Just a touch away: CT-optimal touch perception and its influence on pain and itch

Abstract

In this thesis I aimed to investigate whether CT-optimal touch can ameliorate pain and itch in healthy individuals as well as in Parkinson patients suffering from chronic pain. I created a novel model, used experimental studies, a casereport and a longitudinal study to understand the underlying mechanisms of CT-optimal touch and its interaction with pain processing. I show that CT-optimal touch can ameliorate chronic pain, that it might be used when immediate pain relief is needed and that it is feasible to implement in daily-routine. Furthermore, CT-optimal touch can also reduce electrically induced itch. In addition, I show that the ameliorating effect of CT-optimal touch is independent of the perceived pleasantness. This further emphasizes that it is necessary to differentiate between CT-optimal touch and affective touch, which is substantiated by Case et al. (2023) and Schirmer et al. (2023). Furthermore, the results of an online study showed that people who feel touch deprived, report to observe touch as more pleasant. We also show that this has negative consequences for our general well-being (Hasenack, Meijer, Kamps, et al., 2023). As feeling touch deprived can have a negative impact on our mental health, this is relevant for the post-COVID-19 period as well. It also further emphasizes the importance of receiving touch frequently. Taken together, this thesis further substantiates the importance of promoting receiving as well as providing CT-optimal touch as it appears to have many beneficial effects. Important first steps of implementing CT-optimal touch as a new non-pharmacological pain treatment are provided here as well. Expanding our current knowledge on the neurophysiology behind this type of touch and its interaction with pain and itch is a necessity for our further understanding.