Enhancing Memory and Mental Function
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.
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.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.
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.62,94 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.
Evidence conflicts on whether multivitamin/multimineral tablets may improve cognitive function in people of various age groups.29-32,67,93,95 Note: 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
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.96 Note : Long-term use of beta-carotene might present safety risks. See the full Beta-carotene article for more information.
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.
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
References[ + ]
1. Brautigam MR, Blommaert FA, Verleye G, et al. Treatment of age-related memory complaints with Ginkgo biloba extract: a randomized double blind placebo-controlled study. Phytomedicine. 1998;5:425-434.
2. Mix JA, Crews WD Jr. An examination of the efficacy of Ginkgo biloba extract EGb 761 on the neuropsychologic functioning of cognitively intact older adults. J Altern Complement Med. 2000;6:219-229.
3. Winther K, Randlov C, Rein E, et al. Effects of Ginkgo biloba extract on cognitive function and blood pressure in elderly subjects. Curr Ther Res. 1998;59:881-888.
4. Rai GS, Shovlin C, Wesnes KA. A double-blind, placebo controlled study of Ginkgo biloba extract (Tanakan™) in elderly outpatients with mild to moderate memory impairment. Curr Med Res Opin. 1991;12:350-355.
5. Rigney U, Kimber S, Hindmarch I. The effects of acute doses of standardized Ginkgo biloba extract on memory and psychomotor performance in volunteers. Phytotherapy Res. 1999;13:408-415.
6. Allain H, Raoul P, Lieury A, et al . Effect of two doses of Ginkgo biloba extract (EGb 761) on the dual-coding test in elderly subjects. Clin Ther. 1993;15:549-558.
7. van Dongen MC, van Rossum E, Kessels AG, et al. The efficacy of ginkgo for elderly people with dementia and age-associated memory impairment: new results of a randomized clinical trial. J Am Geriatr Soc. 2000;48:1183-1194.
8. Le Bars P. Conflicting results on ginkgo research. Forsch Komplementarmed Klass Naturheilkd. 2002;9:19-20.
9. Solomon PR, Adams F, Silver A, et al. Ginkgo for memory enhancement: a randomized controlled trial. JAMA. 2002;288:835-840.
10. Nathan PJ, Ricketts E, Wesnes K, et al. The acute nootropic effects of Ginkgo biloba in healthy older human subjects: a preliminary investigation. Hum Psychopharmacol. 2002;17:45-49.
11. Stough C, Neuropsychological changes after 30-day Ginkgo biloba administration in healthy participants. Int J Neuropsychopharm. 2001;4:131-134.
12. Kennedy DO, Scholey AB, Wesnes KA. The dose-dependent cognitive effects of acute administration of Ginkgo biloba to healthy young volunteers. Psychopharmacology (Berl). 2000;151:416-423.
13. Hindmarch I. Activity of Ginkgo biloba extract on short term memory [in French; English abstract]. Presse Med. 1986;15:1592-1594.
14. Warot D, Lacomblez L, Danjou P, et al. Comparative effects of Ginkgo biloba extracts on psychomotor performances and memory in healthy subjects [in French; English abstract]. Therapie. 1991;46:33-36.
15. Kennedy DO, Scholey AB, Wesnes KA. Modulation of cognition and mood following administration of single doses of Ginkgo biloba, ginseng, and a ginkgo/ginseng combination to heathy young adults. Physiol Behav. 2002;75:739-751.
16. Wesnes KA, Faleni RA, Hefting NR, et al. The cognitive, subjective, and physical effects of a Ginkgo biloba / Panax ginseng combination in healthy volunteers with neurasthenic complaints. Psychopharmacol Bull. 1997;33:677-683.
17. Wesnes KA, Ward T, McGinty A, et al. The memory enhancing effects of a Ginkgo biloba / Panax ginseng combination in healthy middle-aged volunteers. Psychopharmacology (Berl). 2000;152:353-361.
18. Maher BF, Stough C, Shelmerdine A, et al. The acute effects of combined administration of Ginkgo biloba and Bacopa monniera on cognitive function in humans. Hum Psychopharmacol. 2002;17:163-164.
