Effect of Orange Essential Oil Inhalation on Mood and Memory in Female Humans

Abstract

Orange essential oil has previously been shown to have anti-anxiety activity in animal and human studies. However, the mood and cognitive enhancing effects have not been investigated. Therefore, the present study aimed to investigate the effect of orange essential oil on working memory and emotion in women. Eighty healthy females which age 18-25 years old were entered into a double-blinded, randomized, placebo-controlled, crossover designed study. Subjects were assigned to inhale placebo or orange essential oil for five minutes, and then their working memory and cognitive function were evaluated using Cognitive Drug Research (CDR) Computer Assessment Battery Test. The mood assessment was also evaluated using Bond-Lader Visual Analogue Scales. The results showed that orange essential oil enhanced spatial working memory, including: 1) the continuing of attention as indicated by increasing digit vigilance accuracy (t = -2.275, P = 0.027) and choice reaction time accuracy (T2) (t = -2.129, P = 0.038); 2) the quality of memory as indicated by the elevation of the percentages of word recognition accuracy (t = -2.312, P = 0.026), picture recognition accuracy (t = -8.286, P = 0.000), and spatial working memory accuracy (t = -2.110, P = 0.041); 3) the speed of memory as indicated by the reduction of reaction time of word recognition (t = 3.558, P = 0.001), picture recognition (t = 5.049, P = 0.000), and spatial working memory (t = 2.694, P = 0.010). The orange essential oil also improved alertness (t = -8.431, P = 0.000) and calmness (t = -3.912, P = 0.000). In conclusion, we suggest that orange essential oil has a potential as a cognitive enhancer and could also be used for relaxation.