Ginkgo Biloba for Dementia
Ginkgo biloba does not prevent dementia or Alzheimer's disease, and the evidence that it meaningfully treats existing dementia is weak and disputed. Major health authorities do not recommend it for memory or cognitive decline.
Why this grade7-layer evidence engine
The strongest evidence concerns prevention, and it is squarely negative. The large government-funded GEM trial (PMID 19017911; n=3,069, ~6 years) found ginkgo no better than placebo at preventing dementia (HR 1.12) or Alzheimer's (HR 1.16), and a pooled meta-analysis (PMID 26058281; n=5,889) confirmed no effect (OR 1.05). Because the only high-quality data point in this direction shows the supplement failing, the claim earns a Counter-Evidence (D) grade.
The grade is marked 'disputed' rather than simply ineffective because the picture for treating people who already have dementia is mixed. One meta-analysis (PMID 25114079) reported modest gains in cognition and daily function with standardized EGb 761 at 240 mg/day, but the Cochrane review (PMID 19160216) judged that benefit 'inconsistent and unreliable,' and the positive trials carry potential manufacturer conflicts of interest. Any signal is small, limited to a specific standardized extract, and does not change disease course.
Regulators and clinicians align with the negative read. The NIH's NCCIH states there is 'no conclusive evidence that ginkgo is helpful for any health condition,' the UK NHS warns there is 'not enough evidence' and advises caution, the Cleveland Clinic notes it is 'not intended to... prevent any disease,' and the Alzheimer's Association cites the NIA trial showing ginkgo 'no more effective than a placebo.' Note the meaningful bleeding-risk interaction with blood thinners.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.391
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (1 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 1 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status