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

Mitochondrial dysfunction: cause and consequence of Alzheimer's disease

The etiology of common, nonfamiliar late-onset Alzheimer's disease (LOAD) is only partly understood and seems to be extremely complex including many genetic and environmental factors. The most important environmental risk factor to develop LOAD is aging itself. Aging and LOAD are considered to be strongly linked to mitochondrial dysfunction and enhanced oxidative stress. In this review, we focus on the interaction between mitochondrial dysfunction in aging especially on defects of the respiratory chain of the oxidative phosphorylation system resulting in enhanced oxidative stress and the interplay between aging-associated mitochondrial defects and LOAD-associated mitochondrial failure. The deleterious effects of the two hallmarks of LOAD, amyloid beta, and hyperphosphorylated tau, on mitochondrial function, movement, and morphology are described as well as the toxic effects of the most relevant genetic risk factor of LOAD, the apolipoprotein E4 allele. Finally, the review provides an overview about drugs and nutritional ingredients which improve mitochondrial function or/and act as antioxidants and discusses their potential role in the treatment of LOAD.

Ginkgo biloba extract individually inhibits JNK activation and induces c-Jun degradation in human chondrocytes: potential therapeutics for osteoarthritis

Osteoarthritis (OA) is a common joint disorder with varying degrees of inflammation. The ideal anti-OA drug should have immunomodulatory effects while at the same time having limited or no toxicity. We examined the anti-inflammatory effects of Ginkgo biloba extract (EGb) in interleukin-1 (IL-1)-stimulated human chondrocytes. Chondrocytes were prepared from cartilage specimens taken from patients with osteoarthritis who had received total hip or total knee replacement. The concentrations of chemokines and the degree of cell migration were determined by ELISA and chemotaxis assays, respectively. The activation of inducible nitric oxide synthase (iNOS), mitogen-activated protein kinases (MAPKs), activator protein-1 (AP-1), and nuclear factor-kappaB (NF-κB) was determined by immunoblotting, immunohistochemistry, and electrophoretic mobility shift assay. We found that EGb inhibited IL-1-induced production of chemokines, which in turn resulted in attenuation of THP-1 cell migration toward EGb-treated cell culture medium. EGb also suppressed IL-1-stimulated iNOS expression and release of nitric oxide (NO). The EGb-mediated suppression of the iNOS-NO pathway correlated with the attenuation of activator protein-1 (AP-1) but not nuclear factor-kappaB (NF-κB) DNA-binding activity. Of the mitogen-activated protein kinases (MAPKs), EGb inhibited only c-Jun N-terminal kinase (JNK). Unexpectedly, EGb selectively caused degradation of c-Jun protein. Further investigation revealed that EGb-mediated c-Jun degradation was preceded by ubiquitination of c-Jun and could be prevented by the proteosome inhibitor MG-132. The results imply that EGb protects against chondrocyte degeneration by inhibiting JNK activation and inducing ubiquitination-dependent c-Jun degradation. Although additional research is needed, our results suggest that EGb is a potential therapeutic agent for the treatment of OA.

Effects of Ginkgo biloba extract EGb 761 ® in dementia with neuropsychiatric features: review of recently completed randomised, controlled trials

OBJECTIVE

We review four randomised, controlled trials investigating the efficacy of Ginkgo biloba extract EGb 761(®) in elderly patients with Alzheimer or vascular dementia with neuropsychiatric features.

METHODS

Patients with a total score of 9-23 in the Syndrom-Kurz test (SKT) cognitive test battery (cognitive domain) and with a composite score 6 and greater in the Neuropsychiatric Inventory (NPI; behavioural domain) were included. Three trials compared 2 × 120 mg/day or 1 × 240 mg/day EGb 761(®) to placebo while one used donepezil as an active control. The duration of randomised treatment was 22 or 24 weeks.

RESULTS

One thousand, two hundred and ninety-four patients were analysed for efficacy. Patients treated with EGb 761(®) showed improvements of cognitive performance and behavioural symptoms that were associated with advances in activities of daily living and a reduced burden to caregivers. Placebo-treated patients, on the other hand, showed only minimal improvements or signs of progression. In each placebo-controlled trial, EGb 761(®) was significantly superior in all mentioned domains (p < 0.01). In the actively controlled trial, EGb 761(®) and donezepil as well as a combination of both drugs had similar effects.

CONCLUSIONS

The review supports the efficacy of EGb 761(®) in age-related dementia with neuropsychiatric features. The drug was safe and well-tolerated.

Dosage strength is associated with medication persistence with Ginkgo biloba drug products: a cohort study of ambulatory drug claims data in Germany

Background

Ginkgo biloba drugs (Gb) are reimbursed within the German statutory health insurance (SHI) scheme for treatment of dementia. In 2008, a novel Gb product containing 240 mg Ginkgo extract EGb761^® per tablet was introduced aiming to facilitate medication use by incorporating the recommended daily dose in one single tablet. The aim of this study was to evaluate the relationship between dosage strength and persistence in a representative population of patients treated with Gb.

Methods

Retrospective cohort study in ambulatory drug claims database within the German SHI system. Persistence was defined as continuous treatment with an allowable gap of 20% between refills. Multivariate regression models were conducted to identify variables associated with persistence.

Results

Among 13,810 patients initiating treatment with Gb in 2008, 430 (3.1%) received a dosage strength of 240 mg, 7,070 (51.2%) a dosage strength of 120 mg and 6,310 (45.7%) dosage strengths containing less than 120 mg Gb per tablet. After 6 months, persistence was highest for patients treated with the 240 mg dosage form (22.8% of patients), although persistence was low in general (5.7% and 0% of patients treated with 120 mg and less than 120 mg, respectively). Risk for non-persistence was reduced in patients receiving 240 mg products compared to 120 mg (HR = 0.63; 95%CI 0.57 – 0.70).

