Treatments of psychosomatic symptoms in Alzheimer's disease: a scoping review of the potential therapeutic effects of essential oils

Alzheimer's disease, a type of dementia, poses serious challenges to patients, especially older people, and no definitive treatment is available for this disease, with drug treatments having many side effects. As essential oils of plants deserve particular attention in the treatment of diseases, this study aimed to review the potential therapeutic effects of essential oils on treatment of psychosomatic aspects of Alzheimer's disease. To collect information, we searched different databases, including MagIran, SID, IranDoc and IranMedex, Embase, Science Direct, PubMed, Google Scholar, Scopus and Web of Science using the keywords of essential oil, Alzheimer, acetylcholinesterase, memory, forgetfulness, aromatherapy, medicinal plant, herbal drugs, and their Persian equivalents from January 2010 to June 2022; the search included both single and multiple keywords. We retrieved 233 articles, reviewed the titles, abstracts, and full texts of the articles, and then included 25 related articles in this review (11 in vitro studies and 14 in vivo studies). The study results of in vitro and in vivo studies showed the effectiveness of different essential oils such as salvia family, tangerine and lemon oils, Juniperus communis, Anthriscus nemorosa, olibanum, inhaled coriander, Schisandra chinensis, lavender, rose essential oil, Nepeta cataria, Cinnamomum zeylanicum and Lippia origanoides, on memory and learning, enzymes, oxidative stress and inflammation, behavioural and cognitive symptoms in Alzheimer's disease. These findings suggest that essential oils can serve as complementary therapies for neurodegenerative diseases like Alzheimer's and for addressing memory impairments, although further research, especially human clinical trials, is needed to validate these findings, determine optimal dosages, and explore the long-term safety of essential oils in clinical settings.