The effect of Ginkgo biloba on memory in healthy male volunteers

Association between dietary folate intake and cognitive impairment in older US adults: National Health and Nutrition Examination Survey

OBJECTIVE

To determine the association between dietary folate intake and low cognitive performance in older adults.

METHODS

In this cross-sectional observational study, 2011-2014 data from the 2010 National Health and Nutrition Examination Survey, including 2,524 adults aged 60 years and older, included 24-hour dietary intakes. Total folic acid intake was calculated as the sum of folic acid supplements and dietary folic acid. Cognitive function was assessed using three tests. The association between folate intake and cognitive function was assessed using a multivariate conditional logistic regression model.

RESULTS

2524 participants from two survey cycles (2011-2014) in the NHANES aged 60 years and over. In the multivariate logistic regression, the OR of developing folate was 0.96 (95% CI: 0.94∼0.98) in participants with Z test. Folate intake was negatively associated with cognitive function. Compared with Q1, Q4(≥ 616.3mg/day) in the AFT and DSST tests reduced the risk of cognitive impairment by 31% (OR = 0.69, 95% CI: 0.52-0.93) and 44% (OR = 0.56). 95% confidence interval: 0.44-0.7). In the comprehensive evaluation of IR and AFT scores, the association between dietary folate intake and low cognitive performance in US adults is linear. We also found a significant interaction between gender and cognitive ability (P value for the interaction was 0.021).

CONCLUSIONS

Dietary intake of folic acid may be inversely associated with cognitive impairment. The DSST study found an L-shaped association between dietary folate intake and cognitive decline in US adults, with an inflection point of approximately 510,383 mg/day.

Efficacy of a mixture of Ginkgo biloba, sesame, and turmeric on cognitive function in healthy adults: Study protocol for a randomized, double-blind, placebo-controlled trial

BACKGROUND AND PURPOSE

Ginkgo biloba extract (GBE) reportedly ameliorates cognitive function in patients with chronic cerebrovascular insufficiency. However, its efficacy in healthy adults is ambiguous. It was reported that concentrations of terpene lactones, active components of GBE that are present in very low concentrations in the brain, were significantly increased following administration of a mixture of GBE, sesame seed, and turmeric (GBE/MST) in mice. This study aims to investigate the effectiveness of GBE/MST on the cognitive function of healthy adults by comparing it with that of GBE alone.

METHODS

Altogether, 159 participants providing informed consent will be recruited from a population of healthy adults aged 20-64 years. Normal cognitive function at baseline will be confirmed using the Japanese version of the Montreal Cognitive Assessment battery. Participants will be randomly assigned in a double-blind manner to the GBE/MST, GBE, and placebo groups in a 1:1:1 ratio. The Wechsler Memory Scale, Trail Making Test, and Stroop Color and Word Test will be used to assess the memory and executive functions at baseline and at the endpoint (24 weeks). For biological assessment, resting state functional magnetic resonance imaging (rs-fMRI) will be performed simultaneously with the neuropsychological tests.

DISCUSSION

This study aims to obtain data that can help compare the profile changes in memory and executive functions among participants consuming GBE/MST, GBE alone, and placebo for 24 weeks. Alterations in the default mode network will be evaluated by comparing the rs-fMRI findings between baseline and 24 weeks in the aforementioned groups. Our results may clarify the impact of GBE on cognitive function and the functional mechanism behind altered cognitive function induced by GBE components.

TRIAL REGISTRATION

This study was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR; registration number: UMIN000043494). This information can be searched on the website of the International Clinical Trials Registry Platform Search Portal of the World Health Organization under the Japan Primary Registries Network.

Cardiovascular Activity of Ginkgo biloba-An Insight from Healthy Subjects

Ginkgo biloba is the oldest living tree species in the world. Despite less than encouraging clinical results, extracts from its leaves are among the most used herbal preparations in the prevention and treatment of cardiovascular diseases. Most data on the efficacy of Ginkgo biloba on cardiovascular disease is from clinical studies, with few results from healthy subjects. This paper aims to provide a comprehensive review of the mechanisms underlying the known beneficial cardiovascular activities of Ginkgo biloba. It displays myocardial suppressant and vasorelaxant activities ex vivo, potentiating endothelial-dependent and -independent pathways. It improves perfusion in different vascular beds, namely ocular, cochlear, cutaneous, cerebral, and coronary. Although scarce, evidence suggests that Ginkgo biloba displays a heterogeneous effect on tissue perfusion which is dependent on the individual elimination pathways. It displays an acceptable safety profile, with most reported adverse reactions constituting rare occurrences. Collectively, Ginkgo biloba positively impacts cardiovascular physiology, improving hemodynamics and organ perfusion. In the future, better controlled clinical studies should be performed in order to identify the target populations who may benefit the most from pharmacotherapeutic interventions involving Ginkgo biloba.

Dietary Flavonoids and Human Cognition: A Meta-Analysis

Improving cognition is important in all age groups, from performance in school examinations to prevention of cognitive decline in later life. Dietary polyphenols, in particular flavonoids, have been examined for their benefits to cognitive outcomes. This meta-analysis evaluates the effects of dietary flavonoids on cognition across the lifespan. In January 2020 databases were searched for randomized controlled trials investigating flavonoid effects on human cognition. Eighty studies, comprising 5519 participants, were included in the final meta-analysis. The global analysis indicates dietary flavonoids induced significant benefit to cognitive performance (g = 0.148, p < 0.001), with subgroup analyses revealing that cocoa (g = 0.224, p = 0.036), ginkgo (g = 0.187, p ≤ 0.001), and berries (g = 0.149, p = 0.009) yielded the most notable improvements. Significant benefits were observed from chronic studies, in middle-aged and older adults, and with low and medium doses. The domains of long-term memory, processing speed, and mood showed sensitivity to flavonoid intervention. This meta-analysis provides evidence for the positive effects of flavonoids on cognition and highlights several moderating factors. Flavonoid-based dietary interventions therefore potentially offer a highly accessible, safe, and cost-effective treatment to help tackle the burden of cognitive decline.

