People who have low levels of omega-3 fatty acids, the “good” fats found in fish, may have thinking and memory problems at a younger age than those who get plenty of the fats. The finding adds to a growing body of evidence that omega-3s are important for brain health and may help to protect against Alzheimer’s and other forms of dementia in old age.
“People with lower blood levels of omega-3 fatty acids had lower brain volumes that were equivalent to about two years of structural brain aging,” said study author Dr. Zaldy S. Tan of the Easton Center for Alzheimer’s Disease Research and the Division of Geriatrics at the University of California, Los Angeles. Smaller brain volumes have been linked to an increased risk of Alzheimer’s disease. The findings appeared in the journal Neurology.
Eating plenty of fish has been tied to a lower risk of heart attacks and strokes, and several large population studies have shown that it lowers the risk of Alzheimer’s and other forms of dementia as well. This study actually measured omega-3 levels in people’s red blood cells, something that previous studies have not done.
For the study, 1,575 people whose average age was 67 had MRI brain scans. They were also given tests to measure thinking and memory. All were free of dementia, strokes and other serious health problems.
The researchers found that people who had low levels of DHA, a type of omega-3 that is linked to brain and heart health, had smaller brain volumes than those with high DHA levels. Those with low levels of DHA and another omega-3 called EPA, which has also been linked to cardiovascular and cognitive health, scored lower on memory tests as well as tests that measure abilities like problem solving, abstract thinking and the ability to multitask.
The findings complement earlier reports that eating fish at least three times a week lowered the risk of vascular problems in the brain. Another recent study found that people who ate baked or broiled fish just once a week had a lower risk of developing Alzheimer’s disease. They were also at lower risk of mild cognitive impairment, a type of memory loss that sometimes leads to Alzheimer’s.
Other reports have found that taking fish oil supplements daily for 24 weeks improved learning and memory in healthy older adults, and that omega-3s may be beneficial for those in the earliest stages of Alzheimer’s.
Scientists aren’t sure why omega-3s may benefit the brain, though they have several potentially beneficial effects on vascular health. They appear to lower blood pressure, reduce the risk of blood clots, and lower levels of triglycerides, a type of unhealthy fat that has been tied to heart attacks and strokes.
Omega-3s also may help to lower levels of beta-amyloid, a toxic protein that builds up in the brains of those with Alzheimer’s, and reduce inflammation, which is thought to play a role in heart disease and dementia. As this study shows, omega-3s also appear to help maintain brain volume, perhaps by increasing levels of brain growth factors, the researchers speculate.
Source: Z.S. Tan, W.S. Harris, A.S. Beiser, et al: “Red Blood Cell Omega-3 Fatty Acid Levels and Markers of Accelerated Brain Aging.” Neurology Vol. 78, 2012, pages 658-664.