Ginkgo biloba for cognitive impairment and dementia

[Pharmacological neuroenhancement and brain doping : Chances and risks]

Pharmacological neuroenhancement refers to the use of psychoactive substances by healthy subjects with the purpose of cognitive enhancement, e.g., vigilance, concentration, memory, or mood. "Brain doping", however, refers to the illicit use of a subcategory of these substances such as prescription drugs. This subcategory includes psychostimulants (e.g., amphetamines, methylphenidate), modafinil, antidementia drugs (acetylcholine-esterase inhibitors, memantine), and antidepressants (selective serotonin reuptake inhibitors) which are being prescribed for the treatment of ADHD (attention deficit/hyperactivity disorder), Alzheimer's disease, and depression. Only psychostimulants and modafinil show significant effects on concentration, attentiveness, and vigilance in healthy subjects. However, a general use by healthy persons can not be justified because of relevant side effects and safety risks. Caffeine for pharmacological neuroenhancement can be seen as an equally effective alternative. "Brain doping" raises numerous ethical and social concerns that require a continued discussion. Demands of liberalization should be critically questioned.

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.

An approach to the psychopharmacologic care of patients: antidepressants, antipsychotics, anxiolytics, mood stabilizers, and natural remedies

The number of safe and effective medication treatments for psychiatric illness has expanded substantially over the past 10 to 15 years. Knowing when and how to prescribe psychotropics--and knowing which medication to prescribe--can be challenging, but with knowledge of some basic principles, this task can be performed adeptly by physicians of all specialties. In this article, the authors discuss basic principles of psychopharmacology and outline an approach to using several commonly prescribed classes of medications.

Herbal therapy: a new pathway for the treatment of Alzheimer's disease

It has been a clinical challenge to treat Alzheimer's disease (AD). In the present commentary we discuss whether herbal therapy could be a novel treatment method for AD on the basis of results from clinical trials, and discuss the implications for potential therapy for AD pathophysiology. There is evidence to suggest that single herbs or herbal formulations may offer certain complementary cognitive benefits to the approved drugs. The current evidence supporting their use alone, however, is inconclusive or inadequate owing to many methodological limitations. Herbal mixtures may have advantages with multiple target regulation compared with the single-target antagonist in the view of traditional Chinese medicine. Several clinical trials using herbal mixtures are being conducted in China and will hopefully show promising results for treating AD in the near future.

Medicinal plants and dementia therapy: herbal hopes for brain aging?

An escalating "epidemic" of diseases like Alzheimer's has not yet been met by effective symptomatic treatments or preventative strategies. Among a few current prescription drugs are cholinesterase inhibitors including galantamine, originating from the snowdrop. Research into ethnobotanicals for memory or cognition has burgeoned in recent years. Based on a multi-faceted review of medicinal plants or phytochemicals, including traditional uses, relevant bioactivities, psychological and clinical evidence on efficacy and safety, this overview focuses on those for which there is promising clinical trial evidence in people with dementia, together with at least one other of these lines of supporting evidence. With respect to cognitive function, such plants reviewed include sage, Ginkgo biloba, and complex mixtures of other traditional remedies. Behavioral and psychological symptoms of dementia (BPSD) challenge carers and lead to institutionalization. Symptoms can be alleviated by some plant species (e.g., lemon balm and lavender alleviate agitation in people with dementia; St John's wort treats depression in the normal population). The ultimate goal of disease prevention is considered from the perspective of limited epidemiological and clinical trial evidence to date. The potential value of numerous plant extracts or chemicals (e.g., curcumin) with neuroprotective but as yet no clinical data are reviewed. Given intense clinical need and carer concerns, which lead to exploration of such alternatives as herbal medicines, the following research priorities are indicated: investigating botanical agents which enhance cognition in populations with mild memory impairment or at earliest disease stages, and those for BPSD in people with dementia at more advanced stages; establishing an ongoing authoritative database on herbal medicine for dementia; and further epidemiological and follow up studies of promising phytopharmaceuticals or related nutraceuticals for disease prevention.

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.