The Sternberg Paradigm: Correcting Encoding Latencies in Visual and Auditory Test Designs

The Sternberg task is a widely used tool for assessing the working memory performance in vision and cognitive science. It is possible to apply a visual or auditory variant of the Sternberg task to query the memory load. However, previous studies have shown that the subjects' corresponding reaction times differ dependent on the used variant. In this work, we present an experimental approach that is intended to correct the reaction time differences observed between auditory and visual item presentation. We found that the subjects' reaction time offset is related to the encoding speed of a single probe item. After correcting for these individual encoding latencies, differences in the results of both the auditory and visual Sternberg task become non-significant, p=0.252. Thus, an equal task difficulty can be concluded for both variants of item presentation.

A Systematic Review of the Effect of Dietary Supplements on Cognitive Performance in Healthy Young Adults and Military Personnel

Intake of dietary supplements has increased, despite evidence that some of these have adverse side effects and uncertainty about their effectiveness. This systematic review examined the evidence for the cognitive benefits of a wide range of dietary supplements in healthy young adult samples; the aim was to identify if any might be useful for optimising cognitive performance during deployment in military personnel. Searches were conducted in 9 databases and 13 grey literature repositories for relevant studies published between January 2000 and June 2017. Eligible studies recruited healthy young adults (18-35 years), administered a legal dietary supplement, included a comparison control group, and assessed cognitive outcome(s). Thirty-seven of 394 identified studies met inclusion criteria and were included for synthesis. Most research was deemed of low quality (72.97%; SIGN50 guidelines), highlighting the need for sound empirical research in this area. Nonetheless, we suggest that tyrosine or caffeine could be used in healthy young adults in a military context to enhance cognitive performance when personnel are sleep-deprived. Caffeine also has the potential benefit of improving vigilance and attention during sustained operations offering little opportunity for sleep. Inconsistent findings and methodological limitations preclude firm recommendations about the use of other specific dietary supplements.

Examination of a New Delivery Approach for Oral Cannabidiol in Healthy Subjects: A Randomized, Double-Blinded, Placebo-Controlled Pharmacokinetics Study

INTRODUCTION

Therapeutic effects of cannabidiol (CBD) in specialized populations continue to emerge. Despite supra-physiological dosing being shown to be tolerable in various pathologies, optimization of CBD absorption has obvious benefits for general health and recreational usage. Our objectives were to: (1) to investigate a joint pharmacokinetic-physiological time course of multiple recreational-equivalent (< 100 mg) dosages of oral CBD in young healthy adults and (2) evaluate a newly developed technology (TurboCBD™) for the enhanced delivery of CBD.

METHODS

In a double-blinded, placebo-controlled, cross-over design, 12 participants received placebo, generic 45 or 90 mg of CBD, or TurboCBD™ delivery technology capsules on five separate occasions.

RESULTS

Although there were no differences in the 45 mg conditions, circulating CBD levels were higher with the TurboCBD™ 90 mg group at both 90 (+ 86%) and 120 (+ 65%) min compared with the 90 mg control (p < 0.05). Total area under the curve tended to be higher with TurboCBD™ 90 mg compared with 90 mg (10,865 ± 6322 ng ml^-1 vs. 7114 ± 2978 ng ml^-1; p = 0.088). Only the TurboCBD™ 90 mg dose was elevated greater than placebo at 30 min (p = 0.017) and remained elevated at 4 h (p = 0.002).

CONCLUSION

Consistent with higher bioavailability, TurboCBD™ 90 mg at the peak CBD concentration was associated with an increase in cerebral perfusion and slight reduction in blood pressure compared with baseline and the 90 mg control. Further studies are needed to establish the mechanisms of action of this technology and to explore the therapeutic potential of acute and chronic dosing on more at-risk populations.

FUNDING

Lexaria Bioscience Corp.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT03295903.

What is the combined effect of intense intermittent exercise and Ginkgo biloba plant on the brain neurotrophic factors levels, and learning and memory in young rats?

BACKGROUND

The present study was conducted to investigate the effect of intense intermittent exercise and Ginkgo biloba on the hippocampal levels of brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4) and also memory and learning in young rats.

METHODS

Forty two eight-week-old rats were randomly divided into six groups including control, low dose of Ginkgo biloba (65 mg/kg), high dose of Ginkgo biloba (100 mg/kg), exercise, exercise + low dose of Ginkgo biloba, exercise + high dose of Ginkgo biloba. The exercise protocol or Ginkgo biloba administration was six days a week for six weeks. The hippocampal levels of BDNF and NT-4 were measured by ELISA method, and learning and memory were evaluated by Morris water maze test in all groups. Data were analyzed using SPSS software.

RESULTS

Increase in hippocampal levels of BDNF and NT-4 appeared following exercise (p < 0.01). The levels do not change following exercise + Ginkgo biloba administration. However, the NT-4 level decreased in the high dose of Ginkgo biloba group (p < 0.01). Disorder in learning and memory was indicated following the use of low dose of Ginkgo biloba or exercise + low dose Ginkgo biloba administration (p < 0.001). Learning elevated in the exercise group (p < 0.05).

CONCLUSIONS

Exercise in young rats may increase brain neurotrophin levels and lead to improved learning. The preventative or protective role of Ginkgo biloba against some diseases has been suggested, but its consumption in young athletes is recommended with caution.

Effects of Ginkgo biloba extract EGb 761® on cognitive control functions, mental activity of the prefrontal cortex and stress reactivity in elderly adults with subjective memory impairment - a randomized double-blind placebo-controlled trial

OBJECTIVE

Cognitive control as well as stress reactivity is assumed to depend on prefrontal dopamine and decline with age. Because Ginkgo biloba extract EGb761 increases prefrontal dopamine in animals, we assessed its effects on cognitive functions related to prefrontal dopamine.

