Essential Oils Studied for Treatment of Alzheimer's
Many of the current memory enhancing/anti-dementia drugs for the treatment of Alzheimer's disease strengthen the actions of the acetylcholine system by inhibiting cholinesterase, the enzyme which breaks down acetylchoilne in the body. This improves the stores and availability of this neurotransmitter, resulting in improved mental cognition.
Several essential oils thought to sharpen the mind have have shown the same action -- inhibition of cholinesterase. These include Lemon and Rosemary essential oils, the top two oils tested for improving study skills and test taking ability. Spanish Sage has also been the subject of many laboratory studies, and even a clinical trial, with successful results. Spanish Sage shares primary chemical constituents with many other oils, including Rosemary (the natural chemical 1,8-cineol is predominant in both oils). Don't get too hung up on the specific species on the studies, as again, many bright-scented essential oils appear to have these effects.
Interestingly, none of the individual constituents seemed to be as potent in preventing the breakdown of acetylcholine as the whole natural oil. Aromatherapists know well that the complete oils will virtually always have a more therapeutic effect than any single compound produced in the laboratory.
To replicate this effect of essential oil yourself, simply use one or more of these oils -- or another oil with a 'bright' aroma that you enjoy -- in a nebulizing diffuser. Be sure not to over-do it, just get enough of the aroma so its uplifting and pleasing, never overwhelming. A timer system is a good idea, running the diffuser only a few minutes every hour helps preserve oils and enhance their effects. Here are the studies involving Sage -- you can find studies involving Lemon and Rosemary elsewhere on our blog, or search Pub Med:
In vitro Biological Activity of Salvia leriifolia Benth Essential Oil Relevant to the Treatment of Alzheimer's Disease.
Loizzo MR, Menichini F, Tundis R, Bonesi M, Conforti F, Nadjafi F, Statti GA, Frega NG, Menichini F. Department of Pharmaceutical Sciences, Faculty of Pharmacy, Nutrition and Health Sciences, University of Calabria.
In this study the chemical composition, cholinesterase inhibitory property and anti-inflammatory activity of S. leriifolia Benth. essential oil was evaluated for the first time. GC and GC-MS analysis revealed the presence of camphor (10.5%), 1,8-cineole (8.6%), camphene (6.2%) and alpha-pinene (4.7%) as main constituents. S. leriifolia oil exhibited a promising antioxidant activity by DPPH assay with an IC(50) 2.26 muL/mL. Interesting cholinesterase inhibitory activity was also found with IC(50) values of 0.32 and 0.29 muL/mL for acetylcholinesterase (AChE) and butyrrylcholinesterase (BChE), respectively. Moreover, this oil inhibited LPS-induced NO production with an IC(50) value of 165 mug/mL. The absence of cytotoxicity at 1000 mug/mL was evaluated by MTT assay in 142BR cells.
In-vitro activity of S. lavandulaefolia (Spanish sage) relevant to treatment of Alzheimer's disease.
Perry NS, Houghton PJ, Sampson J, Theobald AE, Hart S, Lis-Balchin M, Hoult JR, Evans P, Jenner P, Milligan S, Perry EK.Pharmacognosy Research Laboratories, Department of Pharmacy, King's College London, UK.
Salvia lavandulaefolia Vahl. (Spanish sage) essential oil and individual monoterpenoid constituents have been shown to inhibit the enzyme acetylcholinesterase in-vitro and in-vivo. This activity is relevant to the treatment of Alzheimer's disease, since anticholinesterase drugs are currently the only drugs available to treat Alzheimer's disease. Other activities relevant to Alzheimer's disease include antioxidant, anti-inflammatory and estrogenic effects. Results of in-vitro tests for these activities are reported here for S. lavandulaefolia extracts, the essential oil and its major constituents. Antioxidant activity (inhibition of bovine brain liposome peroxidation) was found in the EtOH extract of the dried herb (5 mg mL(-1)) and the monoterpenoids (0.1 M) alpha- and beta-pinene and 1,8-cineole. Thujone and geraniol had lower antioxidant effects, while camphor had no antioxidant effects. Possible anti-inflammatory activity (eicosanoid inhibition in rat leucocytes) was found in the EtOH extract (50 microg mL(-1)) and was shown by the monoterpenoids alpha-pinene and geraniol (0.2 mM), but not 1,8-cineole, thujone or camphor. Possible estrogenic activity (via induction of beta-galactosidase activity in yeast cells) was found in the essential oil (0.01 mg mL(-1)) and the monoterpenoid geraniol (0.1-2 mM). 1,8-Cineole, alpha- and beta-pinene and thujone did not exhibit estrogenic activity in this analysis. These results demonstrate that S. lavandulaefolia, its essential oil and some chemical constituents have properties relevant to the treatment of Alzheimer's disease and provide further data supporting the value of carrying out clinical studies in patients with Alzheimer's disease using this plant species.