19. Crook TH, Tinklenberg J, Yesavage J, et al. Effects of phosphatidylserine in age-associated memory impairment. Neurology. 1991;41:644-649.
20. Jorissen BL, Brouns F, Van Boxtel MP, et al. The influence of soy-derived phosphatidylserine on cognition in age-associated memory impairment. Nutr Neurosci. 2001;4:121-134.
21. Sorensen H, Sonne J. A double-masked study of the effects of ginseng on cognitive functions. Curr Ther Res. 1996;57:959-968.
22. Sandberg F, Dencker L. Experimental and clinical tests on ginseng. Z Phytother. 1994;15:38-42.
23. D'Angelo L, Grimaldi R, Caravaggi M, et al. A double-blind, placebo-controlled clinical study on the effect of a standardized ginseng extract on psychomotor performance in healthy volunteers. J Ethnopharmacol. 1986;16:15-22.
24. Siegl C, Siegl HJ. The possible revision of impaired mental abilities in old age: a double-blind study with Panax ginseng [translated from German]. Therapiewoche. 1979;29:4206,4209-4216.
25. Kay GG, Viirre E, Clark J. Stabilized NADH as a countermeasure for jet lag. Presented at: 48th International Congress of Aviation and Space Medicine; September 17-21, 2000; Rio de Janeiro, Brazil.
26. Carmel R, Gott P, Degiorgio C, et al. Abnormal P300 event-related potentials in mild, preclinical cobalamin deficiency [abstract]. Int J Hematol. 2000;72(suppl 1):207.
27. Louwman MW, van Dusseldorp M, van de Vijver FJ, et al. Signs of impaired cognitive function in adolescents with marginal cobalamin status. Am J Clin Nutr. 2000;72:762-769.
28. Benton D. Micro-nutrient supplementation and the intelligence of children. Neurosci Biobehav Rev. 2001;25:297-309.
29. Schoenthaler SJ, Amos SP, Doraz WE, et al. Controlled trial of vitamin-mineral supplementation on intelligence and brain function. Pers Individual Differences. 1991;12:343-350.
30. Schoenthaler SJ, Amos SP, Eysenck HJ, et al. Controlled trial of vitamin-mineral supplementation: effects on intelligence and performance. Pers Individual Differences. 1991;12:351-362.
31. Schoenthaler SJ, Bier ID. Vitamin-mineral intake and intelligence: a macrolevel analysis of randomized controlled trials. J Altern Complement Med. 1999;5:125-134.
32. Benton D, Fordy J, Haller J. The impact of long-term vitamin supplementation on cognitive functioning. Psychopharmacology. 1995;117:298-305.
33. Deijen JB, Wientjes CJ, Vullinghs HF, et al. Tyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training course. Brain Res Bull. 1999;48:203-209.
34. Neri DF, Wiegmann D, Stanny RR, et al. The effects of tyrosine on cognitive performance during extended wakefulness. Avit Space Environ Med. 1995;66:313-319.
35. Sun QQ, Xu SS, Pan JL, et al. Huperzine-A capsules enhance memory and learning performance in 34 pairs of matched adolescent students. Zhongguo Yao Li Xue Bao. 1999;20:601-603.
36. Hindmarch I, Fuchs HH, Erzigkeit H. Efficacy and tolerance of vinpocetine in ambulant patients suffering from mild to moderate organic psychosyndromes. Int Clin Psychopharmacol. 1991;6:31-43.
37. Barrett-Connor E, Edelstein SL. A prospective study of dehydroepiandrosterone sulfate and cognitive function in an older population: the Rancho Bernardo Study. J Am Geriatr Soc. 1994;42:420-423.
38. Moffat SD, Zonderman AB, Harman SM, et al. The relationship between longitudinal declines in dehydroepiandrosterone sulfate concentrations and cognitive performance in older men. Arch Intern Med. 2000;160:2193-2198.
39. Roodenrys S, Booth D, Bulzomi S, et al. Chronic effects of Brahmi ( Bacopa monnieri) on human memory. Neuropsychopharmacology. 2002;27:279-281.
40. Stough C, Lloyd J, Clarke J, et al. The chronic effects of an extract of Bacopa monniera (Brahmi) on cognitive function in healthy human subjects. Psychopharmacology. 2001;156:481-484.