METHODS

Effects of 240-mg EGb761 daily on task-set-switching, response-inhibition, delayed response, prospective-memory, task-related fMRI-BOLD-signals and the Trier Social Stress-Test were explored in a randomized, placebo-controlled, double-blind pilot-trial in 61 elderly volunteers with subjective memory impairment.

RESULTS

Baseline-FMRI-data showed BOLD-responses in regions commonly activated by the specific tasks. Task-switch-costs decreased with EGb761 compared to placebo (ANOVA-interaction: Group × Time × Switch-Costs p = 0.018, multiple tests uncorrected), indicating improved cognitive flexibility. Go-NoGo-task reaction-times corrected for error-rates indicated a trend for improved response inhibition. No treatment effects were found for the delayed response and prospective-memory tasks and fMRI-data. A non-significant trend indicated a potentially accelerated endocrine stress-recovery. EGb761 was safe and well tolerated.

CONCLUSION

We observed indications for improved cognitive flexibility without changes in brain activation, suggesting increased processing efficiency with EGb761. Together with a trend for improved response inhibition results are compatible with mild enhancement of prefrontal dopamine. These conclusions on potential beneficial effect of EGb761 on prefrontal dopaminergic functions should be confirmed by direct measurements. © 2016 The Authors. Human Psychopharmacology: Clinical and Experimental published by John Wiley & Sons, Ltd.

Ginseng and Ginkgo Biloba Effects on Cognition as Modulated by Cardiovascular Reactivity: A Randomised Trial

Background

There is some evidence to suggest that ginseng and Ginkgo biloba can improve cognitive performance, however, very little is known about the mechanisms associated with such improvement. Here, we tested whether cardiovascular reactivity to a task is associated with cognitive improvement.

Methodology/Principal findings

Using a double-blind, placebo controlled, crossover design, participants (N = 24) received two doses of Panax Ginseng (500, 1000 mg) or Ginkgo Biloba (120, 240 mg) (N = 24), and underwent a series of cognitive tests while systolic, diastolic, and heart rate readings were taken. Ginkgo Biloba improved aspects of executive functioning (Stroop and Berg tasks) in females but not in males. Ginseng had no effect on cognition. Ginkgo biloba in females reversed the initial (i.e. placebo) increase in cardiovascular reactivity (systolic and diastolic readings increased compared to baseline) to cognitive tasks. This effect (reversal) was most notable after those tasks (Stroop and Iowa) that elicited the greatest cardiovascular reactivity during placebo. In males, although ginkgo also decreased cardiovascular readings, it did so from an initial (placebo) blunted response (i.e. decrease or no change from baseline) to cognitive tasks. Ginseng, on the contrary, increased cardiovascular readings compared to placebo.

Conclusions/Significance

These results suggest that cardiovascular reactivity may be a mechanism by which ginkgo but not ginseng, in females is associated with certain forms of cognitive improvement.

Trial Registration

ClinicalTrials.gov NCT02386852

Association of chronic kidney disease and cerebral small vessel disease with cognitive impairment in elderly patients with type 2 diabetes

Background/Aims

In recent years, the relationship between chronic kidney disease (CKD) and cognitive impairment has been attracting attention. Cerebral small vessel disease (SVD) is also associated with an increased risk of cognitive impairment. However, it is still unknown whether CKD markers are associated with cognitive impairment independently of SVD in elderly diabetic patients.

Methods

Seventy-nine type 2 diabetic patients (mean age, 76.0 years) were enrolled in the present study. CKD was defined as the presence of albuminuria and/or a low estimated glomerular filtration rate (eGFR <60 ml/min/1.73 m²). SVD was evaluated by the presence and severity of silent brain infarcts (SBIs) and white matter lesions (WMLs) on brain magnetic resonance imaging. Neuropsychological tests were assessed using four validated cognitive instruments.

Results

In multiple linear regression analyses, albuminuria was associated with worse modified Stroop Color Word scores (β = 0.284, p = 0.017) and low eGFR was associated with reduced Digit Symbol Substitution scores (β = −0.224, p = 0.026) after adjustment for age, sex, education years, diabetes duration, hypertension, multiple SBIs, and advanced WMLs. In contrast, there were no significant associations between CKD markers and Mini-Mental State Examination or Word Recall scores.

Conclusion

Our findings suggest that albuminuria and low eGFR are associated with frontal lobe dysfunction independently of SVD in elderly type 2 diabetic patients.

Is Sternberg’s Memory Scanning Task Really a Short-Term Memory Task?

Sternberg’s paradigm is currently viewed as a typical short-term memory task and is widely used to tap mnemonic capacities in neuroscience studies. However, Sternberg’s original procedure includes an experimental constraint – recalling the sequence of digits in order – which was not reused in the following studies. In previous research ( Corbin & Marquer, 2008 , 2009 ), we showed that the recall constraint has an impact on the quantitative results as well as on the strategies implemented. These findings led us to wonder whether the presence or absence of this simple experimental constraint could also affect the processes implemented in Sternberg’s task. In order to answer this question, we analyzed the relationships between the performance levels of 50 participants on Sternberg’s task on various well-known span tasks and on a classical visual search task. The results showed that, in the recall condition, Sternberg’s paradigm appears to be a verbal working memory task, whereas in the no-recall condition, the task appears to be a recognition task that involves visuospatial memory capacities. In this latter condition, the processes implemented may be more similar to those implemented in visual search tasks.

Is Ginkgo biloba a cognitive enhancer in healthy individuals? A meta-analysis

OBJECTIVE

We conducted a meta-analysis to examine whether Ginkgo biloba (G. biloba) enhances cognitive function in healthy individuals.

METHODS

Scopus, Medline, Google Scholar databases and recent qualitative reviews were searched for studies examining the effects of G. biloba on cognitive function in healthy individuals. We identified randomised controlled trials containing data on memory (K = 13), executive function (K = 7) and attention (K = 8) from which effect sizes could be derived. The analyses provided measures of memory, executive function and attention in 1132, 534 and 910 participants, respectively.

