Correlations between the responses of electrogastrograms, heart rate and respiratory rate to the stress of the mirror drawing test in human subjects.

An electrogastrogram (EGG) recorded on the skin is believed to reflect the electrical activity of the gastrointestinal tract. In this study, linear correlations were calculated for the EGG spectral frequencies and the power ratios, changes in heart and respiratory rate before and during mirror drawing test (MDT) stress and after having meals, with the changes in the sympathetic tone indicator (LF/HF) and HADS anxiety and depression scores in human subjects (n=48). Depression scores had a negative linear correlation with the EGG resting frequencies of the epigastric and supraumbilical 6 cpm groups (5.0-7.4 cpm). Anxiety scores had a positive linear correlation with the EGG area power ratio of the resting to MDT stress responses of the epigastric and infraumbilical 6 cpm groups (6 cpm area during MDT/that during fasting rest). The resting LF/HF had a positive linear correlation with the EGG area power ratio of the resting to MDT stress responses of the epigastric and infraumbilical 3 cpm groups (2.5-4.9 cpm). The resting LF/HF ratio had a negative correlation with the area power ratio of the resting to postprandial responses (postprandial power/resting power) in the epigatric, supraumbilical and infraumbilical 6 cpm groups. The resting LF/HF ratio had a positive linear correlation with the heart rate at rest and during MDT-stress. In contrast, the resting LF/HF ratio had a negative linear correlation with the respiratory rate at rest and during MDT-stress. EGGs of the surface electrical activities of the gastrointestinal tract were influenced by acute MDT-stress and their frequencies and their response power ratios were correlated linearly with anxiety scores, depression scores and the sympathetic tone indicator, the LF/HF ratio.