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.     

The memory enhancing effects of a Ginkgo biloba/Panax ginseng combination in healthy middle-aged volunteers

The effects of capsules containing 60 mg of a standardised extract of Ginkgo biloba (GK501) and 100 mg of a standardised extract of Panax ginseng (G115) on various aspects of cognitive function were assessed in healthy middle-aged volunteers. A double blind, placebo controlled, 14 week, parallel group, repeated assessment, multi-centre trial of two dosing regimens, 160 mg b.i.d. and 320 mg o.d. was conducted. Two hundred and fifty-six healthy middle-aged volunteers successfully completed the study. On various study days (weeks 0, 4, 8, 12 and 14) the volunteers performed a selection of tests of attention and memory from the Cognitive Drug Research computerised cognitive assessment system prior to morning dosing and again, at 1, 3 and 6 h later. The volunteers also completed questionnaires about mood states, quality of life and sleep quality. The Ginkgo/ginseng combination was found significantly to improve an Index of Memory Quality, supporting a previous finding with the compound. This effect represented an average improvement of 7.5% and reflected improvements to a number of different aspects of memory, including working and long-term memory. This enhancement to memory was seen throughout the 12-week dosing period and also after a 2-week washout. This represents the first substantial demonstration of improvements to the memory of healthy middle-aged volunteers produced by a phytopharmaceutical.     

The dose-dependent cognitive effects of acute administration of Ginkgo biloba to healthy young volunteers

RATIONALE: Chronic administration of extracts from the leaves of the tree Ginkgo biloba is known to improve aspects of cognitive performance. However, little is known about the effects of acute doses of Ginkgo on coherent cognitive domains. Recent factor analysis of test measures from subtasks of the Cognitive Drug Research (CDR) computerised assessment battery has revealed that four primary cognitive 'factors' corresponding to speed of attention, accuracy of attention, speed of memory and quality of memory can be useful to describe cognitive function changes. OBJECTIVE: The present study aimed at assessing whether acute administration of Ginkgo biloba had any consistent effect on the four CDR factors. METHODS: The study utilised a placebo-controlled, multi-dose, double-blind, balanced, crossover design. Twenty participants received 120 mg, 240 mg and 360 mg of a standardised extract of Ginkgo (GK501, Pharmaton, SA) or a matching placebo. Cognitive performance was assessed using the CDR computerised test battery immediately prior to dosing and at 1, 2.5, 4 and 6 h thereafter. The primary outcome measures were the four aspects of cognitive performance, which have previously been derived by factor analysis of CDR subtests. RESULTS: Compared with the placebo, administration of Ginkgo produced a number of significant changes on the performance measures. The most striking of these was a dose-dependent improvement of the 'speed of attention' factor following both 240 mg and 360 mg of the extract, which was evident at 2.5 h and was still present at 6 h. Additionally, there were a number of time- and dose-specific changes (both positive and negative) in performance of the other factors. CONCLUSIONS: We conclude that acute administration of Ginkgo biloba is capable of producing a sustained improvement in attention in healthy young volunteers.     

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.     

Pharmacodynamic interaction studies of Ginkgo biloba with cilostazol and clopidogrel in healthy human subjects

AIMS: Ginkgo biloba is available as an over-the-counter drug and reported to cause haemorrhage when coadministered with other antiplatelet agents. We set out to study the interactions of G. biloba with cilostazol and clopidogrel. METHODS: A randomized, open-label, crossover study of 10 healthy male volunteers. The dosage schedules were 120 mg G. biloba, 240 mg G. biloba, 100 mg cilostazol, 200 mg cilostazol, 75 mg clopidogrel, 150 mg clopidogrel, 120 mg G. biloba+ 100 mg cilostazol and 120 mg G. biloba+ 75 mg clopidogrel. Platelet aggregation, platelet count, bleeding time and clotting time were measured 0 and 6 h after drug administration. Platelet aggregation was performed using a dual channel aggregometer, by the turbimetric technique using adenosine diphosphate 5 micromol and 10 micromol, and collagen 1 microg ml(-1). RESULTS: Platelet inhibition with the combination of G. biloba and clopidogrel or cilostazol was not statistically significant compared with individual doses of drugs, with all the three aggregants. There was significant (P < 0.05) potentiation of prolongation of bleeding time with the combination of cilostazol and G. biloba compared with individual doses of both the drugs. There was no significant change in clotting time and platelet count. CONCLUSIONS: Coadministration of G. biloba either with cilostazol or clopidogrel did not enhance antiplatelet activity compared with individual agents. Ginkgo biloba potentiated the bleeding time prolongation effect of cilostazol. There was no significant correlation between prolongation of bleeding time and inhibition of platelet aggregation.     