RESULTS

Effect sizes were non-significant and close to zero for memory (d = -0.04: 95%CI -0.17 to 0.07), executive function (d = -0.05: 95%CI -0.17 to 0.05) and attention (d = -0.08: 95%CI -0.21 to 0.02). Meta-regressions showed that effect sizes were not related to participant age, duration of the trial, daily dose, total dose or sample size.

CONCLUSIONS

We report that G. biloba had no ascertainable positive effects on a range of targeted cognitive functions in healthy individuals.

Herbal extracts and phytochemicals: plant secondary metabolites and the enhancement of human brain function

Humans consume a wide range of foods, drugs, and dietary supplements that are derived from plants and which modify the functioning of the central nervous sytem (CNS). The psychoactive properties of these substances are attributable to the presence of plant secondary metabolites, chemicals that are not required for the immediate survival of the plant but which are synthesized to increase the fitness of the plant to survive by allowing it to interact with its environment, including pathogens and herbivorous and symbiotic insects. In many cases, the effects of these phytochemicals on the human CNS might be linked either to their ecological roles in the life of the plant or to molecular and biochemical similarities in the biology of plants and higher animals. This review assesses the current evidence for the efficacy of a range of readily available plant-based extracts and chemicals that may improve brain function and which have attracted sufficient research in this regard to reach a conclusion as to their potential effectiveness as nootropics. Many of these candidate phytochemicals/extracts can be grouped by the chemical nature of their potentially active secondary metabolite constituents into alkaloids (caffeine, nicotine), terpenes (ginkgo, ginseng, valerian, Melissa officinalis, sage), and phenolic compounds (curcumin, resveratrol, epigallocatechin-3-gallate, Hypericum perforatum, soy isoflavones). They are discussed in terms of how an increased understanding of the relationship between their ecological roles and CNS effects might further the field of natural, phytochemical drug discovery.

Do specific dietary constituents and supplements affect mental energy? Review of the evidence

The numbers of marketing claims and food, beverage, and drug products claiming to increase mental energy have risen rapidly, thus increasing the need for scientific specificity in marketing and food label claims. Mental energy is a three-dimensional construct consisting of mood (transient feelings about the presence of fatigue or energy), motivation (determination and enthusiasm), and cognition (sustained attention and vigilance). The present review focuses on four dietary constituents/supplements (Ginkgo biloba, ginseng, glucose, and omega-3 polyunsaturated fatty acids) to illustrate the current state of the literature on dietary constituents and mental energy. The strongest evidence suggests effects of Ginkgo biloba on certain aspects of mood and on attention in healthy subjects, as well as associations between omega-3 polyunsaturated fatty acids and reduced risk of age-related cognitive decline. Limitations of the current data and challenges for future research are discussed.

Assessment of health claims, content, and safety of herbal supplements containing Ginkgo biloba

BACKGROUND

European Regulation 1924/2006 states that all health claims made on foods need to be substantiated scientifically.

OBJECTIVE

To apply the PASSCLAIM criteria for the scientific substantiation of health claims on foods to herbal supplements containing Ginkgo biloba. Evaluation of three selected claimed health effects for G. biloba (improvement of blood circulation, improvement of symptoms of old age, and improvement of memory) was achieved through review of publicly available scientific data. A total of 35 human intervention studies were evaluated. Commercially available products claimed to contain mainly G. biloba (N=29) were randomly sampled in the Netherlands and analyzed for their content on ginkgo extract. Also, a toxicological risk assessment was performed.

RESULTS

The three selected health claims investigated could not be substantiated. This was mainly because of a lack of data from studies in healthy volunteers. In most studies results performed with a 24% standardized G. biloba extract were described. However, our chemical analysis showed that 25 of the 29 sampled products did not contain the required minimum 24% standardized extract. Moreover, in most preparations the content of substances typical for G. biloba did not conform to what was declared on the label. Since toxicity data for G. biloba are very limited, a safety limit could not be established.

CONCLUSIONS

Evidence is lacking for three health claims of herbal products with G. biloba. Neither safety nor efficacy can be guaranteed at the recommended daily dose. The multidisciplinary approach described in this paper provides good insight into issues that are relevant for the evaluation of health claims for herbal food supplements.

Ginkgo biloba e memória - revisão sistemática

INTRODUÇÃO: Com o envelhecimento da população, os distúrbios de memória têm-se tornado patologias cada vez mais frequentes. Com exceção de uma minoria dos casos cujas causas são reversíveis, estas doenças possuem prognóstico desanimador, curso inexorável e opções terapêuticas muito limitadas. O medicamento fitoterápico mais frequentemente utilizado para distúrbios de memória é o extrato seco de ginkgo biloba (GB). Suas ações antioxidantes, antiagregantes e vasodilatadoras têm encorajado diversos profissionais a utilizarem-no neste tratamento, porém não há registros convincentes que comprovem a eficácia do uso desta substância para tal fim. OBJETIVOS: Avaliar a eficácia do GB na prevenção e no tratamento de distúrbios de memória. MÉTODOS: Revisão sistemática da literatura dos últimos dez anos dos estudos clínicos duplo-cegos, randomizados, placebo-controlados, publicados na língua inglesa. RESULTADOS E CONCLUSÕES: Embora tenhamos obtido poucos ensaios controlados sobre o tema, não há evidências suficientes para se indicar o uso da droga com a finalidade de tratar e/ou prevenir distúrbios de memória.

