Memory loss is unusual forgetfulness that can be caused by brain damage due to disease or injury, or it can be caused by severe emotional trauma. Normal aging may result in trouble learning new material or requiring longer time to recall learned material. However, it does not lead to dramatic memory loss unless diseases are involved. Research presented at the World Alzheimer's Congress in July 2001 suggested that high intakes of vitamin E effectively tapered memory loss and cognitive decline in a group of more than 6,000 elderly subjects whose vitamin E intake was generally between 200 to 400 IU per day.
Cognitive function includes a wide range of processes, none of which is a generally conscious action: Thinking, calculating, perceiving and judging occur in the mind without conscious effort. Unfortunately, environmental toxins, vitamin deficiencies and the process of aging can alter cognition. The aging process generally leads to difficulties with memory, which causes many people to fear they have dementia. However, dementia is not a normal part of aging.
Dementia, the loss of intellectual functions such as remembering and reasoning, is itself a disease and can also be a symptom of other diseases, including Alzheimer's, multi-infarct dementia (vascular dementia), Parkinson's and Creutzfeldt-Jakob disease. According to the U.S. Congress Office of Technology Assessment, 1.8 million Americans have severe dementia and another 1 million to 5 million have mild to moderate dementia. Approximately 4 million of these people suffer from dementia due to Alzheimer's disease, which is expected to affect more than 6 million by the year 2040.
There is no cure for dementia or Alzheimer's, although medications can limit the severity of the afflictions. Dietary supplements may also slow the progression of dementia, as well as increase cognitive function impaired as a part of the aging process. The National Institute on Aging recommends maintaining a healthy diet and exercise regimen to preserve cognitive function, especially for the elderly. In support of this theory, a recent Italian study indicated cognitive function is higher in those who have a healthy diet, as defined by the World Health Organization guidelines for the prevention of chronic disease (Eur J Clin Nutr, 55, 12:1053-58, 2001) (http://content.naturesj.com).
Many nutrients have been indicated in improving cognitive function, as well as preventing or slowing age-related cognitive decline. Many times, ingredients are recommended in combination with each other--vitamin B complex, vitamin E, Coenzyme Q10 (CoQ10), Ginkgo biloba and phosphatidylserine (PS), combined with a 15-percent fat diet, were shown to prevent memory loss and Alzheimer's (Altern Ther Health Med, 4, 6:38-43, 1998) (www.alternative-therapies.com).
While numerous combinations are suggested for treating and preventing cognitive decline, antioxidants are a popular part of the combination because they combat the free radicals that have been implicated in causing damage to brain cells. Canadian scientists tested this theory by supplementing 96 elderly subjects with trace elements and vitamins. They found that cognitive function in the supplement group improved in comparison to the placebo group (Nutrition, 17, 9:709-12, 2001) (www.nutrition.org).
Vitamin E, including tocopherols and tocotrienols, is one antioxidant vitamin particularly thought to improve cognitive function and stall cognitive decline. A suspected reason for this nutrient's success at preventing oxidative damage in brain cells is its fat-soluble status, which makes it well absorbed by the brain, the body's fattiest organ.
Alpha-tocopherol combined with antioxidant vitamin A (retinol) may play a role in preventing Alzheimer's related dementia. According to French researchers, Alzheimer's patients exhibit low plasma concentrations of tocopherols and retinol as compared to control subjects because of high amounts of free radicals in the brain; the researchers theorized that much of the patients' dietary tocopherol and retinol had been utilized to fight oxidative damage (Age and Ageing, 30:235-41, 2001) (http://ageing.oupjournals.org).
Tocotrienols are a group of antioxidants thought to reduce oxidative damage to the brain. Preliminary research demonstrated that tocotrienols are effective in reducing neuronal cell death in mouse hippocampal cells (J Biol Chem, 275:13049-55, 2000) (www.jbc.org). Additional animal research has demonstrated that palm tocotrienol complex, which contains high levels of alpha-tocotrienol and gamma-tocotrienol, is effective in protecting against oxidative damage to brain cells (Neuro Lett, 195:179-82, 1995).
