Emotional and physiological responses to touch massage

Abstract

Background: Clinical findings indicate that touch massage has the ability to induce positive emotions and influence stress responses. However, little is known about mechanisms that can explain observed responses. Aim: To understand mechanisms behind observed emotional and physiological responses during and after touch massage. Methods: This thesis is based upon healthy volunteers in Studies I, II, IV and patients undergone aortic surgery in Study III. Study I had a crossover design, participants served as their own controls. After randomization they received TM on one occasion and the other occasion served as control. Heart rate variability (HRV), heart rate (HR) saliva cortisol concentration, glucose, insulin in serum and extracellular (ECV) levels of glucose, lactate, glycerol and pyruvat were measured before, during and after TM/control. In study II, functional magnetic resonance imaging (fMRI) was used in order to measure brain activity during TM movement. The study design included four different touch stimulations, human touch with movement (TM movement) human stationary touch and rubber glove with or without movement. Force (2.5 N) and velocity (1.5 cm/s) were held constant across conditions. The pleasantness of the four different touch stimulations was rated on a visual analog scale (VAS-scale). Study III had a randomized controlled design. The intervention group received TM and the control group rested. HRV, cortisol, glucose, insulin in serum, blood pressure, oxygen saturation, respiratory frequency and anxiety levels were measured before, during and after TM/control. In study IV participants were interviewed about experiences after TM and the text was analyzed in by qualitative content analyze. Results: Study I. TM reduced the stress response as indicated by decreased heart rate and decreased activity in the sympathetic nervous system, followed by a compensatory decrease in parasympathetic nervous activity in order to maintain balance. Cortisol and insulin levels decreased significantly after intervention, while serum glucose levels remained stable. A similar, though less prominent, pattern was seen during the control session. There were no significant differences in ECV concentrations of analyzed substances. Study II. Human moving touch (TM movement) was significantly rated as the most pleasant touch stimulation. The fMRI results revealed that human moving touch (TM movement) most strongly activated the pregenual anterior cingulate cortex (pgACC). Study III. Selfrated anxiety levels significantly decreased in the patient group that received TM compared with control group. There were no significant differences in physiological stress-related outcome parameters between patients who received touch massage and controls. Study IV. In this study participants talked about the experience of TM in terms of rewards. Expressions like need, desire, pleasure and conditioning could be linked with a theoretical model of reward. Four different categories were identified as wanting, liking, learning and responding. In conclusion: Results from these studies indicate that receiving TM is experienced as rewarding. Touch massage movement activates a brain area involved in coding of rewarding pleasant stimulations. TM decreases anxiety and dampens the stress response by a decreased activation of the sympathetic nervous activity. Our results indicate that TM is a caring intervention that can be used to induce pleasure, decrease anxiety and stress in the receiver