Role of psychophysiological factors in acute and chronic itch and pain.
The major aim is to unravel the processes underlying psychological factors, such as attention and emotions, influencing the experience of itch and pain in healthy and chronic state.
Although itch and pain are distinct somatosensory sensations, they share neurobiological pathways, can interact at the spinal cord level (e.g., pain can reduce itch by scratching), and activate corresponding brain areas. When symptoms of itch and pain are chronic, comparable processes of sensitization are supposed to play a role that result in an increased sensitivity to somatosensory sensations. Furthermore, psychophysiological factors, such as attention and cognitions, have frequently been shown to play an important role in acute and chronic pain. However barely investigated, it is likely that psychophysiological factors also play a role in acute and chronic itch. Research into the psychophysiology of itch in comparison to pain is the focus of different projects (see also research program “Placebo research: Pain and itch” and “Psychoneurobiology in itch and pain”):
1. Role of attentional processes in itch and pain
Attentional processes are one of the earliest psychophysiological information processes that highly determine the experience of somatosensory sensations. However, research into attentional processes regarding itch is very limited, although itch demands attention and is hard to ignore (attentional disengagement). To investigate itch- and pain-related attentional processes, with a particular focus on attentional disengagement. To this end, different behavioural attention tasks were developed, including a somatosensory attention task (SAT) with somatosensory itch and pain stimuli and computer tasks with visual itch and pain stimuli. Using these tasks, we investigate the extent to which people attend to itch and pain stimuli and whether attentional disengagement can be trained.
Supervisors Leiden University: Dr. Antoinette van Laarhoven & Prof.dr. Andrea Evers
Researcher: Jennifer M. Becker
2. Psychoneurobiology of post-burn itch: a pilot study
This project, subsidized by the Dutch Burn Wound Foundation, investigates the processing of itch and the role of itch sensitization processes in patients with burn wounds suffering from long-term itch in comparison to healthy subjects. The study explores four different aspects. Sensory aspects are investigated by measuring sensitivity to and conditioned modulation of itch and pain by use of quantitative sensory testing (QST) stimuli; neurophysiological processing of itch is measured using electroencephalography (EEG); automatic responses to itch stimuli are measured by use of computer tasks such as the modified Stroop task modified for itch and the approach avoidance task; and cognitive-affective responses to itch are measured with validated questionnaires.
Researchers Leiden University: Dr. Antoinette van Laarhoven & Prof.dr. Andrea Evers
3. Itch and pain: Common and distinct psychophysiological factors
In this project, different psychophysiological aspects, i.e., sensory, cognitive and affective factors, were investigated regarding both itch and pain. Studies investigating sensory aspects showed that patients with chronic itch and pain generally displayed a heightened sensitivity to itch and pain, generally and symptom-congruently (e.g., patients with chronic itch to itch). In addition, patients with chronic itch also showed an impaired central modulation of itch by conditioned itch modulation. With respect to affective-motivational factors, was shown that negative rather than positive emotions resulted in a heightened itch and pain sensitivity. As to cognitive aspects, it has been shown that inducing negative expectations led to increases in itch and pain, with stronger effects for itch.
Finished PhD project
These studies were conducted in the context of the PhD project of Antoinette van Laarhoven, with Prof. dr. Andrea Evers as the first promotor.
This research program is part of the Research Group Psychoneurobiology of Health and Disease (www.andreaevers.nl)