Conclusions

Patients initially treated with Gb 240 mg were more persistent compared to those receiving lower dosage strengths. Nevertheless, persistence with Gb therapy is generally low and should be improved in order to better realize therapeutic effects.

Proteomic analysis of the low mutation rate of diploid male gametes induced by colchicine in Ginkgo biloba L

Colchicine treatment of G. biloba microsporocytes results in a low mutation rate in the diploid (2n) male gamete. The mutation rate is significantly lower as compared to other tree species and impedes the breeding of new economic varieties. Proteomic analysis was done to identify the proteins that influence the process of 2n gamete formation in G. biloba. The microsporangia of G. biloba were treated with colchicine solution for 48 h and the proteins were analyzed using 2-D gel electrophoresis and compared to protein profiles of untreated microsporangia. A total of 66 proteins showed difference in expression levels. Twenty-seven of these proteins were identified by mass spectrometry. Among the 27 proteins, 14 were found to be up-regulated and the rest 13 were down-regulated. The identified proteins belonged to five different functional classes: ATP generation, transport and carbohydrate metabolism; protein metabolism; ROS scavenging and detoxifying enzymes; cell wall remodeling and metabolism; transcription, cell cycle and signal transduction. The identification of these differentially expressed proteins and their function could help in analysing the mechanism of lower mutation rate of diploid male gamete when the microsporangium of G. biloba was induced by colchicine.

Nutrition and neurodegeneration: epidemiological evidence and challenges for future research

The prevention of dementias, such as Alzheimer's disease (AD), is a growing public health concern, due to a lack of effective curative treatment options and a rising global prevalence. Various potential risk or preventive factors have been suggested by epidemiological research, including modifiable lifestyle factors such as diet. Current epidemiological data are in favour of a protective role of certain micronutrients (B vitamins related to homocysteine metabolism, the anti-oxidant vitamins C and E, flavonoids, polyunsatured omega-3 fatty acids, vitamin D) and macronutrients (fish) in the prevention of cognitive decline and dementia/AD. Some factors have been targeted by interventions tested in randomized controlled trials (RCTs), but many of the results are conflicting with observational evidence. Epidemiological analysis of the relations between nutrient consumption and cognitive decline is complex and it is highly unlikely that a single component plays a major role. In addition, since multiple factors across the life course influence brain function in late life, multidomain interventions might be more promising in the prevention of cognitive decline and dementia/AD. Designing such trials remains very challenging for researchers. The main objective of this paper is to review the epidemiologic data linking potential protective factors to cognitive decline or dementia/AD, focusing particularly on the roles of adiposity, caloric restriction, micro (group B vitamins related to homocysteine metabolism, the anti-oxidant vitamins C and E, flavonoids, polyunsatured omega-3 fatty acids, vitamin D) and macronutrients (fish). Limitations of the current data, divergence with results of interventional prevention studies and challenges for future research are discussed.

An exploration of the potential mechanisms and translational potential of five medicinal plants for applications in Alzheimer's disease

Alzheimer's disease (AD) is the most common type of dementia, and represents a vast worldwide socio-economic burden, and in the absence of a current cure, effective therapeutic strategies are still needed. Cholinergic and cerebral blood flow deficits, excessive levels of oxidative stress, neuroinflammation and glutamate excitatory mechanisms are all believed to contribute to the development and progression of the disease. Scoparia dulcis, Catharanthus roseus, Sesamum indicum, Erythrina senegalensis and Vigna unguiculata represent five plants that have been used as traditional medicines for the treatment of AD in certain cultures. Review of the scientific literature was conducted to explore the properties of these plants that might be beneficial and explain what would be perceived by many to be largely anecdotal evidence of their benefit. All plants were found to possess varying levels of anti-oxidant capability. Scoparia dulcis was also found to potentiate nerve growth factor-like effects upon cell lines. Catharanthus roseus appears to inhibit acetylcholinesterase with relatively high potency, while Sesamum indicum demonstrated the strongest antioxidant ability. Comparisons with currently used plant derived therapeutics illustrate how these plants may be likely to have some therapeutic benefits in AD. The evidence presented also highlights how appropriate dietary supplementation with some of these plants in various cultural settings might have effects analogous or complementary to the so-called protective Mediterranean diet. However, prior to embarking on making any formal recommendations to this end, further rigorous evaluation is needed to better elucidate the breadth and potential toxicological aspects of medicinal properties harboured by these plants. This would be vital to ensuring a more informed and safe delivery of preparations of these plants if they were to be considered as a form of dietary supplementation and where appropriate, how these might interact with more formally established therapies in relation to AD.

A Systematic Review and Meta-Analysis of Ginkgo biloba in Neuropsychiatric Disorders: From Ancient Tradition to Modern-Day Medicine

Ginkgo biloba (Gb) has demonstrated antioxidant and vasoactive properties as well as clinical benefits in several conditions such as ischemia, epilepsy, and peripheral nerve damage. Additionally, Gb is supposed to act as potential cognitive enhancer in dementia. So far, several trials have been conducted to investigate the potential effectiveness of Gb in neuropsychiatric conditions. However, the results of these studies remain controversial. We conducted a systematic review and a meta-analysis of three randomised controlled trials in patients with schizophrenia and eight randomised controlled trials in patients with dementia. Gb treatment reduced positive symptoms in patients with schizophrenia and improved cognitive function and activities of daily living in patients with dementia. No effect of Gb on negative symptoms in schizophrenic patients was found. The general lack of evidence prevents drawing conclusions regarding Gb effectiveness in other neuropsychiatric conditions (i.e., autism, depression, anxiety, attention-deficit hyperactivity disorder, and addiction). Our data support the use of Gb in patients with dementia and as an adjunctive therapy in schizophrenic patients.

