Aromatherapy can help both to improve, if already present, but also to prevent neurodegeneration such as Alzheimer's disease. Therefore, inhaling particular essential oils seems to help protect the brain, as emerges from a scientific research published a few years ago by a Japanese team (Jimbo et al, Psychogeriatrics, 2010) but perfected and deepened thanks to a work published a few months ago by the same team that not only was able to confirm the previous results but also offered an explanation on the mechanisms of action of essential oils (Okuda et al, PLoS One, 2020).
The researchers recruited 28 people with an average age of 86 and all with a diagnosis of dementia or Alzheimer's. For 28 days, these people underwent aromatherapy. In particular, during the day between 9 and 11 a.m. a blend of 0.04 ml of lemon essential oil and 0.08 ml of rosemary essential oil, with a stimulating action on the sympathetic nervous system able to strengthen memory and concentration, was released into the room with an essence-burning lamp. In the evening, between 7.30 and 9 p.m., a blend given by 0.08 ml of lavender essential oil and 0.04 ml of orange essential oil, with a stimulating action on the parasympathetic nervous system able to induce calm and relaxation, was released into the room. Then, the study participants underwent tests to assess their cognitive function. What emerged was that all patients, at the end of the treatment period, showed an improvement in their ability to form abstract ideas. Moreover, also their movements and orientation had benefited from it. However, patients with Alzheimer's showed more significant improvements.
A few years after the results of this study, the same researchers were able to investigate the mechanisms of action of essential oils on the brain and what emerged was that, following aromatherapy with the essential oils presented in the previous paragraph, there was a decrease in the levels of tau and beta amyloid proteins, whose accumulation is one of the markers of Alzheimer's disease, and an increase in the BDNF factor, or brain neutrophic factor, which promotes growth, survival and regeneration of neurons and which results decreased in people with Alzheimer's. Scientists believe that some substances in essential oils are absorbed by the brain and can act directly on neurons. Then, the olfactory stimulus is also transmitted to the rest of the brain allowing the beneficial and regenerative action on neurons. Finally, a change in the balance between the sympathetic and parasympathetic nervous systems induced by essential oils can modify thermoregulation and, as a consequence, promote blood flow. An increase in blood circulation can lead to a higher ability of the brain to get rid of beta amyloid proteins, just as occurs with an antiplatelet drug, cilostazol, which increases blood flow and, at the same time, decreases the presence of beta amyloid proteins.