June 17, 2015
Many older adults make a point of eating fish or taking fish oil capsules in the hopes of keeping the mind sharp in old age. Various studies suggest that omega-3 fatty acids, the “good” fats found in fish, may be good for the heart and blood vessels and help to keep the brain sharp. Now a new study lends further support for the possible brain-boosting effects of a fish-rich diet.
The study found that people at higher risk of developing Alzheimer’s disease with higher levels of omega-3s were better able to switch between mental tasks than their peers who got little of the fats. Those with high levels of omega-3s also had larger volumes in the anterior cingulate cortex, a part of the brain known to be involved in the brain’s executive function. Executive function is critical for mental processes like planning, reasoning, paying attention, problem solving, impulse control and the ability to switch between tasks, all of which are typically severely compromised by Alzheimer’s disease.
“Recent research suggests that there is a critical link between nutritional deficiencies and the incidence of both cognitive impairment and degenerative neurological disorders, such as Alzheimer’s disease,” said Aron Barbey, a study author and professor of neuroscience, psychology, and speech and hearing science at the University of Illinois at Urbana-Champaign. “Our findings add to the evidence that optimal nutrition helps preserve cognitive function, slow the progression of aging and reduce the incidence of debilitating diseases in healthy aging populations.” The findings appeared in the journal Frontiers in Aging Neuroscience.
For the study, researchers looked at 40 older adults, aged 65 to 75, all of whom were free of Alzheimer’s or other forms of dementia. They also all carried the APOE-E4 gene, which put them at increased risk of developing Alzheimer’s disease.
Study participants were given tests of mental agility, including cognitive flexibility, or the ability to switch between complex mental tasks. Researchers also measured blood levels of the fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), the “good” fats in fish, and were given M.R.I. brain scans.
“We wanted to confirm that higher omega-3 fatty acids related to better cognitive flexibility, and we did in fact see that,” said study author Marta Zamroziewicz of the University of Illinois. “We also wanted to confirm that higher omega-3 fatty acids related to higher volume in the anterior cingulate cortex, and we saw that.”
The study does not prove that eating fish or taking fish oil pills can ward off Alzheimer’s. Many factors seem to play a role in who gets the disease. But it does suggest that fish oils can help to keep the brain healthy as we age.
The findings build on earlier studies showing that a diet rich in fish, particularly oily fish like tuna, salmon, mackerel, sardines and anchovies, may lower the risk of Alzheimer’s disease and other forms of dementia. Studies of people who eat a traditional Mediterranean diet rich in fish as well as fruits and vegetables have also shown that such a diet may have brain-protective effects.
Another survey of seniors in Asia, Latin American and the Caribbean found that those who ate fish almost every day were almost 20 percent less likely to develop dementia than those who ate fish a few days a week. Eating fish may also help to ease the agitation and depression of Alzheimer’s, other research shows.
Researchers speculate that the omega-3s in fish oil may quell inflammation, which is emerging as a possible underlying cause of heart disease and other ills, including Alzheimer’s disease.
Fish oil supplements containing DHA and other omega-3s are widely available in pharmacies and health-food stores. But more study is needed to better define the effects of diet on brain health. Advancing age, family history, genes and many other factors likely all influence the risk for Alzheimer’s disease.
Source: Marta K. Zamroziewicz, Erick J. Paul, Rachael D. Rubin, Aron K. Barbey: “Anterior cingulate cortex mediates the relationship between O3PUFAs and executive functions in APOE e4 carriers.” Frontiers in Aging Neuroscience May 21, 2015, 7:87. doi: 10.3389/fnagi.2015.00087