Neuromodulatory property of standardized extract Ginkgo biloba L. (EGb 761) on memory: behavioral and molecular evidence

Although it has been suggested that the standardized Ginkgo biloba leaf extract (Egb 761) may have a beneficial effect on memory, the cellular and molecular changes that underlie this process are not yet well defined. The present study evaluated the effects of acute (one dose) or subacute treatments (one daily dose/seven days) with EGb 761 (0.5 g kg(-1) and 1.0 g kg(-1)) on rats submitted to a conditioned emotional response (CER) in comparison with positive (4 mg kg(-1) Diazepam) and negative (12%Tween 80) control groups. To this end, eighty (n=10/group) adult, male, Wistar rats (+/-250-300 g) were used in an off-baseline CER procedure. We here observed that the rats submitted to an acute and subacute EGb 761 treatments had acquisition of fear conditioning. Additionally, we investigate if the expression of genes previously associated with classical conditioning (CREB-1 and GAP-43) and new candidate genes (GFAP) are modulated following EGb 761 acute treatment. CREB-1, GAP-43 and GFAP mRNA and protein expressions were evaluated using both quantitative PCR (qPCR) and immunohistochemical analysis, respectively. We here show, for the first time, that EGb 761 modulated GAP-43, CREB-1 and GFAP expression in the prefrontal cortex, amygdala and hippocampus. We observed an underexpression of GAP-43 in all structures evaluated and over-expression of GFAP in the amygdala and hippocampus following acute G. biloba treatment when compared to control group (Tween; p<0.01). GAP-43 expression was decreased in prefrontal cortex and hippocampus in the subacute treatment with EGb 761. Subacute treatment with EGb 761 lead to a decreased CREB-1 in mPFC (p<0.001) and increased in the hippocampus to 1.0 g kg(-1)G. biloba group (p<0.001). The results obtained from immunohistochemical analysis support our aforementioned findings and revealed that the changes in expression occurred within specific regions in the areas evaluated. All together, our findings not only provide new evidence for a role of EGb 761 on memory but also identify molecular changes that underlie the fear memory consolidation.

Modulation of cognitive performance following single doses of 120 mg Ginkgo biloba extract administered to healthy young volunteers

Previous research from our laboratory demonstrated that administration of single doses (120, 240, 360 mg) of standardised Ginkgo biloba extract (GBE) had linear, dose-dependent, positive effects on the speed of performing attention tasks in comparison to placebo. However, whilst the lowest dose, which is typical of a recommended daily dose, had no effect on the speed of attention task performance it did engender mild improvements in secondary memory performance. The current study presents a reanalysis of data from three methodologically identical studies that each included a treatment of 120 mg GBE and matched placebo. All three studies were of a multiple dose, placebo-controlled, double-blind, balanced-crossover design, employing four or five treatment arms in total. Across the studies 78 healthy young participants received 120 mg GBE and placebo in randomly counterbalanced order, separated by a wash-out period of at least 7 days. On each study day participants' performance on the Cognitive Drug Research (CDR) computerised cognitive assessment battery was measured immediately prior to dosing and at 1, 2.5, 4 and 6 hr following treatment, with scores collapsed into the six measures (speed of attention, accuracy of attention, secondary memory, working memory, speed of memory, quality of memory) which have previously been derived by factor analysis of the data from CDR subtests. The results showed that 120 mg of Ginkgo engendered a significant improvement on the 'quality of memory' factor that was most evident at 1 and 4 hr post-dose, but had a negative effect on performance on the 'speed of attention' factor that was most evident at 1 and 6 hr post-dose. The current study confirmed the previous observation of modestly improved memory performance following 120 mg of GBE, but suggests that acute administration of this typical daily dose may have a detrimental effect on the speed of attention task performance which is opposite to that seen previously following higher doses.

Ginkgo biloba is not a smart drug: an updated systematic review of randomised clinical trials testing the nootropic effects of G. biloba extracts in healthy people

Here, we update our earlier systematic review of 2001, which critically evaluated the data from clinical trials to determine whether Ginkgo biloba enhances cognitive function in healthy subjects. Literatures searches of six computerised databases, updated to January 2007, were made for randomised, placebo-controlled, double-blind clinical trials of the effects of standardised Ginkgo biloba (G. biloba) extracts on cognitive function in healthy subjects under the age of 60 years. Trials published in any language were included, and data were extracted independently by the two authors following a standardised protocol. We include 15 randomised clinical trials of which 7 are single-dose studies and 8 are longer term studies with treatment periods ranging from 2 days to 13 weeks. Three single dose studies and 4 longer term studies are newly included. Several of the studies have methodological flaws. A number of the acute studies used multiple outcomes and report positive effects on one or more of these at particular time points with particular doses but these findings are either not replicated, or are directly contradicted by other studies. The evidence from longer term studies is largely negative. Of those studies which measured subjective effects, only one of five acute studies and one of six longer term studies reported any significant positive results. Overall, and in line with our previous conclusions, we have found no convincing evidence from randomised clinical trials for a robust positive effect of G. biloba ingestion upon any aspect of cognitive function in healthy young people, after either acute or longer term administration.

Ethnicity and Use of Alternative Products in Psychiatric Patients

The use of herbal and natural products for medical purposes is common in all human civilizations, and use in Western societies has grown considerably in recent years. However, differences in usage patterns between different ethnic groups are yet to be delineated. The current study examined the frequency and type of complementary/alternative medications used by a sample of 453 rural psychiatric outpatients of two different ethnic groups. The products were classified as "natural" (herbal products requiring some preparation before consumption) and "processed" (products in "ready-to-use" form). There were significant ethnic differences in usage patterns of the various preparations: Hispanics, relative to Caucasians, were twice as likely to use natural products, whereas Caucasians were more likely than Hispanics to use processed products. The symptoms addressed were predominantly psychiatric, with natural products, and nonpsychiatric, with processed products. These results may increase awareness among healthcare providers regarding the usage frequency of such complementary/alternative medications products and the different usage patterns across ethnic groups.

Herbal Supplements: Facts and Myths—Talking to Your Patients About Herbal Supplements

The use of herbal supplements in the United States is steadily growing and raises concerns about safety, efficacy, and how they affect safe patient care. The direct health risks associated with herbal supplements include hypertension, prolonged bleeding, and the potential for drug-herb interactions. These potential drug interactions are of particular concern for patients undergoing anesthesia. This article provides a review of literature on the 10 most popular herbal supplements and addresses the herbal supplements' reported use, possible adverse effect(s), patient teaching, possible drug interaction(s), and recommendations regarding discontinuation before surgery.

