Influence of Chronic Mental Stress on Taste and Pungency Due to End-of-Semester Examination

Abstract

Mental stress is a known risk factor for lifestyle-related diseases. Previously, we reported that short-term stress sharpens the sense of taste and dulls the sense of pungency, but in this study, we examined the effects of chronic mental stress on taste and pungency by comparing normal days with end-of-semester examination days. Furthermore, the relationship between pungency measured on the tongue and the corresponding skin current value causing forearm pain was investigated. Taste and pungency were blindly measured using the filter paper disc method on a normal day and the day before the end-of-semester examination (chronic mental stress day) in 27 healthy male university students. A commercially available taste liquid for taste testing and a capsaicin solution for pungency were used. Taste perception was also tested using cognitive thresholds, and pungency was tested using a unified concentration and maximum tolerated threshold concentration. With a PainVision^® device, currents were gradually increased in forearm skin to quantify the sensation of pain. Stress levels were measured with electrocardiography and a questionnaire. The median cognitive threshold for taste (salty, sweet, sour, and bitter) was slightly dulled due to chronic mental stress on the day before examination day and was duller than that on the normal day, but the difference was not significant. Pungency and forearm skin pain were significantly dulled on the day before examination day, and pungency correlated significantly with forearm skin pain. Chronic mental stress appeared to dull especially the sensitivity to pungency and skin pain.