Vitamin E in combination with a water-soluble antioxidant, vitamin C, may protect against vascular dementia and improve cognitive function later in life, according to the Honolulu-Asia Aging Study (Neurology, 54:1265-72, 2000) (www.neurology.org). Vitamin C also may be able to assist those suffering from neurodegenerative diseases by improving the ability of medications to cross the blood-brain barrier, according to a study published in the Dec. 21, 2001, Web edition of the Journal of Medicinal Chemistry (http://pubs.acs.org/journals/jmcmar).
CoQ10 is another antioxidant that has been studied in relation to improving cognitive function. Specifically, oral administration of CoQ10 has been studied in Parkinson's disease patients for increasing cognitive activity (Biofactors, 9, 2-4:261-6, 1999) (http://www.iospress.nl). Researchers concluded that while the antioxidant may have benefit in patients with neurodegenerative diseases, no clinical studies have demonstrated a guaranteed benefit. However, a study conducted at the University of California, Irvine, noted that CoQ10 administration had no effect on improving cognitive function in mice (Neurochem Int, 40, 2:123-30, 2002) (www.elsevier.com).
Flavonoids, polyphenolic compounds with antioxidant effects, may improve cognitive function by reducing oxidative damage. Flavonoids are found in a range of extracts, including blueberry, grapeseed, bilberry, hawthorn and rosemary.
Blueberries may be helpful in aging gracefully, according to preliminary research presented at the American Dietetic Association (www.eatright.org) conference in October 2000. The symposium, "Fruits and Vegetables' Effects on Brain Aging," was presented by James Joseph, Ph.D., chief of the Neuroscience Laboratory at the U.S. Department of Agriculture (USDA) Human Nutrition Research Center on Aging at Tufts University. Joseph reported that blueberries may improve motor skills and reverse short-term memory loss associated with aging, and USDA trials showed improved navigational skills in animals fed a diet supplemented with blueberry extract for two months. Additionally, a study focusing on the cognitive effects of blueberries, spinach and strawberries singled out blueberries as the most effective (J Neuroscience, 19, 18:8114-21, 1999) (www.jneurosci.org).
Grapeseed extract contains oligomeric proanthocyanidins (OPCs), a class of flavonoid known for antioxidant activity. When compared to the antioxidant activity of vitamins C, E and beta-carotene, researchers at Creighton University in Omaha, Neb., stated that grape seed proanthocyanidin extract is highly bioavailable and provides greater protection against free radical damage (Toxicology, 148, 2-3:187-97, 2000) (www.elsevier.com).
Bilberry, Vaccinium myrtillus L., also contains OPCs, which may explain why it is thought to positively affect cognitive function through free radical scavenging. Bilberry has strong free radical scavenging properties, and its active constituents may inhibit lipid peroxidation (Phytother Res, 12, S1:S104-S106, 1998) (www.interscience.wiley.com).
Hawthorn's antioxidant activity lies within its large makeup of flavonoids, including OPCs (Z Naturforsch, 56, 9-10:739-44, 2001). Another herb, rosemary, Rosmarinus officinalis, contains rosmarinic acid, which has been shown to inhibit cancer formation in animal studies and acts as an antioxidant.
While numerous antioxidant ingredients appear to improve cognitive function and stave off oxidative damage, vitamin deficiencies may exacerbate cognitive decline. It has been suggested that dementia may occur in those with deficiencies of vitamin B12, as well as deficiencies of the other B vitamins. Research gathered from the NHANES III study in December 2001 indicated that elderly people with high homocysteine levels, as a result of low B vitamin intake, could be affected in terms of memory loss and cognition. Further, according to researchers in Stockholm, vitamin B12 and folic acid deficiencies may be involved in the development of Alzheimer's disease (Neurology, 56:1188-94, 2001).
Compounds derived from the brain may also be able to assist cognitive function in supplement form. Phosphatidylserine (PS) is a phospholipid that has been studied for its ability to slow cognitive decline because it is responsible for assisting in brain function and helping the brain process energy. PS can be derived from both plant and bovine sources, although there has been concern in recent years with the latter because of "mad cow" disease.
Both plant- and bovine-derived PS have been shown in clinical trials to positively affect cognitive function. According to a study conducted in Israel at the Tel Aviv University Sackler School of Medicine, plant- and bovine-sourced PS act similarly in vivo (Isr J Psychiatry Relat Sci, 37, 4:302-7, 2000) (http://www.niwi.knaw.nl). In addition, PS has been shown in clinical trials to improve memory, learning, concentration, word recall and mood in middle-aged and elderly subjects with dementia or age-related cognitive decline (Alt Med Rev (4, 3:144-61, 1999) (www.thorne.com/altmedrev).