In-vitro inhibition of human erythrocyte acetylcholinesterase by salvia lavandulaefolia essential oil and constituent terpenes.
Perry NS, Houghton PJ, Theobald A, Jenner P, Perry EK.Department of Pharmacy, King's College London, UK.
Sage (Salvia spp) is reputed in European herbal encyclopaedias to enhance memory, and current memory-enhancing/anti-dementia drugs are based on enhancing cholinergic activity by inhibiting cholinesterase. In this study the effects of Salvia lavandulaefolia Vahl. (Spanish sage) essential oil and some of its constituent terpenes on human erythrocyte acetylcholinesterase were examined in-vitro. The main constituents in the essential oil batch used for analysis of cholinesterase inhibition were camphor (27%), 1,8-cineole (13%), alpha- and beta-pinene (10-15%) and bornyl acetate (10%) with other minor constituents (1% or less) including geraniol, limonene, linalool, terpineol and gamma-terpinene. Using the Ellman spectrophotometric method, kinetic analysis was conducted on the interaction of the essential oil and the main monoterpenoids, camphor, 1,8-cineole and alpha-pinene. IC50 values were obtained for the essential oil, 1,8-cineole and alpha-pinene and were 0.03 microL [corrected] mL(-1), 0.67 mM and 0.63 mM, respectively. Camphor and other compounds tested (geraniol, linalool and gamma-terpinene) were less potent (camphor IC50: >10mM). The essential oil, alpha-pinene, 1,8-cineole and camphor were found to be uncompetitive reversible inhibitors. These findings suggest that if the inhibitory activity of the essential oil is primarily due to the main inhibitory terpenoid constituents identified, there is a major synergistic effect among the constituents. Since no single constituent tested was particularly potent, it remains to be determined whether these in-vitro cholinesterase inhibitory activities are relevant to in-vivo effects of the ingestion of S. lavandulaefolia essential oil on brain acetylcholinesterase activity.
Salvia for dementia therapy: review of pharmacological activity and pilot tolerability clinical trial.
Perry NS, Bollen C, Perry EK, Ballard C.Department of Pharmacology and Toxicology, University of Otago, Dunedin, New Zealand.
S. lavandulaefolia Vahl. (Spanish sage) extracts and constituents have demonstrated anticholinesterase, antioxidant, anti-inflammatory, oestrogenic and CNS depressant (sedative) effects all of which are currently relevant to the treatment of Alzheimer's disease (AD). The essential oil inhibits the enzyme acetylcholinesterase (AChE) from human brain tissue and bovine erythrocyte and individual monoterpenoid constituents inhibit AChE with varying degrees of potency. In vivo AChE inhibition of select brain (striatal and hippocampal over cortical) AChE was obtained following oral administration of the essential oil to rats. In a study in healthy volunteers essential oil administration produced significant effects on cognition. In a pilot open-label study involving oral administration of the essential oil to patients with AD, a significant increase in diastolic and systolic blood pressure was observed in two patients, however this may have been due primarily to preexisting hypertension and there were no abnormalities in other vital signs or blood samples during the trial period. Although an open label trial is not free from practice effects or rater-caregiver expectations, statistically significant differences between baseline and 6 weeks treatment were a reduction in neuropsychiatric symptoms and an improvement in attention.