Ginkgo biloba extract and long-term cognitive decline: a 20-year follow-up population-based study

Background

Numerous studies have looked at the potential benefits of various nootropic drugs such as Ginkgo biloba extract (EGb761®; Tanakan®) and piracetam (Nootropyl®) on age-related cognitive decline often leading to inconclusive results due to small sample sizes or insufficient follow-up duration. The present study assesses the association between intake of EGb761® and cognitive function of elderly adults over a 20-year period.

Methods and Findings

The data were gathered from the prospective community-based cohort study ‘Paquid’. Within the study sample of 3612 non-demented participants aged 65 and over at baseline, three groups were compared: 589 subjects reporting use of EGb761® at at least one of the ten assessment visits, 149 subjects reporting use of piracetam at one of the assessment visits and 2874 subjects not reporting use of either EGb761® or piracetam. Decline on MMSE, verbal fluency and visual memory over the 20-year follow-up was analysed with a multivariate mixed linear effects model. A significant difference in MMSE decline over the 20-year follow-up was observed in the EGb761® and piracetam treatment groups compared to the ‘neither treatment’ group. These effects were in opposite directions: the EGb761® group declined less rapidly than the ‘neither treatment’ group, whereas the piracetam group declined more rapidly (β = −0.6). Regarding verbal fluency and visual memory, no difference was observed between the EGb761® group and the ‘neither treatment’ group (respectively, β = 0.21 and β = −0.03), whereas the piracetam group declined more rapidly (respectively, β = −1.40 and β = −0.44). When comparing the EGb761® and piracetam groups directly, a different decline was observed for the three tests (respectively β = −1.07, β = −1.61 and β = −0.41).

Conclusion

Cognitive decline in a non-demented elderly population was lower in subjects who reported using EGb761® than in those who did not. This effect may be a specific medication effect of EGb761®, since it was not observed for another nootropic medication, piracetam.

Ginkgo biloba leaf extract improves the cognitive abilities of rats with D-galactose induced dementia

Standardized Ginkgo biloba leaf extract has been used in clinical trials for its beneficial effects on brain functions, particularly in dementia. Substantial experimental evidences indicated that Ginkgo biloba leaf extract (EGB) protected neuronal cells from a variety of insults. We investigated the effect of EGB on cognitive ability and protein kinase B (PKB) activity in hippocampal neuronal cells of dementia model rats. Rats received an intraperitoneal injection of D-galactose to induce dementia. Forty-eight Spraque-Dawley rats were randomly divided into six groups, including the control group, D-galactose group (Gal), low-dose EGB group (EGB-L), mid-dose EGB group (EGB-M), high-dose EGB group (EGB-H) and treatment group. The EGB-L, EGB-M and EGB-H groups were administered with EGB and D-galactose simultaneously. Y-maze, cresyl violet staining, TUNEL assays and immunohistochemistry staining were performed to detect learning and memory abilities, morphological changes in the hippocampus, neuronal apoptosis and the expressing level of phospho-PKB, respectively. Rats in the Gal group showed decreased abilities of learning and memory, and hippocampal pyramidal cell layer was damaged, while EGB administration improved learning and memory abilities. The Gal group exhibited many stained, condensed nuclei and micronuclei, either isolated or within the cytoplasm of cells (39.5±1.4). Apoptotic cells decreased in the groups of EGB-L (35.9±0.9), EGB-M (16.8±1.0) and EGB-H (10.1±0.8), and there were statistical significances compared with the Gal group. Immunoreactivity of phospho-PKB was localized diffusely throughout the cytosol of cells in all groups, while the immunoreactivity of the Gal group was weak. EGB significantly attenuated learning and memory impairment in a dose-dependent manner, while it could decrease the nmber of TUNEL-positive cells, and increase the activity of PKB. Our results demonstrated that EGB attenuated memory impairment and cell apoptosis in galactose-induced dementia model rats by activating PKB.

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.

[Self-medication in the elderly population of Campinas, São Paulo State, Brazil: prevalence and associated factors]

The aim of this study was to evaluate the prevalence and causative factors associated with self-medication in the elderly and identify the main drugs consumed without prescription. A cross-sectional population-based study with stratified clustered two-stage sampling was performed in Campinas, São Paulo, Brazil in 2008 and 2009. Of the 1,515 elderly studied, 80.4% reported using at least one drug during the three days preceding the survey. Of these, 91.1% reported the use of prescription drugs only and the remainder (8.9%) reported simultaneous use of prescribed and non prescribed drugs. After adjustment, a negative association between age ≥ 80 years, hypertension, chronic diseases, use of health services, dental consultations and adherence to a medical plan,and self-medication was found, whereas a positive association was found with per capita income. Dipyrone, acetylsalicylic acid, diclofenac, Ginkgo biloba, paracetamol and homeopathic medicines were among the most used non-prescribed drugs. Pharmaceutical assistance should be provided as a priority to the elderly, to avoid the misuse of medicines and ensure access to the correct drugs.

The influence of nutritional factors on the prognosis of multiple sclerosis

The effect of nutrition and dietary supplements on the course of multiple sclerosis (MS) is a topic of great interest to both patients and clinicians. In particular, vitamin D status has been shown to influence both the incidence and the course of MS. High vitamin D levels are probably protective against the development of MS, although the efficacy of vitamin D supplementation in slowing progression of MS remains to be established. The influence of polyunsaturated fatty acids (PUFAs) on the development and course of MS has also long been under investigation. Small clinical trials suggest a modest reduction in the severity and duration of relapses in patients with MS receiving PUFA supplements. Other nutritional factors have been evaluated for their effect on MS disease progression, including milk proteins, gluten, probiotics, antioxidants (uric acid, vitamins A, C and E, lipoic acid), polyphenols, Ginkgo biloba extracts and curcumin. However, further studies are needed to evaluate the effects of these dietary components on the relapse rate and progression of MS. This Review gives an overview of the literature on the nutritional factors most commonly implicated as having an effect on MS and discusses the biological rationale that is thought to underlie their influence.

