Effect of Oregano, Apple mint and Thyme on Human Cognitive Functions

The essential oils are widely used in perfumery products due to their unique fragrance characteristics. Especially, the essential oils of oregano (Thymus capitatus), apple mint (Mentha suaveolens) and thyme (Thymus vulgaris) are used in various areas. Thus, this study aimed to evaluate the exposure of these essential oils on human electroencephalographic (EEG) activity. The EEG was recorded from 32 electrodes according to the International 10-20 system, in 20 male and 20 female volunteers. The samples were provided by one of our authors Edoardo Napoli from Italy. The exposure of three essential oils produced significantly different EEG activity. The inhalation of oregano oil exhibited a significant (P < 0.05) decrease of SEF50, and RA power spectrum in both sexes, but RB power spectrum was increased in male meanwhile decreased in female. The results of apple mint oil showed the significant decrease of SEF50 and increase of SEF90, which highly associated with the alertness state. A significant increase of SEF90, RG and RMB power spectrum were observed during the inhalation of the thyme oil. Further, the essential oils produced different effects according to gender, though all types of oils altered the EEG power spectra values which indicate the pleasant state of the brain. By this results, these essential oils can be used in the aromatherapy treatment for enhancing the cognitive functions.