Retrospect and prospect of active principles from Chinese herbs in the treatment of dementia

With an ageing population, dementia has become one of the world's primary health challenges. However, existing remedies offer limited benefits with certain side effects, which has prompted researchers to seek complementary and alternative therapies. China has long been known for abundant usage of various herbs. Some of these herbal decoctions are effective in stimulating blood circulation, supplementing vital energy and resisting aging, the lack of which are believed to underlie dementia. These herbs are regarded as new and promising sources of potential anti-dementia drugs. With the rapid evolution of life science and technology, numerous active components have been identified that are highly potent and multi-targeted with low toxicity, and therefore meet the requirements for dementia therapy. This review updates the research progress of Chinese herbs in the treatment of dementia, focusing on their effective principles.

Neuroprotective herbs and foods from different traditional medicines and diets

Plant secondary metabolites include an array of bioactive constituents form both medicinal and food plants able to improve human health. The exposure to these phytochemicals, including phenylpropanoids, isoprenoids and alkaloids, through correct dietary habits, may promote health benefits, protecting against the chronic degenerative disorders mainly seen in Western industrialized countries, such as cancer, cardiovascular and neurodegenerative diseases. In this review, we briefly deal with some plant foods and herbs of traditional medicines and diets, focusing on their neuroprotective active components. Because oxidative stress and neuroinflammation resulting from neuroglial activation, at the level of neurons, microglial cells and astrocytes, are key factors in the etiopathogenesis of both neurodegenerative and neurological diseases, emphasis will be placed on the antioxidant and anti-inflammatory activity exerted by specific molecules present in food plants or in remedies prescribed by herbal medicines.

Effect of Ginkgo biloba on blood pressure and incidence of hypertension in elderly men and women

BACKGROUND

Accumulating evidence suggests that Ginkgo biloba is cardioprotective, in part, through its vasodilatory and antihypertensive properties. However, definitive data on its blood pressure (BP)-lowering effects in humans is lacking.

METHODS

We determined the effects of G. biloba extract (240 mg/day) on BP and incident hypertension in 3,069 participants (mean age, 79 years; 46% female; 96% white) from the Ginkgo Evaluation of Memory (GEM) study. We also examined whether the treatment effects are modified by baseline hypertension status.

RESULTS

At baseline, 54% of the study participants were hypertensive, 28% were prehypertensive, and 17% were normotensive. Over a median follow-up of 6.1 years, there were similar changes in BP and pulse pressure (PP) in the G. biloba and placebo groups. Although baseline hypertension status did not modify the antihypertensive effects of G. biloba, it did influence the changes in BP variables observed during follow-up, with decreases in hypertensives, increases in normotensives, and no changes in prehypertensives. Among participants who were not on antihypertensive medications at baseline, there was no difference between treatment groups in medication use over time, as the odds ratio (95% confidence interval (CI)) for being a never-user in the G. biloba group was 0.75 (0.48-1.16). The rate of incident hypertension also did not differ between participants assigned to G. biloba vs. placebo (hazard ratio (HR), 0.99, 95% CI, 0.84-1.15).

CONCLUSIONS

Our data indicate that G. biloba does not reduce BP or the incidence of hypertension in elderly men and women.

Complementary and alternative medicine for the treatment of multiple sclerosis

Multiple sclerosis (MS) is a chronic disabling disease of the CNS that affects people during early adulthood. Despite several US FDA-approved medications, the treatment options in MS are limited. Many people with MS explore complementary and alternative medicine (CAM) treatments to help control their MS and treat their symptoms. Surveys suggest that up to 70% of people with MS have tried one or more CAM treatment for their MS. People with MS using CAM generally report deriving some benefit from the therapies. The CAM therapies most frequently used include diet, omega-3 fatty acids and antioxidants. There is very limited research evaluating the safety and effectiveness of CAM in MS. The most promising among CAM therapies that warrant further investigation are a low-fat diet, omega-3 fatty acids, lipoic acid and vitamin D supplementation as potential anti-inflammatory and neuroprotective agents in both relapsing and progressive forms of MS. There is very limited research evaluating the safety and effectiveness of CAM in MS. However, in recent years, the NIH and the National MS Society have been actively supporting the research in this very important area.

Effects of Ginkgo biloba in dementia: systematic review and meta-analysis

Background

The benefit of Ginkgo biloba has been discussed controversially. The aim of this review was to assess the effects of Ginkgo biloba in Alzheimer's disease as well as vascular and mixed dementia covering a variety of outcome domains.