41. Nathan PJ, Clarke J, Lloyd J, et al. The acute effects of an extract of Bacopa monniera (Brahmi) on cognitive function in healthy normal subjects. Hum Psychopharmacol. 2001;16:345-351.
42. Agrawal A, Dubey M, Dubey G. Effects of Mentat on memory span, attention, galvanic skin resistance (GSR) and muscle action potential (EMG) among normal adults. Pharmacopsychoecologia. 1990;3:39-42.
43. Sharma AK, Agrawal A, Agrawal U, et al. Influence of Mentat (BR-16A) on memory and mental fatigue in cases of anxiety neurosis and depression. Ind J Cancer Res. 1990;3:27.
44. Montgomery SA, Thal LJ, Amrein R. Meta-analysis of double blind randomized controlled clinical trials of acetyl-L-carnitine versus placebo in the treatment of mild cognitive impairment and mild Alzheimer's disease. Int Clin Psychopharmacol. 2003;18:61-71.
45. Darbinyan V, Kteyan A, Panossian A, et al. Rhodiola rosea in stress induced fatigue—a double blind cross-over study of a standardized extract SHR-5 with a repeated low-dose regimen on the mental performance of healthy physicians during night duty. Phytomedicine. 2000;7:365-371.
46. Spasov AA, Wikman GK, Mandrikov VB, et al. A double-blind, placebo-controlled pilot study of the stimulating and adaptogenic effect of Rhodiola rosea SHR-5 extract on the fatigue of students caused by stress during an examination period with a repeated low-dose regimen. Phytomedicine. 2000;7:85-89.
47. Shevtsov VA, Zholus BI, Shervarly VI, et al. A randomized trial of two different doses of a SHR-5 rhodiola rosea extract versus placebo and control of capacity for mental work. Phytomedicine. 2003;10:95-105.
48. Meguid MM, Shenkin A. Introduction: nutritional supplements and the quest to improve human performance—the need for the strictest standards and rigor when reporting clinical trials. Nutrition. 2003;19:955-956.
49. Smith R. Validity of Canadian studies: response of editor of BMJ. BMJ. 2004;328:465.
50. Duffy R, Wiseman H, File SE. Improved cognitive function in postmenopausal women after 12 weeks of consumption of a soya extract containing isoflavones. Pharmacol Biochem Behav. 2003;75:721-729.
51. Kreijkamp-Kaspers S, Kok L, Grobbee DE, et al. Effect of soy protein containing isoflavones on cognitive function, bone mineral density, and plasma lipids in postmenopausal women: a randomized, controlled trial. Obstet Gynecol Surv. 2004;60:41-43.
52. Howes JB, Bray K, Lorenz L, et al. The effects of dietary supplementation with isoflavones from red clover on cognitive function in postmenopausal women. Climacteric. 2004;7:70-77.
53. Rae C, Digney AL, McEwan SR, et al. Oral creatine monohydrate supplementation improves brain performance: a double-blind, placebo-controlled, cross-over trial. Proc R Soc Biol Sci. 2003;270:2147-2150.
54. Tildesley NT, Kennedy DO, Perry EK, et al. Salvia lavandulaefolia (Spanish Sage) enhances memory in healthy young volunteers. Pharmacol Biochem Behav. 2003;75:669-674.
55. Hvas AM, Juul S, Lauritzen L, et al. No effect of vitamin B-12 treatment on cognitive function and depression: a randomized placebo controlled study. J Affect Disord. 2004;81:269-273.
56. Malouf R, Grimley EJ. The effect of vitamin B6 on cognition. Cochrane Database Syst Rev. 2003;CD004393
57. Burns NR, Bryan J, Nettelbeck T, et al. Ginkgo biloba: no robust effect on cognitive abilities or mood in healthy young or older adults. Hum Psychopharmacol. 2005 Dec 5. [Epub ahead of print].
58. Elsabagh S, Hartley DE, File SE, et al. Limited cognitive benefits in Stage +2 postmenopausal women after 6 weeks of treatment with Ginkgo biloba. J Psychopharmacol. 2005;19:173-181.
