The largest clinical trials ever conducted on ginkgo biloba for dementia found that it does not prevent the disease. The GEM study, which followed 3,069 adults aged 75 and older across four U.S. clinical sites for a median of six years, concluded that 240 mg per day of ginkgo biloba was ineffective in reducing dementia development. The GuidAge study in France reached the same conclusion after tracking roughly 2,854 participants aged 70 and older for five years.
Between these two trials alone, nearly 6,000 people took ginkgo or placebo, and neither study found a statistically significant difference in who developed dementia. For anyone considering ginkgo as a preventive measure, the evidence from the highest-quality research is clear. The picture gets more complicated when you shift from prevention to treatment. For people who already have dementia, some clinical trials have found modest cognitive benefits from a specific ginkgo extract called EGb 761, particularly at doses of 240 mg per day. But the Cochrane review, which examined 36 clinical trials, called the overall evidence “inconsistent and unreliable.” This article breaks down what each major study actually found, where the limited positive results come from, what the most recent research from 2024 and 2025 adds, and what all of this means for families trying to make practical decisions about dementia care.
Table of Contents
- What Did the Largest Ginkgo Biloba Dementia Prevention Trials Actually Find?
- Does Ginkgo Biloba Help People Who Already Have Dementia?
- The 240 mg EGb 761 Treatment Trials and Who They Helped
- How Does Ginkgo Compare to Approved Dementia Medications?
- What Do the Most Recent Studies From 2024 and 2025 Say?
- Safety Concerns and Drug Interactions Worth Knowing
- Where Ginkgo Research Is Heading
- Conclusion
- Frequently Asked Questions
What Did the Largest Ginkgo Biloba Dementia Prevention Trials Actually Find?
The GEM study, published by DeKosky and colleagues in JAMA in 2008, remains the gold standard. Researchers enrolled 3,069 participants aged 75 and older and randomly assigned them to receive either 120 mg of EGb 761 twice daily or a placebo. After a median follow-up of approximately six years, 523 participants had developed dementia. Of those, 277 were in the ginkgo group and 246 were in the placebo group. If anything, the numbers trended slightly in the wrong direction for ginkgo, though the difference was not statistically significant. The study was large enough and long enough that a meaningful protective effect would have shown up. It did not. The GuidAge study, published in The Lancet Neurology in 2012, tested the same dose in a French population.
Vellas and colleagues followed roughly 2,854 participants aged 70 and older who had spontaneous memory complaints, the kind of people you might expect to benefit most from a preventive intervention. After a median of five years, 61 ginkgo participants developed probable Alzheimer’s disease compared to 73 in the placebo group. That difference sounds encouraging at first glance, but it was not statistically significant. The trial could not conclude that ginkgo reduced the risk of progression to Alzheimer’s. What makes these two studies so important is their scale and rigor. Smaller trials with 50 or 100 participants can produce all sorts of results that do not hold up. When you test the same supplement in thousands of people over many years and see no benefit twice, that tells you something reliable. The prevention question, for practical purposes, has been answered.
Does Ginkgo Biloba Help People Who Already Have Dementia?
This is where the research gets genuinely mixed, and where honest disagreement among scientists still exists. The Cochrane review looked at 36 clinical trials involving thousands of patients who already had dementia or cognitive impairment. Only one of those 36 trials showed a significant benefit. The review’s conclusion was blunt: the evidence that ginkgo biloba provides “predictable and clinically significant benefit” for people with dementia is “inconsistent and unreliable.” For a supplement that has been studied this extensively, that is a damning summary. However, a more focused systematic review published in BMC Geriatrics in 2010 reached a somewhat different conclusion. Weinmann and colleagues analyzed nine randomized controlled trials involving 2,372 patients and found a statistically significant, though moderate, advantage for ginkgo over placebo in cognitive measures.
The trials ranged from 12 to 52 weeks and included patients with Alzheimer’s, vascular, and mixed dementia. The catch is that the effect sizes were comparable to those seen with approved dementia drugs like donepezil, which themselves offer only modest benefits. So ginkgo may help in some cases, but the improvement is not dramatic, and it is not consistent across all studies. The critical limitation here is that the positive results tend to cluster around a specific extract, EGb 761, at a specific dose of 240 mg per day. If you pick up a random ginkgo supplement at a pharmacy, it may contain a different extract, a different dose, or inconsistent concentrations of the active compounds. The research that shows any benefit at all is not a blanket endorsement of ginkgo products in general. It applies to a particular pharmaceutical-grade preparation tested under controlled conditions.