Methods

We searched MEDLINE, EMBASE, the Cochrane databases, CINAHL and PsycINFO for controlled trials of ginkgo for Alzheimer's, vascular or mixed dementia. Studies had to be of a minimum of 12 weeks duration with at least ten participants per group. Clinical characteristics and outcomes were extracted. Meta-analysis results were expressed as risk ratios or standardized mean differences (SMD) in scores.

Results

Nine trials using the standardized extract EGb761^® met our inclusion criteria. Trials were of 12 to 52 weeks duration and included 2372 patients in total. In the meta-analysis, the SMDs in change scores for cognition were in favor of ginkgo compared to placebo (-0.58, 95% confidence interval [CI] -1.14; -0.01, p = 0.04), but did not show a statistically significant difference from placebo for activities in daily living (ADLs) (SMD = -0.32, 95% CI -0.66; 0.03, p = 0.08). Heterogeneity among studies was high. For the Alzheimer subgroup, the SMDs for ADLs and cognition outcomes were larger than for the whole group of dementias with statistical superiority for ginkgo also for ADL outcomes (SMD = -0.44, 95% CI -0.77; -0.12, p = 0.008). Drop-out rates and side effects did not differ between ginkgo and placebo. No consistent results were available for quality of life and neuropsychiatric symptoms, possibly due to the heterogeneity of the study populations.

Conclusions

Ginkgo biloba appears more effective than placebo. Effect sizes were moderate, while clinical relevance is, similar to other dementia drugs, difficult to determine.

A vitamin/nutriceutical formulation improves memory and cognitive performance in community-dwelling adults without dementia

Adults of both genders without dementia consumed a nutriceutical formulation ("NF," consisting of folic acid, B12, Vitamin E, S-adenosylmethionine, N-acetyl cysteine and Acetyl-L-carnitine), previously shown to improve cognitive performance in Alzheimer's disease, or placebo. Participants receiving NF but not placebo improved statistically and clinically in the California Verbal Learning Test II and the Trail-Making Test. Both groups improved further during a 3-month open-label extension. Additional individuals displayed identical improvement during a separate 6-month open-label trial. Performance declined to baseline following withdrawal of NF, and statistically improved when participants resumed taking NF. Additional participants receiving NF but not placebo demonstrated improvement within 2 weeks in Trail-making and Digit-Memory tests; both groups improved in a 2-week open-label extension. An increased percentage of participants > or = 74 years of age did not show improvement with NF, which may relate to age-related difficulties in adsorption and/or basal nutritional deficiencies, or age-related cognitive decline during the course of this study. These findings support the benefit of nutritional supplements for cognitive performance and suggest that additional supplementation may be required for the elderly.

Ginkgo biloba extract in Alzheimer's disease: from action mechanisms to medical practice

Standardized extract from the leaves of the Ginkgo biloba tree, labeled EGb761, is one of the most popular herbal supplements. Numerous preclinical studies have shown the neuroprotective effects of EGb761 and support the notion that it may be effective in the treatment and prevention of neurodegenerative disorders such as Alzheimer’s disease (AD). Despite the preclinical promise, the clinical efficacy of this drug remains elusive. In this review, possible mechanisms underlying neuroprotective actions of EGb761 are described in detail, together with a brief discussion of the problem of studying this herb clinically to verify its efficacy in the treatment and prevention of AD. Moreover, various parameters e.g., the dosage and the permeability of the blood brain barrier (BBB), impacting the outcome of the clinical effectiveness of the extract are also discussed. Overall, the findings summarized in this review suggest that, a better understanding of the neuroprotective mechanisms of EGb761 may contribute to better understanding of the effectiveness and complexity of this herb and may also be helpful for design of therapeutic strategies in future clinical practice. Therefore, in future clinical studies, different factors that could interfere with the effect of EGb761 should be considered.

Current treatment and recent clinical research in Alzheimer's disease

The transition from either epidemiological observation or the bench to rigorously tested clinical trials in patients with Alzheimer's disease is crucial in understanding which treatments are beneficial to patients. The amyloid hypothesis has undergone scrutiny recently, as many trials aimed at reducing amyloid and plaque have been completed or are in the testing phase. Examples include modulation of the secretases involved in beta amyloid formation, anti-aggregation agents, and immunotherapeutic trials. Other therapies targeting hyperphosphorylated tau and novel targets such as enhancement of mitochondrial function, serotonin receptors, receptor for advanced glycation end products, and nerve growth factor, as well as other strategies, are discussed. A brief review of the current Food and Drug Administration-approved treatments is included.