Phosphatidylcholine (PC), another phospholipid nutrient, may also play a part in cognitive function. According to an animal study conducted in France, levels of PC (as well as PS) are lower in the brains of aged mice than younger mice (Prostaglandins Leukot Essent Fatty Acids, 64, 3:189-95, 2001). In an earlier human trial, researchers from the University of Guelph in Ontario discovered that patients with Alzheimer's disease, other dementias or general cognitive impairment had lower plasma phospholipid and PC concentrations (Lipids, 35, 12:1305-12, 2000) (www.aocs.org).
Acetyl-l-carnitine (ALC) is another compound found in the human body that may be relevant to cognitive function. ALC is an ester of the trimethylated amino acid, L-carnitine, which is synthesized in the human brain, liver and kidney. "[ALC] benefits mitochondrial efficiency and functions as an antioxidant within the mitochondria, helping neurons maintain optimal energy levels," wrote Robert Crayhon, Ph.D., in the May/June 2000 issue of International Journal of Integrative Medicine. The consumption of alcoholic beverages is contraindicated with ALC, and epileptics should avoid the supplement, Crayhon noted.
In an animal study conducted at the Tokyo Metropolitan Institute of Gerontology, ALC-treated rats had a superior learning capacity when compared to the control group (J Neurosci Res, 66, 2:266-71, 2001) (www.amedeo.com). Another study conducted at the University of California, San Diego, concluded that early-onset Alzheimer's patients may benefit more than late-onset Alzheimer's patients from ALC supplementation (Neurology, 47, 3:705-11, 2001). However, the same researchers conducted another double blind, placebo-controlled, randomized trial and ended up with different findings: ALC supplementation failed to slow cognitive decline in early-onset Alzheimer's patients (Neurology, 55, 6:805-10, 2000).
Herbs and Botanicals
Herbal products have also been extensively studied for their ability to improve cognitive function. Huperzine A, prepared from the moss Huperzia serrata, is a Chinese herb said to benefit cognitive health. According to a Chinese study, huperzine A shows promise for treating mental decline (Xhongguo Yao Li Xue Bao, 16, 5:391-5, 1995). In more recent research, scientists at the Chinese Academy of Sciences in Shanghai discovered that huperzine A treatment on transient global ischemia in gerbils resulted in lessened memory deficits and neuronal damage. Scientists concluded that huperzine A may have benefit in cerebrovascular type dementia (Neurosci Lett, 313, 3:137-40, 2001).
Lion's mane (Hericium erinaceus) is a mushroom thought to possess the ability to improve cognitive function. The correlation is suggested because the mushroom seems to be able to stimulate nerve growth factor (NGF), which may help inhibit cognitive decline. According to an early study, Lion's mane contains six compounds that were found to induce the synthesis of NGF, which is believed to be associated with Alzheimer's disease. The authors concluded that the mushroom may have potential in slowing progression of Alzheimer's (Tetrahedron Letters, 30, 3:373-76, 1990).
Vinpocetine is derived from vincamine, an alkaloid found in the periwinkle plant, and is recommended for cognitive function improvement--specifically memory and improving blood circulation to the brain. "Experiments with vinpocetine indicate that it can dilate blood vessels, enhance circulation in the brain, improve oxygen utilization, make red blood cells more pliable and inhibit aggregation of platelets," wrote Ray Sahelian, M.D., in his book Mind Boosters (St. Martins Griffin, 2000). Sahelian cited three clinical trials in which vinpocetine improved cognitive function and one trial that failed to demonstrate an effect. "The long-term effects of vinpocetine are not known," Sahelian warned. "It does have blood-thinning potential, hence those taking warfarin or high doses of aspirin or other blood thinners need to inform their physician before use."
Sahelian also reviewed Ginkgo biloba, stating "the primary indications for Ginkgo use are age-related cognitive decline and Alzheimer's disease ... A well-publicized study in the Journal of the American Medical Association indicated that 120 mg of Ginkgo extract per day for one year was able to slightly improve cognitive performance in patients with Alzheimer's disease (Le Bars 1997)."
