Scientists have studied the profound effect of smells on the brain and body for decades. A large body of research has concluded that smell has a powerful effect on the brain's ability to recall memories. Aromatherapy is closely linked to this process.
How it Works
The Howard Hughes Medical Institute hypothesizes that each smell has its own DNA, and that the brain discriminates between smells, determining whether the smell is pleasant, foul or soothing. Therapeutic smells from plant and fruit oils trigger certain physiological reactions. Dr. Gary Schwartz, a clinical psychologist and professor at the University of Arizona, first studied aromatherapy as a professor at Yale University. His research shows the sense of smell affects the part of the brain that controls fear and anxiety. Pleasant or soothing smells can allay feelings of nervousness, which can translate to physiological effects including lower blood pressure and heart rate.
Mental Health and Accuity
The primary use for aromatherapy is in improving mental health---relieving depression, reducing stress and relaxing an anxious mind. As previously mentioned, the relationship is close between smell and triggering nerves of fear and anxiety. A review of aromatherapy studies conducted at the Universities of Newcastle and Northumbria in England reported "aromatherapy provides a potentially effective treatment for a range of psychiatric disorders." The results of the study were published in a 2006 edition of the journal "CNS Drugs."
Research performed at the medical schools of Duke University and the University of Miami measured adult brain response to specific smells. Adults in the study, published in the December 1998 issue of the "International Journal of Neuroscience," were asked to answer simple math questions, given a three-minute treatment and asked to take another battery of math questions. A group dosed with lavender exhibited less depression and greater relaxation, resulting in both faster and more accurate completion of the second math test. A group treated with rosemary showed increased alertness and lower anxiety. They completed their math test faster, but were not more accurate.
Behavioral Treatment
People with cognitive disorders, such as Alzheimer's disease or other dementia, may exhibit agitated behavior. Researchers at the University of Southampton examined how aromatherapy could allay these symptoms. A small sample of 15 patients were given a daily two-hour treatment of either lavender oil mist or a placebo of regular steam. The study, published in the April 2002 edition of "The International Journal of Geriatric Psychology," found that the majority of patients in the treatment group showed improved scores in a widely accepted scale of dementia behaviors when compared with those given a placebo.
Improved Cardiovascular Health
Stress directly affects the heart, as a lower stress level eases blood pressure and heart rate. Scientists at Japan's Chiba University examined whether the stress-lowering benefits of aromatherapy could improve cardiac circulation in patients. Men ranging in age from 24 to 40 underwent echocardiograms and had their cortisol levels measured. Cortisol is an enzyme released by the brain as a response to stress. Study participants received 30-minute aromatherapy treatments using lavender oil and were immediately assessed. No change was found in the control group. The treatment group saw lower cortisol levels and greater circulatory blood flow. Results from the study were published in the September 26, 2008 edition of "International Journal of Cardiology."
References
- Macalester College Department of Psychology: Olfaction and Memory
- Howard Hughes Medical Institute: The Mystery of Smell
- "Aromatherapy: A Complete Guide to the Healing Art"; Kathi Kelville, Mindi Green; 2008
- "CNS Drugs": Aromatherapy in the Management of Psychiatric Disorders
- "International Journal of Neuroscience": Aromatherapy Positively Affects Mood, Eeg Patterns of Alertness and Math Computations
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