Effects of a combined extract of Ginkgo biloba and Bacopa monniera on cognitive function in healthy humans

Extracts of Ginkgo biloba and Bacopa monniera have been shown to produce positive effects on cognitive function in healthy subjects. While the exact mechanisms are not known, it has been suggested that antioxidant properties and cholinergic modulation may play a role. In the current study the sub-chronic (2 weeks) and chronic (4 weeks) effects of an extract containing Ginkgo biloba (120 mg) and Bacopa monniera (300 mg) (Blackmores Ginkgo Brahmi) on cognitive function were examined. The study was a randomized, double-blind, placebo-controlled, independent group design in which 85 healthy subjects were allocated to one of two treatment conditions (placebo or combined Ginkgo biloba and Bacopa monniera extract). Testing was conducted at baseline and 2 and 4 weeks post treatment. The results showed that the combined extract relative to placebo did not demonstrate any significant effects on tests investigating a range of cognitive processes including attention, short-term and working memory, verbal learning, memory consolidation, executive processes, planning and problem solving, information processing speed, motor responsiveness and decision making. These findings suggest that at least within the current treatment duration and doses, an extract containing Ginkgo biloba and Bacopa monniera had no cognitive enhancing effects in healthy subjects.     

Effects of Ginkgo biloba on alertness and chemosensory function in healthy adults

Ginkgo biloba is reported to enhance cognitive function in patients with selected neural disorders. Its effects in healthy, young adults are less well characterized. This work explored whether Ginkgo biloba could ameliorate decrements in alertness post-prandially and/or enhance chemosensory function. Both are functions that could be influenced by enhanced cerebral blood flow and neuronal metabolism, reported properties of the compound. A double-blind placebo-controlled study was conducted with 19 males and 20 females with a mean age of 23.6 +/- 5.4 years and mean weight of 70.0 +/- 1.9 kg. Participants were supplemented for 13 weeks with either Ginkgo biloba (mean dose 184.5 mg/d (range 130-234 mg/d)) or placebo and administered various alertness, performance, affective state and chemosensory tests at weeks 1, 5, 9 and 13. Participants did experience the post-prandial affective state decrement (i.e. post-lunch dip), but not the performance decrement. Performance on the chemosensory tests improved over the 13-week study. However, Ginkgo biloba was ineffective at alleviating the symptoms of the post-lunch dip or at enhancing taste and smell function.     

Assessment of a pharmacokinetic and pharmacodynamic interaction between simvastatin and Ginkgo biloba extracts in healthy subjects

Abstract

1. Ginkgo biloba extract (GBE) is one of the most commonly used herbal remedies worldwide. It is usually concomitantly administrated with statins to treat diseases in geriatric patients. We aim to determine the influence of GBE on the pharmacokinetics (PK) and pharmacodynamics of simvastatin, which is currently unknown.

2. An open-label, randomized, two-period, two-treatment, balanced, crossover study was performed in 14 healthy volunteers. Subjects received simvastatin 40?mg once daily, co-treated with placebo or GBE 120?mg twice daily. Each treatment was administered for 14?d, separated by a wash-out period of 1 month. Simvastatin, simvastatin acid and lipoprotein concentrations were assessed.

3. GBE administration reduced mean simvastatin area under the curve (AUC)_0–24, AUC_0–∞ and C_max by 39% (p?=?0.000), 36%(p?=?0.001) and 32% (p?=?0.002), respectively, but did not cause significant differences in simvastatin acid PK or its cholesterol-lowering efficacy.

4. GBE consumption decreased simvastatin system exposure, but did not affect simvastatin acid PK. However, we cannot rule out the possibility for a pharmacodynamic interaction between GBE and simvastatin in vivo.     