59. Nathan PJ, Ricketts E, Wesnes K, et al. The acute nootropic effects of Ginkgo biloba in healthy older human subjects: a preliminary investigation. Hum Psychopharmacol. 2002;17:45-49.
60. Mattes RD, Pawlik MK. Effects of Ginkgo biloba on alertness and chemosensory function in healthy adults. Hum Psychopharmacol. 2004;19:81-90.
61. Elsabagh S, Hartley DE, Ali O, et al. Differential cognitive effects of Ginkgo biloba after acute and chronic treatment in healthy young volunteers. Psychopharmacology (Berl). 2005 Mar 1. [Epub ahead of print].
62. Burns NR, Bryan J, Nettelbeck T, et al. Ginkgo biloba: no robust effect on cognitive abilities or mood in healthy young or older adults. Hum Psychopharmacol. 2005 Dec 5. [Epub ahead of print].
63. Polich J, Gloria R. Cognitive effects of a Ginkgo biloba /vinpocetine compound in normal adults: systematic assessment of perception, attention and memory. Hum Psychopharmacol. 2001;16:409-416.
64. Hartley DE, Elsabagh S, File SE, et al. Gincosan (a combination of Ginkgo biloba and Panax ginseng): the effects on mood and cognition of 6 and 12 weeks' treatment in post-menopausal women. Nutr Neurosci. 2005;7:325-333.
65. Nathan PJ, Tanner S, Lloyd J, et al. Effects of a combined extract of Ginkgo biloba and Bacopa monniera on cognitive function in healthy humans. Hum Psychopharmacol. 2004;19:91-96.
66. Hartley DE, Elsabagh S, File SE, et al. Gincosan (a combination of Ginkgo biloba and Panax ginseng): the effects on mood and cognition of 6 and 12 weeks' treatment in post-menopausal women. Nutr Neurosci. 2005;7:325-333.
67. Wolters M, Hickstein M, Flintermann A, et al. Cognitive performance in relation to vitamin status in healthy elderly German women-the effect of 6-month multivitamin supplementation. Prev Med. 2005;41:253-259
68. Casini ML, Marelli G, Papaleo E, et al. Psychological assessment of the effects of treatment with phytoestrogens on postmenopausal women: a randomized, double-blind, crossover, placebo-controlled study. Fertil Steril. 2006;85:972-978.
69. McMorris T, Harris RC, Swain J, et al. Effect of creatine supplementation and sleep deprivation, with mild exercise, on cognitive and psychomotor performance, mood state, and plasma concentrations of catecholamines and cortisol. Psychopharmacology (Berl). 2006 Jan 17. [Epub ahead of print]
70. Kennedy DO, Pace S, Haskell C, et al. Effects of Cholinesterase Inhibiting Sage (Salvia officinalis) on mood, anxiety and performance on a psychological stressor battery. Neuropsychopharmacology. 2005 Oct 5. [Epub ahead of print]
71. Benton D, Griffiths R, Haller J, et al. Thiamine supplementation mood and cognitive functioning. Psychopharmacology (Berl). 1997;129:66-71.
72. Markus CR, Jonkman LM, Lammers JH, et al. Evening intake of alpha-lactalbumin increases plasma tryptophan availability and improves morning alertness and brain measures of attention. Am J Clin Nutr. 2005;81:1026-1033.
73. Markus CR, Olivier B, de Haan EH, et al. Whey protein rich in alpha-lactalbumin increases the ratio of plasma tryptophan to the sum of the other large neutral amino acids and improves cognitive performance in stress-vulnerable subjects. Am J Clin Nutr. 2002;75:1051-1056.
74. Schmitt JA, Jorissen BL, Dye L, et al. Memory function in women with premenstrual complaints and the effect of serotonergic stimulation by acute administration of an alpha-lactalbumin protein. J Psychopharmacol. 2005;19:375-384
Alhaj HA, Massey AE, McAllister-Williams RH, et al. Effects of DHEA administration on episodic memory, cortisol and mood in healthy young men: a double-blind, placebo-controlled study. Psychopharmacology (Berl). 2005 Oct 18. [Epub ahead of print]
76. Moss M, Cook J, Wesnes K, et al. Aromas of rosemary and lavender essential oils differentially affect cognition and mood in healthy adults. Int J Neurosci. 2003;113:15-38.
