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Bowles EJ 2006, 'Effects of essential oils and aromatherapy on cognitive function in dementia : laboratory studies and application in aged care facility residents', PhD thesis, Southern Cross University, Lismore, NSW.

Copyright EJ Bowles 2006


This thesis investigates the use of aromatherapy for the improvement of cognitive function in aged care facility residents with dementia. A four-phase cascading research framework was used, comprising four phases: investigation; hypothesis formation; laboratory testing of the hypothesis; use of laboratory results in a randomised controlled trial of aromatherapy for cognitive function in aged care facility residents with dementia. The investigation phase comprised a background literature review and an exploratory survey of existing aromatherapy use in aged care facilities in northern NSW. The hypothesis was formed that certain essential oils already being used in aged care would have potential activity against acetylcholinesterase (one of the major drug targets in dementia). The laboratory phase screened the twenty-five essential oils identified in the survey using a modified Ellman acetylcholinesterase technique. Five of the oils showed >50% acetylcholinesterase inhibition at 0.454 mg/mL (Cypress (Cupressus sempervirens), Lime (Citrus latifolia), Rosemary (Rosmarinus officinalis), Eucalyptus (Eucalyptus globulus) and Sage (Salvia officinalis)). The final clinical trial phase compared two essential oils lotions (up to 2.7% essential oil w/w) and a placebo, with repeated cognitive testing using the well-accepted Mini-Mental State Examination (MMSE) over a three month period. One essential oil lotion contained three of the most active essential oils; the other contained three of the least active oils from the laboratory tests. Blends were used so that participants would not be distracted by being able to identify individual aromas. Lotions were applied once a day in the morning to the shoulders and neck of the 98 participants (selected from 10 facilities). Neither essential oil blend nor placebo were statistically different, and the overall decline over the treatment period was 0.9 (+/- 1.07) MMSE points. The conclusion was that aromatherapy is not effective for short-term improvement of cognitive function in people with mild to moderate dementia (baseline scores 10-26 on MMSE). Use of stronger doses of essential oils over a six or twelve month period, and inclusion of a no-treatment arm could further test the hypothesis that some essential oils can affect cognitive function in dementia.