Effect of Ginkgo biloba extract on lopinavir,midazolam and fexofenadine pharmacokinetics in healthy subjects

ABSTRACT

Objective: Animal and in vitro data suggest that Ginkgo biloba extract (GBE) may modulate CYP3A4 activity. As such, GBE may alter the exposure of HIV protease inhibitors metabolized by CYP3A4. It is also possible that GBE could alter protease inhibitor pharmacokinetics (PK) secondary to modulation of P-glycoprotein (P?gp). The primary objective of the study was to evaluate the effect of GBE on the exposure of lopinavir in healthy volunteers administered lopinavir/ritonavir. Secondary objectives were to compare ritonavir exposure pre- and post-GBE, and assess the effect of GBE on single doses of probe drugs midazolam and fexofenadine.

Methods: This open-label study evaluated the effect of 2 weeks of standardized GBE administration on the steady-state exposure of lopinavir and ritonavir in 14 healthy volunteers administered lopinavir/ritonavir to steady-state. In addition, single oral doses of probe drugs midazolam and fexofenadine were administered prior to and after 4 weeks of GBE (following washout of lopinavir/ritonavir) to assess the influence of GBE on CYP3A and P?gp activity, respectively.

Results: Lopinavir, ritonavir and fexofenadine exposures were not significantly affected by GBE administration. However, GBE decreased midazolam AUC_0–∞ and C_max by 34% (?p = 0.03) and 31% (?p = 0.03), respectively, relative to baseline. In general, lopinavir/ritonavir and GBE were well tolerated. Abnormal laboratory results included mild elevations in hepatic enzymes, cholesterol and triglycerides, and mild-to-moderate increases in total bilirubin.

Conclusions: Our results suggest that GBE induces CYP3A metabolism, as assessed by a decrease in midazolam concentrations. However, there was no change in the exposure of lopinavir, likely due to ritonavir's potent inhibition of CYP3A4. Thus, GBE appears unlikely to reduce the exposure of ritonavir-boosted protease inhibitors, while concentrations of unboosted protease inhibitors may be affected. Limitations to our study include the single sequence design and the evaluation of a ritonavir-boosted protease inhibitor exclusively.     

银杏叶提取物影响急性脑梗死患者血小板聚集率的研究

目的 探讨银杏叶提取物对急性脑梗死患者血小板聚集率的影响.方法 选取急性脑梗死患者102例,按数字表法随机分为观察组与对照组,每组51例.对照组患者给予常规药物治疗,观察组组患者在对照组的基础上给予银杏叶提取物药物治疗.结果 两组患者治疗后ADP、AA和PAF诱导的血小板聚集率分别为（65.1±8.1）％、（71.2±3.6）％、（30.1±5.2）％、（39.8±5.8）％、（42.1±6.3）％、（49.6±6.1）％均显著低于治疗前的（78.1±9.2）％、（77.6±9.0）％、（57.1±8.2）％、（56.8±8.4）％、（62.4±8.6）％、（61.9±8.3）％,差异均有统计学意义（均P ＜0.05）.观察组患者治疗后ADP诱导的血小板聚集率为（65.1±8.1）％,显著低于对照组（t=5.732,P＜0.05）;观察组患者治疗后AA诱导的血小板聚集率为（30.1±5.2）％,显著低于对照组（t=6.897,P＜0.05）;观察组患者治疗后PAF诱导的血小板聚集率为（42.1±6.3）％,显著低于对照组（t=6.013,P＜0.05）.两组患者治疗后神经功能缺损评分分别为（5.98±1.09）分、（7.11±1.56）分,显著低于治疗前的（12.98 ±2.09）分、（11.75 ±1.74）分,差异均有统计学意义（均P ＜0.05）;观察组患者治疗后的评分为（5.98±1.09）分,显著低于对照组的（7.11±1.56）分（t=5.469,P＜0.05）.结论 银杏叶提取物可显著降低急性脑梗死患者的血小板聚集率,值得在临床中推广应用.     

Effects of Ginkgo biloba extract on the pharmacokinetics of bupropion in healthy volunteers

AIMS

To assess the effects of Ginkgo biloba extract on the pharmacokinetics of bupropion in healthy volunteers.

METHODS

Fourteen healthy male volunteers (age range 19–25 years) received orally administered bupropion (150 mg) alone and during treatment with G. biloba 240 mg day⁻¹ (two 60-mg capsules taken twice daily) for 14 days. Serial blood samples were obtained over 72 h after each bupropion dose, and used to derive pharmacokinetic parameters of bupropion and its CYP2B6-catalysed metabolite, hydroxybupropion.

