A low omega-3 index in middle aged people may be associated with a higher rate of brain aging, a new study in Neurology concluded.
 
The authors of the present study evaluated the third generation of the Framingham Offspring Study cohort, using the omega-3 index in order to evaluate the levels of EPA and DHA in the participants’ blood.
 
According to the authors, previous research has provided evidence that dietary intake and circulating levels of EPA and DHA are related to dementia risk, but the pathway underlying this association is unclear.
 
The team of researchers compared measurements of omega-3s found in the red blood cells of 2,183 dementia- and stroke-free participants to determine possible associations with brain MRI measures and several measurements of cognitive function, adjusting for potential cofounders.
 
Further, the authors tested for interactions between omega-3 levels and APOE genotype on MRI and cognitive outcomes. APOE genotype determines whether an individual is a carrier of a gene associated with Alzheimer’s disease risk.
 
According to the authors, higher omega-3 index was linked to larger hippocampal volumes, and higher scores in tests for abstract reasoning, with similar results obtained for EPA and DHA concentrations individually. There was an association between higher DHA concentrations or omega-3 index and larger hippocampal volumes specifically for those who did not carry the APOE-e4 genotype, while higher EPA concentrations were related to better abstract reasoning in the APOE-e4 carriers.
 
Notably, all three omega-3 predictors (EPA, DHA, total omega-3) appeared to lower white matter hyperintensity burden in APOE-e4 carriers. White matter hyperintensity is a prevalent form of small-vessel disease in the brain, and is a risk factor for post-stroke cognitive dysfunction.
 
“Our results, albeit exploratory, suggest that higher Omega-3 fatty acid concentrations are related to better brain structure and cognitive function in a predominantly middle-aged cohort free of clinical dementia,” the authors concluded. “These associations differed by APOE genotype, suggesting potentially different metabolic patterns by APOE status.”
 
The authors noted that the inconsistency seen in studies involving dietary interventions could be due to the fact that the interventions used in these studies might have been carried out too late in life for significant improvements in symptomatic participants. “Epidemiological and intervention studies suggest omega-3 may be most beneficial to preserve brain health from early midlife, as our study suggests, and just before the onset of moderate cognitive changes,” they wrote.
 
“What’s important about this study is that it replicates what we saw in the Framingham Offspring 10 years ago, in subjects who had an average age of 66. However, this study represents Generation 3, their kids essentially, who had an average of 46,” explained William S. Harris, PhD, FACN, President of the Fatty Acid Research Institute (FARI), and one of the study authors
 
“The results of this study show that low red blood cell DHA levels are associated with smaller brain volumes and a ‘vascular’ pattern of cognitive impairment, even in persons free of clinical dementia,” Harris continued. “This suggests that intervening early and maintaining an optimal omega-3 index (8% or higher) could play an important role in staving off cognitive decline, as well as dementia and Alzheimer’s in the long-term.”