers examined whether baseline Omega-3 fatty acid status modifies the effect of B vitamin treatment. In the study, 266 participants aged 70 years and older with MCI were randomized to B vitamins (folic acid, vitamins B6 and B12) or placebo for two years. Baseline measures included cognitive tests, Clinical Dementia Rating (CDR) scale scores, and plasma concentrations of total homocysteine, total DHA and total EPA (Omega-3 fatty acids).
Final outcomes for verbal delayed recall, global cognition, and CDR sum-of-boxes improved in the B vitamin group as baseline Omega-3 concentrations increased, whereas placebo group scores remained similar across Omega-3 levels. Among participants with good Omega-3 status, 33% of those on B vitamin treatment had global CDR scores greater than 0 compared with 59% in the placebo group. Higher DHA concentrations in particular significantly enhanced the cognitive effects of B vitamins; EPA appeared less influential in this interaction. When Omega-3 concentrations were low, B vitamin treatment produced no measurable benefit, but when Omega-3 levels were in the upper normal range, B vitamins interacted with those fatty acids to slow cognitive decline. The authors conclude that a clinical trial combining B vitamins and Omega-3 fatty acids is needed to test whether this strategy can reduce progression from MCI to Alzheimer’s disease.