Many people take fish oil supplements for heart health, and there is some research to suggest that fish oils may be good for the brain as well. Now researchers have shown that fish oil supplements may affect parts of the brain critical for memory and thinking skills.
For the study, scientists at Rhode Island Hospital's Alzheimer's Disease and Memory Disorders Center studied 819 men and women, 117 of whom were taking fish oil supplements. All were part of the Alzheimer's Disease Neuroimaging Initiative, a large and ongoing study at multiple medical centers across the country. The participants were given memory tests at the start of the study, and periodically over the next three years. Their brains were also scanned as part of the study.
The researchers found that among those who were healthy at the study's start, those who were taking fish oil supplements scored higher, over all, on tests of memory and thinking than those who were not taking fish oils. Fish oils seemed to provide benefits for those who did not carry a gene called APOE-E4, which increases the risk for Alzheimer's disease.
In addition, the brains of those taking fish oils were larger than those who were not taking the supplements, particularly in two brain structures critical for memory and thinking: the hippocampus and the cerebral cortex. A larger brain is generally a sign of better cognitive health; conversely, brain shrinkage has been associated with Alzheimer's disease. Again, the brain benefits applied only to those who did not carry the APOE-E4 gene.
The findings, reported at the International Conference on Alzheimer's Disease in Paris, "should motivate further study of the possible effects of long-term fish oil supplementation on important markers of cognitive decline and the potential influence of genetics on these outcomes," said Dr. Lori Daiello, who led the study.
Other studies have shown 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, for example, have shown that the 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.
Fish oils contain omega-3 fatty acids like DHA, or docosahexaenoic acid, which is known to be good for cardiovascular health. People with high levels of DHA in their bodies had a lower risk of developing Alzheimer's disease in one large study. 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 and genes like APOE-E4, as this study indicates, can all influence the risk for Alzheimer's disease.
Source: Lori Daiello, Brian Ott, Assawin Gongvatana, et al: Rhode Island Hospital's Alzheimer's Disease and Memory Disorders Center.