Our Immune System: The Key to Cellular Rejuvenation of the Brain

New research shows that immune cells contribute to maintaining the brain’s ability to preserve cognitive ability and cell renewal throughout life. It has been generally accepted, until recently, that each individual is born with a fixed number of nerve cells in the brain. As these cells gradually degenerate and die during the person’s lifetime, they cannot be replaced. This is especially alarming when we realize that chronically high levels of stress-induced cortisol, so common in the world of today, cause the brain to shrink.

However, this theory was disproved when researchers discovered that certain areas of the adult brain do retain their ability to support and promote cell renewal (neurogenesis) throughout life, especially under conditions of mental stimuli and physical activity. The hippocampus, which supports certain memory functions, is one such area. A team of scientists, led by Professor Michal Schwartz of the Neurobiology Department of the Weizmann Institute of Science in Rehovot, Israel, one of the world’s top-ranking multidisciplinary research institutions, has come up with new findings that may have implications in delaying and slowing down cognitive deterioration in old age. These findings showed that the primary role of the immune system’s T-cells (white blood cells responsible for the body’s immunity) is to enable areas of the brain such as the hippocampus to form new nerve cells and maintain cognitive function. We still don’t know how the body delivers the message instructing the brain to step up its formation of new cells. However, animal studies have shown that exposure to an environment rich with mental stimulations and opportunities for physical activity led to increased formation of new nerve cells in the hippocampus. (As with muscle, it appears that the phrase “use it or lose it” also applies to brain power.) When the scientists experimented with mice that lacked T-cells and other important immune cells, significantly fewer new cells were formed.

According to Professor Schwartz, “These findings give a new meaning to ‘a healthy mind in a healthy body.’ They show that we rely on our immune system to maintain brain functionality, and so they open up exciting new prospects for the treatment of cognitive loss.”

Knowing that the immune system contributes to the renewal of nerve cells has potentially great significance for aging populations because aging itself is associated with a decrease in immune system function. Aging is also associated with a decrease in memory skills and the formation of new brain cells. Therefore, by manipulating and boosting the immune system, it might be possible to prevent or at least slow down age-related loss of memory and learning abilities.

Stress and Cholesterol

Previous studies have established that stress is linked to increased heart rate and weakened immune systems. Now researchers have discovered that elevated stress levels appear to raise cholesterol levels over the long term. This is alarming because elevated cholesterol is a risk factor for heart and circulatory disease, the number-one killer of both men and women in the United States.

A team of researchers, led by Professor Andrew Steptoe from University College London, put forth three hypotheses on how stress increases cholesterol levels:

• Stress may encourage the body to produce more energy in the form of fatty acids and glucose, requiring the liver to produce and secrete more low-density lipoprotein (LDL) so that they can be transported to the other tissues of the body.
• Stress interferes with the body's ability to rid itself of excess cholesterol.
• Stress triggers a number of inflammatory processes that also increase cholesterol production.

Stress-Fighting Supplements

The Life Extension Foundation has compiled the latest news and research on targeted nutritional supplements and herbal adaptogens than can, along with exercise and meditation, help many individuals manage stress-filled lives. The following supplements may help keep the HPA axis in equilibrium, reduce elevated cortisol levels, and help optimize health.

Vitamin C

Along with its beneficial effects as a connective tissue regenerator and in maintaining proper immune system function, vitamin C has been shown to help modulate high levels of cortisol brought about by stress. A study in 2001 examined the effects of supplemental vitamin C on high cortisol levels brought about by physical stress in marathon runners. In a randomized, placebo-controlled study, ultramarathon runners were given 500 mg a day of vitamin C, 1500 mg a day of vitamin C, or a placebo seven days before a marathon, the day of the race, and two days after the race. Researchers found that athletes who took 1500 mg per day of vitamin C had significantly lower post-race cortisol levels then those taking either 500 mg a day or placebo.

Another study published in the journal Psychopharmacology reviewed evidence showing that vitamin C can reduce high cortisol levels brought about by psychologically induced stress. In a randomized, double-blind, placebo-controlled trial, researchers gave 3000 mg per day of vitamin C or a placebo to 120 volunteers who were subjected to psychological stress through the Trier Social Stress Test (TSST), which consists of 15 minutes of psychological stress induced via a mock job interview, followed by a mental arithmetic challenge. Subjects who took vitamin C had lower blood pressure, subjective stress, and cortisol measures compared to those who were given placebo. Recommended dosage: 1000-3000 mg per day.

