February 11, 2023
Aromatherapy has been one of the most common complementary and alternative treatments for psychological diseases, such as sleep disorders, anxiety, and depression. Essential oils have high efficacy with fewer side effects as compared to conventional drugs. However, the underlying mechanisms that mediate the beneficial effects of essential oils in the treatment of psychiatric disorders remain to be elucidated.
Anxiety is one of the most common mental disorders and is characterized by excessive and uncontrollable nervousness and fear. Typical subtypes of anxiety include generalized anxiety disorder, obsessive-compulsive disorder, post-traumatic stress disorder, social anxiety disorder, panic disorder (with or without agoraphobia comorbidity), and phobias. The first-line medications for most anxiety subtypes are selective serotonin (5-HT) reuptake inhibitors (SSRIs), including paroxetine, sertraline, citalopram, escitalopram, fluvoxamine, and fluoxetine. However, the long-term use of these SSRIs is associated with various adverse effects, such as bleeding, digestive problems, hyponatremia, excessive sweating, emotional blunting, and increased risk of suicidality.
Cinnamon, the bark of Cinnamomum cassia, has been widely used in traditional medicine to treat various diseases, such as ischemia, diabetes, peptic ulcer, and cancers. The essential oil derived from cinnamon bark possesses a variety of pharmacological activities, such as antibacterial, antioxidative, and anti-inflammatory effects. Cinnamon essential oil largely contains volatile compounds, such as cinnamaldehyde and its derivatives, which are small molecules that easily penetrate the brain by crossing the blood–brain barrier (BBB) and could be involved in the regulation of the neuroendocrine system and neurotransmitters and thus affect behavioral outcomes.
Calming essential oils are frequently used to reduce anxious feelings, but it is important to reduce brain inflammation as well. Inhalation of cinnamon bark essential oil, or its main constituent trans-cinnamaldehyde, showed the ability to reduce anxiety in several preclinical models. The researchers found that the oil modified expression of several genes associated with anxiety, particularly those related to brain cell survival and neuroinflammation.