04 Mar Herbs for Memory
Though nothing so far can cure or prevent dementia, many herbs show promise in combating its memory-impairing disease.
Imagine this. You’re driving in the city. Nothing is familiar. You’re not even sure of the cardinal directions. You hesitate at an intersection, car horns blaring behind you. Yet you’re not a new arrival to this place. You’ve lived in this city for many years, are within five miles of your house—and you have recently received the diagnosis of dementia.
Defining Dementia
Many people wonder whether mislaying the keys or blanking on the names of acquaintances at cocktail parties telegraph an insidious downslide into dementia. Taken alone, minor episodes of forgetfulness are normal. People with dementia don’t just forget a friend’s name, but much of their shared history. It becomes difficult to interact with other people, think abstractly, solve problems, speak, write, and comprehend printed and spoken words. This chronic, progressive condition can eventually erode the ability to perform simple tasks as basic as getting dressed in the morning.
There are more than 60 types of dementia. The most common type is Alzheimer’s disease (AD), which afflicts more than 35 million people worldwide and 5.5 million Americans. This is followed by vascular dementia (also called multi-infarct dementia) and Parkinson’s disease (a disease that impairs muscle control).
Unfortunately, dementia lacks a cure. Drugs such as Aricept and Namenda can produce modest improvements, but do not stop the course of the disease.
Herbal Defense
Worldwide, traditional healers prize selected herbs for sustaining mental function. So far, the research on herbs to enhance memory in normal people and in those with dementia remains preliminary. As with pharmaceuticals, no herb has yet been shown to cure dementia, or to prevent it from developing. Nevertheless, some experts are quite optimistic about particular herbs.
One such expert is Con Stough, Ph.D., a professor of neuropsychology at the Brain Sciences Institute at Swinburne University in Melbourne, Australia. He points out that, while pharmaceuticals tend to have a single action, herbs can have multiple, often synergistic actions. Because AD and other dementias have multiple causes, this herbal multitasking is important.
The herb best supported by research is ginkgo (Ginkgo biloba). So says neuropsychopharmacologist Jerry Cott, Ph.D., a renowned researcher, lecturer and writer. Standardized leaf extracts are antioxidant and anti-inflammatory, improve circulation to the brain, and protect brains cells from beta-amyloid (a misfolded protein that accumulates in the brains of those with AD). In mice with an Alzheimer’s-like condition, ginkgo extracts inhibit damage to nerve cells and promote nerve cell growth and the generation of new cells in vulnerable brain areas.
In a recent trial of people with dementia, 240 mg a day of ginkgo standardized extract improved memory and attention, as well as relieving some of the depression, anxiety and agitation that can complicate the disease. Reviews of the ginkgo research conclude the herb is significantly more effective than placebo in stabilizing or improving cognitive function in people with AD. Ginkgo has also been shown comparable to the drug Aricept.
Furthermore, a couple of studies suggest ginkgo perks up mental function in elders with mild age-related memory impairment. Some but not all studies show improved cognitive processes in healthy people, particularly those older than 50.
The million-dollar question is, can ginkgo prevent this dreaded disease? Two recent trials say no—not if you wait to start the in herb in your 80s, particularly if you don’t remember to take your pills. In one of these studies, a subgroup analysis did show some benefit among those who consistently took their ginkgo. Preliminary results are now available for a much-awaited French trial called the GuidAge Study, in which 2,854 elderly people with memory problems (but no dementia) took either 120 mg of a ginkgo extract or a placebo twice a day for five years. Again, overall there was no statistically significant difference in the rate of progression to dementia. However, among the people who took their ginkgo as directed for at least four years, the development of dementia was cut in half.
The Ayurvedic herb bacopa (Bacopa monnieri) is also gaining a reputation as a brain aid. Stough, who has done much of the research on bacopa, says the herb has several anti-Alzheimer’s actions. “It removes beta-amyloid. And it is a strong anti-inflammatory, antioxidant and metal chelator.” He adds, “There is a growing consensus indicating that bacopa and particularly CDRI08 [a special standardized extract] improve memory and cognition in non-AD patients.”
