Longitudinal intra-individual variation of salivary alpha-amylase activity and its relation to perceived psychological stress

In order to assess stress levels by means of an objective and quantitative method, salivary alpha-amylase (sAMY), as a parameter of sympathetic nervous activity, has been considered to be useful, because saliva collection is easy, stress-free and noninvasive. Although a rapid and easy-to-use analytical device for the measurement of sAMY activity (Amylase monitor, Nipro Co., Ltd.) has been developed, whether the device is valuable in assessing stress still remains uncertain. To clarify this issue, an examination of longitudinal individual variation of sAMY activity is also considered to be valuable, in addition to previous experimental and epidemiological studies. We investigated longitudinal intra-individual variation of sAMY activity at the workplace and its relation to perceived psychological stress in a male non-smoking office worker. A total of 391 measurements of sAMY activity were carried out during 15 months on the basis of the subject\u27s willingness. In addition, perceived psychilogical stress, blood pressure, and health rate were partially investigated. Perceived psychological stress was assessed by means of a modified visual analogue scale. The levels of sAMY showed a 5-81 KU/L range. There were seasonal variations indicating an increase in the values of sAMY during winter and spring. The levels of sAMY were slightly and positively correlated to those of perceived psychological stress. Perceived psychological stress had a positive asociation with diastolic blood pressure. Perceived psychological stress was positively, and heart rate was negatively related to the investigated time at work. However, no significant associatoin between sAMY activity and the investigated time was found. The present study suggested that repeated measurement of sAMY activity, similar to that of blood pressure, may be useful to estimate perceived psychological stress