Dementia

INTRODUCTION

Dementia is characterised by chronic, global, non-reversible deterioration in memory, executive function, and personality. Speech and motor function may also be impaired.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments on cognitive symptoms of dementia (Alzheimer's, Lewy body, or vascular)? What are the effects of treatments on behavioural and psychological symptoms of dementia (Alzheimer's, Lewy body, or vascular)? We searched: Medline, Embase, The Cochrane Library, and other important databases up to July 2011 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 49 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review, we present information relating to the effectiveness and safety of the following interventions: acetylcholinesterase inhibitors (donepezil, galantamine, rivastigmine), antidepressants (clomipramine, fluoxetine, imipramine, sertraline), antipsychotics (haloperidol, olanzapine, quetiapine, risperidone), aromatherapy, benzodiazepines (diazepam, lorazepam), cognitive behavioural therapy (CBT), cognitive stimulation, exercise, ginkgo biloba, memantine, mood stabilisers (carbamazepine, sodium valproate/valproic acid), music therapy, non-steroidal anti-inflammatory drugs (NSAIDs), omega 3 (fish oil), reminiscence therapy, and statins.

What is a food and what is a medicinal product in the European Union? Use of the benchmark dose (BMD) methodology to define a threshold for "pharmacological action"

The decision criterion for the demarcation between foods and medicinal products in the EU is the significant "pharmacological action". Based on six examples of substances with ambivalent status, the benchmark dose (BMD) method is evaluated to provide a threshold for pharmacological action. Using significant dose-response models from literature clinical trial data or epidemiology, the BMD values were 63mg/day for caffeine, 5g/day for alcohol, 6mg/day for lovastatin, 769mg/day for glucosamine sulfate, 151mg/day for Ginkgo biloba extract, and 0.4mg/day for melatonin. The examples for caffeine and alcohol validate the approach because intake above BMD clearly exhibits pharmacological action. Nevertheless, due to uncertainties in dose-response modelling as well as the need for additional uncertainty factors to consider differences in sensitivity within the human population, a "borderline range" on the dose-response curve remains. "Pharmacological action" has proven to be not very well suited as binary decision criterion between foods and medicinal product. The European legislator should rethink the definition of medicinal products, as the current situation based on complicated case-by-case decisions on pharmacological action leads to an unregulated market flooded with potentially illegal food supplements.

Ginkgo biloba leaf extract (EGb 761®) and its specific acylated flavonol constituents increase dopamine and acetylcholine levels in the rat medial prefrontal cortex: possible implications for the cognitive enhancing properties of EGb 761®

Experimental and clinical data suggest that the Ginkgo biloba standardized extract EGb 761® exerts beneficial effects in conditions which are associated with impaired cognitive function. However, the neurochemical correlates of these memory enhancing effects are not yet fully clarified. The aim of this study was to examine the effect of repeated oral administration of EGb 761® and some of its characteristic constituents on extracellular levels of dopamine (DA), noradrenaline (NA), serotonin (5-HT), acetylcholine (ACh) and the metabolites 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in the medial prefrontal cortex (mPFC) of awake rats by use of in vivo microdialysis technique. Subacute (14 days, once daily), but not acute, oral treatment with EGb 761® (100 and 300 mg/kg) or the flavonoid fraction, which represents about 24% of the whole extract caused a significant and dose-dependent increase in extracellular DA levels in the mPFC. Repeated administration of EGb 761® also caused a modest but significant increase in the NA levels, whereas the concentrations of 5-HT and those of the metabolites DOPAC, HVA and 5-HIAA were not affected. The same treatment regimen was used in a subsequent study with the aim of investigating the effects of two Ginkgo-specific acylated flavonols, 3-O-(2''-O-(6'''-O-(p-hydroxy-trans-cinnamoyl)-β-D-glucosyl)-α-L-rhamnosyl)quercetin (Q-ag) and 3-O-(2''-O-(6'''-O-(p-hydroxy-trans-cinnamoyl)-β-D-glucosyl)-α-L-rhamnosyl)kaempferol (K-ag). Both compounds together represent about 4.5% of the whole extract. Repeated oral treatment with Q-ag (10 mg/kg) for 14 days caused a significant increase in extracellular DA levels of 159% and extracellular acetylcholine (ACh) levels of 151% compared to controls. Similarly, administration of K-ag (10 mg/kg) induced a significant rise of DA levels to 142% and ACh levels to 165% of controls, whereas treatment with isorhamnetin, an O-methylated aglycon component of EGb 761® flavonol glycosides had no effect. None of the tested flavonoids had a significant effect on extracellular DOPAC and HVA levels. The present findings provide evidence that the subacute treatment with EGb 761® and its flavonol constituents increases DA and ACh release in the rat mPFC, and suggest that the two Ginkgo-specific acylated flavonol glycosides Q-ag and K-ag are active constituents contributing to these effects. As seen for isorhamnetin, the effect on neurotransmitter levels seems not to be a general effect of flavonols but rather to be a specific action of acylated flavonol glycosides which are present in EGb 761®. The direct involvement of these two flavonol derivatives in the increase of dopaminergic and cholinergic neurotransmission in the prefrontal cortex may be one of the underlying mechanisms behind the reported effects of EGb 761® on the improvement of cognitive function.

In vitro and ex vivo anticholinesterase activities of Erythrina velutina leaf extracts

CONTEXT

Erythrina velutina (EV) Willd (Fabaceae-Faboideae) is a medicinal tree that is commonly used in Brazil for the treatment of several central nervous system disorders.