The effect of the ingestion of Ginkgo biloba extract (EGb 761) on the pharmacokinetics of metformin in non-diabetic and type 2 diabetic subjects--a double blind placebo-controlled, crossover study

BACKGROUND & AIMS

Ginkgo biloba extract (EGb 761) has been shown to ameliorate some defects associated with the insulin resistance syndrome and so patients with Type 2 diabetes mellitus (T2DM) may be inclined to co-ingest the herb with their medications, such as metformin. This study was designed to determine if the co-ingestion of EGb 761 and metformin would alter the pharmacokinetic properties of metformin in T2DM patients and persons without diabetes, who may ingest it for other purposes.

METHOD

Normal glucose tolerance (NGT) subjects (n=10; age, 39.2+/-14.0 years; fasting plasma glucose (FPG), 90+/-7 mg/dl; body mass index (BMI), 24.1+/-3.7 kg/m(2)) and 10 T2DM patients (n=10; age, 51.7+/-8.9 years; FPG, 150+/-7 mg/dl; BMI, 33.7+/-5.7 kg/m(2)) completed a randomized, double-blind, placebo-controlled crossover study. They ingested either EGb 761 (12 0mg/day as a single dose) or a vegetable-based placebo during each arm for 3 months. At the end of each arm, the NGT subject ingested a single 500 mg dose of metformin (non-diabetics) and the T2DM subject took his/her prescribed metformin dose (250-850 mg) with 120 mg EGb 761. Blood and urine samples were collected over an 8-h period, and in the case of T2DM subjects, additionally over the first 2h of the subsequent 3 days.

RESULTS

Ingestion of EGb 761 produced no significant changes in diagnostic laboratory tests in either group, except reducing glycosylated hemoglobin A(1c) levels (from 7.7+/-1.2 to 7.2+/-0.9%, P<0.05) in T2DM the subjects. The pharmacokinetic parameters of metformin were all significantly different (P<0.05) between the NGT (500 mg) and 8 out of 10 of the T2DM subjects who were prescribed 500 mg of metformin during the placebo cycles. During the EGb 761 cycles, only the elimination half-life in the T2DM subjects was significantly increased (0.117+/-0.085 to 0.141+/-0.100, P<0.05).

CONCLUSION

The co-ingestion of 120 mg of EGb 761 and 500 mg of metformin did not significantly affect the pharmacokinetic properties of metformin. Further studies are required to verify this observation for smaller and larger dose of metformin with other doses of EGb 761, since T2DM patients on medication constitute a very heterogeneous group.

Effects of Ginkgo biloba administered after spatial learning on water maze and radial arm maze performance in young adult rats

Ginkgo biloba is reported to improve learning and memory in animals. However, many studies do not directly test the effects of Ginkgo on memory because the drug is administered during the learning phase of the experiments. In this study, we examined the effect of 10 mg/kg, 20 mg/kg, or 40 mg/kg G. biloba extract on spatial memory by administering the drug in the interval between training and testing. Rats were tested for long-term reference memory retention in the radial arm maze and in the Morris water maze during daily probe trials in which the hidden platform was removed. G. biloba had no effect on reference memory in either the water maze or radial arm maze. To test short-term working spatial memory using the radial arm maze, animals were removed after receiving the reward from 4 of the 8 arms and were returned to complete the maze 2 h later. While Ginkgo had no effect on working memory, over time animals exposed to Ginkgo learned task better than control animals. Thus, Ginkgo appears to enhance neither short-term working memory nor long-term reference memory, but it may promote learning of spatial information.

Ginkgo biloba: no robust effect on cognitive abilities or mood in healthy young or older adults

Ginkgo biloba extracts are commonly used to prevent or treat memory problems but evidence on the efficacy of ginkgo is equivocal. In any case, the psychological locus of ginkgo's effects is unknown. A 12-week, double-blind, placebo-controlled study assessed effects of ginkgo (120 mg per day) on a wide range of cognitive abilities, executive function, attention and mood in 93 healthy older adults (55-79 years) and in 104 young adults (18-43 years). For the older adult sample, longer-term memory assessed by associational learning tasks showed improvement with ginkgo (d = 0.52, p = 0.04). There was no statistically significant difference on any other measure. For the young adult group no measure showed statistically significant effects of ginkgo enhancement. There were no side effects unequivocally attributable to treatment with ginkgo and those reported by participants in the ginkgo groups were mild and similar to those reported elsewhere.

Differential cognitive effects of Ginkgo biloba after acute and chronic treatment in healthy young volunteers

RATIONALE

Acute doses of Ginkgo biloba have been shown to improve attention and memory in young, healthy participants, but there has been a lack of investigation into possible effects on executive function. In addition, only one study has investigated the effects of chronic treatment in young volunteers.

OBJECTIVES

This study was conducted to compare the effects of ginkgo after acute and chronic treatment on tests of attention, memory and executive function in healthy university students.

METHODS

Using a placebo-controlled double-blind design, in experiment 1, 52 students were randomly allocated to receive a single dose of ginkgo (120 mg, n=26) or placebo (n=26), and were tested 4 h later. In experiment 2, 40 students were randomly allocated to receive ginkgo (120 mg/day; n=20) or placebo (n=20) for a 6-week period and were tested at baseline and after 6 weeks of treatment. In both experiments, participants underwent tests of sustained attention, episodic and working memory, mental flexibility and planning, and completed mood rating scales.

RESULTS

The acute dose of ginkgo significantly improved performance on the sustained-attention task and pattern-recognition memory task; however, there were no effects on working memory, planning, mental flexibility or mood. After 6 weeks of treatment, there were no significant effects of ginkgo on mood or any of the cognitive tests.

CONCLUSIONS

In line with the literature, after acute administration ginkgo improved performance in tests of attention and memory. However, there were no effects after 6 weeks, suggesting that tolerance develops to the effects in young, healthy participants.