RESULTS

Ginkgo biloba extract administration resulted in no significant effects on the AUC_0–∞ of bupropion and hydroxybupropion. Bupropion mean AUC_0–∞ value was 1.4 µg·h ml⁻¹[95% confidence interval (CI) 1.2, 1.6] prior to G. biloba treatment and 1.2 µg·h ml⁻¹ (95% CI 1.1, 1.4) after 14 days of treatment. Hydroxybupropion mean AUC_0–∞ value was 8.2 µg·h ml⁻¹ (95% CI 6.5, 10.4) before G. biloba administration and 8.7 µg·h ml⁻¹ (95% CI 7.1, 10.6) after treatment. The C_max of hydroxybupropion increased from 221.8 ng ml⁻¹ (95% CI 176.6, 278.6) to 272.7 ng ml⁻¹ (95% CI 215.0, 345.8) (P = 0.038) and the t_1/2 of hydroxybupropion fell from 25.0 h (95% CI 22.7, 27.5) to 21.9 h (95% CI 19.9, 24.1) (P = 0.000).

CONCLUSIONS

Ginkgo biloba extract administration for 14 days does not significantly alter the basic pharmacokinetic parameters of bupropion in healthy volunteers. Although G. biloba extract treatment appears to reduce significantly the t_1/2 and increase the C_max of hydroxybupropion, no bupropion dose adjustments appear warranted when the drug is administered orally with G. biloba extract, due to the lack of significant change observed in AUC for either bupropion or hydroxybupropion.     

银杏叶提取物对脑缺血再灌注大鼠的保护作用

目的探讨银杏叶提取物(GbE)对缺血性脑卒中神经元保护作用机制。方法SD大鼠60只随机分为假手术组、再灌注组及银杏叶组。脑缺血再灌注损伤模型以脑中动脉建立。银杏叶组在术前给予口服GbE,再灌注组给予生理盐水,用免疫组化染色检测海马CA1区凋亡细胞数。结果再灌注组各时段的细胞凋亡数明显高于假手术组(P<0.05),银杏叶组各时段的细胞凋亡数明显低于再灌注组(P<0.05)。结论银杏叶可能对海马神经元有保护作用。     

Ginkgo biloba: specificity of neuropsychological improvement—a selective review in search of differential effects

Extracts of Ginkgo biloba are widely used for the treatment of cognitive impairment. Whereas reviews have focused on the question whether ginkgo is effective to enhance cognition in general, little is known about specificity of improvement. This might be crucial for future trials, thus enabling hypotheses about sensitive outcome measures. Therefore, this article summarizes such information, i.e. neuropsychological effects of chronic administration of ginkgo in healthy and cognitively impaired subjects of any age. Objective psychometric test results were considered if they reflected distinct cognitive functions from randomized controlled group‐studies (RCT). We reviewed 29 RCTs yielding 209 placebo‐drug comparisons of psychometric scores in four different cognitive domains comprising 14 sub‐functions. Whereas little specific information can be obtained from trials for treatment of dementia, a pattern of pharmacological actions on cognitive processes emerges here from studies for mild cognitive impairment (MCI), depression, multiple sclerosis and healthy young and elderly subjects. There is consistent evidence that chronic administration improves selective attention, some executive processes and long‐term memory for verbal and non‐verbal material. Further trials should be more comprehensive as there are few data available on some cognitive functions and psychometric flaws in the selection of tests and the interpretation of their results favouring predominantly β‐errors. Thus, though this pattern is encouraging it also asks for a cautious interpretation to date. Copyright © 2009 John Wiley & Sons, Ltd.     

The memory-enhancing effects of Ginseng and Ginkgo biloba in healthy volunteers

Rationale The use of herbal remedies, such as Ginkgo biloba and Ginseng, for improving cognitive performance has become increasingly popular during recent years. Several previous studies have indicated that administration of Ginkgo biloba and Ginseng may improve aspects of learning and memory in healthy volunteers. These results, however, are generally not supported by well-controlled clinical studies. Also, positive results have often been reported from studies investigating effects related to short-term, chronic administration of the extract. Nonetheless, both Ginkgo biloba and Ginseng are marketed as having the capacity to enhance cognitive functions, such as memory and learning, in the long term.Objective This study aimed at investigating whether the use of Ginkgo biloba and Ginseng for a long period of time has positive effects on performance on learning and memory.Methods Community-dwelling volunteers (n=3500) from The Betula prospective cohort study: memory, health, and aging were included in the study.Results It was found that the use of neither Ginkgo biloba (n=40) nor Ginseng (n=86) was associated with enhanced memory performance in any of the eight memory tests examined, relative to control groups either using or not using nutritional supplements.Conclusions These findings indicate that use of Ginkgo biloba or Ginseng does not provide any quantifiable beneficial effects on memory performance in the long-term in healthy adult volunteers.     

