By Ram Rao, Ph.D., Principal Research Scientist for Apollo Health

In the last newsletter, I highlighted a “scent study” whose findings suggested that cognition improved severalfold in normal individuals by diffusing a different choice of perfume in the bedroom before sleep. Several readers posted questions pertaining to the study and aromatherapy in general. In this article, I address some of these queries.

Does Sense of smell affect only brain and cognitive functions or other physiological aspects as well?

Olfaction (the sense of smell) is one of the oldest senses and is closely linked to areas of the brain that control emotion, memory, mood behavior, and overall energy – this explains why smelling something familiar brings back past experiences, vivid memories, and emotions. Furthermore, research studies have shown that aroma-associated electrical signals modulate other physiological functions, including cognition, blood pressure, muscle tension, pupil dilation, skin temperature, pulse rate, and sleep.

Is Aromatherapy a new subject, and what in the scents is responsible for the manifold functions?

Since immemorial, essential oils extracted from various parts of a plant have been used for everything from personal hygiene and cooking to spiritual practices. The oils are extracted by steaming or pressing roots, barks, flowers, leaves, resins, or seeds to isolate the compounds that give the plant its unique scent. The scent or fragrance is attributed to volatile chemical components that humans perceive through the olfactory system. These numerous volatile compounds, including alcohol, aldehydes, ketones, esters, terpenes, and phenols, possess numerous biological activities. They bind to specific odorant receptors present in the nasal area and generate electrical signals that get transmitted to the brain via the olfactory sensory neurons.  Essential oils typically contain several of these volatile chemicals, with the vast majority at levels of less than 1%. These chemicals work in sync to maximize the effectiveness of the oil.

How do you use essential oils?

Essential oils are concentrated and potent, and it takes only a small amount to create a possible well-being effect or an adverse reaction. Most essential oils will cause skin irritation if applied directly to the skin without being diluted first. Essential oils for topical application are often mixed with a carrier oil to prevent skin allergic reactions. Common carrier oils include jojoba oil, avocado oil, grapeseed oil, and sweet almond oil. In addition to topical application, other ways to use essential oils are to inhale them or use them in diffusers and humidifiers.

Are all essential oils the same and safe to use?

Essential oils are not regulated in the United States, which means that the quality of the essential oils may vary widely. As a result, spurious essential oils have flooded the market. These may smell like the natural essential oil from a plant source, but they also contain petrochemical compounds. Additionally, other factors can impact the quality of the essential oil, including the place and environment where the plants are grown, use of pesticides, packaging and handling errors, improper storage, and shelf life. It is always a good practice to consult your doctor or a certified aromatherapist about which essential oils are safe to use and how to use them.

Is Aromatherapy and the use of essential oils recommended as a stand-alone therapy for restoring memory?

Scientists have long known that the loss of olfaction is associated with the development of dementias, including Alzheimer’s disease (AD) and Parkinson’s disease (PD). It is also well understood that olfaction deficits occur even before AD or PD clinical symptoms are fully developed. Losing the sense of smell correlates with a loss in the brain’s memory circuits, hinting at a strong connection between smell and brain function. Since most of the research studies on aromatherapy follow the participants for a short time, it is unclear if the benefits are sustained.

Please remember that aromatherapy is one small part of an umbrella of strategies called the Bredesen Seven (B7) that promote neuroplasticity — the ability of the brain to heal and grow new neurons and connections between neurons in response to stimuli. While each strategy alone can provide some benefits, combining strategies becomes more powerful when practiced together. So, if you are into essential oils, I would suggest using them in conjunction with the B7 strategies for long-term benefits.

Do you have specific brands or sources that you like to recommend?

While there are hundreds of companies dealing in essential oils, I have used the oils from a few companies that I find to be pure, natural, and safe. See the list below for companies that use good manufacturing practices to ensure that consumers receive the best quality essential oil.

Plant Therapy
Aura Cacia
Pure Aroma

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