Ginkgo biloba for preventing cognitive decline in older adults: a randomized trial

CONTEXT

The herbal product Ginkgo biloba is taken frequently with the intention of improving cognitive health in aging. However, evidence from adequately powered clinical trials is lacking regarding its effect on long-term cognitive functioning.

OBJECTIVE

To determine whether G. biloba slows the rates of global or domain-specific cognitive decline in older adults.

DESIGN, SETTING, AND PARTICIPANTS

The Ginkgo Evaluation of Memory (GEM) study, a randomized, double-blind, placebo-controlled clinical trial of 3069 community-dwelling participants aged 72 to 96 years, conducted in 6 academic medical centers in the United States between 2000 and 2008, with a median follow-up of 6.1 years.

INTERVENTION

Twice-daily dose of 120-mg extract of G. biloba (n = 1545) or identical-appearing placebo (n = 1524).

MAIN OUTCOME MEASURES

Rates of change over time in the Modified Mini-Mental State Examination (3MSE), in the cognitive subscale of the Alzheimer Disease Assessment Scale (ADAS-Cog), and in neuropsychological domains of memory, attention, visual-spatial construction, language, and executive functions, based on sums of z scores of individual tests.

RESULTS

Annual rates of decline in z scores did not differ between G. biloba and placebo groups in any domains, including memory (0.043; 95% confidence interval [CI], 0.034-0.051 vs 0.041; 95% CI, 0.032-0.050), attention (0.043; 95% CI, 0.037-0.050 vs 0.048; 95% CI, 0.041-0.054), visuospatial abilities (0.107; 95% CI, 0.097-0.117 vs 0.118; 95% CI, 0.108-0.128), language (0.045; 95% CI, 0.037-0.054 vs 0.041; 95% CI, 0.033-0.048), and executive functions (0.092; 95% CI, 0.086-0.099 vs 0.089; 95% CI, 0.082-0.096). For the 3MSE and ADAS-Cog, rates of change varied by baseline cognitive status (mild cognitive impairment), but there were no differences in rates of change between treatment groups (for 3MSE, P = .71; for ADAS-Cog, P = .97). There was no significant effect modification of treatment on rate of decline by age, sex, race, education, APOE*E4 allele, or baseline mild cognitive impairment (P > .05).

CONCLUSION

Compared with placebo, the use of G. biloba, 120 mg twice daily, did not result in less cognitive decline in older adults with normal cognition or with mild cognitive impairment.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00010803.

Ginkgo biloba for tinnitus

BACKGROUND

Tinnitus can be described as the perception of sound in the absence of external acoustic stimulation. At present no specific therapy for tinnitus is acknowledged to be satisfactory in all patients. There are a number of reports in the literature suggesting that Ginkgo biloba may be effective in the management of tinnitus. However, there also appears to be a strong placebo effect in tinnitus management.

OBJECTIVES

To assess the effect of Ginkgo biloba in patients who are troubled by tinnitus.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library Issue 4 2003), MEDLINE (1966 - 2003), EMBASE (1974 - 2003), and reference lists of identified publications. Date of the most recent search was December 2003.

SELECTION CRITERIA

Adults (18 years and over) complaining of tinnitus. Adults with a primary complaint of cerebral insufficiency where tinnitus forms part of the syndrome.

DATA COLLECTION AND ANALYSIS

Both reviewers independently extracted data and assessed trials for quality.

MAIN RESULTS

Twelve trials were identified from the search as being relevant to the review. Ten trials were excluded on methodological grounds. No trials of tinnitus in cerebral insufficiency reached a satisfactory standard for inclusion in the review. There was no evidence that Ginkgo biloba was effective for the primary complaint of tinnitus. The incidence of side effects was small.

REVIEWERS' CONCLUSIONS

The limited evidence did not demonstrate that Ginkgo biloba was effective for tinnitus which is a primary complaint. There was no reliable evidence to address the question of Ginkgo biloba for tinnitus associated with cerebral insufficiency.