The Omega 3 fatty acid DHA and Cognitive Decline

Note: This is not an official Alzheimer’s Association publication. It was compiled for information purposes only. If you have a concern regarding your health, or what to take or do for any mental or physical ailment you should consult with a licensed physician.

Recently we had a doctor call our office asking about the value of fish for reducing the risk of Alzheimer’s disease (AD). One of his patients had read an article claiming a 50% reduction in the risk for AD simply by eating more fish. So is this true or is it just hype from the Norwegian fishing industry?

From a review of relevant research it appears this claim may be substantiated. A 4 year study involving 815 individuals, reported in the July 2003 Archives of Neurology, found that, “Participants who consumed fish once per week or more had 60% less risk of Alzheimer’s disease compared with those who rarely or never ate fish.”1

Of particular interest was the fact that DHA (docosahexaenoic acid) levels had the strongest correlation to risk reduction of the Omega 3 fatty acids found in fish, and saturated fat intake tended to inhibit this protective effect. So what is DHA and why is it so important?

Our brain needs many nutrients, but it’s delicate membranes are said to be primarily composed of essential fats, or polyunsaturated fatty acids. DHA reportedly constitutes between 30 and 50 percent of these fatty acids in the human brain.2 “High levels of DHA are found in the more metabolically active areas of the brain, including the cerebral cortex, mitochondria, synaptosomes, and synaptic vesicles. And Fish is a direct dietary source of preformed DHA.” 1 The best source of DHA for humans is a mother’s milk, and that is why it is now added to most infant formulas. But for adults fish appears to be the next best source.

Studies have found individuals with Alzheimer’s disease (AD) typically have significantly lower levels of DHA in the neurons of their hippo-campus, an area of the brain severely affected by the disease. This area is vital to creating recent or declarative memories.3 Prasad and co-workers from the University of Kentucky found that phospholipids such as phosphatidyl-ethanolamine (PE), which normally contain the highest levels of DHA, are severely depleted in those regions of the brain most affected by Alzheimer’s disease.4

As most people know, fish oil has been shown to support the integrity of the cardiovascular system, which is also related to the risk for AD. If the brain can’t get the oxygen and nutrients it needs, it’s going to have a problem. It’s not surprising, therefore, that fish consumption and DHA levels have been correlated with the risk for Alzheimer’s and other dementias. In another 10-year study that tracked the DHA levels of 1188 elderly subjects, Alzheimer’s disease was reported to be 67 percent more likely to develop in those whose DHA levels were in the lower half of the distribution.5

Another reason for this was revealed just last month (Feb 08) by Dr. Greg Cole, professor of medicine and neurology at UCLA (University of California in Los Angeles) and associate director of UCLA’s Alzheimer Disease Research Center, and colleagues who found that DHA can increase production of a protein called LR11 which reduces the beta amyloid plague of Alzheimer’s disease.6

Not only has DHA supplementation been shown to reduce the risk for AD, it has also been shown to reduce depression,7 age-related memory loss,8 and improve the quality of life of Alzheimer’s patients.8,9 DHA has also been shown to improve memory in animals with Alzheimer’s disease by suppressing oxidative damage in the brain.10

Animal studies, both in mice and non-human primates, show that DHA-depleted diets impair learning and memory, and that re-feeding DHA-containing diets reverses these impairments.11,12 Feeding rats diets high in DHA improves both working memory (short-term memory) and reference memory (longer-term) in both old and young animals.11,12,13

Another mechanism for DHA’s effect is through inflammation control. Inflammation has been shown to be a significant contributor to AD. It is believed to play a role in the generation of free radicals and the formation of plaque. Studies have shown that EPA and DHA activate PPARs, which in turn suppress nuclear factor-kappab (NF-kb), the main transcription system that activates inflammation.14 Thus, DHA, which is more potent than EPA in activating PPARs, may have important implications for reducing inflammation in the brain. A high intake of DHA and EPA also reduces inflammation by displacing arachidonic acid (a proinflammatory precursor) and cholesterol from the cell membrane, reducing the starting material used to make inflammatory mediators. Furthermore, DHA inhibits inflammatory eicosanoid production induced by the release of arachidonic acid from cell membranes. As we age, brain inflammation progressively increases, but a diet higher in DHA relative to other fatty acids may reduce this age-related brain inflammation.15
DHA has also been documented to increase phosphatidylserine, a naturally occurring component found in every cell membrane of the body.16 Phosphatidylserine supports healthy levels of the memory neurotransmitter acetylcholine, facilitates brain cell energy metabolism, and provides structural support for brain cell membranes. Several studies confirm the benefits of phosphatidylserine as a key component in fostering healthy brain function.17 And scientists have recently discovered that DHA attaches itself to phosphatidylserine molecules and acts as an important ally in the promotion of brain cell energy production.18 A number of brain researchers, such as Dr. Norman Salem, head of the Laboratory of Membrane Biochemistry and Biophysics at the National Institutes of Health, are convinced that phosphatidylserine with attached DHA is among the most critically important molecules for healthy brain function. And it appears that lecithin or phosphatidylserine supplementation works optimally if DHA levels are kept commensurately high.19

The Take Home Studies show consuming two meals containing fish high in DHA will provide 400 to 500 mg of DHA and EPA, though research suggests some with deficiencies may need more than twice that amount for optimal benefit.20 So what are the best safest sources? And what if you don’t like fish? A report published in the March, 2008 issue of Mayo Clinic Proceedings notes “those who need higher amounts of omega-3 fatty acids can use supplements to reach these levels.” The supplements are relatively inexpensive and appear to show little in the way of side effects.21

