Table 3.
Other natural products and supplements suggested for the treatment of cognitive impairment
| Herb/Supplement | Suggested Dose | Possible Mechanism of Action | Evidence Base | Side Effects |
|---|---|---|---|---|
| Bacopa monniera | 300 mg/day | An Ayurvedic medicinal plant that acts as a free radical scavenger and in animal models reduces Aβ; may also boost cholinergic function | No convincing evidence: 9 RCTs; 518 subjects in meta-analysis. Limited evidence given poor study design. | GI upset |
| Curcumin (yellow curry) | 2,000–8,000 mg/day | Antioxidant, anti-inflammatory, induces heat shock proteins; anti-amyloid effects in animals | Mixed results; no convincing evidence: 2 studies find no effect; 1 study finds beneficial effect. | GI upset |
| Dehydroepiandro- sterone (DHEA) | 100 mg/day | Adrenal steroid that declines with aging, is lower in Alzheimer’s disease patients, and is neurotrophic in animals | No convincing evidence of benefit. 3 RCTs | Acne, balding, insulin resistance, dyslipidemia, mood changes, hepatic dysfunction, possible effects on hormone- sensitive cancers |
| Hydergine | 3 mg/day | Combination of 4 ergot derivatives with vasodilatory effects and possible effect on mono-amine and cholinergic transmission | 2000 Cochrane meta-analysis of 19 trials found some evidence of modest efficacy but many trials conducted before standardized criteria for diagnosing dementia | GI upset, psychosis, flushing, blood pressure changes |
| Lecithin | 3,600 mg/day | An acetylcholine precursor | Review of 11 randomized trials showed no consistent benefit | GI upset, rash, headache, dizziness |
| Resveratrol | Unknown (phase 1 trials 2,500–5,000 mg/day) | Polyphenol in the skin of red grapes and red wine with antioxidant and anti-amyloid properties in animals | Clinical trial linking to increased cerebral blood flow. Needs further study on cognitive effects | Possible estrogen-like effects, as its chemical structure is similar to phytoestrogens |
| Vitamin E | 800 – 2000 IU/day | Free radical scavenging | No convincing evidence. Cochrane review – 3 studies. | High dose increases all-cause mortality. |
D, Alzheimer’s disease; ChAT, choline acetyl transferase (the enzyme that synthesizes acetylcholine); GI, gastrointestinal; RCT, randomized controlled trial.