In the largest and most recent study, 107 healthy adults took either a placebo or a standardized bacopa extract (two 150-mg tablets a day) for three months. Those who faithfully took the herb performed significantly better on memory tests. A 12-week study of healthy adults showed bacopa improved learning and memory and reduced anxiety. So far, one-time doses of bacopa do not seem to have an appreciable impact on cognitive function.
Ginkgo and bacopa combined may also improve mental function in healthy adults. While study results are mixed, outcomes may depend upon the dose and the duration of treatment.
Stough is excited about ongoing investigations into the effects of 12 months of bacopa extract (CDRI08) in healthy elderly people and of three to six months of bacopa in people with AD.
Ashwagandha (Withania somnifera) has a long history in Ayurvedic medicine as a rasayana, or rejuvenative tonic—a substance to promote longevity, sharpen the mind, protect against the ravages of stress, and reduce anxiety. In test-tube studies, root extracts protect nerve cells from beta-amyloid, increase the healthy branching of nerve cells in the hippocampus (a brain area damaged by stress overload and AD), and improve memory in normal and demented mice. So far, no studies have investigated its potential benefits in preventing or treating dementia in humans.
Long used to enhance vitality, Asian ginseng (Panax ginseng) and American ginseng (P. quinquefolius) benefit the brain. Like ginkgo, Asian ginseng protects nerve cells from beta-amyloid and other toxins. Both species are adaptogens, substances that mitigate stress overload. Chronic stress, according to animal studies, atrophies brain areas involved in memory.
Alexander Panossian, Ph.D., head of research and development at the Swedish Herbal Institute, has published numerous articles on adaptogens such as ginseng and rhodiola (Rhodiola rosea). He believes both that stress overload is a risk factor for dementia and that “adaptogens might be very beneficial in preventing dementia.”
While research has yet to prove that theory, two preliminary studies found that Asian ginseng, as an add-on to drug treatment, improved cognitive function in people with Alzheimer’s disease. Both Asian and American ginseng (with or without ginkgo) have been shown to boost memory in healthy people.
Another promising adaptogen is rhodiola (Rhodiola rosea) The root of this Arctic plant has a long history in folk medicine. Research in the former Soviet Union revealed enhancement of physical and mental function during times of stress. In more recent research by Panossian and others, rhodiola extracts improve symptoms of anxiety, depression and stress burnout, and reduce mental fatigue. One study showed improvement in people with “cognitive deficiencies.” In rat studies, extracts increase key brain chemicals (including acetylcholine), protect nerves and reduce cognitive impairment in a condition like AD.
Rhodiola hasn’t yet been studied in people with dementia. Nevertheless, Richard P. Brown, M.D., and Patricia Gerbarg, M.D., authors of The Rhodiola Revolution (Rodale, 2005), have found that standardized extracts can enhance memory and cognitive function in their patients, including those with age-related memory decline and mild dementia. Even more effective, they say, is the combination of rhodiola with two other adaptogens—eleuthero (Eleutherococcus senticosus) and schisandra (Schisandra chinensis).
Gotu kola (Centella asiatica) is a ground cover native to India, Australia and Southeast Asia. The herb is an adaptogen, wound healer, circulatory stimulant and brain tonic. Scientific research only recently has begun to validate its ability to improve cognition. In a 2008 Thai study, a gotu kola extract enhanced working memory and improved mood in a group of 28 elderly adults.
Sage (Salvia lavandulaefolia, S. officinalis) has a tradition in European herbalism for improving memory. The leaf’s essential oils are anti-inflammatory, antioxidant, help preserve the brain’s acetylcholine (a neurotransmitter decreased in AD) and protect neurons from beta-amyloid’s toxic effects. Several studies demonstrated memory enhancement with oral consumption of dried leaf extracts or small amounts of diluted essential oil in healthy people, both old and young. At least one study has shown that inhalation of the essential oil improves memory and mood.
Chinese club moss (Huperzia serrata) contains huperzine A, a chemical that inhibits destruction of acetylcholine and protects nerve cells from beta-amyloid and other noxious agents. A half dozen preliminary human trials show huperzine A improves some measures of cognitive function and behavior in people with AD.
