The research, published in Neurology, investigated whether levels of the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in red blood cells is associated with later changes in brain volumes.
Led by Dr James Pottala from the University of South Dakota, the team assessed data on the levels of EPA and DHA in more than 1,000 women and related this to brain volumes measured eight years later - finding that those with higher levels of the omega-3 polyunsaturated fatty acids (PUFAs) had a larger total brain volumes eight years later.
Indeed, those with twice as high levels of fatty acids (7.5% vs. 3.4%) had a 0.7% larger brain volume, they revealed.
"These higher levels of fatty acids can be achieved through diet and the use of supplements, and the results suggest that the effect on brain volume is the equivalent of delaying the normal loss of brain cells that comes with aging by one to two years," said Pottala - who added that people with higher levels of DHA and EPA also had a 2.7% larger volume in the hippocampus area of the brain.
The hippocampus is an area which plays an important role in memory, noted the team - adding that in Alzheimer's disease, the hippocampus begins to shrink (atrophy) even before symptoms appear.
Pottala and his team analysed data from 1,111 women who took part in the Women's Health Initiative Memory Study. As part of the study red blood cell (RBC) levels of EPA and DHA were taken, and brain volumes as measured by magnetic resonance imaging (MRI) eight years later - when the women were an average age of 78.
The endpoints measured using MRI imaging were total brain volume and anatomical regions.
"In fully adjusted models, a 1 SD greater RBC EPA + DHA (omega-3 index) level was correlated with 2.1 cm3 larger brain volume," revealed the research team - adding that DHA alone was marginally correlated (p = 0.063) with total brain volume, while EPA 'was less so' (p = 0.11).
Pottala and his colleagues concluded that a higher omega-3 index was correlated with larger total normal brain volume and hippocampal volume in postmenopausal women measured eight years later.
"While normal aging results in overall brain atrophy, lower omega-3 index may signal increased risk of hippocampal atrophy," they said. "Future studies should examine whether maintaining higher RBC EPA + DHA levels slows the rate of hippocampal or overall brain atrophy."
Published online ahead of print, doi: 10.1212/WNL.0000000000000080
"Higher RBC EPA + DHA corresponds with larger total brain and hippocampal volumes"
Authors: James V. Pottala, Kristine Yaffe, et al