Which of us would not want a boost in mental function if we could get it? Whether it is remembering names, numbers, computer passwords, or why we walked into a room (so-called “destinesia”), we have all been frustrated by the occasional limitations of our ability to remember.

Mental function often declines particularly under conditions of stress or fatigue. In addition, most people over the age of 40 experience some memory loss, technically known as age-related cognitive decline (ARCD) or age-associated memory impairment (AAMI). We do not know what causes this normal experience, and there is no conventional treatment available for it. As you shall see in this section, there are a few natural treatments that might be helpful for these problems.

Certain conditions can cause a far more serious loss of mental function. These are discussed in the article on Alzheimer's disease and related conditions.

Principal Proposed Natural Treatments

Statistically speaking, it is easier to demonstrate a big improvement than a small one, and for that reason it is more difficult to prove the effectiveness of a treatment in a mild condition than in a severe one. Because of this, there is far more evidence supporting the use of natural supplements for treating Alzheimer’s disease than for improving mental function in healthy people. Nonetheless, there is some evidence for the latter, and we present it here.

An extract made from the herb Ginkgo biloba is a well-established herbal treatment for Alzheimer's disease. Ginkgo may also be helpful for improving normal age-related memory loss, and even for enhancing mental function in younger people.

In 6 out of 9 double-blind studies, use of Ginkgo biloba extract significantly improved age-related mental decline compared to placebo.

For example, in a double-blind, placebo-controlled trial, 241 seniors complaining of mildly impaired memory were given either placebo or ginkgo for 24 weeks.1 The results showed that ginkgo produced modest improvements in certain types of memory.

Another double-blind, placebo-controlled trial examined the effects of ginkgo extract in 40 men and women (ages 55 to 86) who did not suffer from any mental impairment.2 Over a 6-week period, the results showed improvements in measurements of mental function. Benefits were seen in four other trials as well, involving a total of about 135 participants.3-6

Set against these positive findings is a large (214 people) 24-week study that found no benefit in ordinary age-related memory loss.7 It has been suggested that flaws in the trial’s design led to this negative outcome.8 However, three other studies enrolling a total of about 400 seniors also failed to find significant benefit with daily use of ginkgo.9,57-58 Another double-blind, placebo-controlled study used a one-time dose of ginkgo, and again found no benefits.59

A small, double-blind, placebo-controlled study looking for immediate mind-stimulating effects did not find them.10

Besides these negative trials, there is another weakness in the evidence. There are numerous measurable aspects of memory and mental function, and studies of ginkgo for improving memory and mental function have examined a great many of these. Unfortunately the exact areas of benefits seen vary widely. For example, in one positive study, ginkgo may speed up the ability to memorize letters but not expand the number of letters that can be retained; while in another positive study, the reverse may be true. This type of inconsistency tends to decrease the confidence one can place in these apparently positive studies, because if ginkgo were really working, one would expect its effects to be more reproducible.

The bottom line: Ginkgo may help normal age-related memory loss, but more research is necessary before we will know for sure.

Several studies enrolling a total of about 250 people have examined the effects of ginkgo on memory and mental function in younger people.11-15,60-62 However, the benefits seen in the positive trials were inconsistent in the manner described above, and the largest study failed to find any effect.62,94 One study hints that benefits may occur at first, and then decline after several weeks.61

Besides ginkgo alone, several double-blind, placebo-controlled studies evaluated combined treatment with ginseng and ginkgo, or vinpocetine and ginkgo, for enhancing mental function in young people, and most found some evidence of benefit.15-17,63-64 Weak evidence suggests that combining phosphatidylserine with ginkgo might increase its efficacy.92 However, in two studies, ginkgo combined with the Ayurvedic herb brahmi failed to improve mental function.18,65 ( See the further discussion of brahmi below.)

For more information, including dosage and safety issues, see the full Ginkgo article.

Like ginkgo, the supplement phosphatidylserine (PS) is widely used in Europe to treat various forms of dementia. There is some evidence that PS can also help people with ordinary age-related memory loss.

In one double-blind study that enrolled 149 people with memory loss (but not dementia), PS provided significant benefits compared to placebo.19 People with the most severe memory loss showed the most improvement.

However, another double-blind trial of 120 older people with memory complaints (but not dementia) found no benefits.20 This discrepancy may have to do with the type of PS used—the second trial used the more modern soy-derived form of the supplement.

