Avaliação dos efeitos psicofisiológicos da L-Teanina em Modelo de ansiedade em humanos

Abstract

Anxiety is characterized by a state of tension, apprehension and discomfort that arise from internal or external danger imminent and may be a response to stress or environmental stimuli, and can measured by psychological and physiological changes of the individual. The L-theanine (gamma-L-glutamic acid ethylamide) or theanine is an amino acid found in Camellia sinensis, commonly known as "green tea". This amino acid has been used to reduce mental and physical stress, improving memory function and for treating anxiety. Because the anxiety disorders are among the most common disorders seen in both the general population and in the services of primary health care, it is relevant to the investigation of non-pharmacological methods for their treatment. The aim of this study was to investigate the psychophysiological effects of L-theanine on a model of anxiety in healthy humans. The study was an experimental, kind of randomized controlled clinical trial. Thirtie was composed of healthy students, male or female, which were inserted into one of three groups (control, L-theanine 1 or L-theanine 2). The participants of the experimental groups received 200 mg of L-theanine by a capsule as a single dose. The human anxiety was induced by Simulated Public Speaking Test - SPST and was assessed by physiological parameters (blood pressure, heart rate, ending temperature and electrical conductance of the skin) and psychological parameters (anxiety Inventory, trait - STAI-T and state - STAI-E). Statistical tests were considering parametric data the ANOVA (one way) and ANOVA for repeated measures data and considering the nonparametric Kruskal-Wallis and Friedman. Results were considered significant when showed a significance level of 95% (p < 0,05). There was a reduction in the levels of systolic blood pressure and heart rate in group L-Theanine 2 (p <0,05) and the electrical conductance of the skin in group L-theanine 1. There was also a reduction in the score of the STAI-E in both experimental groups since the score remained within the range of anxiety low throughout the test (<40 points). These results suggest that L-theanine has an anxiolytic effect on the physiological and psychological parameters that change in anxiety. Thus, this amino acid may be a non-pharmacological strategy in the treatment thereof.