The 240 mg EGb 761 Treatment Trials and Who They Helped
One of the most frequently cited positive results comes from a 24-week randomized controlled trial published by Ihl and colleagues in the Journal of Psychiatric Research in 2012. This study specifically enrolled patients who had dementia along with neuropsychiatric symptoms such as agitation, depression, or apathy. At 240 mg per day of EGb 761, patients showed statistically significant improvements over placebo in cognition, global clinical assessment, activities of daily living, and quality of life. The numbers were meaningful: 35 percent of EGb 761 patients met the threshold for treatment response, defined as at least a 4-point improvement on the ADAS-cog scale, compared to 19 percent of patients on placebo. That 35 versus 19 percent responder rate is worth putting in context. It does not mean ginkgo worked for everyone.
Nearly two-thirds of patients taking EGb 761 did not meet the response threshold. But for a condition where approved medications also help only a minority of patients, a response rate nearly double that of placebo is notable. This particular trial focused on patients with behavioral and psychological symptoms of dementia, which suggests EGb 761 may be more useful for certain symptom profiles than for dementia broadly. The challenge is replicating these results consistently. When the Cochrane review looked across all available trials, the overall picture was unreliable. A single positive study, even a well-designed one, does not override dozens of others that found no benefit. What it does suggest is that certain subgroups of dementia patients, particularly those with neuropsychiatric symptoms, might respond to EGb 761 in ways that get washed out in larger pooled analyses.
How Does Ginkgo Compare to Approved Dementia Medications?
The most commonly prescribed medications for Alzheimer’s disease, cholinesterase inhibitors like donepezil, rivastigmine, and galantamine, produce effect sizes that are themselves modest. They slow cognitive decline for a period of months to a couple of years in some patients, but they do not halt or reverse the disease. When the BMC Geriatrics review found that ginkgo’s cognitive benefits were comparable in size to these drugs, it raised an uncomfortable question: if ginkgo performs similarly to approved medications in some trials, why is it not taken more seriously? The answer comes down to consistency. Donepezil has been shown to work across many well-designed trials, and its effect, while modest, is reproducible. Ginkgo’s positive results are scattered among a larger number of negative or inconclusive findings. A drug that works sometimes in some studies is not the same as a drug that works reliably.
Regulatory agencies and clinical guidelines require a consistent evidence base, which ginkgo does not have. In Germany and some other European countries, EGb 761 is actually prescribed as a treatment for dementia, reflecting a different regulatory interpretation of the same data. In the United States and United Kingdom, it remains a supplement with no approved medical indication for dementia. For families weighing their options, the tradeoff looks like this: approved dementia drugs have better-established evidence and are covered by insurance, but their benefits are also limited. Ginkgo, specifically EGb 761 at 240 mg per day, has shown benefits in some trials with a generally favorable safety profile, but the evidence is not consistent enough for most medical guidelines to recommend it. Adding ginkgo on top of standard medication is something some patients do, but it should be discussed with a physician because of potential drug interactions, particularly with blood thinners.
What Do the Most Recent Studies From 2024 and 2025 Say?
A systematic review published in the journal Antioxidants in May 2024 examined 15 clinical trials of EGb 761. Of those, 11 studies found improvements in cognitive function as measured by MMSE and SKT scores, as well as reductions in neuropsychiatric symptoms. Four studies found no significant difference from placebo. The authors’ interpretation leaned positive, but the four negative studies are a reminder that the inconsistency identified by the Cochrane review has not been resolved. A separate meta-analysis published in The World Journal of Biological Psychiatry in 2024 concluded that EGb 761 is “safe and effective in the treatment of mild dementia” based on subgroup analysis of randomized controlled trials. The key word there is mild.
For moderate to severe dementia, the evidence remains weak. This is an important limitation because many families begin exploring supplements after a loved one has already progressed beyond the mild stage. A 2025 study published in Frontiers in Neurology tried something new by looking at ginkgo specifically in patients with amyloid PET-positive mild cognitive impairment, meaning people with biomarker-confirmed early Alzheimer’s pathology. This represents an effort to test ginkgo in a more precisely defined population rather than the broad diagnostic categories used in earlier trials. The results noted that efficacy as monotherapy remains uncertain. This line of research is still developing, and it may eventually clarify whether ginkgo helps a specific biological subgroup, but that answer is not yet available.
Safety Concerns and Drug Interactions Worth Knowing
Ginkgo biloba is generally well tolerated in clinical trials, with side effect rates comparable to placebo in most studies. The GEM trial, which ran for six years, did not find significant safety concerns. However, ginkgo has mild blood-thinning properties, and this matters for the elderly population most likely to consider it. Many older adults take anticoagulants like warfarin or antiplatelet drugs like aspirin, and combining these with ginkgo could theoretically increase bleeding risk. Case reports of bleeding events exist, though large trials have not confirmed a statistically significant increase.
