Aromatherapy

Aromatherapy is the ancient practice of using aromatic essential oils of plants to treat human illnesses. The technique has been utilized in the management of a variety of illnesses and discomforts. While effects on  psychiatric concerns ranging from mood disorders to autism to schizophrenia have been reported, it is only mild to moderate anxiety and insomnia that reliably respond to aromatherapy. 

Most physicians discount aromatherapy. But blanket dismissal is unwarranted. There are many small, but well-performed studies showing benefits of aromatic oils in humans. Essential oils of lavender, rose, orange, chamomile, jasmine, and sandalwood, alone or in combination, are among those found to be helpful. There are even studies finding significant effects in rats, sheep, cats, and dogs—none of whom are subject to suggestion or placebo effects. One compelling study at a college of veterinary medicine demonstrated effectiveness of aromatherapy in horses. Measurements of changes in electrical activity in the head and neck muscles clearly showed that horses were calmed by exposure to the aromas of specific essential oils. Thus, there should no longer be doubt that aromatherapy works. The important question is, “How does it work?”

The most satisfying explanation for how aromatherapy might work—especially for doctors trained in Western medicine—is that active components of the essential oils enter the body to produce their effects like any other medication. There are two methods used in aromatherapy to expose a person to essential oils. One is to have the person inhale vapors of the oil. The other is to apply the essential oils during massage. When essential oils are inhaled, volatile components of the oil can be absorbed through mucous membranes of the nasal cavity and taken into the bloodstream. Such absorption has been verified in animal studies. During massage, phytochemicals in the essential oil can be absorbed through the skin and into the body. Of course, the massaged patient will also inhale vapors of the oil.

Many chemicals from plants have proven medicinal effects, and if absorbed in sufficient quantity through the nasal mucosa or the skin those effects can manifest. Lavendar oil is a good example. Linalool is a chemical component of lavender known to have significant effects on brain activity. It enhances the activity of the neurotransmitter GABA in the brain, which is similar to the mechanism of action of the benzodiazepine drugs such as Valium and Xanax. It also dampens the effects of the neurotransmitter glutamate, which produces a complimentary calming effect. Inhaling lavender oil vapors or massaging it into the skin puts linalool into the blood and subsequently into the brain where it can produce those effects.  

There is strong evidence that aromatherapy techniques can introduce psychoactive substances into the body and into the brain. But a more interesting question is if aromas themselves have effects. Ways in which aromas might relieve anxiety are by distraction or association. A pleasant smell might relieve anxiety as would listening to a Bach fugue or pausing to watch a beautiful bird in flight. Floral aromas might trigger calming memories of pleasant walks in a garden or grandma’s lavender soap. However, it is possible that some responses to smells are mediated by specific mechanisms hard-wired in the brain.

In many animal species there is an organ of smell called the vomeronasal organ. This organ is extremely sensitive to airborne molecules called pheromones. When pheromones land on special receptors in the vomeronasal organ, they trigger rapid  changes in behavior. An example is male animals responding to the pheromones produced by females in heat. Such responses are mediated by the sense of smell alone, not by substances absorbed into the bloodstream. 

There is evidence that humans release pheromones that affect other humans. For example, it has been shown that the scent of ovulating women causes immediate changes in brain activity in men. Women sniffing secretions swabbed from the armpits of men show similar, nearly instantaneous changes in brain activity. Those changes are too rapid to be due to substances being carried to the brain by the bloodstream. They are mediated by some aspect of the sense of smell.

Is there anything in between an aroma being generically pleasant and it causing a specific, hardwired response such as a pheromone might produce? Can certain aromas reliably elicit specific responses, such as relaxation, joy, alertness, or congeniality? Might certain types of olfactory stimulation evoke specific emotional tones in the same ways that music in minor keys elicits feelings of melancholy and bright yellow and green colors give rise to cheerfulness? Most aromatherapists would insist this is the case. Perfumers agree, and studies support them. They show that women, even their photographs, look more attractive to men when perfume is in the air. Is this stimulation or simply association? It remains to be determined what mechanisms in the brain might mediate such effects through smell alone. 

An important and growing body of work has shown that aromatherapy can be useful in the treatment and care of demented patients. A number of essential oils commonly used in aromatherapy, including lavender, bergamot, lemon balm, ylang ylang and sweet orange, have been shown in multiple studies to reduce agitation, even in patients with severe dementia. Furthermore, whereas aromatherapy focusses on aromas of specific essential oils, some recent studies show that stimulating the sense of smell, per se,  can have beneficial effects in patients with dementia. Olfactory function deteriorates in these patients. Tests of olfaction can predict cognitive decline even before it is revealed by standard cognitive tests. Just as exercise strengthens muscles, olfactory stimulation strengthens olfactory function, and this in turn appears able to improve brain function. In a study of healthy, elderly subjects at UC Irvine, alternating exposure to different essential oils during sleep every night over a period of 6 months  improved cognitive function by a remarkable 226%. In another study, elderly subjects with mild cognitive impairment sniffed 40 different odors each day and gradually experienced improvements in olfactory function, as well as improvements in memory, symptoms of depression, attention, and language skills. Thus, in some cases, aroma alone can positively affect brain function. Of course, while aromatherapy has been shown to offer benefits, its best features may be that it is easy, accessible, agreeable, and perfectly safe.