77. Decker MW, Majchrzak MJ, Arneric SP. Effects of lobeline, a nicotinic receptor agonist, on learning and memory. Pharmacol Biochem Behav. 1993;45:571-576.
78. Da Silva AL, Piato AL, Bardini S, et al. Memory retrieval improvement by Ptychopetalum olacoides in young and aging mice. J Etnopharmacol. 2004;95:199-203.
79. Siqueira IR, Fochasatto C, da Silva AL, et al. Ptychopetalum olacoides, a traditional Amazonien “nerve tonic”, possesses anticholinesterase activity. Pharmacol Biochem Behav. 2003;75:645-50.
80. Abe K, Saito H. Effects of saffron extract and its constituent crocin on learning behaviour and long-term potentiation. Phytother Res. 2000;14:149-52.
81. Crews WD, Harrison DW, Griffin ML, et al. A double-blinded, placebo-controlled, randomized trial of the neuropsychologic efficacy of cranberry juice in a sample of cognitively intact older adults: pilot study findings. J Altern Complement Med. 2005;11:305-309.
82. Pathansali R, Mangoni AA, Creagh-Brown B, et al. Effects of folic acid supplementation on psychomotor performance and hemorheology in healthy elderly subjects. Arch Gerontol Geriatr. 2005 Dec 13. [Epub ahead of print]
83. Marshall JR, Sakr W, Wood D, et al. Design and Progress of a Trial of Selenium to Eussen SJ, de Groot LC, Joosten LW, et al. Effect of oral vitamin B-12 with or without folic acid on cognitive function in older people with mild vitamin B-12 deficiency: a randomized, placebo-controlled trial. Am J Clin Nutr. 2006;84:361-370.
84. Maylor EA, Simpson EE, Secker DL, et al. Effects of zinc supplementation on cognitive function in healthy middle-aged and older adults: the ZENITH study. Br J Nutr. 2006;96:752-760.
85. Kang JH, Cook N, Manson J, et al. A randomized trial of vitamin E supplementation and cognitive function in women. Arch Intern Med. 2006;166:2462-2468.
86. Crook TH, Ferris SH, Alvarez XA, et al. Effects of N-PEP-12 on memory among older adults. Int Clin Psychopharmacol. 2005;20:97-100.
87. Balk EM, Raman G, Tatsioni A, et al. Vitamin B6, B12, and folic acid supplementation and cognitive function: a systematic review of randomized trials. Arch Intern Med. 2007;167:21-30.
88. Durga J, van Boxtel MP, Schouten EG, et al. Effect of 3-year folic acid supplementation on cognitive function in older adults in the FACIT trial: a randomised, double blind, controlled trial. Lancet. 2007;369:208-216.
89. Ho SC, Chan AS, Ho YP, et al. Effects of soy isoflavone supplementation on cognitive function in Chinese postmenopausal women: a double-blind, randomized, controlled trial. Menopause. 2007 Feb 15. [Epub ahead of print]
90. Murray-Kolb LE, Beard JL. Iron treatment normalizes cognitive functioning in young women. Am J Clin Nutr. 2007;85:778-787.
91. Fournier LR, Ryan Borchers TA, Robison LM, et al. The effects of soy milk and isoflavone supplements on cognitive performance in healthy, postmenopausal women. J Nutr Health Aging. 2007;11:155-164.
92. Kennedy DO, Haskell CF, Mauri PL, et al. Acute cognitive effects of standardised ginkgo biloba extract complexed with phosphatidylserine. Hum Psychopharmacol. 2007 Apr 25. [Epub ahead of print]
93. McNeill G, Avenell A, Campbell MK, et al. Effect of multivitamin and multimineral supplementation on cognitive function in men and women aged 65 years and over: a randomised controlled trial. Nutr J. 2007 May 2. [Epub ahead of print]
94. Kennedy DO, Jackson PA, Haskell CF, et al. Modulation of cognitive performance following single doses of 120 mg Ginkgo biloba extract administered to healthy young volunteers. Hum Psychopharmacol. 2007 Sep 28. [Epub ahead of print]
95. The NEMO Study Group. Effect of a 12-mo micronutrient intervention on learning and memory in well-nourished and marginally nourished school-aged children: 2 parallel, randomized, placebo-controlled studies in Australia and Indonesia. Am J Clin Nutr. 2007;86:1082-1093.
