457. EXPLORATION OF THE MECHANISM OF ACTION OF MASSAGE INTERVENTIONS IN HUMAN SUBJECTS

Abstract Background We have previously demonstrated that a structured Swedish Massage (SMT) intervention versus a touch control intervention (LT) has profound acute and longer term effects on immune function, HPA function, oxytocin and vasopressin (Rapaport et al 2010; Rapaport et al 2012) in healthy control subjects. We have also demonstrated that 12 session of SMT (vs. LT) causes a clinical and statistically significant decrease in both Hamilton Anxiety and Hamilton Depression scores in subjects with GAD (Rapaport et al 2016; Rapaport et al 2018). For a subset of these subjects the effect was sustained for months to years after the intervention (Rapaport et al 2023). We have also demonstrated that SMT vs. LT has a profound effect in decreasing fatigue and increasing quality of life in breast cancer survivors with chronic cancer-related fatigue (Kinkead et al 2018). At this time there are no brain imaging studies investigating the impact of a single (pre-to-post) whole-body massage on brain function. Aims & Objectives This study investigated the acute effects of SMT vs. LT on brain circuitry in healthy subjects. Based on our previous work suggesting that SMT can enhance immune function and decrease markers of inflammation, while increasing oxytocin and decreasing vasopressin and HPA activity, we hypothesized that SMT activates two distinct but overlapping neural networks: vagus nerve stimulation of ascending afferent fibers to the brain via the nucleus tractus solitarus (NTS) and C-tactile fibers which enervate hairy areas of the skin. We therefore investigated brain activation in brain regions implicated in these pathways after a single whole body touch intervention. Method This study was a 2 arm, randomized, masked study investigating the effects of SMT vs. LT control on brain activity in normal control subjects. Subjects, medically healthy subjects ≥18 years of age but less than 65 years of age, underwent fMRI followed by one 45 minute SMT (n=20) or LT (n=20) session, followed immediately by a second fMRI. Resting state fMRI and task-based fMRI during a neutral/fearful/angry faces task were collected and analyzed in brain regions of interest including the anterior cingulate cortex, amygdala, dorsolateral and ventrolateral prefrontal cortex and post central gyrus. We also evaluated heart rate variability, EKG, pulse, respirations, and blood pressure. Results Preliminary analyses in 10 subjects per group indicate that relative to LT, SMT increases BOLD activity for neutral faces vs shapes (p = 0.08) during the faces task in the dorsolateral and ventrolateral prefrontal cortex and post central gyrus. Future analyses will investigate the relationship between change in brain activity and sympathetic and parasympathetic function. Discussion & Conclusions These results are the first indication that a single session of a manualized touch intervention (SMT) vs a touch control (LT) changes brain activity during a neutral/angry/fearful faces task and will provide insight into the mechanism of action of massage interventions.