Various essential oils have improved cognitive function in human beings in clinical trials. Jimbo and colleagues used a diffuser to deliver rosemary and lemon essential oils in the morning and lavender and orange essential oils in the evening to 28 patients with dementia (including those with Alzheimer's disease). After 28 days, all 28 patients "showed significant improvement in personal orientation related to cognitive function. " Akhondzadeh and colleagues using tinctures of lemon balm (Melissa officinalis) and sage (Salvia officinalis) saw significant improvements in cognitive function over placebo in 84 patients with Alzheimer's disease over a four month period. Essential oils high in methoxyphenols (such as clove, cinnamon leaf, rosemary, sage, lemon balm, oregano, thyme, and laurel) appear to provide a particular effective treatment for Alzheimer's disease. These compounds scavenge peroxynitrites (convert them into a less dangerous form) and partially reverse the damage that they do to receptors involved in short-term memory, sleep, mood, smell, alertness, and awareness.
My sisters and I began to give our mother rosemary essential oil to smell four years ago (she has had Alzheimer's disease for seven years). This year we added many of the essential oil listed above. As a result of aromatherapy (she takes no medications), she can recognize her own home again, sleeps through the night, feels comfortable around relatives, has some short-term memory (can spell her own name, can sometimes remember the order of days and month, can complete sayings such as I scream, you scream, we all scream for... Ice cream, etc. ), and is much more alert and aware than before she began aromatherapy. Except for allergies or excessive use (my mother smells the oils for just a few seconds under each nostril every morning), there appears to be few side effects from aromatherapy. Essential oils are one of the few treatments for Alzheimer's disease that has worked both in animal models and in human beings.