Eating fish at least once a week could help lower older patients' risk of developing dementia, according to Cyrus Raji, MD, PhD, from the University of Pittsburgh and colleagues reported at the Nov. 2011 Radiological Society of North America meeting.

Those who ate baked or broiled -- but not fried -- fish on a weekly basis had a greater volume of gray matter in areas of the brain associated with Alzheimer's disease than people who didn't eat fish as often.  Preserving brain volume was also associated with lower rates of developing cognitive impairment, he said.

"Fish consumption benefits gray matter volume, potentially reducing the risk of [Alzheimer's disease and dementia] long-term," Raji said during a press briefing.

Although a National Institutes of Health panel decided last year that nothing conclusively prevents Alzheimer's disease, researchers continue to investigate whether a healthy diet, or specific components thereof, can have any beneficial effects.

For their study, Raji and colleagues assessed 260 people, mean age 71, when they enrolled in the Cardiovascular Health Study between 1989 and 1990. At that time, they filled out questionnaires on dietary intake; 163 reported eating fish at least weekly, and some did so as often as four times a week.

All patients had an MRI 10 years later to assess brain volume, and then had follow-up cognitive testing between 2002 and 2003.

The researchers found that patients who ate fish at least once a week had greater volume in the frontal lobes and the temporal lobes, areas responsible for memory and learning, which are severely affected in Alzheimer's disease, Raji said.

Five years after the MRI, they found that 30.8% of patients who had low fish intake had developed mild cognitive impairment or dementia, compared with just 3.2% of those who had the highest fish intake and the greatest preservation of brain volume.

They also saw that 47% of patients with brain atrophy who didn't eat fish had abnormal cognition five years later compared with 28% of those who ate more fish and had more gray matter volume, Raji reported. "That's an impressive reduction in the risk of developing mild cognitive impairment of Alzheimer's," Raji said.

In further analyses, the researchers found that mean scores for working memory -- a function severely impaired in Alzheimer's disease -- were significantly higher among those who ate fish weekly and those findings persisted even after accounting for potential confounders.

This "simple lifestyle choice" of eating more fish increases the brain's "resistance" to Alzheimer's disease, Raji said, potentially via a few mechanisms: Fish are rich in omega-3 fatty acids, which can help increase blood flow to the brain and can also act as an antioxidant, thereby reducing inflammation, he said.

Omega-3s may also prevent the accumulation of amyloid plaques in the brain, he added.   He noted that fatty fish like salmon have more omega-3s, while smaller fish, such as cod, have less.

Although dietary intake of fish was measured only twice -- once at baseline and again in 1995 -- Raji said patients tended to maintain their levels of consumption, and he suspects that the observed benefits "are more likely to be observed if eating fish is a long-term habit as opposed to a short-term approach."

Mary Mahoney, MD, of the University of Cincinnati, who was not involved in the study, said that future studies should investigate whether omega-3s specifically are leading to benefits in brain volume.

"We're making the assumption" that fish is a marker for healthy lifestyle, she said. "If we could just cut to the chase and look at the protective mechanism, that would be better."

It's important to note  that the findings are preliminary and should be replicated in a larger sample and sex differences should be included since Altzeimer's is more prevalent in women.  In the meantime, it can't hurt to add fish to your diet...for many reasons!

Source reference:
Raji C, et al "Fish consumption, brain structure, and risk of Alzheimer's disease" RSNA 2011.

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Comments

I wonder why doctors and scientists are in favour of eating fish, yet seem to have a down on fish oil supplements. You can only estimate the amount of omega 3 you get from fish and you can't know what contaminants it might contain. The levels of active ingredients in a supplement can be measured and it can be tested for purity.

Fish is a great food. It's not only tasty but also healthy. Thank you for this great post.

I wonder if the benefits of fish oils and dementia would out rule mercury tolerances and the negative effects that come with that. Thank you for this information.

This is encouraging news. Long-held concerns about hardening of the arteries and its role in dementia seems to support the finding of Omega-3 fatty acids stimulating blood flow to the brain. It makes sense the good cardiovascular health most likely goes hand in hand with staving off the effects of senility.

While salmon is high in Omega-3s, we should be careful where the salmon we're eating comes from. With increased radiation in our ocean waters, it's wise to check out the source of the salmon we're eating. Also unwise to eat the new hybrid salmon? Best to stick with the foods nature supplies to us. Thanks for your informative article.

The more we can do the better. Omega 3 has so many benefits, heart, arthritis, and now the brain!

Study after study show how good fish is for you. I think the more important fact is that increasing your Omega 3 levels is so important for your health. I have read many articles that some fish has high quantities of heavy metals like mercury etc. So a better way to get your omega 3 may be other foods or omega 3 supplements tested for low levels of contaminants. Start getting healthier by increasing that omega 3.

I think not just once a week... You could do it everyday and still, you will not have any untoward effects. Fish are great, it is sad that most people don't like it. But still nice way to promote fish.. Thanks for posting

I only know that fish is good for the body because it is rich in omega 3. Another information gained from your site. This is the reason why I loved reading your post. Its not only interesting but also expands your knowledge.

I remember when I was a youngster my grandmother always told me that I should always eat plenty of fish because it was "good for the brain". I had always thought it was a bit of an old wives tale but I am glad to see it is now being supported by scientific evidence. I must admit that until reading this article I always thought it did not matter whether the fish was steamed, broiled or friedif it was to do you any good. I see now that I shall have to cut back on the traditional English version of fish and chips.

Studies also say that the more you read the less chances that you will acquire dementia when you are older.

I wonder if the benefits of fish oils and dementia would out rule mercury tolerances and the negative effects that come with that. Thank you for this information. EDITOR's NOTE: Mercury is definitely a risky metal. To read more on mercury poisoning visit: http://www.niehs.nih.gov/health/topics/agents/mercury/index.cfm

To become healthier as a nation, people must make healthy lifestyle a top priority. Obesity need not become the societal norm; proper nutrition, regular exercise and mental relaxation can reverse the trend and improve both quality and quantity of life.

Fish oils are not only good for memory. They help lubricate the joints. Great article, and I agree with the above posters about being careful where you get your fish from.

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