Table 2.
Quality assessment and inclusion and exclusion criteria of each included systematic review.
| References | Quality assessment | Quality of randomized controlled trials | Inclusion criteria | Exclusion criteria |
|---|---|---|---|---|
| Yang et al., 2014 | Jadad score | Good | All published, double-blinded, randomized, placebo-controlled trials examining efficacy of natural medicine sinpatients with AD (Alzheimer's disease) were included. Diagnostic criteria included Diagnostic and Statistical Manual of Mental Disorders (DSM), National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA). | N.R: |
| Weinmann et al., 2010 | Modified cochrane collaboration | Good | We selected controlled clinical trials, with or without randomization, assessing the effects of treating people with a diagnosis of AD, vascular or mixed dementia according to internationally valid diagnostic criteria, with a standardized Ginkgo biloba extracts (GBEs). | (1) Studies witha majority of people with specific types of non-vascularand non-Alzheimer's dementia, such as Lewy-bodydementia or dementia due to Parkinson's disease; (2) Apublication language other than English, German, French, Italian or Spanish. |
| Tan et al., 2015 | The cochrane collaboration | Good | (1) Double-blind, parallel-group, placebo-controlled, with random assignment to a standardized Ginkgo biloba extract EGb 761; (2) Inclusion of patients who have a diagnosis of AD, vascular dementia (VD), or mixed dementia according to internationally validdiagnostic criteria for the dementia diagnosis, including the International Classification of Diseases (ICD), the Diagnostic and Statistical Manual of MentalDisorders (DSM), the NINCDS-ADRDA, or the National Institutefor Neurological Disorders and Stroke and AssociationInternationale pour la Recherche et l'Enseignement enNeurosciences (NINDS-AIREN) criteria; inclusion of patients suffering from age-associated memoryimpairment according to the diagnostic criteria proposed by Crook et al. (1990). Inclusion of patientssuffering from Mild Cognitive Impairment (MCI) according to international consensus criteria proposed by Winblad et al. (2004); (3) Inclusion of treatments which last 22–26 weeks, contain a number of participants of more than 10 pergroup, and at least one measure reflecting the following: cognition, function, behavior or global assessmentof change. | Studies with fatal flaws in study designerdata analysis were excluded, as were trials whose datawere not readily available. |
| Gauthier and Schlaefke, 2014 | Jadad score | Good | Trials were eligible for inclusion if they were placebo-controlled, randomized, double-blind clinical trials of atleast 20 weeks induration, assessing the effects of an oral dosage form of EGb 761 in patients with a diagnosis of AD, VaD, or mixed dementia (i.e., with features of both AD andcerebrovascular disease), if the diagnosis was established inaccordance with internationally accepted diagnostic criteria DSM, Third Revised or Fourth Edition (DSM-III-R, DSM-IV),International Classification of Diseases (ICD)-10, National Institute of Neurological and Communicative Disorders and Stroke, Alzheimer's Diseaseand Related Disorders Association (NINCDS-ADRDA), or the NINDS-AIREN, 19andif outcome measures were defined for at least two of the three typical domains of assessment in dementia, i.e., cognition, activities of daily living (ADL), and clinical global judgment. | Trials including mostly patients with other diagnoses, suchas aging-associated memory impairment or mild cognitiveimpairment, and trials using EGb 761 as add-on treatmentto cholinesterase inhibitors, were excluded. |
| Yang et al., 2011 | The cochrane collaboration (RevMan 4.2 software) | Variable | (1) Randomized placebo-controlled clinicaltrials, blind or open; (2) Over all patients: a clinicaldiagnosis of mild to moderate AD, age ≥50 years old, male and female; met the diagnostic criteria for dementia according to the American Psychiatric Association's“DSM” Fourth revised edition, mini-mental state examination(MMSE), score ≤ 26 points, mild and moderate ADpatients; (3) Outcome assessment: outcomemeasurement indicators included before and afterassessment of MMSE, ADL scale, Hasegawa Dementia Scale, Clinical Global Impression, Wechsler memory quotient scores, as well as treatmentefficiency, the number of cases and other adverse events; (4) Patients who were followed up for at least 8 weeks;the number of cases was at least 10 cases.Thetreatment group received GBEs, and thecontrol group received placebo. | (1) Original documents were not located in thecontrol group. (2) No rigorous experimental designliterature. (3) Repeated published literature. (4) Reviewof the literature. (5) Rawdata did not provide adequatedocumentation. (6) Did not contain full text of the originaldocument. |