96. Grodstein F, Kang JH, Glynn RJ, et al. A randomized trial of beta carotene supplementation and cognitive function in men: The Physicians' Health Study II. Arch Intern Med. 2007;167:2184-2190.
97. Malaguarnera M, Cammalleri L, Gargante MP, et al. L-carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial. Am J Clin Nutr. 2007;86:1738-1744.
98. Kennedy DO, Haskell CF, Wesnes KA, et al. Improved cognitive performance in human volunteers following administration of guarana ( Paullinia cupana) extract: comparison and interaction with Panax ginseng. PharmacolBiochem Behav. 2004;79:401–411.
99. Galduroz JC, Carlini EA. The effects of long-term administration of guarana on the cognition of normal, elderly volunteers. Rev Paul Med. 1996;114:1073–1078.
100. Galduroz JC, Carlini Ede A. Acute effects of the Paulinia cupana, "guarana" on the cognition of normal volunteers. Rev Paul Med. 1994;112:607–611.
101. Kennedy DO, Haskell CF, Robertson B, et al. Improved cognitive performance and mental fatigue following a multi-vitamin and mineral supplement with added guarana ( Paullinia cupana). Appetite. 2007 Oct 30.
102. Ataka S, Tanaka M, Nozaki S, et al. Effects of oral administration of caffeine and D-ribose on mental fatigue. Nutrition. 2008 Jan 4. [Epub ahead of print]
103. Wattanathorn J, Mator L, Muchimapura S, et al. Positive modulation of cognition and mood in the healthy elderly volunteer following the administration of Centella asiatica. J Ethnopharmacol. 2007 Dec 4.
104. van Uffelen JG, Chinapaw MJ, van Mechelen W, et al. Walking or vitamin B for cognition in older adults with mild cognitive impairment? A randomized controlled trial. Br J Sports Med. 2008 Feb 28.
105. Scholey AB, Tildesley NT, Ballard CG, et al. An extract of Salvia (sage) with anticholinesterase properties improves memory and attention in healthy older volunteers. Psychopharmacology (Berl). 2008 Mar 19.
106. Kritz-Silverstein D, von Muhlen D, Laughlin GA, et al. Effects of dehydroepiandrosterone supplementation on cognitive function and quality of life: the DHEA and Well-Ness (DAWN) trial. J Am Geriatr Soc. 2008 May 14.
107. Rawson ES, Lieberman HR, Walsh TM, et al. Creatine supplementation does not improve cognitive function in young adults. Physiol Behav. 2008 May 15.
108. Calabrese C, Gregory WL, Leo M, et al. Effects of a standardized Bacopa monnieri extract on cognitive performance, anxiety, and depression in the elderly: A randomized, double-blind, placebo-controlled trial. J Altern Complement Med. 2008 Jul 8. [Epub ahead of print]
109. Kang JH, Cook N, Manson J, Buring JE, Albert CM, Grodstein F. A trial of B vitamins and cognitive function among women at high risk of cardiovascular disease. Am J Clin Nutr. 2008 Dec;88:1602-10.
110. Makrides M, Gibson RA, McPhee AJ, et al. Effect of DHA supplementation during pregnancy on maternal depression and neurodevelopment of young children: a randomized controlled trial. JAMA. 2010;304(15):1675-1683.
111. Geng J, Dong J, Ni H, et al. Ginseng for cognition. Cochrane Database Syst Rev. 2010;(12):CD007769.
112. van de Rest O, Geleijnse JM, Kok FJ, et al. Effect of fish oil on cognitive performance in older subjects: a randomized, controlled trial. Neurology. 2008;71:430-438.
113. Andreeva VA, Kesse-Guyot E, Barberger-Gateau P, Fezeu L, Hercberg S, Galan P. Cognitive function after supplementation with B vitamins and long-chain omega-3 fatty acids: ancillary findings from the SU.FOL.OM3 randomized trial. Am J Clin Nutr. 2011;94(1):278-286.
Last reviewed December 2015 by EBSCO CAM Review Board
Last Updated: 12/15/2015
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