Caution: Fish oil may tend to thin the blood, and reduce clotting. Therefore, as noted above, it’s important to check with one’s doctor before adding significant amounts to one’s diet, especially if the person is on any type of blood thinner such as Coumadin.
Last month an educational group called BioMed sponsored a PhD nutritionist – Laura Pawlak, who taught an all day seminar in SLC on “Brain Health over 30.” In her presentation she noted not all fish are particularly high in DHA, and many contain mercury and other chemicals not good for the brain. So her recommendations, from a review of the literature, were tuna packed in water, not Albacore tuna. Tuna in water is both cheaper and safer. Of course Salmon is one of the best sources of Omega 3s, but preferably wild salmon, like Alaskan sockeye salmon to be safe. Smaller fish like krill and sardines, are also high in DHA and less likely to contain significant contaminants. Otherwise she suggested fish oil, or cod liver oil in capsules or liquid (which is what I take flavored). Pharmaceutical grade from Norway seems to be the safest. Plant sources of Omega-3’s like flax seed, can be converted into DHA by our bodies, but only in small amounts. Fish is 4 times more potent, except for Algae. But algae doesn’t tastes as good, is not readily available and may also be contaminated. DHA supplements (and fish oils) are available in health food stores or health sections of most grocery stores.

For questions, comments or more information on this topic and related subjects for brain health and memory enhancement contact David R. Larsen at the Utah Alzheimer’s Association at 1 800 272-3900.

References

1. Morris MC, Evans DA, Bienias JL, et al. Consumption of fish and omega-3 fatty acids and risk of incident Alzheimer disease. Arch Neurol. 2003 Jul;60(7):940-6.
2. Young G, Conquer J. Omega-3 fatty acids and neuropsychiatric disorders. Reprod Nutr Dev. 2005 Jan;45(1):1-28.
3. Soderberg M, Edlund C, Kristensson K, Dallner G. Fatty acid composition of brain phospholipids in aging and in Alzheimer’s disease. Lipids. 1991 Jun;26(6):421-5.
4. Prasad MR, Lovell MA, Yatin M, Dhillon H, Markesbery WR. Regional membrane phospholipid alterations in Alzheimer’s disease. Neurochem Res. 1998 Jan;23(1):81-8.
5. Kyle DJ, Schaefer E, et al. Low serum docosahexaenoic acid is a significant risk factor for Alzheimer’s dementia. Lipids. 1999;34(suppl):S245.
6. http://www.naturalnews.com/022649.html Omega 3 fatty acid confirmed to deter Alzheimer’s. Originally published February 15 2008.
7. http://www.naturalnews.com/omega-3.html Omega 6 found to be dietary cause of depression, heart disease. 3/18/2008; Raeder MB, Steen VM, Vollset SE, Bjelland I. Associations between cod liver oil use and symptoms of depression: The Hordaland Health Study. J Affect Disord. 2006 Dec 18.
8. Morris MC, Evans DA, Tangney CC, Bienias JL, Wilson RS. Fish consumption and cognitive decline with age in a large community study. Arch Neurol.2005 Dec;62(12):1849-53.
9. Yehuda S, Rabinovtz S, Carasso RL, Mostofsky DI. Essential fatty acids preparation (SR-3) improves Alzheimer’s patients quality of life. Int J Neurosci. 1996 Nov; 87 (3-4):141-9.
10. Hashimoto M, Tanabe Y, et al. Chronic administration of docosahexaenoic acid ameliorates the impairment of spatial cognition learning ability in amyloid beta-infused rats. J Nutr. 2005 Mar;135(3):549-55.
11. Gamoh S, Hashimoto M, Hossain S, Masumura S. Chronic administration of docosahexaenoic acid improves the performance of radial arm maze task in aged rats.Clin Exp Pharmacol Physiol. 2001 Apr;28(4):266-70.
12. Neuringer M, Connor WE. omega-3 fatty acids in the brain and retina: evidence for their essentiality. Nutr Rev. 1986 Sep;44(9):285-94.
13. Sugimoto Y, Taga C, Nishiga M, et al. Effect of docosahexaenoic acid-fortified Chlorella vulgaris strain CK22 on the radial maze performance in aged mice. Biol Pharm Bull. 2002 Aug;25(8):1090-2.
14. Zhao G, Etherton TD, Martin KR et al. Anti-inflammatory effects of polyunsaturated fatty acids in THP-1 cells. Biochem Biophys Res Commun.2005 Oct 28;336(3):909-17.
15. Blaylock, Russell L. MD, “DHA Supports Brain Development and Protects Neurological Function,” Life Extension Magazine, January 2008.
16. Akbar M, Calderon F, et al. Docosahexaenoic acid: a positive modulator of Akt signaling in neuronal survival. Proc Natl Acad Sci U S A. 2005 Aug 2;102(31):10858-63.
17. Crook T, Petrie W, et al. Effects of phosphatidylserine in Alzheimer’s disease. Psychopharmacol Bull. 1992;28(1):61-6.
18. Klinkhammer P, Szelies B, et al. Effect of phosphatidylserine on cerebral glucose metabolism in Alzheimer’s disease. Dementia. 1990;1:197-201.
19. Kidd P. Phosphatidylserine: Nature’s Brain Booster for Memory, Mood, and Stress. Total Health Communications, Inc.; 2005.
20. Braverman, Eric R., MD The Edge Effect. Sterling Publishing, NY, 2004 p.154.
21. http://www.mayoclinicproceedings.com/ see Omega-3 Fatty Acids for Cardioprotection