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.

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.

Age-related Mental Decline

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.2Over 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.7It has been suggested that flaws in the trial’s design led to this negative outcome.8However, three other studies enrolling a total of about 400 seniors also failed to find significant benefit with daily use of ginkgo.9,57-58Another 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.

Improving Memory and Mental Function in Younger People

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.62,94One 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 vinpocetineand ginkgo, for enhancing mental function in young people, and most found some evidence of benefit.15-17,63-64 Weak evidence suggests that combining phosphatidylserinewith ginkgo might increase its efficacy.92 However, in two studies, ginkgo combined with the Ayurvedicherb 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.21However, 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.22A 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 ginsengproduced 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.

Bacopa monniera (Brahmi)

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. monniericompared 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,41while 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.