OBJECTIVE

The anticholinesterase activity of EV is described in this work.

METHODS

Concentration-response curves (0-1.6 mg/mL) for EV leaf aqueous extract (AE) and alkaloid-rich extracts (AKEs) were performed in vitro. Cholinesterase inhibition was examined in mouse brains, as the cholinesterase source, and in pure acetylcholinesterase (AChE) or butyrylcholinesterase (BuChE). Mice were treated with AE or AKE (100, 200, and 400 mg/kg, p.o.) and their brains were used for the measurement of cholinesterase activity (CA) ex vivo.

RESULTS

CA was inhibited by AE (IC(50) = 0.57 [0.43-0.75] mg/mL) and AKE (IC(50) = 0.52 [0.39-0.70] mg/mL) in brain homogenates in a concentration-dependent manner. The ex vivo experiments indicated that AE (400 mg/kg, p < 0.05, 32.2 ± 3.9% of inhibition) and AKE (all doses: p < 0.05-p < 0.001, 29.6 ± 3.2% as the maximum inhibition) significantly inhibited CA in the central nervous system after oral administration. AE and AKE inhibited AChE and BuChE activities in a concentration-dependent manner (AE: IC(50AChE) = 0.56 [0.38-0.81] mg/mL, IC(50BuChE) = 2.95 [1.51-5.76] mg/mL, AKE: IC(50AChE) = 0.87 [0.60-12.5] mg/mL, IC(50BuChE) = 2.67 [0.87-8.11] mg/mL).

DISCUSSION AND CONCLUSIONS

These data indicated that AE and AKE crossed the blood-brain barrier to inhibit CA in the brain. AE and AKE also exhibited a dual inhibitory action on acetyl- and BuChE.

Effects of polyphenols on brain ageing and Alzheimer's disease: focus on mitochondria

The global trend of the phenomenon of population ageing has dramatic consequences on public health and the incidence of neurodegenerative diseases. Physiological changes that occur during normal ageing of the brain may exacerbate and initiate pathological processes that may lead to neurodegenerative disorders, especially Alzheimer's disease (AD). Hence, the risk of AD rises exponentially with age. While there is no cure currently available, sufficient intake of certain micronutrients and secondary plant metabolites may prevent disease onset. Polyphenols are highly abundant in the human diet, and several experimental and epidemiological evidences indicate that these secondary plant products have beneficial effects on AD risks. This study reviews current knowledge on the potential of polyphenols and selected polyphenol-rich diets on memory and cognition in human subjects, focusing on recent data showing in vivo efficacy of polyphenols in preventing neurodegenerative events during brain ageing and in dementia. Concentrations of polyphenols in animal brains following oral administration have been consistently reported to be very low, thus eliciting controversial discussion on their neuroprotective effects and potential mechanisms. Whether polyphenols exert any direct antioxidant effects in the brain or rather act by evoking alterations in regulatory systems of the brain or even the body periphery is still unclear. To understand the mechanisms behind the protective abilities of polyphenol-rich foods, an overall understanding of the biotransformation of polyphenols and identification of the various metabolites arising in the human body is also urgently needed.

Ginkgo biloba extract EGb 761® in dementia with neuropsychiatric features: a randomised, placebo-controlled trial to confirm the efficacy and safety of a daily dose of 240 mg

A multi-centre, double-blind, randomised, placebo-controlled, 24-week trial with 410 outpatients was conducted to demonstrate efficacy and safety of a 240 mg once-daily formulation of Ginkgo biloba extract EGb 761(®) in patients with mild to moderate dementia (Alzheimer's disease or vascular dementia) associated with neuropsychiatric symptoms. Patients scored 9 to 23 on the SKT cognitive battery, at least 6 on the Neuropsychiatric Inventory (NPI), with at least one of four key items rated at least 4. Primary outcomes were the changes from baseline to week 24 in the SKT and NPI total scores. The ADCS Clinical Global Impression of Change (ADCS-CGIC), Verbal Fluency Test, Activities of Daily Living International Scale (ADL-IS), DEMQOL-Proxy quality-of-life scale and 11-point box scales for tinnitus and dizziness were secondary outcome measures. Patients treated with EGb 761(®) (n = 200) improved by 2.2 ± 3.5 points (mean ± sd) on the SKT total score, whereas those receiving placebo (n = 202) changed only slightly by 0.3 ± 3.7 points. The NPI composite score improved by 4.6 ± 7.1 in the EGb 761(®)-treated group and by 2.1 ± 6.5 in the placebo group. Both drug-placebo comparisons were significant at p < 0.001. Patients treated with EGb 761(®) also showed a more favourable course in most of the secondary efficacy variables. In conclusion, treatment with EGb 761(®) at a once-daily dose of 240 mg was safe and resulted in a significant and clinically relevant improvement in cognition, psychopathology, functional measures and quality of life of patients and caregivers.

[Exercise and psychological well-being]

Research on the association between physical activity and mental health addresses the beneficial effects of physical activity on emotional and cognitive functioning. With regard to emotional functioning, most studies focus on the influence of physical activity on depressive symptoms or affective disorders. These studies show that the beneficial effects of aerobic exercise and pharmacotherapy on depressive symptoms seem to be comparable and discuss a variety of neurobiological mechanisms that improve symptoms. The positive effects of physical activity on anxious mood and anxiety disorders are also well documented. Desensitization to physiological changes, improved self-esteem, and self-efficacy seem to play an important part. However, aerobic exercise does not improve mental health in every case, as seen for instance in over-trained athletes. Research on the relationship between physical activity and cognitive functioning reveals that physical activity can prevent the age-related cognitive decline and can delay the onset of dementia. Physical activity has beneficial effects not only on adults but also on children's and adolescents' mental health and cognitive performance, particularly on their executive functions that are still developing throughout adolescence. Finally, physical activity also affects the endocrine stress-regulation system: trained people reveal stronger reactivity and quicker regeneration when faced with stressful events.

