Modern society is reviving the practice of aromatherapy, and lavender is reported to be the most worldwide purchased plant for essential oils (EO) extraction. Since odors can modulate cognitive functions acting through specific neuroanatomical pathways, lavender EO inhalation can enhance cognition. Taking into account EO quality and diffusion devices, we conducted a systematic review on the effects of lavender EO inhalation on arousal, attention and memory in healthy subjects. Starting from this new multidisciplinary perspective, cognitive effects were revised to link outcomes to effective and reproducible aromatherapy protocols. A systematic search on MEDLINE database using Cognitive Atlas and plant authenticity-related keywords was performed. Among the 806 articles yielded, 11 articles met eligibility criteria. Subjects administered with lavender EO displayed arousal decrease and sustained attention increase. Puzzling results were obtained regarding memory. Lack of EO quality assessment and high heterogeneity in inhalation protocols did not allow assessing whether different EO composition differently modulates cognition and whether placebo or expectancy effect can be discerned from EO effect itself. However, GABAergic pathway modulation exerted by linalool, a major lavender EO constituent, explains arousal reduction and sustained attention enhancement. In conclusion, aromatherapy can be an innovative, practical and non-invasive tool to prevent cognitive lapses.
Commentary: Yawning, acute stressors, and arousal reduction in Nazca booby adults and nestlings