Short-term oral ingestion of Ginkgo biloba extract (EGb 761) reduces malondialdehyde levels in washed platelets of type 2 diabetic subjects

We have recently reported that ingestion of Ginkgo biloba extract (EGb 761) (a) significantly reduced collagen-induced platelet aggregation and thromboxane B2 (TXB2) production in both non-diabetic individuals as well as those with type 2 diabetes mellitus (T2DM), (b) significantly reduced platelet malondialdehyde (MDA), an index of lipid peroxidation, in non-diabetic subjects. In the present study we report that ingestion of EGb 761 (120 mg daily for 3 months), significantly decreased platelet MDA-thiobarbituric acid reacting substances (TBARS) (41 +/- 9 pmol/10(7) platelets versus 30 +/- 11 pmol/10(7) platelets) (p < 0.005) in T2DM subjects with normal cholesterol levels (total cholesterol, 164 +/- 22 mg/dl; age, 54 +/- 9 years; BMI, 35.0 +/- 8.8 kg/m2, n = 12). In T2DM subjects with high cholesterol (total cholesterol, 218 +/- 15 mg/dl; age, 52 +/- 5 years; BMI, 36.2 +/- 6.6 kg/m2, n = 7), EGb 761 ingestion reduced the platelet TBARS from 29 +/- 9 to 22 +/- 9 pmol/10(7) platelets (p < 0.04). Because ingestion of EGb 761 did not alter platelet counts it is concluded that EGb 761, probably due to the flavonoid fraction, reduced the TBARS by inhibiting cyclooxygenase (COX)-1-mediated arachidonic acid oxygenation or by reducing the arachidonic acid pool. This is likely to lead to a reduction of platelet hyperactivity, a significant contributor to the development of cardiovascular disease in T2DM patients. Because of other reported beneficial properties of EGb 761, such as stimulation of pancreatic beta-cell function in T2DM subjects with pancreatic exhaustion, it appears that T2DM subjects might benefit from ingesting EGb 761 as a dietary supplement.

Limited cognitive benefits in Stage +2 postmenopausal women after 6 weeks of treatment with Ginkgo biloba

Gingko biloba has cognitive benefits both in populations suffering from dementia and after acute treatment in healthy volunteers, with some evidence indicating that those with poorer cognitive performance show greater benefit. We have previously found that 1 week of treatment with ginkgo improved attention, memory and mental flexibility in post-menopausal women, but the evidence for any beneficial effects of longer treatment is less well-established. The present study aimed to determine whether cognitive benefits, similar to those previously found after 1 week of treatment, would persist after 6 weeks of treatment, and whether those with poorer cognitive performance would benefit more. In a placebo-controlled, double-blind study, postmenopausal women (aged 51-67 years) were randomly allocated to receive a standardized extract of ginkgo (LI 1370, Lichtwer Pharma, Marlow, UK) (one capsule/day of 120 mg, n = 45) or matching placebo (n = 42) for 6 weeks. According to an established reproductive staging system, subjects were divided into those in the early (Stage +1; mean age 55 years) and late (Stage +2: mean age 61 years) stages of menopause. At baseline and after 6 weeks of treatment, subjects completed tests of mental flexibility, planning, memory and sustained attention, and ratings of mood, sleepiness, bodily and menopausal symptoms. The only significant effects of ginkgo were in the test of mental flexibility, in which there were significant menopausal stage-ginkgo interactions. This was because subjects in Stage +2 required fewer trials to complete the task and made fewer errors after ginkgo treatment, whereas those in Stage +1 showed no benefits. Subjects in Stage +2 had poorer performance at baseline compared to those in Stage +1 both in this task and the test of planning ability. The beneficial effects of ginkgo were limited to the test of mental flexibility and to those with poorer performance.

Effects of Yukmijihwang-tang Derivatives (YMJd), a Memory Enhancing Herbal Extract, on the Gene-Expression Profile in the Rat Hippocampus

The herbal extract Yukmijihwang-tang (YMJ) has been widely used for centuries as an anti-aging herbal medicine in Asian countries. Among the various modified prescriptions of YMJ, YMJ derivatives (YMJd) were formulated to enhance memory retention. This study has three goals: 1) to quantitatively evaluate the memory-enhancing effect of YMJd using behavior tasks; 2) to use cDNA micro-array tools to identify candidate genes responsible for enhancing memory; and 3) to statistically evaluate the specific gene expression patterns using Real-time PCR. Memory retention abilities are addressed by the passive avoidance task with SD male rat. The retention time of the YMJd group was significantly delayed (ca. 100%), whereas with Ginkgo biloba and Soya lecithin treatment, this was only delayed 20% and 10%, respectively. The cDNA from the hippocampi of YMJd and rat control groups were applied to an Incyte rat GEM2 cDNA microarray. The microarray results showed that transthyretin and PEP-19 were abundantly expressed in the YMJd treated group. Importantly, PEP-19 is a neuron-specific protein that inhibits apoptotic processes. On the other hand, neuronal genes involved in neuronal death or neurodegeneration, such as pentraxin and spectrin, were abundantly expressed in the control group. The list of differentially expressed genes may provide further insight into the action and mechanism behind the memory-enhancing effect of herbal extracts of YMJd.

Therapy for neurobehavioral disorders in epilepsy

Neurobehavioral disorders commonly affect patients with epilepsy. In addition to the behavioral changes during and immediately after seizures, the epileptogenic disorder of function often extends further into the postictal and interictal period. Cognitive impairments commonly affect attention, memory, mental speed, and language, as well as executive and social functions. Reducing seizure frequency and the antiepileptic drug burden can reduce these problems. Attentional deficits may respond to therapies for attention-deficit/hyperactivity disorder, but apart from patients with this comorbid disorder, their efficacy is unproven in other epilepsy patients. No effective therapies are established for other cognitive problems, but pragmatic, compensatory strategies can be helpful. Behavioral disorders include fatigue, depression, anxiety, and psychosis. Many of these disorders usually respond well to pharmacotherapy, which can be supplemented by psychotherapy. Cognitive and behavioral disorders can be the greatest cause of morbidity and impaired quality of life, often overshadowing seizures. Yet these problems often go unrecognized and, even when identified, are often undertreated or untreated.