While it has been suggested that Ginkgo extract improves cognitive function more effectively in patients with dementia (Public Health Nutr, 3, 4A:495-9, 2000), a trial conducted in The Netherlands did not find any effect on people with mild to moderate dementia or age-related memory impairment (J Am Geriatr Soc, 48, 10:1183-94, 2000) (www.lww.com/AGS).
Another herb that may have application in cognitive health is ashwagandha, otherwise known as Withania somnifera. According to Indian researchers at M.L. Sukhadia University in Udaipur, ashwagandha demonstrates anti-stress and neuroprotective effects when applied to the hippocampal region of stressed rats (Phytother Res, 15, 6:544-8, 2001).
While the numerous ingredients being studied for improving cognitive function are proving themselves in scientific research, additional research and media coverage sometimes casts a negative light on the supplement industry. The U.S. Senate Special Committee convened on Sept. 10, 2001, for a hearing titled, "Swindlers, Hucksters and Snake Oil Salesmen: The Hype and Hope of Marketing Anti-Aging Products to Seniors" (www.senate.gov/~aging/hr73.htm). The committee focused on companies that mislead consumers in regard to dietary supplements.
"As with any industry, the vast majority of manufacturers and marketers of supplements are reputable and law abiding," said Sen. John Breaux (D-La.), chairman of the committee. "It is the bad actors that we are concerned with." He added that the hearing was focused only on those marketing misleading or ineffective products and not the science of complementary therapies.
Industry organizations attempted to pre-empt and respond to the negative press coverage. The Dietary Supplement Education Alliance and the Council for Responsible Nutrition issued releases the day of the hearing discussing positive news about dietary supplements and the elderly. Both discussed ongoing studies on supplements and aging conducted by the National Institutes of Health, as well as recently published clinical studies on the benefits of dietary supplements for the elderly.
Ginkgo biloba has been especially persecuted this year in the media. In the July 11 Journal of the American Medical Association (286:208-16, 2001) (www.jama.com), researchers found that certain herbs, including Ginkgo biloba, may interfere with a patient's recovery time after surgery. Research indicated that complications could occur during post-op recovery because of the anti-clotting attributes of Ginkgo.
Another negative review of Ginkgo was printed in the September issue of Chemical Research in Toxicology (14, 9:1254-8, 2001) (http://pubs.acs.org), with researchers reporting they found colchicine--a substance that might cause birth malformations--in Ginkgo biloba supplements. The researchers, led by Howard Petty, Ph.D., from Wayne State University, concluded that Ginkgo may create fetal malformations and that "the potential detrimental roles of natural plant products in reproductive health merit further analysis." (More on this story can be found at http://www.naturalproductsinsider.com/articles/191news1.html.)
All in all, the research on dietary supplements is positive, demonstrating the supportive benefits they lend to cognitive function. As the numerous industry organizations continue to promote the clinical evidence behind dietary supplements, and the supplement manufacturers continue to sponsor peer-reviewed clinical trials, this industry will have additional support to combat negative media.
Cognitive Function Factoids
To the Detriment
· Age-related cognitive incline can slightly impair memory and mood.
· Dementia is not a symptom of old age.
· Dementia is a disease characterized by serious changes in memory, personality and behavior.
· 1.8 million Americans suffer from severe dementia.
· 1 million to 5 million Americans have mild to moderate dementia.
· 4 million dementia cases are because of Alzheimer's disease.
· Alzheimer's disease is expected to affect more than 6 million by the year 2040.
· The prevalence of Alzheimer's disease doubles every five years after age 65.
· Nearly half of all people age 85 and older are thought to have some form of dementia.
To the Benefit
· Fat-soluble vitamin E fights free radical damage in the body's fattiest organ--the brain.
· Antioxidant CoQ10 increases brain activity in Parkinson's patients.
· Flavonoids combat free radical damage and may improve cognitive function.
· Phosphatidylserine assists brain function and helps the brain process energy.
· Low phosphatidylcholine concentrations are common in dementia patients.
· Acetyl-l-carnitine helps neurons maintain optimal energy levels.
· Huperzine A may improve memory, cognitive and behavioral function.
· Lion's mane stimulates nerve growth factor, which may inhibit cognitive decline.
· Vinpocetine improves blood circulation to the brain.
· Ginkgo biloba may improve cognitive performance in Alzheimer's patients.
· Ashwagandha has shown neuroprotective effects in animal studies.