Acetyl-L-Carnitine for Cognitive Function
Acetyl-L-carnitine shows only a small, unreliable benefit in people with mild cognitive impairment or early Alzheimer's disease, and no measurable effect in cognitively healthy adults. It is not a proven way to boost memory or focus.
Why this grade7-layer evidence engine
The grade stays weak because the clinical signal is small and does not survive objective testing. The pivotal 2003 meta-analysis (PMID 12598816), pooling 21 RCTs in 1,204 people with mild cognitive impairment or mild Alzheimer's disease, found only a small advantage over placebo (effect size ~0.20). Its trials are old, heterogeneous, and of undisclosed funding, with many sponsored by manufacturers during that era.
A Cochrane review from the same year (PMID 12804452) found a benefit only on the subjective Clinical Global Impression scale, none on objective cognitive or functional outcomes, and explicitly advised against routine clinical use for dementia. A 2020 critical update (PMID 32408706) concluded results across trials remain inconsistent and that the role of acetyl-L-carnitine is still under debate.
For the healthy users targeted by 'brain and memory' marketing, a 2017 Cochrane review (PMID 28349514, ~200 analysable participants) found no measurable effect on reaction time, vigilance, or memory, on very-low-quality evidence. Regulators reinforce this: EFSA formally rejected the cognitive-function health claim for lack of a cause-and-effect relationship, the US FDA treats carnitine only as a nutrient supplement, the WHO does not list it, and no major clinic (Mayo, Cleveland, Harvard) endorses it for cognition.
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 = 0.472
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (2 篇 > 1 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status