Key messages
• For people who are worried about their thinking or memory, it is uncertain whether ginkgo is better than placebo (dummy treatment) for improving their overall condition at six months.
• For people with multiple sclerosis and problems with thinking or memory, ginkgo is probably not better than placebo for improving thinking at three months.
• For people diagnosed with mild cognitive impairment but not dementia, ginkgo is probably not better than placebo for improving their overall condition, thinking, or the skills needed to complete everyday tasks at six months.
• For people diagnosed with dementia, ginkgo may be better than placebo for improving their overall condition, overall thinking, and the skills needed to complete everyday tasks at six months. However, individual studies had very different estimates about the effects of ginkgo, making it difficult to form strong conclusions.
• Studies comparing ginkgo to placebo for mild cognitive impairment or dementia found that there is probably no increased risk of harm with ginkgo.
What are cognitive impairment and dementia?
Cognitive impairment is a pattern of problems with thinking, learning, remembering, or making decisions. It may also include changes in mood, behavior, or motivation. Dementia is an umbrella term for serious cognitive impairment that interferes with daily life and usual activities. Dementia risk increases with age, and the most common type of dementia diagnosed in older adults is Alzheimer's disease.
How are cognitive impairment and dementia treated?
No available treatments have been proven to stop or slow the progression of cognitive impairment or dementia. Medicines such as cholinesterase inhibitors may improve symptoms, and nonmedical therapies may also be helpful.
What did we want to find out?
We wanted to find out whether medicine based on the plant Ginkgo biloba (ginkgo) could help treat cognitive impairment or dementia, particularly whether it might help with thinking skills and the skills needed to complete everyday tasks. We also wanted to know whether ginkgo could help people who were worried about their thinking, or had problems with thinking that were related to multiple sclerosis.
What did we do?
We searched for studies testing ginkgo for people with thinking problems or diagnoses of mild cognitive impairment or dementia. People had to be treated for at least three months. We summarized the results of these studies separately for different types of thinking problems or diagnoses. We rated our confidence in the evidence based on factors such as how well the studies were carried out, how big the studies were, and whether different studies had similar or different results.
What did we find?
We found 82 studies including 10,613 people who were worried about problems with thinking, had problems with thinking associated with multiple sclerosis, or had diagnoses of mild cognitive impairment or dementia. Studies compared ginkgo to placebo (dummy treatment) or to other medicines, or they added ginkgo to other treatments. More than half the studies were conducted in China.
Main results
For people who are worried about their memory and thinking, it is uncertain whether ginkgo is better than placebo for improving their overall condition at six months. One study found no difference in harms between ginkgo and placebo at six months. However, another study lasting only three months found there may be more overall harms with ginkgo.
For people with cognitive problems associated with multiple sclerosis, treatment with ginkgo instead of placebo for three months probably makes little or no difference to thinking skills. No studies reported the total number of people experiencing harms. Two people in one study experienced serious harms that were probably unrelated to ginkgo.
For people diagnosed with mild cognitive impairment, treatment with ginkgo instead of placebo for six months probably makes little or no difference to their overall condition, thinking skills, or the skills needed to carry out everyday activities. There may be little or no difference between ginkgo and placebo in the risk of any harms up to 12 months, and there is little to no difference in the risk of serious harms.
For people diagnosed with dementia, treatment with ginkgo instead of a placebo for six months may lead to some improvements in their overall condition, thinking skills, and the skills needed to carry out everyday activities. There is probably little or no difference between ginkgo and placebo in the risk of any harms at up to 12 months, and there may be little to no difference in the risk of serious harms.
What are the limitations of the evidence?
Many studies had problems with their methods, and there were sometimes inconsistent findings between studies, which makes us less certain about the results. Few studies tested ginkgo for dementia beyond six months, so the potential benefits and harms of longer-term use for dementia are unknown.
How up to date is this evidence?
The evidence is current to November 2024.
Vollständige Zusammenfassung lesen
Dementia is a neurocognitive disorder that interferes with cognition and independent functioning. Common dementia subtypes include Alzheimer's disease, vascular dementia, and mixed type. Mild cognitive impairment (MCI) is a risk factor for dementia, and subjective cognitive complaints may be the earliest manifestation. Although cholinesterase inhibitors may help reduce some cognitive and behavioral symptoms, there is no established treatment that cures or slows dementia progression. Ginkgo biloba (ginkgo) is a popular herbal preparation that is used to improve brain and circulatory health, and neuroprotective effects are biologically plausible.
Zielsetzungen
To assess the benefits and harms of Ginkgo biloba for the treatment of people with cognitive impairment or dementia.
Suchstrategie
We searched the Cochrane Dementia and Cognitive Improvement Group's register, MEDLINE, Embase, four other databases, and two trials registries on 8 December 2022. The search was updated in MEDLINE, Embase, CENTRAL, and the trials registers on 18 November 2024.