Omega-3 Fish Oil

In a number of clinical tests, fish oil has been shown to reduce cardiovascular risk in women and men. Now, preliminary research has shown that fish oil may also help individuals cope with psychological stress and lower their cortisol levels. In a study published in 2003, researchers gave seven study volunteers 7.2 grams per day of fish oil for three weeks and then subjected them to a battery of mental stress tests. Blood tests showed that these psychological stressors elicited changes in the subjects’ heart rate, blood pressure, and cortisol levels. After three weeks of fish oil supplementation, however, the rise in cortisol levels secondary to stress testing was significantly blunted, leading the authors to conclude that supplementation with omega-3 fatty acids from fish oil “inhibits the adrenal activation elicited by a mental stress, presumably through effects exerted at the level of the central nervous system.”

Thanks to a flood of research published in recent years, we now know that the omega-3 essential fatty acids in fish help prevent or ameliorate a wide range of mental disorders and disturbances, ranging from depression, bipolar disorder, and Alzheimer’s disease to aggression, memory loss, and learning difficulties. In fact, it appears clear that these and many other conditions result from or are exacerbated by America’s dietary deficiencies of omega-3s, and not solely from environmental or genetic risk factors.

Now, the results of a new clinical study add to existing evidence indicating a close connection between low intake of omega-3s and angry, aggressive behavior. Emerging clinical evidence—including landmark studies funded by the National Institutes of Health—suggests that low dietary levels of omega-3s—specifically, the omega-3 fats EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), which are found only in fish and marine organisms—promote anger, depression, and aggression.

The good news is that the preponderance of available clinical evidence shows that taking supplemental marine omega-3s may help alleviate all of these psychological disorders. The study in question took place at a Veterans Administration facility in Brooklyn, New York, and involved 24 male outpatients with a history of substance abuse and aggressive behaviors. The subjects were randomly assigned to two groups: one receiving 3 grams (five capsules) per day of purified fish oil containing 2250 mg of EPA, 500 mg of DHA, and 250 mg of other omega-3 EFAs. The second group received a placebo. The 13 patients who received the fish oil enjoyed a significant and ongoing decrease in their anger scores on psychological tests.

Unfortunately the average American is woefully deficient in these miracle fats. We have long known that “type A” personalities run a significantly greater risk of stroke and heart attack, and the possibility that low levels of the omega-3s may be an important contributing factor offers new hope for the proverbial hothead. Just the simple addition of high-quality fish and fish oil capsules taken daily may help alleviate many of these unwanted feelings and behaviors.

It might seem hard to believe that something as simple as a few meals of fish or capsules of fish oil could confer such huge health and cosmetic benefits. But the available evidence indicates that humans evolved and thrived on diets high in omega-3-rich seafood, which is why marine omega-3 fatty acids make up much of the fat in our brain cell membranes, and are such critically important anti-aging nutrients and agents of good mental health.

It well may be that our depressed, overweight society—plagued by inflammatory “lifestyle diseases” such as arteriosclerosis, diabetes, Alzheimer’s, and cancer—is suffering unnecessarily. Never before in human history have diets been so low in omega-3 fatty acids and so high in inflammatory omega-6 fatty acids. In fact, it is estimated that omega-3 intake has dropped by about half over the past 50 years, while intake of inflammatory, cancer-promoting omega-6 fats has risen even more sharply. This is a preventive-health disaster of epic proportions. This crucial imbalance needs to be rectified if we are to regain and maintain optimal mental, physical, and emotional health.

To redress this fatty acid imbalance, you need to take two simple steps:

First, cut way back on omega-6-rich vegetable oils (corn, soy, canola, safflower, etc.)—which are abundant in most processed, frozen, and fast foods—and switch to heart-healthy extra-virgin olive oil, which is high in non-inflammatory monounsaturated fats and potent anti-inflammatory antioxidants. Second, add fatty cold-water fish such as wild salmon, sardines, anchovies, trout, sablefish, and herring to your diet at least three times per week and take fish oil capsules daily. Recommended dosage: 1-4 grams per day.