Aromatherapy is one of the traditional remedies that uses essential oils extracted from plants based on their scent effects and is currently used in many fields. Aromatherapy is based on the theory that inhaling or absorbing essential oils causes changes within the limbic system, the part of the brain associated with memory and emotion. Aromatherapy stimulates physiological responses in the nervous, endocrine, or immune systems and can affect heart rate, blood pressure, breathing, brain wave activity, and the release of various hormones throughout the body. The limbic system comprises subcortical (amygdala, hippocampus) and cortical structures (parahippocampal cortex, cingulate cortex, etc.) and plays a central role in emotional regulation and memory. Numerous functional magnetic resonance imaging (fMRI) studies conducted in healthy, normal people have shown that olfactory stimuli activate primary and secondary olfactory cortical areas.
A clinical study consisting of women aged 41 to 69 evaluated the effects of continuous rose essential oil inhalation on the brain. The reasons for limiting the target audience to women are that women are generally more sensitive to odors than men, respond more emotionally to odors, and are more susceptible to emotional conditioning with odors. Participants wore a patch containing one to three drops of a 0.5% dilution of rose essential oil or water daily on their clothes for one month. Brain effects were measured using magnetic resonance imaging. Remarkably, continuous inhalation of rose essential oil increased gray matter volume in the whole brain and posterior cingulate cortex, which suggests inhaling rose oil could shield against brain atrophy and cognitive decline.
https://www.sciencedirect.com/.../pii/S0361923024000297