Cognitive effects of a Ginkgo biloba/vinpocetine compound in normal adults: systematic assessment of perception,attention and memory

A computerized test battery was used in a double-blind design to assess the cognitive effects of a nutrient compound containing Ginkgo biloba in 24 normal adults. Ten tasks (perceptual, attention and short-term memory) were presented in a standardized manner designed to maximize performance, with substantial pre-test practice employed to minimize response variability. Subjects were given either placebo or Ginkgo biloba extract capsules to consume for 14 days, after which they performed all tasks twice. They then received the other condition, and after 14 days completed the final test session. Response time and error rate stabilized after pre-test practice. A 'working memory capacity' paradigm demonstrated a reliable 50 ms response time decrease between the placebo and Ginkgo biloba testing, suggesting that Ginkgo biloba speeds short-term working memory processing in normal adults. Copyright 2001 John Wiley & Sons, Ltd.     

A double-blind,placebo-controlled,randomized trial of Ginkgo biloba extract EGb 761 in a sample of cognitively intact older adults: neuropsychological findings

There appears to be an absence of large-scaled clinical trials that have examined the efficacy of Ginkgo biloba extract on the neuropsychological functioning of cognitively intact older adults. The importance of such clinical research appears paramount in light of the plethora of products containing Ginkgo biloba that are currently being widely marketed to predominantly cognitively intact adults with claims of enhanced cognitive performances. The purpose of this research was to conduct the first known, large-scaled clinical trial of the efficacy of Ginkgo biloba extract (EGb 761) on the neuropsychological functioning of cognitively intact older adults. Two hundred and sixty-two community-dwelling volunteers (both male and female) 60 years of age and older, who reported no history of dementia or significant neurocognitive impairments and obtained Mini-Mental State Examination total scores of at least 26, were examined via a 6-week, randomized, double-blind, fixed-dose, placebo-controlled, parallel-group, clinical trial. Participants were randomly assigned to receive either Ginkgo biloba extract EGb 761(n = 131; 180 mg/day) or placebo (n = 131) for 6 weeks. Efficacy measures consisted of participants' raw change in performance scores from pretreatment baseline to those obtained just prior to termination of treatment on the following standardized neuropsychological measures: Selective Reminding Test (SRT), Wechsler Adult Intelligence Scale-III Block Design (WAIS-III BD) and Digit Symbol-Coding (WAIS-III DS) subtests, and the Wechsler Memory Scale-III Faces I (WMS-III FI) and Faces II (WMS-III FII) subtests. A subjective Follow-up Self-report Questionnaire was also administered to participants just prior to termination of the treatment phase. Analyses of covariance indicated that cognitively intact participants who received 180 mg of EGb 761 daily for 6 weeks exhibited significantly more improvement on SRT tasks involving delayed (30 min) free recall (p < 0.04) and recognition (p < 0.01) of noncontextual, auditory-verbal material, compared with the placebo controls. The EGb 761 group also demonstrated significantly greater improvement on the WMS-III FII subtest assessing delayed (30 min) recognition (p < 0.025) of visual material (i.e. human faces), compared with the placebo group. However, based on the significant difference (p < 0.03) found between the two groups' pretreatment baseline scores on the WMS-III FII, this result should be interpreted with caution. An examination of the participants' subjective ratings of their overall abilities to remember by treatment end on the Follow-up Self-report Questionnaire also revealed that significantly more (p = 0.05) older adults in the EGb 761 group rated their overall abilities to remember by treatment end as 'improved' compared with the placebo controls. Overall, the results from both objective, standardized, neuropsychological tests and a subjective, follow-up self-report questionnaire provided complementary evidence of the potential efficacy of Ginkgo biloba EGb 761 in enhancing certain neuropsychological/memory processes of cognitively intact older adults, 60 years of age and over.     