Specific memory effects of Ginkgo biloba extract EGb 761 in middle-aged healthy volunteers

INTRODUCTION

Recent reviews showed that Ginkgo biloba extract EGb 761(1) is effective to enhance performance in patients with cognitive impairment (e.g., dementia). The aim of this study was to investigate the effects of EGb 761 on memory and the specificity of such effects on distinct memory functions in middle-aged healthy volunteers.

METHODS

A total of 188 healthy subjects aged 45-56 years were randomised to receive EGb 761 (240 mg once daily) or placebo for 6 weeks. Outcome measures were the change in memory performance in a demanding standardised free recall paradigm (list of appointments) and a less demanding standardised recognition test (driving-route). Based on previous findings we predicted superiority of EGb 761 in recall testing. Specificity in effects was assessed by separating immediate vs. delayed and quantitative vs. qualitative free recall measures.

RESULTS

After 6 weeks, EGb 761-treated subjects improved significantly in quantity of recall, i.e., the number of correctly recalled appointments (drug-placebo differences: p=0.038 for immediate and p=0.008 for delayed recall). Effects on qualitative recall performance (ratio of false to correct items) were similar (drug-placebo differences: p=0.092 for immediate and p=0.010 for delayed recall). No superiority of Ginkgo was evident in another everyday memory test which asked for recognition of a driving route (drug-placebo differences: p>0.10). The incidence of adverse events was low and not significantly different between treatment groups.

DISCUSSION

EGb 761 (240 mg once daily) improves free recall of appointments in middle-aged healthy volunteers, which requires high demands on self-initiated retrieval of learned material. This function is known to be sensitive to normal aging, i.e., reduced in healthy middle-aged subjects. No effects are seen in a less demanding everyday memory task which does not tap this critical function. This ties in with previous studies which found specific patterns of benefit from EGb 761 in demanding cognitive tasks.

Natural substances and Alzheimer's disease: from preclinical studies to evidence based medicine

Over the last 10 years, the potential therapeutic effects of nutraceuticals to prevent or delay Alzheimer's disease were proposed. Among dietary antioxidants curcumin, Ginkgo biloba and carnitines were extensively studied for their neuroprotective effects. The rationale for this alternative therapeutic approach was based on several preclinical studies which suggested the neuroprotective effects for curcumin, Ginkgo biloba and acetyl-l-carnitine due to either a free radical scavenging activity or the inhibition of pro-inflammatory pathways or the potentiation of the cell stress response. However, although these are interesting premises, clinical studies were not able to demonstrate significant beneficial effects of curcumin, Ginkgo biloba and acetyl-l-carnitine in improving cognitive functions in Alzheimer's disease patients. The aim of this review is to summarize the main pharmacologic features of curcumin, Ginkgo biloba and carnitines as well as to underlie the main outcomes reached by clinical studies designed to demonstrate the efficacy of these natural substances in Alzheimer's disease patients. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

The facilitative effects of bilobalide, a unique constituent of Ginkgo biloba, on synaptic transmission and plasticity in hippocampal subfields

Bilobalide, a unique constituent of Ginkgo biloba, has been reported to potentiate population spikes in hippocampal CA1 pyramidal cells and to protect the brain against cell death. In this study, the effects of bilobalide on synaptic transmission and its plasticity in rat hippocampal subfields were electrophysiologically investigated. Bilobalide (50 μM) significantly potentiated the input-output relationship at Schaffer collateral (SC)-CA1 synapses but not at medial perforant path (MPP)-dentate gyrus (DG), lateral perforant path (LPP)-DG, or mossy fiber (MF)-CA3 synapses. Facilitative effects of bilobalide on synaptic plasticity were only observed at MPP-DG synapses, in which the induction of long-term depression was blocked in the presence of bilobalide. However, no effect on synaptic plasticity was observed at SC-CA1 synapses. These results suggest that bilobalide has differential effects on synaptic efficacy in each hippocampal subfield.

Isoform-selective activation of human constitutive androstane receptor by Ginkgo biloba extract: functional analysis of the SV23, SV24, and SV25 splice variants

Naturally occurring splice variants of human constitutive androstane receptor (hCAR) exist, including hCAR-SV23 (insertion of amino acids SPTV), hCAR-SV24 (APYLT), and hCAR-SV25 (SPTV and APYLT). An extract of Ginkgo biloba was reported to activate hCAR-SV24 and the wild type (hCAR-WT). However, it is not known whether it selectively affects hCAR splice variants, how it activates hCAR isoforms, and which chemical is responsible for the effects of the extract. Therefore, we evaluated the impact of G. biloba extract on the functionality of hCAR-SV23, hCAR-SV24, hCAR-SV25, and hCAR-WT and compared it with that of phenobarbital, di-(2-ethylhexyl)phthalate (DEHP), 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime (CITCO), and 1,4-bis-[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) in cell-based reporter gene assays. Among the hCAR splice variants investigated, only hCAR-SV23 was activated by G. biloba extract, and this required cotransfection of a retinoid X receptor α (RXRα) expression plasmid. The extract activated hCAR-SV23 to a lesser extent than hCAR-WT, but ginkgolide A, ginkgolide B, ginkgolide C, ginkgolide J, and bilobalide were not responsible for the effects of the extract. CITCO activated hCAR-SV23, hCAR-SV24, and hCAR-WT. By comparison, phenobarbital activated hCAR-WT, whereas DEHP activated hCAR-SV23, hCAR-SV24 (with exogenous RXRα supplementation), and hCAR-WT. TCPOBOP did not affect the activity of any of the isoforms. G. biloba extract and phenobarbital did not bind or recruit coactivators to the ligand-binding domains of hCAR-WT and hCAR-SV23, whereas positive results were obtained with the controls (CITCO for hCAR-WT and DEHP for hCAR-SV23). In conclusion, G. biloba extract activates hCAR in an isoform-selective manner, and hCAR-SV23, hCAR-SV24, and hCAR-WT have overlapping, but distinct, sets of ligands.

