Effects of Cang-Ai volatile oil on depressed mood and cortical excitability in human

Cang-Ai Volatile Oil (CAVO) is a traditional Chinese medicine prescription that can be used for improving depressive symptoms through the regulation of dopamine (DA) and 5-hydroxytryptamine (5-HT) and inhibition of the inflammation. The purpose of this study is to verify whether CAVO has effects on depressed mood and cortical excitability in human. Forty-six healthy individuals were enrolled and instructed to inhale the CAVO for a month (five times per day). Each inhalation lasted for at least one minute. Depressed mood was assessed using Hamilton Rating Scale for Depression (24-items) (HAM-D24), and cortical excitability was tested using functional near-infrared spectroscopy (fNIRS). During fNIRS assessment, two types of verbal fluency tests (VFT) were adopted. One month of CAVO inhalation led to significant decreases in HAM-D24 score, and the mean concentration of oxygenated hemoglobin (HbO2) was significantly increased in the right frontal pole. Inhaling the CAVO can significantly improve depressed mood and cortical excitability in human. The improvement of cortical excitability is mainly focused on the right frontal pole, which is closely associated with emotional processing and executive functioning.