The other practical concern is supplement quality. The trials that produced positive results used a standardized pharmaceutical-grade extract called EGb 761. Over-the-counter ginkgo supplements in the United States are not regulated to the same standard, and independent testing has found significant variation in active ingredient concentrations across brands. A 2019 analysis found that some commercial ginkgo products contained little to no detectable ginkgo compounds. If someone decides to try ginkgo based on the clinical evidence, using a product that matches what was actually tested in trials matters.
Where Ginkgo Research Is Heading
The trend in dementia research broadly is toward precision medicine, identifying which patients will respond to which interventions based on biomarkers, genetics, and disease stage. The 2025 Frontiers in Neurology study examining ginkgo in amyloid PET-positive patients reflects this shift. Rather than asking whether ginkgo helps “dementia” as a broad category, future trials may ask whether it helps a specific molecular subtype at a specific stage. If ginkgo’s benefits are real but limited to a subgroup, that would explain why large prevention trials found nothing while smaller treatment trials sometimes found modest effects.
Over 10,000 people have now participated in controlled clinical trials of ginkgo for dementia across all studies combined. That is a substantial evidence base, and the honest summary is that ginkgo does not prevent dementia and its value as a treatment is uncertain. The supplement is not worthless, but it is not the answer that many families hope for. Future research with better patient selection and biomarker endpoints may eventually carve out a narrow role for EGb 761, but that work is still in its early stages.
Conclusion
The weight of evidence from the largest and most rigorous clinical trials is that ginkgo biloba does not prevent dementia. The GEM and GuidAge studies together enrolled nearly 6,000 older adults and followed them for five to six years, and neither found a protective effect. For treatment of existing dementia, the picture is more nuanced. A specific extract, EGb 761, at 240 mg per day has shown modest cognitive benefits in some trials, particularly for patients with mild dementia and neuropsychiatric symptoms.
But the Cochrane review’s assessment that the evidence is “inconsistent and unreliable” has not been overturned by more recent research. For families navigating dementia care, the practical takeaway is that ginkgo should not be relied upon as a primary strategy for prevention or treatment. If someone with mild dementia wants to try EGb 761 alongside standard medical care, the safety profile is generally acceptable, but the decision should involve their physician, especially if they take blood thinners or other medications. The most productive use of time and resources remains working with a healthcare team on evidence-based interventions, staying physically active, managing cardiovascular risk factors, and maintaining social engagement, all of which have stronger evidence than any supplement on the market.
Frequently Asked Questions
Does ginkgo biloba prevent Alzheimer’s disease?
No. The two largest prevention trials, the GEM study with 3,069 participants and the GuidAge study with roughly 2,854 participants, both found that 240 mg per day of ginkgo biloba did not reduce the risk of developing dementia or Alzheimer’s disease.
Can ginkgo biloba help someone who already has dementia?
Possibly, but the evidence is mixed. Some trials of the standardized extract EGb 761 at 240 mg per day showed modest improvements in cognition and daily functioning, particularly in patients with mild dementia and neuropsychiatric symptoms. However, the Cochrane review of 36 trials found the overall evidence inconsistent and unreliable.
What is EGb 761 and is it different from regular ginkgo supplements?
EGb 761 is a standardized, pharmaceutical-grade extract of ginkgo biloba that contains specific concentrations of active compounds. It is the formulation used in nearly all major clinical trials. Over-the-counter ginkgo supplements vary widely in quality and may not contain the same active ingredients at the same concentrations.
Is ginkgo biloba safe for elderly people to take?
In clinical trials lasting up to six years, ginkgo biloba was generally well tolerated with side effects comparable to placebo. However, it has mild blood-thinning properties, so people taking anticoagulants or antiplatelet medications should consult their doctor before using it.
How does ginkgo compare to prescription dementia medications?
Some analyses found that ginkgo’s cognitive benefits in positive trials were comparable in size to those of approved drugs like donepezil. However, prescription medications have more consistent evidence across multiple trials, whereas ginkgo’s results vary significantly from study to study.
What does the latest 2024-2025 research say about ginkgo and dementia?
A 2024 meta-analysis concluded EGb 761 is safe and effective for mild dementia specifically. A 2024 systematic review found 11 of 15 trials showed cognitive improvements, while 4 did not. A 2025 study examining ginkgo in biomarker-confirmed pre-Alzheimer’s patients found that its efficacy as monotherapy remains uncertain.
