Two new studies
link patterns of polyunsaturated fatty acids in the blood to the integrity of
brain structures and cognitive abilities that are known to decline early in
The studies add to the evidence that dietary intake of
omega-3 and omega-6 fatty acids can promote healthy aging, the researchers
said. Further research is needed to test this hypothesis, they said.
The brain is a collection of interconnected parts,
each of which ages at its own pace. Some brain structures, and the abilities
they promote, start to deteriorate before others, said University of Illinois
M.D./Ph.D student Marta Zamroziewicz, who led the new research with psychology
professor Aron Barbey.
"We studied a primary network of the brain -- the
frontoparietal network -- that plays an important role in fluid intelligence
and also declines early, even in healthy aging," Zamroziewicz said. Fluid
intelligence describes the ability to solve problems one has never encountered
"In a separate study, we examined the white
matter structure of the fornix, a group of nerve fibers at the center of the
brain that is important for memory," she said.
Previous research has shown that the fornix is one of
the first brain regions to be compromised in Alzheimer's disease.
In both studies, the researchers looked for patterns
of polyunsaturated fatty acids in the blood of adults ages 65 to 75. They
analyzed the relationship between these nutrient patterns and subjects' brain
structure and performance on cognitive tests. This research differs from other
such studies, which tend to focus on only one or two polyunsaturated fatty
acids, Zamroziewicz said.
"Most of the research that looks at these fats in
health and healthy aging focuses on the omega-3 fatty acids DHA and EPA, but
those come from fish and fish oil, and most people in the Western Hemisphere
don't eat enough of those to really see the benefits," she said. Other
fatty acids, like alpha-linolenic acid and stearidonic acid, are precursors of
EPA and DHA in the body. Those fats can be derived from land-based foods such
as nuts, seeds and oils.
"A central goal of research in nutritional
cognitive neuroscience is to understand how these nutrients affect brain
health," Zamroziewicz said. "Some of these nutrients are thought to
be more beneficial than others."
In a study reported in the journalNutritional Neuroscience, the
researchers looked for relationships between several omega-3 fatty acids in the
blood, the relative size of structures in the frontal and parietal cortices of
the brain, and performance on tests of fluid intelligence in healthy elderly
The team found correlations between blood levels of
three omega-3 fatty acids -- ALA, stearidonic acid and ecosatrienoic acid --
and fluid intelligence in these adults. Further analyses revealed that the size
of the left frontoparietal cortex played a mediating role in this relationship.
People with higher blood levels of these three nutrients tended to have larger
left frontoparietal cortices, and the size of the frontoparietal cortex predicted
the subjects' performance on tests of fluid intelligence.
"A lot of research tells us that people need to
be eating fish and fish oil to get neuroprotective effects from these
particular fats, but this new finding suggests that even the fats that we get
from nuts, seeds and oils can also make a difference in the brain,"
Zamroziewicz said. Related: 6 Things Omega 3's can Do For Your Health And 3 Things They Can't.
In the second study, the team found that the size of
the fornix was associated with a balance of omega-3 and omega-6 fatty acids in
the blood, and that a more robust fornix coincided with memory preservation in
older adults. Again, the researchers saw that brain structure played a
mediating role between the abundance and balance of nutrients in the blood and
cognition (in this case, memory). The findings are reported in the journalAging & Disease.
"These findings have important implications for
the Western diet, which tends to be misbalanced with high amounts of omega-6
fatty acids and low amounts of omega-3 fatty acids," Zamroziewicz said.
"These two studies highlight the importance of
investigating the effects of groups of nutrients together, rather than focusing
on one at a time," Barbey said. "They suggest that different patterns
of polyunsaturated fats promote specific aspects of cognition by strengthening
the underlying neural circuits that are vulnerable to disease and age-related