Examining brain-cognition effects of ginkgo biloba extract: brain activation in the left temporal and left prefrontal cortex in an object working memory task

Ginkgo Biloba extract (GBE) is increasingly used to alleviate symptoms of age related cognitive impairment, with preclinical evidence pointing to a pro-cholinergic effect. While a number of behavioral studies have reported improvements to working memory (WM) associated with GBE, electrophysiological studies of GBE have typically been limited to recordings during a resting state. The current study investigated the chronic effects of GBE on steady state visually evoked potential (SSVEP) topography in nineteen healthy middle-aged (50-61 year old) male participants whilst completing an object WM task. A randomized double-blind crossover design was employed in which participants were allocated to receive 14 days GBE and 14 days placebo in random order. For both groups, SSVEP was recorded from 64 scalp electrode sites during the completion of an object WM task both pre- and 14 days post-treatment. GBE was found to improve behavioural performance on the WM task. GBE was also found to increase the SSVEP amplitude at occipital and frontal sites and increase SSVEP latency at left temporal and left frontal sites during the hold component of the WM task. These SSVEP changes associated with GBE may represent more efficient processing during WM task completion.

Prescribing patterns in dementia: a multicentre observational study in a German network of CAM physicians

BACKGROUND

Dementia is a major and increasing health problem worldwide. This study aims to investigate dementia treatment strategies among physicians specialised in complementary and alternative medicine (CAM) by analysing prescribing patterns and comparing them to current treatment guidelines in Germany.

METHODS

Twenty-two primary care physicians in Germany participated in this prospective, multicentre observational study. Prescriptions and diagnoses were reported for each consecutive patient. Data were included if patients had at least one diagnosis of dementia according to the 10th revision of the International Classification of Diseases during the study period. Multiple logistic regression was used to determine factors associated with a prescription of any anti-dementia drug including Ginkgo biloba.

RESULTS

During the 5-year study period (2004-2008), 577 patients with dementia were included (median age: 81 years (IQR: 74-87); 69% female). Dementia was classified as unspecified dementia (57.2%), vascular dementia (25.1%), dementia in Alzheimer's disease (10.4%), and dementia in Parkinson's disease (7.3%). The prevalence of anti-dementia drugs was 25.6%. The phytopharmaceutical Ginkgo biloba was the most frequently prescribed anti-dementia drug overall (67.6% of all) followed by cholinesterase inhibitors (17.6%). The adjusted odds ratio (AOR) for receiving any anti-dementia drug was greater than 1 for neurologists (AOR = 2.34; CI: 1.59-3.47), the diagnosis of Alzheimer's disease (AOR = 3.28; CI: 1.96-5.50), neuroleptic therapy (AOR = 1.87; CI: 1.22-2.88), co-morbidities hypertension (AOR = 2.03; CI: 1.41-2.90), and heart failure (AOR = 4.85; CI: 3.42-6.88). The chance for a prescription of any anti-dementia drug decreased with the diagnosis of vascular dementia (AOR = 0.64; CI: 0.43-0.95) and diabetes mellitus (AOR = 0.55; CI: 0.36-0.86). The prescription of Ginkgo biloba was associated with sex (female: AOR = 0.41; CI: 0.19-0.89), patient age (AOR = 1.06; CI: 1.02-1.10), treatment by a neurologist (AOR = 0.09; CI: 0.03-0.23), and the diagnosis of Alzheimer's disease (AOR = 0.07; CI: 0.04-0.16).

CONCLUSIONS

This study provides a comprehensive analysis of everyday practice for treatment of dementia in primary care in physicians with a focus on CAM. The prescribing frequency for anti-dementia drugs is equivalent to those found in other German studies, while the administration of Ginkgo biloba is significantly higher.

An update on the neuropsychiatric symptoms of dementia

SUMMARY Neuropsychiatric symptoms in dementia, such as apathy, agitation, aggression, depression and psychosis are common serious problems that impair quality of life for patients and their caregivers. This article provides a focused update on recent studies that have examined the assessment and treatment of these problems and helps provide clinicians with useful tips for their management. In general, it is becoming increasingly evident that current therapies are only variably and modestly effective and carry significant risks associated with their use. A better understanding of their causes and more sophisticated assessment tools will hopefully pave the way for future studies and safer, more effective therapies.

Ginkgo biloba in Alzheimer's disease: a systematic review

This systematic review determines the benefit of treatment with Ginkgo biloba (Ginkgo) in Alzheimer's disease (AD) concerning patient-relevant outcomes. Bibliographic databases, clinical trial and study result registries were searched for randomized controlled trials (RCTs) in patients with AD (follow-up ≥16 weeks) comparing Ginkgo to placebo or a different treatment option. Manufacturers were asked to provide unpublished data. If feasible, data were pooled by meta-analysis. Six studies were eligible; overall, high heterogeneity was shown for most outcomes, except safety aspects. Among studies administering high-dose Ginkgo (240 mg), all studies favour treatment though effects remain heterogeneous. In this subgroup, a benefit of Ginkgo exists for activities of daily living. Cognition and accompanying psychopathological symptoms show an indication of a benefit. A harm of Ginkgo is not evident. An estimation of the effect size was not possible for any outcome. Further evidence is needed which focuses especially on subgroups of AD patients.

Investigational drugs for the treatment of AD: what can we learn from negative trials?