As noted above, phosphatidylserine might enhance the effectiveness of ginkgo.92

For more information, including dosage and safety issues, see the full Phosphatidylserine article.

Several studies have found indications that the herb ginseng might enhance mental function. However, the specific benefits seen have varied considerably from trial to trial, tending to make the actual cognitive effects of ginseng (if there are any) difficult to discern.

For example, in a 2-month, double-blind, placebo-controlled study of 112 healthy, middle-aged adults given either ginseng or placebo, results showed that ginseng improved abstract thinking ability.21 However, there was no significant change in reaction time, memory, concentration, or overall subjective experience between the two groups. Another double-blind, placebo-controlled study of 50 men found that 8-week treatment with a ginseng extract improved ability to complete a detail-oriented editing task.22 A double-blind trial of 16 healthy males found favorable changes in ability to perform mental arithmetic in those given ginseng for 12 weeks.23

More comprehensive benefits were seen in a double-blind, placebo-controlled trial of 60 seniors given 50 or 100 days of treatment.24 The results showed that Panax ginseng produced improvements in numerous measures of mental function, including memory, attention, concentration, and ability to cope.24 Benefits were still evident at the 50-day follow-up. However, virtually no improvement was seen in the placebo group, a result that is highly unusual and raises doubts about the accuracy of the study.

Not all of the studies are positive. A systematic review of 8 randomized, placebo-controlled trials found that ginseng did not improve cognitive function in healthy adults.111

The combination of ginseng with ginkgo has also been investigated. Four double-blind, placebo-controlled trials found inconsistent evidence of improved mental function for this herbal mixture.15-17,66

For more information, including dosage and safety issues, see the full Ginseng article.

The Ayurvedic herbBacopa monniera (brahmi) has a traditional reputation for improving memory. However, a 12-week, double-blind, placebo-controlled trial of 76 individuals that tested the potential memory-enhancing benefits of brahmi generally failed to find much evidence of benefit.39 The only significant improvement seen among all the many measures used was one that evaluated retention of new information. While this may sound at least somewhat promising, in fact it means almost nothing. Here is why: When a study uses many different techniques to assess improvement, mere chance ensures that at least one of them will come up with results. Properly designed studies should focus on one test of benefit alone (the primary outcome measure) that is selected prior to running the trial. The use of multiple tests is sometimes called “fishing for results” and is frowned upon by researchers. Similarly, a randomized trial involving 48 healthy elderly subjects found some memory enhancing effects of B. monnieri compared to placebo, but the outcomes measured were too numerous to be convincing.108

However, if several independent studies use multiple tests of improvement, and the pattern of response is reliably maintained, then the results begin to appear more significant. Unfortunately, this does not seem to be the case concerning brahmi. In another double-blind, placebo-controlled study of 38 individuals, short-term use of brahmi failed to produce any measurable improvements in memory,41 while in a third double-blind, placebo-controlled study, use of brahmi over a 2-week period did produce some benefits, but in quite a different pattern.40 Finally, a study found that one-time combined treatment with Ginkgo biloba (120 mg) and brahmi (300 mg) failed to improve mental function.18

Slightly more promising results have been seen in studies of a proprietary Ayurvedic mixture containing brahmi and about 30 other ingredients.42,43 However, these studies were generally not up to modern scientific standards.

For more information, including dosage and safety issues, see the full Bacopa monniera article.

Other Proposed Natural Treatments

On the basis of one small double-blind study, a proprietary mixture of substances called neuropeptides have been extensively marketed for improving mental function.86 Radio, television, and Internet advertisements state that this product has been shown to bring about “a reversal of ten years of short-term memory decline.” However, this claim is not founded in reliable evidence.