Ginkgo biloba promotes short-term retention of spatial memory in rats

This study examines possible interactions between exposure to Ginkgo biloba extract and enriched environments on the acquisition and retention of spatial learning following massed and spaced trials. After 4 weeks of exposure to either ginkgo or vehicle, 8-week-old rats were tested using a Morris Water Maze in either massed or spaced trials. While ginkgo did not have an effect on maze acquisition or long-term retention, it did promote short-term retention of spatial memory. Following reversal training, ginkgo promoted short-term retention for two groups but impaired retention for a third. These results suggest that ginkgo has powerful effects on short-term retention that vary with training conditions.

Effect of the ingestion of Ginkgo biloba extract on platelet aggregation and urinary prostanoid excretion in healthy and Type 2 diabetic subjects

Enhanced platelet function, particularly in response to collagen, is a common occurrence in diabetes that increases the risk of cardiovascular disease. Ginkgo biloba extract is ingested primarily to improve mental focus but it possesses a blood-thinning potential, which has not been well characterized. This study was designed to compare the effect of ingesting G. biloba extract on platelet aggregation in platelet-rich plasma (PRP) and prostanoid urinary excretion in healthy volunteers and subjects with Type 2 diabetes mellitus (T2DM). Before and after ingesting 120 mg of standardized G. biloba extract for 3 months, platelet aggregation was studied in PRP and urinary metabolites of thromboxane B(2) (TXB(2)) and prostacyclin (PGI(2)) were measured. In healthy volunteers (age, 42+/-11 years; BMI, 28.4+/-4.8 kg/m(2); n=28), the ingestion of G. biloba extract significantly increased fasting insulin and C-peptide (10+/-4 vs. 12+/-6 microU/ml, p<0.007 and 1.3+/-0.8 vs. 2.1+/-1.1 ng/ml, p<0.001, respectively) and significantly reduced collagen but not PAF-mediated platelet aggregation, converting 21 of 28 subjects with [COL+/EPI+] platelets to the [COL-/EPI+] phenotype. This was accompanied by a reduction of 11-dehydro-TXB(2) from 12.4+/-6.1 to 10.3+/-6.1 ng/mg Cr (p<0.04) and PGI(2) metabolites (2,3-dinor-6-keto-PGF(1alpha) and 6-keto-PGF(1alpha)) from 2.2+/-0.8 to 1.8+/-0.8 ng/mg Cr (p<0.05). In the T2DM subjects (age, 54+/-8; BMI, 36.6+/-7.9 kg/m(2); n=19), G. biloba ingestion did not affect pancreatic beta-cell function but significantly reduced platelet aggregation, converting 16 of 19 [COL+/EPI+] platelets to the [COL-/EPI+] phenotype. Unlike the healthy volunteers, this was not accompanied by a reduced urinary prostanoid excretion. G. biloba-induced reduction of both classes of prostanoid metabolites in healthy volunteers, but not in T2DM subjects, may suggest a nonselective inhibition of COX-1-mediated TXA(2) in platelets and COX-2-mediated PGI(2) production by the endothelial cells and perhaps platelet-enriched levels of arachidonic acid or COX-1 activity, or both, in T2DM subjects.

Treatment of memory disorders in epilepsy

Impaired memory is a common and often debilitating complaint in patients with epilepsy. Overlapping variables such as seizure control, attentional dysfunction, and mood disorders further complicate diagnosis and management. Direct therapy for memory deficits associated with epilepsy is rarely attempted. The varied pharmacological (AED selection, cholinesterase inhibitors, stimulants, antidepressants, and herbal supplements) and nonpharmacological approaches to cognitive remediation in epilepsy patients are reviewed.

Modification of brain aging and neurodegenerative disorders by genes, diet, and behavior

Multiple molecular, cellular, structural, and functional changes occur in the brain during aging. Neural cells may respond to these changes adaptively, or they may succumb to neurodegenerative cascades that result in disorders such as Alzheimer's and Parkinson's diseases. Multiple mechanisms are employed to maintain the integrity of nerve cell circuits and to facilitate responses to environmental demands and promote recovery of function after injury. The mechanisms include production of neurotrophic factors and cytokines, expression of various cell survival-promoting proteins (e.g., protein chaperones, antioxidant enzymes, Bcl-2 and inhibitor of apoptosis proteins), preservation of genomic integrity by telomerase and DNA repair proteins, and mobilization of neural stem cells to replace damaged neurons and glia. The aging process challenges such neuroprotective and neurorestorative mechanisms. Genetic and environmental factors superimposed upon the aging process can determine whether brain aging is successful or unsuccessful. Mutations in genes that cause inherited forms of Alzheimer's disease (amyloid precursor protein and presenilins), Parkinson's disease (alpha-synuclein and Parkin), and trinucleotide repeat disorders (huntingtin, androgen receptor, ataxin, and others) overwhelm endogenous neuroprotective mechanisms; other genes, such as those encoding apolipoprotein E(4), have more subtle effects on brain aging. On the other hand, neuroprotective mechanisms can be bolstered by dietary (caloric restriction and folate and antioxidant supplementation) and behavioral (intellectual and physical activities) modifications. At the cellular and molecular levels, successful brain aging can be facilitated by activating a hormesis response in which neurons increase production of neurotrophic factors and stress proteins. Neural stem cells that reside in the adult brain are also responsive to environmental demands and appear capable of replacing lost or dysfunctional neurons and glial cells, perhaps even in the aging brain. The recent application of modern methods of molecular and cellular biology to the problem of brain aging is revealing a remarkable capacity within brain cells for adaptation to aging and resistance to disease.