| Wang et al., 2010 | The cochrane collaboration | Good | (1) The study needed to be randomized, placebo-controlled, double-blind. (2) Patients needed to be diagnosed with dementia by prospective criteria. (3) The use of standardized GBEs in any stated dose was required(24% or 25% ginkgoflavone glycosides and 6% terpenoids). GBEs could be given by any route of administration. (4) At least 1 outcome measure needed to be an objectiveassessment of cognitive function. (5) Trial durations of treatment needed to be 24 ± 2 weeks ordata of assessments at 24 ± 2 weeks were available. | Studies needed to clearly state their exclusion criteria, i.e., those studies that had not stated exclusions for depression, other neurological disease, and taking central nervous system active medications were excluded. |
| Jiang et al., 2013 | The cochrane collaboration | Good | (1) Randomized controlled trial. (2) Subjects diagnosed with AD, VD, mixed dementia using widely accepted critia. (3) Treatment group used GBEs and control group used placebo for at least 22 weeks. (4) Outcome assessed using widely accepted measures of cognitive and social function. | Studies were excluded if: (a) they were animals studies; (b) they were reviews, conference presentations, or unpublished reports; (c) they were duplicated reports; (d) other cognitive boosting medications were used as adjunctive treatments; (e) there was no placebo control; or (f) there was no control group. |
| Janssen et al., 2010 | Jadad score | Variable | *Randomized controlled design. *Follow-up period 16 weeks, to be able to assess along-term effect. *Investigation of patients with mild, moderately severe and severe AD.Diagnosis had to be confirmedeither by the criteria of the European Medicines Agency or by commonlyaccepted ones such as ICD-9, ICD-10, DSM-II-R, DSM-IV, or NINCDS-ADRDA. *Comparison of Ginkgo with placebo or other medicinal or non-medicinal interventions. *Evaluation of at least one predefined patient-relevantoutcome.(In this context, the term “patient-relevant” refers to how a patient feels, functions or survives.) The following outcomes were considered: activitiesof daily living, cognitive functioning, psychopathology, quality of life and safety aspects. *Language of publication: English, Dutch, French, German, Portuguese and Spanish. *Availability of a full-text document (e.g., journalarticle or clinical study report). No restrictions applied for the date of publication. | N.R: |
| Hu et al., 2013 | Jadad score | Poor | (1) Randomized controlled trialsand/or semirandomized controlled trials, regardless of whether with blind method or not andlanguageis not restricted. (2) Satisfy withdiagnosisstandard of vascular dementia, regardless ofgender, age, country. (3) Basic treatment+GBEs orwith the basic treatment +otherinterventions(a singlemedicine) | N.R: |
| Yang et al., 2016 | The cochrane collaboration | Good | (1) Study design. Randomized control trials with at least one group involving GBEs for the treatment of AD or MCI were eligible to this review. (2) Participants. Participants diagnosed with any one of the following criteria as AD were included, regardless of severity and disease course: (a) The Diagnostic and Statistical Manual of Mental Disorder (DSM) III, III-R or IV; (b) The International Classification of Disease (ICD) (9th or 10th edition); (c) The National Institute of Neurological and Communicative Disorder and Stroke-Alzheimer's disease and Related Disorder Association (NINCDS/ADRDA). Participants diagnosed with any one of the following criteria as MCI were also included: (a) The Diagnostic and Statistical Manual of Mental Disorder (DSM) III, III-R or IV; (b) The International Classification of Disease (ICD) version 9 or 10; (c) Petersen criteria; (d) European Consortium on AD. The key differences of diagnostic criteria between AD and MCI were as follows: (1) AD can be diagnosed only if at least two domains (including memory) demonstrating cognitive impairment, while MCI can be diagnosed if there is impairment in memory; (2) AD can be diagnosed only if cognitive impairment is so severe that the ability to perform ADLs is interfered, while for MCI, there is just a slight cognitive decline and functional disturbance. (3) Interventions. Any forms of GBEs, were included. (4) Control. The control included no treatment, placebo, and conventional medications such as memantine, donepezil, galantamine and rivastigmine. Co-intervention if applied in all arms was also included. (5) Outcome measures. The primary outcomes included cognitive function and quality of life. The secondary outcomes included safety, ADL, and global clinical assessment. | (1) Study design. We excluded quasi-randomized trials. (2) Participants. We excluded trials involving participants with other types of dementia. |
N.R, not reported; AD, Alzheimer's diseas; ADL, Activities of daily living; DSM, Diagnostic and Statistical Manual of Mental Disorders; EGb 761, Extract Ginkgo biloba number 761; GBEs, Ginkgo biloba extracts; ICD, International Classification of Disease; MCI, Mild Cognitive Impairment; NINCDS–ADRDA, National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association; NINDS-AIREN, National Institutefor Neurological Disorders and Stroke and AssociationInternationale pour la Recherche et l'Enseignement enNeurosciences; RCT, Randomized Controlled Trials; VD, Vascular dementia.