Another single study suggests that the supplement NADH might help improve temporary mental impairment caused by jet lag.25

Evidence conflicts on whether multivitamin/multimineral tablets may improve cognitive function in people of various age groups.29-32,67,93,95Note: Serious allegations of fraud have been raised regarding the work of one of the scientists involved in this research.48-49 In general, the best designed studies have failed to find benefit. However, it is quite possible that multivitamin/multimineral supplements are helpful for people with marked vitamin or mineral malnutrition.93

Studies of isoflavone -rich soy or red clover for enhancing mental function in women have found little to no beneficial effects at best.50-52,68, 89, 91

Huperzine A is a potent chemical derived from a particular type of club moss ( Huperzia serrata). This substance is really more a drug than an herb, but it is sold over the counter as a dietary supplement for memory loss and mental impairment. Some evidence indicates that it may be helpful for Alzheimer’s disease and related conditions; very weak evidence suggests benefit for healthy people.35 Much the same can also be said about the substance vinpocetine.36

Creatine, best known for its use as a sports performance enhancer, may improve mental function in sleep deprived,53,69 but not necessarily well-rested young subjects.107Sage54,70,105 and vitamin B171 have at least slight supporting evidence from preliminary double-blind trials.

Mild vitamin B12 deficiency may impair mental function.26,27 Because such deficiency is relatively common in the elderly, it has been suggested that vitamin B 12 supplements may be appropriate in this age group. However, in the two studies that tried it, no benefits were seen.55,83

Seniors are also commonly deficient in vitamin B 6, but a review of the literature failed to find meaningful evidence that B 6 offers any benefits.56 One study failed to find folate helpful either;82 however, in another study, folate supplementation improved mental function in seniors with high levels of homocysteine.88 Combinations of B-vitamins, including B 12, B 6, and folate, have proved ineffective.83,87,104,109

One study failed to find any benefit with zinc.84

Preliminary double-blind trials suggest that the amino acid tyrosine may improve memory and mental function under conditions of sleep deprivation or other forms of stress.33,34 Other double-blind trials suggest that a proprietary extract of the herb Rhodiola rosacea may offer a similar benefit.45-47

Whey protein contains alpha-lactalbumin, a protein that in turn contains high levels of the amino acid tryptophan. Tryptophan is the body’s precursor for serotonin and is thought to affect mental function. In a small double-blind study, use of alpha-lactalbumin in the evening improved morning alertness perhaps by enhancing sleep quality.72 Another small double-blind study found weak evidence that alpha-lactalbumin improved mental function in people sensitive to stress.73 A third study failed to find that alpha-lactalbumin significantly improved memory in women experiencing premenstrual symptoms.74

Herbs that contain caffeine would be expected to enhance mental function in healthy people, at least temporarily. These include green tea, black tea, maté, and guarana. For example, in a double-blind, placebo-controlled study of 129 healthy young adults, one-time use of guarana plus vitamins and minerals improved mental function and reduced mental fatigue among those undergoing a battery of cognitive tests.101 In another double-blind, placebo-controlled study, use of guarana alone or guarana plus ginseng appeared to improve mental function.98 However, these studies suffered from some design problems. In two other studies, no benefits were seen.99,100

Some reports suggested that declining levels of the hormone DHEA cause impaired mental function in the elderly. On this basis, DHEA has been promoted as a brain-boosting supplement. However, large studies have failed to find any correlation between DHEA levels and mental function, and there is no direct evidence that DHEA supplements provide any benefit in seniors.37-38,106 One study did find potential benefits in younger people.75

Weak evidence culled from a large double-blind, placebo-controlled study hints that use of beta-carotene over many years might enhance mental function.96Note: Long-term use of beta-carotene might present safety risks. See the full Beta-carotene article for more information.

Other herbs and supplements proposed for enhancing memory and mental function, but lack meaningful supporting evidence, include gotu kola, rosemary, saffron, muira puama, sage, and lobelia.76-81,103

In one small, double-blind study, the supplement ribose failed to prove effective for enhancing mental function.102 However, the researchers suggested that the dose they used (2 g daily) may have been insufficient.

A very large study failed to find that use of vitamin E helped maintain healthy mental function in women over 65.85

Women who are marginally deficient in iron may experience improved mental function when they correct this deficiency.90

Carnitine has shown some benefit for reducing mental fatigue and enhancing cognitive function in centenarians.97

Fish oil has been studied to determine its effects on the neurodevelopment of children. In a large study, 2,399 pregnant women were randomized to take a fish oil capsule—a combination docosahexaenoic acid (DHA) 800 mg/day and eicosapentaenoic Acid (EPA)—or a placebo. During follow-up, when the children were around ages 1-4 years old, researchers found that fish oil did not provide an extra boost to the cognitive and language development of in these children.110 In addition, two randomized trials have failed to find any benefit of fish oil for enhancing memory and mental function in older adults without dementia.112,113