银杏叶提取物的胃粘膜保护作用(英文)

目的:研究银杏叶提取物的胃粘膜保护作用.方法:采用大鼠束缚-冷冻应激(RCS)模型和小鼠无水乙醇损伤模型观察GbE对胃粘膜损伤指数的影响;采用幽门结扎法收集胃液,观察GbE对胃液分泌量,胃液酸度和胃蛋白酶活性的影响;采用硫代巴比妥酸(TBA)法测定胃粘膜及血清中丙二醛(MDA)含量.结果:GbE(25,50,100 mg/kg,bid×5 d,ig)剂量依赖性地抑制RCS和无水乙醇引起的胃粘膜损伤.用药组应激后的胃粘膜损伤指数分别为对照组的58％,43％和31％;用药组乙醇诱发的胃粘膜损伤指数降至对照组的62％,36％和26％;GbE尚能增强西米替丁对胃粘膜的保护作用,但对大鼠胃液分泌量、胃液酸度及胃蛋白酶活性GbE并无明显影响.小鼠经无水乙醇ig后1 h,胃粘膜和血清中的MDA含量显著升高(P<0.01),而GbE(25,50,100 mg/kg,ig)预处理则可以明显抑制MDA的升高.结论:GbE具有胃粘膜保护作用,并且与西米替丁在治疗急性胃粘膜损伤方面具有协同作用.     

复方银杏滴丸对糖皮质激素诱导的脑功能衰退小鼠的保护作用

目的: 观察复方银杏滴丸 (CO GBE)对糖皮质激素(GC)诱导的脑功能衰退小鼠的保护作用。方法: 6月龄小鼠隔日皮下注射氢化可的松 30mg·kg-1共计 11次造成脑功能衰退模型,分别采用跳台法和水迷宫法测定小鼠的学习记忆能力,并检测其体重、脾脏指数和胸腺指数。结果:与空白对照组相比,模型小鼠的学习记忆能力明显下降 [跳台试验中,学习能力测定的反应期 (2. 4±s1. 9 )s、潜伏期(41±81)s、停留时间 (13±14 )s、错误次数 (2. 5±2. 4)次。记忆能力测定的潜伏期 (159±144)s、停留时间(3±4)s、错误次数 (0. 6±1. 0)次。水迷宫试验中,学习能力测定的B点到达时间 (61±37)s、错误次数(3. 2±2. 4)次、C点到达时间(65±65)s、错误次数(3. 9±2. 9)次,记忆能力测定的B点到达时间(60±41)s、错误次数(3. 0±1. 0)次,C点到达时间(71±59)s,错误次数 (3. 2±2. 2)次 ];体重明显减轻;脾脏指数减小(P<0.05,P<0. 01);胸腺指数呈减小趋势。CO GBE 15, 30, 60mg·kg-1不同程度地增强模型小鼠的学习记忆能力 (P<0.05,P<0. 01), 60mg·kg-1还可以明显抑制模型小鼠体重下降,P<0. 05,增加其脾脏指数 (98±33 )mg·10g-1体重,P<0. 05,未见药物对模型动物胸腺指数有影响。结论:CO GBE可以明显改善GC诱导的脑功能衰退小鼠的学     

Acute,dose-dependent cognitive effects of Ginkgo biloba,Panax ginseng and their combination in healthy young volunteers: differential interactions with cognitive demand

The present paper describes three studies examining the acute effects of single doses of Ginkgo biloba (GK501), Ginseng (G115) and their combination (Ginkoba M/E, Pharmaton SA) on the performance of healthy young adults (mean age 21 years) during serial arithmetic tasks with differing cognitive load. In each double-blind, placebo-controlled study three different treatment doses and a placebo were administered, according to a balanced crossover design, with a 7-day washout period between each dose. Participants' scores on two computerised serial subtraction tasks (Serial Threes and Serial Sevens) were assessed pre-dosing and at 1, 2.5, 4 and 6 h thereafter. A number of significant time, dose and task-specific effects were associated with each treatment. There was a dose-dependent improvement in speed of responding during Serial Threes following Ginkgo biloba. Different doses of Ginseng improved accuracy and slowed responses during Serial Sevens. The most striking result, however, was a highly significant and sustained increase in the number of Serial Sevens responses following 320 mg of the Ginkgo-Ginseng combination at all post-treatment testing times. This was accompanied by improved accuracy during Serial Sevens and Serial Threes following the 640 mg and the 960 mg dose, respectively. The paper concludes with speculation into the possible mechanisms underlying these effects.     

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.