Comparison of the effects of two amino acids, Gamma-aminobutyric acid (GABA) and L-theanine, on sedation, anxiety, and cognition in preoperative surgical patients – A randomized controlled study

Preoperational anxiety affects the outcome of anesthesia and surgery. Benzodiazepines impair psychomotor performance and cause excessive sedation. L-theanine is a unique amino acid found in green tea. It prevents stress, produces anxiolysis, modulates alpha activity, and provides beneficial effects on mental state, including sleep quality. Gamma-aminobutyric acid (GABA) is a non-proteinogenic amino acid and a phytochemical that is the main inhibitory neurotransmitter in the mammalian brain. It is beneficial in anxiety and stress regulation. Hence, alternative premedicants such as L-theanine and GABA will have a widespread appeal and are safer. The primary objective was to study and compare the effects of L-theanine and GABA on preoperative anxiety, sedation, and cognition in patients posted for major elective surgeries. The secondary objective was to study adverse reactions. A total of 168 patients aged between 18 and 55 years, belonging to the American Society of Anesthesiologists physical status class I and II, and satisfying all inclusion criteria were randomly divided into three groups that received either oral L-theanine, oral GABA, or oral alprazolam 0.25 mg. The anxiety score, sedation score, and psychomotor and cognitive performance scores were noted 60 minutes before and after the administration of the drugs. Alprazolam produced more sedation than GABA and L-theanine (P = 0.0001). Psychomotor and cognitive functions improved with L-theanine and GABA (P = 0.0001) and decreased with alprazolam (P = 0.0001). GABA and L-theanine result in effective preoperative anxiolysis with minimal sedation and improvement of cognitive skills.