Laughter therapy intervention resulted in a significant reduction in systolic blood pressure and heart rate, accompanied by a significant increase in plasma concentration of serotonin and a significant decrease in salivary concentration of chromogranin A. Questionnaire surveys of SF‐8, GDS‐15, and Vitality Index demonstrated alleviation of depression and improvement of sociability and activity in older people. This evidence concerns the gene CHGA and major depressive disorder.