While huperzine A sells as a dietary supplement, it’s not something you’d take unless you had AD. Cott notes that this purified extract has a pharmaceutical effect much like the drug Aricept, though it may have fewer side effects. Brown and Gerbarg agree that that huperzine A is generally well tolerated, although some patients do report mild nausea, diarrhea and dizziness.
Another isolated plant chemical, curcumin, comes from the curry spice turmeric (Curcuma longa). A potent antioxidant and anti-inflammatory agent, curcumin also inhibits formation of beta-amyloid and improves its clearance from the body. Experiments suggest that vitamin D and curcumin may have an additive effect in clearing beta-amyloid. Studies investigating the potential benefits in AD have just begun.
Intestinal absorption of curcumin is poor, though once in the blood this chemical passes readily into the brain. Things that enhance absorption include cooking turmeric in oil (as is the case in Indian cooking), encapsulating curcumin with bromelain and piperine (from pepper) or binding it with phosphatidylcholine. Cott’s recipe is to heat a cup of full-fat milk, add a teaspoon of turmeric and a half teaspoon of pepper, and drink morning and evening. My recipe substitutes full-fat milk for almond milk with 1/2 tsp of raw coconut oil or organic skim milk with 1 tsp of raw coconut oil.
Chemically speaking, curcumin is a polyphenol. Other polyphenol-rich plants include red grapes, berries, pomegranates, green and black tea, chocolate, and coffee. Berries are rich in a particular type of neuroprotective polyphenol called anthocyanins. People who regularly consume berries are less likely to develop Parkinson’s disease. Grape polyphenols reduce production of beta-amyloid, inhibit its tendency to clump, and protect the brain cells from its toxic effects. They also reduce activation of microglia, brain cells associated with inflammation. Lab experiments also show green tea (Camellia sinensis) polyphenols protect against beta-amyloid-induced nerve toxicity. Humans and lab animals who drink green tea have a reduced risk of dementia, including AD and Parkinson’s disease. Green tea drinkers also enjoy protection against cardiovascular disease, which is a risk factor for dementia.
Reducing Risks
Research has yet to prove that changing one’s lifestyle reduces the risk of dementia. However, several strategies have at least preliminary support.
Diet matters. What you eat influences the composition of your brain; provides nutrients that protect against oxidative stress and inflammation; contributes raw materials to make neurotransmitters; and keeps the arteries to the brain healthy. Whereas diets high in saturated fat (which comes mainly from meat and dairy) increase dementia risk, those replete with vegetables and fish lower it. The Mediterranean diet, which emphasizes fruits, vegetables, fish, nuts and olive oil, seems to protect against AD and slow the rate of age-related cognitive decline.
The type of fish consumed may be important. People who eat cold-water fish, which is rich in the brain-friendly fatty acid docosahexaenoic acid (DHA), reduce their dementia risk. Fatty fish is also a food source of vitamin D, which promotes good brain function and nerve protection. Many Americans have insufficient blood levels of this vitamin, and low levels correlate with dementia.
Stay active. In an exciting new study of 120 older adults, an aerobic training program increased the size of the hippocampus (a brain region that shrinks some with advancing age and more dramatically in AD) and improved spatial memory. Earlier research has supported the notion that physical exercise promotes brain health.
Use it or lose it. Higher educational attainment, spending more time on intellectual activities and working are associated with a reduced probability of AD. Perhaps people build their brain reserves and can lose more neurons before impairment shows. Or perhaps people continue solving Sudoku puzzles because they don’t have dementia. Nevertheless, some research shows that memory exercises and less-structured intellectual pursuits can yield benefits for healthy older adults and those beginning to lose their mental edge.
Your best bets to maintain your brain are to eat a plant-based diet rich in berries, red grapes and curried food, drink green tea, regularly participate in an exercise that makes you smile and that you can do with friends, take time to relax, and keep learning. If you’ve entered the autumn of your life, should you take any herbs? Research hasn’t answered that question. In the meantime, Dr. Jerry Cott and I are both taking our daily doses of bacopa and ginkgo.