Alzheimer’s Disease (AD) is characterized by the buildup of amyloid deposits in the brain. Studies have shown that populations with high consumption of the fatty acid DHA have a lower incidence of AD. Research has also shown that AD patients have below-average levels of DHA in the brain. Scientists recently examined DHA and amyloid deposition in an aged Alzheimer mouse model. They concluded that DHA could be protective against amyloid production and accumulation. To see their article, click here. "A diet enriched with the omega-3 fatty acid docosahexaenoic acid reduces amyloid burden in an aged Alzheimer mouse model." J Neurosci. 2005 Mar 23;25(12):3032-40.8. This Research Update column highlights articles related to recent scientific inquiry into the process of human aging. It is not intended to promote any specific ingredient, regimen, or use and should not be construed as evidence of the safety, effectiveness, or intended uses of the Juvenon product. The Juvenon label should be consulted for intended uses and appropriate directions for use of the product.

By Benjamin V. Treadwell, Ph.D.

Did you realize that the organ situated on the top of your body and encased in a hard bony structure requires an inordinate amount of energy to keep you alive and mentally active?

This organ, the brain, consumes the equivalent of a quarter pound of fuel (glucose) per day, more than any other organ in the body (except muscles during heavy exercise). But, on the other hand, it does have a tremendous amount of work to carry out each day. The bulk of the energy is used to manufacture neurotransmitters required to initiate and propagate electro-chemical signals via the electrical circuitry of the nervous system. It controls virtually everything we do, including hormone release, breathing, growth, memory, eating, and sleeping, as well as emotional state.

In fact, other tissues of the body sense the dominance of the brain, and will make sacrifices when necessary to keep it alive and healthy. For example, if we are on a starvation diet and the important nutrient glucose is in short supply, the tissues of the body, such as muscle, will decrease their glucose consumption so that the brain, a glucose-consuming machine, will have enough of this nutrient. This is also true for certain vitamins such as biotin (vitamin B7). When its supply is low, the tissues of the body cease using the vitamin to allow a greater supply for the brain, which requires significant amounts of this vitamin for the synthesis of neurotransmitters. The body knows its master and will do all that is necessary to maintain a healthy brain.

Why the brain slows down with age

Unfortunately, as we age so does the brain, as is exhibited by the all-too-familiar decrease in quickness of mind. This effect, for the most part, is due to a gradual age-associated diminution in the capacity of brain cells to produce energy. The question, of course, is: Can we do anything to help prevent or at least attenuate the scourge of age on our nervous system and its control center, the brain?

Last month's Journal described the potential of curcumin, an ingredient in the spice turmeric, in protecting the brain from age-associated damage. Today we examine the requirement of the essential nutrients, the omega-3 fatty acids, in supporting the health of the nervous system.

"Fish is food for the brain"

The old wives' tale "fish is food for the brain" may be surprisingly accurate. The major constituent of the brain is fat (comprising 70% of the weight excluding water), and roughly half of this fat is the omega-3 fatty acid, DHA. (So think again before you use the seemingly disparaging remark, "Fat Head".) Since we cannot synthesize this essential fatty acid, we must obtain it from our diet. Fish is the major source of the omega-3 fats. (They also come from green algae.)

Why does our brain have so much DHA? Several studies of people in fish-eating communities that consume significant quantities of the omega-3 fats have shown a protective effect on the brain with respect to improved mental function, and a decreased incidence of Alzheimer's disease (AD), relative to communities with low intake of these essential fats. Furthermore, the omega-3's have also been demonstrated to be of critical importance to the development of the prenatal nervous system. Therefore, these critical fats, especially DHA, play a crucial role during development of the fetal nervous system, and then later in life in protecting the nervous system from degeneration.

What causes deficiency in DHA?

The omega-3 fat molecules contain unsaturated chemical bonds that hold the individual carbon atoms together. The fact that the bonds are unsaturated means that they are flexible, which is important for biological activity. Unfortunately, these bonds are choice targets for free-radical attack. Once oxidized by a free radical, the omega-3 is inactivated. As we age, these oxidation events become more common due to an age-associated increase in free-radical production. The result is a depletion of the omega-3's with age. Additional evidence for free-radical involvement in DHA loss comes from studies showing that patients with AD have a significant increase in free-radical oxidation. Brain tissue from these patients typically is deficient in DHA.

Why would DHA deficiency cause impaired mental function and AD? A final answer to this question is not yet available, but recent research with animals has led to some hypotheses. First, as mentioned above, DHA decreases in quantity with age. This change parallels an increase in the incidence of neurodegenerative disease, including AD. Another association with a decrease in DHA is a parallel increase in the quantity of beta amyloid protein, a protein toxic to our nervous tissues. However, an even more impressive change, which may precede the increase in beta amyloid, is a loss of structures known as synaptic vesicles. These are little sacs at the ends of neurons that contain specific biomolecules (neurotransmitters) required for nerve transmission. Remember, they require most of the brain's energy to be synthesized and stored in discrete packets (synaptic vesicles). The synaptic vesicles contain DHA. It is quite possible that depletion in this fatty acid prevents synaptic vesicle synthesis and therefore results in a sharp reduction in neurotransmission. This latter event may precede, and be responsible for, the subsequent over-production of the nerve-toxic amyloid beta protein.

Therefore, insufficient DHA may be a key element in age-associated loss of mental acuity. Supplementing with the omega-3 fatty acids may help attenuate this effect. Another potential method to increase the brain level of DHA is to take an antioxidant, such as vitamin E or alpha lipoic acid, which may help prevent the destruction of this important nutrient.

Next month's Journal will describe the role of acetyl-L-carnitine in maintaining a healthy nervous system. The action of acetyl L-carnitine too may involve improving the synthesis of neurotransmitters.