Given the level of interest and activity in the race to find a treatment for Alzheimer's disease, it is expected that a reasonably safe and effective drug will be identified within the next decade. It may be worthwhile to pause periodically during the course of this race to take stock of what we have learned. Over the past few years, a number of trials have been conducted with promising new compounds (including some with novel mechanisms of action) that failed to meet primary endpoints and so were discontinued from clinical development. This article reviews a set of molecules with a range of mechanisms that have been trialed but with negative results. This article also examines the reasons for the negative findings and summarizes some of what we have learned from these experiences.

Alleviating neuropsychiatric symptoms in dementia: the effects of Ginkgo biloba extract EGb 761. Findings from a randomized controlled trial

PURPOSE

To examine the effects of Ginkgo biloba extract EGb 761(®) on neuropsychiatric symptoms of dementia.

PATIENTS AND METHODS

Randomized, controlled, double-blind, multicenter clinical trial involving 410 outpatients with mild to moderate dementia (Alzheimer's disease with or without cerebrovascular disease, vascular dementia), scoring at least 5 on the Neuropsychiatric Inventory (NPI), with at least one item score of 3 or more. Total scores on the SKT cognitive test battery (Erzigkeit's short syndrome test) were between 9 and 23. After random allocation, the patients took 240 mg of EGb 761(®) or placebo once daily for a period of 24 weeks. Changes from baseline to week 24 in the NPI composite and in the SKT total score were the primary outcomes. The NPI distress score was chosen as a secondary outcome measure to evaluate caregivers' distress.

RESULTS

The NPI composite score improved by -3.2 (95% confidence interval -4.0 to -2.3) in patients taking EGb 761(®) (n = 202), but did not change (-0.9; 0.9) in those receiving placebo (n = 202), which resulted in a statistically significant difference in favor of EGb 761(®) (P < 0.001). Treatment with EGb 761(®) was significantly superior to placebo for the symptoms apathy/indifference, sleep/night-time behavior, irritability/lability, depression/dysphoria, and aberrant motor behavior. Caregivers' distress evaluation revealed similar baseline pattern and improvements.

CONCLUSION

Treatment with EGb 761(®), at a once-daily dose of 240 mg, was safe, effectively alleviated behavioral and neuropsychiatric symptoms in patients with mild to moderate dementia, and improved the wellbeing of their caregivers.

Human pregnane X receptor agonism by Ginkgo biloba extract: assessment of the role of individual ginkgolides

Ginkgo biloba extract activates pregnane X receptor (PXR), but how this occurs is not known. Therefore, we investigated the mechanism of PXR activation by the extract and the role of five individual terpene trilactones in the activation. In a cell-based reporter gene assay, G. biloba extract activated human PXR (hPXR), and at a concentration present in the extract, ginkgolide A, but not ginkgolide B, ginkgolide C, ginkgolide J, or bilobalide was partially responsible for the increase in hPXR activity of the extract. Likewise, in cultured human hepatocytes, only ginkgolide A contributed to the increase in hPXR target gene expression (CYP3A4 mRNA and CYP3A-mediated testosterone 6β-hydroxylation). The extract, but none of the terpene trilactones, bound to hPXR ligand-binding domain, as analyzed by a time-resolved fluorescence resonance energy transfer competitive binding assay. Only the extract and ginkgolide A recruited steroid receptor coactivator-1, as determined by a mammalian two-hybrid assay. Compared with hPXR, rat PXR (rPXR) was activated to a lesser extent by G. biloba extract. Similar to hPXR, only ginkgolide A contributed to rPXR activation by the extract. In contrast to the effect of G. biloba extract on PXR function, it did not affect hPXR expression. Overall, the main conclusions are that G. biloba extract is an hPXR agonist, and among the five terpene trilactones investigated, only ginkgolide A contributes to the actions of the extract. Our findings provide insights into the biological and chemical mechanisms of hPXR activation by G. biloba extract.

Huperzine A for vascular dementia

BACKGROUND

Huperzine A, a form of herbal medicine, has been considered as an alternative treatment for vascular dementia (VaD) in China.

OBJECTIVES

To assess the efficacy and safety of Huperzine A in patients with vascular dementia.

SEARCH STRATEGY

The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (CDCIG) was searched on 7 July 2008 using the terms: huperzi* OR ayapin OR scoparon*. The CDCIG Specialized Register contains records from all major health care databases (The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS) as well as from many trials databases and grey literature sources. The review authors searched the following databases in August 2008 using the terms 'Huperzine A', 'Shishanjianjia', 'Haboyin' and 'Shuangyiping': The Chinese Biomedical Database (CBM) (1977 to August 2008); Chinese Science and Technique Journals Database (VIP) (1989 to August 2008); China National Knowledge Infrastructure (CNKI) (1979 to August 2008); The Chinese Clinical Trials Register (ChiCTR, August 2008); Google (August 2008). In addition, the review authors searched reference lists, relevant clinical trials and contacted researchers in an effort to identify further published and unpublished studies.

SELECTION CRITERIA

Randomized controlled trials comparing Huperzine A with placebo in patients with vascular dementia were considered eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial quality, and extracted data.

MAIN RESULTS

Only one small trial, involving 14 participants, was included. No significant beneficial effect of Huperzine A on the improvement of cognitive function measured by MMSE for VaD (WMD 2.40; 95% CI -4.78 to 9.58) was observed. No death from all causes at the end of treatment were reported. At present, other outcome measures were not available in any of the trials. Although no statistically significant differences were found between the Huperzine A-treated and control groups, the confidence intervals for the treatment effect estimates were wide and included both clinically significant benefits and clinically significant harms.

AUTHORS' CONCLUSIONS

There is no [convincing] evidence that Huperzine A is of value in vascular dementia based on one small trial. It deserves further research.