Auswahlkriterien
We included randomized controlled trials (RCTs) comparing ginkgo with placebo, usual treatment, or other treatments for cognitive problems in people with cognitive complaints or diagnoses of MCI or dementia.
Datensammlung und ‐analyse
Two review authors independently selected trials, extracted data, and assessed studies for risk of bias. Key outcomes were global clinical status, global cognitive function, activities of daily living (ADLs), adverse events (AEs), and serious adverse events (SAEs) at six months. When clinically appropriate, we pooled data using a random-effects model and expressed treatment effects as mean differences (MDs), standardized mean differences (SMDs), or risk ratios (RRs), each with its 95% confidence interval (CI). We used GRADE methods to assess the certainty of the evidence for each estimate.
Hauptergebnisse
We included 82 studies with 10,613 participants; 72 studies with 9783 participants provided extractable data. Four studies were at low risk of bias in all domains. Below we present data for the comparison of ginkgo versus placebo in people with different clinical conditions.
Subjective cognitive impairment
Three studies (597 participants) compared ginkgo with placebo for people with subjective cognitive complaints. Based on one study that lasted six months, it is uncertain whether ginkgo has any effect on global clinical status measured on a five-point Likert scale (MD 0.00, 95% CI −0.33 to 0.33; P = 1.00; 1 study, 197 participants; very low-certainty evidence). There were no data on cognition or ADLs. One study reported no difference in minor side effects between treatment groups and did not mention SAEs. A larger study lasting three months found that the risk of AEs may be higher with ginkgo versus placebo. It provided very uncertain evidence on the risk of SAEs.
Multiple sclerosis and cognitive impairment
Two studies (164 participants) tested ginkgo versus placebo over three months in people with multiple sclerosis and cognitive problems. Ginkgo probably has little or no effect on cognition measured on the Perceived Deficits Questionnaire (MD −0.09, 95% CI −0.41 to 0.22; P = 0.55, I² = 0%; 2 studies, 152 participants; moderate-certainty evidence). There were no data on global clinical status or ADLs. The studies suggested no important difference in numbers of AEs between groups, and there was no indication of SAEs due to ginkgo.
Mild cognitive impairment
Twelve studies (1913 participants) tested ginkgo against placebo in people with MCI. At six months, moderate-certainty evidence suggests that ginkgo probably has little to no effect on global clinical status measured on the Clinical Dementia Rating Scale (MD −0.03, 95% CI −0.06 to 0.01; 3 studies, 631 participants; I² = 0%), cognition measured on the Alzheimer's Disease Assessment Scale – cognition (MD −0.07, 95% CI −0.67 to 0.51; I² = 0%; 2 studies, 508 participants), and ADLs measured on the Instrumental ADL scale (MD −0.05, 95% CI −0.29 to 0.19; 1 study, 350 participants). There may be little or no difference between ginkgo and placebo at up to 12 months in the risk of AEs (RR 0.98, 95% CI 0.77 to 1.24; I² = 58%; 7 studies, 991 participants, 379 events; low-certainty evidence), and there is little or no difference in the risk of SAEs (RR 0.95, 95% CI 0.82 to 1.09; I² = 0%; 3 studies, 714 participants, 327 events; high-certainty evidence).
Dementia
Thirteen studies (3288 participants) compared ginkgo with placebo for dementia. At six months, low-certainty evidence suggests that people taking ginkgo may have better global clinical status on a six-point Likert scale (lower is better; MD −0.06, 95% CI −1.00 to −0.20; I² = 88%; 5 studies, 1359 participants), better cognition measured by decreases on a short cognitive performance test (Syndrom-Kurztest; MD −1.86, 95% CI −3.48 to −0.24; I² = 96%; 9 studies, 2801 participants), and slightly better ADLs measured on the ADL International Scale (MD −0.19, 95% CI −0.35 to −0.03; I² = 91%; 8 studies, 2571 participants). There is probably little or no difference between ginkgo and placebo in the risk of AEs at up to 12 months (RR 0.95, 95% CI 0.90 to 1.00; I² = 0%; 9 studies, 2746 participants, 1480 events; moderate-certainty evidence). There may be little or no difference in risk of SAEs at six months (RR 0.88, 95% CI 0.58 to 1.33; I² = 0%; 6 studies, 2463 participants, 89 events; low-certainty evidence).
Schlussfolgerungen der Autoren
In people with cognitive complaints, we are unsure whether ginkgo improves global clinical status at six months, and it may be associated with an increased risk of AEs at three months. Ginkgo probably has no benefit at three months for cognition in multiple sclerosis; numeric data on AEs were unavailable, but studies did not suggest concerns. In people with MCI, ginkgo probably has little or no effect at six months on global status, cognition, or ADLS. There may be little or no difference in AEs, and there is little or no difference in SAEs, at up to 12 months. In people with dementia, there may be small to moderate benefits at six months for global status, cognition, and ADLs. There is probably little or no difference in AEs at up to 12 months, and there may be no difference in SAEs.
