Traditional Medicine for Memory Enhancement

Keywords • Acetylcholinesterase inhibitors • Alzheimer’s disease • Anti-inflammatory • Antioxidant • Estrogenic • Memory • Traditional medicine In traditional practices of medicine, numerous plants have been used to alleviate memory impairment both in healthy individuals and those with disease states which are now recognised as specific cognitive disorders such as Alzheimer’s disease. An ethnopharmacological approach has provided leads to identify plants and their compounds that may have potential to modulate cognitive abilities by different modes of action. A variety of therapeutic targets have been identified as relevant in the treatment of cognitive disorders, including modulation of the cholinergic system, which may be achieved by the inhibition of acetyl-cholinesterase, and neuroprotection against glutamate-induced overstimulation of N-methyl-D-aspartate (NMDA) receptors, by the use of NMDA receptor modulators. Other activities considered to be relevant in the alleviation of cognitive impairment include anti-inflammatory, antioxidant and estrogenic activities. Two of the currently licensed drugs used to treat cognitive symptoms in Alzheimer’s disease, galantamine and rivastigmine, Read more […]

Activities Relevant to the Treatment of Cognitive Disorders

Precursors of Acetylcholine Adequate availability of choline has been proposed to enable sufficient acetylcholine synthesis for neurotransmission. Precursors of acetylcholine (e.g. choline and lecithin) have been investigated for their effects on synthesis and release of acetylcholine, with a view to increasing acetylcholine release and cholinergic activity. Few clinical or animal studies have reported any significant beneficial effects on cognitive function with these compounds. Therapy failure may be due to impaired uptake mechanisms of choline causing the reduction in acetylcholine synthesis, and not due to insufficient choline supply. This is apparent as it has been reported that more choline occurs in the cerebrospinal fluid of Alzheimer’s disease patients than in patients without Alzheimer’s disease, and that choline levels increase with disease progression. Therapy with acetylcholine precursors may be limited by side-effects, including gastrointestinal disturbances such as nausea, vomiting and diarrhoea. Muscarinic Receptor Stimulation Direct cholinergic receptor stimulation has been explored as one therapeutic target to enhance cognitive function. Cholinergic agonists are reported to facilitate learning Read more […]

Ginkgo biloba

In Europe, leaf preparations of Ginkgo biloba L. (Ginkgoaceae) were used for the treatment of circulatory disorders in the 1960s, and they are now a popular herbal remedy with a reputation for alleviating memory problems. In Iran, Ginkgo biloba has been used traditionally to improve memory associated with blood circulation abnormalities. The use of Ginkgo biloba in TCM dates back for centuries, and the Pharmacopoeia of the People’s Republic of China (2005) includes G biloba seeds as a remedy for cough and asthma and to reduce leukorrhoea and urination. There has been extensive research to determine any pharmacological basis which might explain the reputed effects of Ginkgo biloba on memory, and a number of clinical studies have also been conducted. Much of this research has used a standardised extract of Ginkgo biloba known as EGb 761, which contains flavonoid glycosides and terpenoid lactones amongst various other constituents. This extract has shown a variety of activities relevant to improving cognitive function, particularly neurodegenerative-related disorders such as Alzheimer’s disease, thus indicating that the extract may have a number of different modes of action. EGb 761 has shown favourable effects on Read more […]

Huperzia serrata

In TCM a prescription prepared from Huperzia serrata (Thunb.) Trevis. (Lycopodiaceae) has been a treatment for memory loss. Of the alkaloids isolated from Huperzia serrata, huperzine A has been extensively studied for pharmacological and clinical effects in relation to treatment of cognitive disorders. A range of studies in animals have shown this alkaloid to improve memory-retention processes in cognitively impaired aged and adult rats and to attenuate cognitive deficits in chronically hypoperfused rats and in gerbils following ischemia. The principal mechanism of action thought to be responsible for the cognitive-enhancing effects of huperzine A is modulation of cholinergic function by inhibition of cholinesterase; it reversibly inhibits acetylcholinesterase both in vitro and in vivo. Huperzine A is more selective for acetylcholinesterase than butyrylcholinesterase, was less toxic than the synthetic acetylcholinesterase inhibitors donepezil and tacrine and significantly improved memory and behaviour in Alzheimer’s disease patients in a multicentre, double-blind trial. In phase IV clinical trials in China, huperzine A improved memory in elderly, Alzheimer’s disease and vascular dementia patients, with limited Read more […]

Herb-Drug Interactions: Ginkgo

Ginkgo biloba L. (Ginkgoaceae) Synonym(s) and related species Fossil tree, Kew tree, Maidenhair tree. Salisburia adiantifolia Sm., Salisburia biloba Hoffmanns. Pharmacopoeias Ginkgo (US Ph 32); Ginkgo capsules (US Ph 32); Ginkgo dry extract, refined and quantified (British Ph 2009, European Ph 2008); Ginkgo leaf (British Ph 2009, European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4); Ginkgo tablets (US Ph 32); Powdered ginkgo extract (The United States Ph 32). Constituents Ginkgo leaves contain numerous flavonoids including the biflavone glycosides such as ginkgetin, isoginkgetin, bilobetin, sciadopitysin, and also some quercetin and kaempferol derivatives. Terpene lactones are the other major component, and these include ginkgolides A, B and C, and bilobalide, Ginkgo extracts may be standardised to contain between 22 and 27% flavonoids (flavone glycosides) and between 5 and 12% terpene lactones, both on the dried basis. The leaves contain only minor amounts of ginkgolic acids, and some pharmacopoeias specify a limit for these. The seeds contain ginkgotoxin (4-O-methylpyridoxine) and ginkgolic acids. Use and indications The leaves of ginkgo are the part usually used. Ginkgo is often used Read more […]

Ginkgo biloba: Clinical Use

Ginkgo biloba is a complex herb that contains many different active constituents and works by means of multiple mechanisms. In practice, its therapeutic effect is a result of interactions between constituents and mechanisms, giving it applications in many varied conditions. To date, most of the research conducted in Europe has used a standardised preparation known as EGb 761, available commercially as Rokan, Tanakan or Tebonin. DEMENTIA, MEMORY IMPAIRMENT Ginkgo biloba has been used and studied as a cognitive activator in a variety of populations, such as cognitively intact people, those with cerebral insufficiency, age-related memory impairment, Alzheimer’s dementia or multi-infarct dementia. A 2002 Cochrane review of the scientific literature concluded that Ginkgo biloba produces benefits superior to placebo within 12 weeks’ treatment in people with acquired cognitive impairment, including dementia, of any degree of severity. Cognition, activities of daily living and measures of mood and emotional function show significant benefit for ginkgo compared with placebo. Some clinical studies have also found that EGb 761 improves the capacity of geriatric patients to cope with the stressful demands of daily life. Clinical Read more […]