Oxytocin has traditionally been known as a hormone involved in promoting parturition and milk ejection. However, recently, its role has been revealed to extend to metabolic control, weight control, social behavior, and emotional regulation. Oxytocin’s anti-anxiety effect has been particularly noteworthy. Previous human studies have reported that the intranasal administration of oxytocin reduces social anxiety and fear. Aromatherapy and hand treatment reportedly have anxiolytic effects and are effective in reducing anxiety, as it relaxes the nervous system, lowers the cortisol levels, and suppresses the activity of the amygdala. Oxytocin can potentially be applied in clinical settings, given that the number of individuals with anxiety has continued to increase and oxytocin has been suggested to be involved in the anti-anxiety effects of aromatherapy and hand treatment. In the present review, we focus on the anti-anxiety effect of oxytocin and discuss its relationship with the effects of aromatherapy and hand treatment.

Background: The findings of existing studies on the effects of olfactory stimulation on cognitive function in older adults with normal cognitive function and patients with Alzheimer’s disease are discordant. This study aimed to investigate the relationship between olfactory stimulation and olfactory and cognitive functions in healthy older adult participants. Methods: Six healthy men and 22 women aged 65–74 years (68.9±2.9 years) with unremarkable medical histories were included in this study. They were randomly assigned to two groups—an intervention group whose participants were given three essential oils (lavender, hinoki cypress, and yuzu) to choose one each time and inhale twice daily (evening and morning) for 20 seconds over 4 weeks and a control group whose participants were given odorless purified water to inhale twice a day (evening and morning) for 20 seconds over 4 weeks. Each participant’s olfactory and cognitive functions, profile of mood states, and visual analog scale were assessed before and after the intervention. Olfactory function was evaluated by using the Olfactory Identification Investigation (Open Essence), and cognitive function was assessed using the Montreal Cognitive Assessment–Japanese version (MoCA-J). Results: The participants in the intervention group showed significant increments in olfactory identification ability and cognitive function scores after the intervention, suggesting a link between a person’s changes in MoCA-J scores and in olfactory identification ability. Conclusions: This study suggests that healthy older people could prevent olfactory function decline, and, by extension, cognitive function decline, by consciously scenting essential oils daily.

Volatile compounds emitted by herbivore-damaged plants enhance the defense responses of neighboring, undamaged plants. However, the practical application of such damaged plants in agriculture has yet to be realized due to various constraints. To address this challenge, recent studies have demonstrated that komatsuna and soybean plants grown near peppermint or candy mint, which continuously and abundantly release volatile organic compounds, exhibit increased expression of defense-related genes, such as pathogenesis-related 1(PR1), in their leaves, thereby strengthening their resistance to pests and diseases. However, the potential effects of this approach on tomato, a globally significant crop in the Solanaceae family, remain unexplored. In this study, young tomato plants were cultivated for seven days in a growth chamber, positioned 10 cm from peppermint. The results revealed an upregulation of PR1 expression in tomato leaves, indicating that peppermint effectively enhances tomato defense responses. Additionally, a field experiment was conducted in which tomato plants were placed at varying distances from peppermint and grown for three weeks. The findings showed that tomatoes positioned 20 cm, 50 cm, and 100 cm from peppermint experienced damage rates of 20.9%, 37.4%, and 74.3%, respectively, compared to control plants grown 200 cm away. These results suggest that peppermint may serve as an effective companion plant for pest management in tomato cultivation.