Background & Aims
The fear-avoidance model of chronic pain describes how negative expectations, pain-related fear and avoidance behavior can reinforce each other and contribute to the development and maintenance of chronic pain disability (Vlaeyen & Linton, 2012). While there is ample evidence for reinforcing relationships between these variables (Leeuw et al., 2007; Meulders, 2019), the dynamics of these relationships have not been examined in detail. Furthermore, experimental studies have shown that there are substantial individual differences in fear learning (Lonsdorf & Merz, 2017), and interventions aimed at reducing pain-related fear have shown mixed results (Pincus et al., 2010), warranting a closer look at the underlying dynamics of fear learning and extinction processes. Here, we apply the complex systems approach recently adopted in mental health research (Hayes & Andrews, 2020) to the study of pain and extend it to an experimental setting to better capture the complex dynamics involved.
Methods
University students without pain complete a fear conditioning experiment consisting of three phases: At baseline, simple visual stimuli (conditioned stimulus; CS) are presented next to randomly administered painful electrocutaneous stimuli (unconditioned stimulus; US); During the acquisition phase only the CS+ is accompanied by a US. During the extinction phase, no USs are presented anymore. Between the CS and US on every trial, participants give pain expectancy and fear ratings, and have the opportunity to avoid the US by firmly gripping a hand dynamometer. We also measure skin conductance as an unconscious measure of fear. We use time-varying VAR models to examine the relationships between expectancy, fear and avoidance, and to examine how they change across experimental phases. We analyze the data both at the group level, to see the commonalities across participants, and at the individual level, to get insights into differences among participants.
Results
The fear-avoidance model suggests that during pain-related fear learning, people first form expectancies between a conditioned stimulus and pain, which then leads to fear responses to the conditioned stimulus, which subsequently induces avoidance behavior. In the acquisition phase, we test if this cascading effect is indeed present during fear learning in a controlled environment, both at the group and individual level, and examine individual differences in the dynamics of fear learning. Exposure therapy for chronic pain is built on the premise that a disruption in avoidance behavior will change expectancies and gradually lower pain-related fear. We do not manipulate avoidance behavior directly, but examine if such a pattern of decreased avoidance leading to changes in expectancy and fear occurs spontaneously in (some of) our participants during the extinction phase of the experiment.
Conclusions
This study contributes to a better understanding of the temporal relationships between expectancy, fear and avoidance at a short time scale, and as such, the complex processes involved in pain-related fear learning (Vlaeyen & Linton, 2012). The results may also provide useful insights for optimizing treatment (Gatzounis et al., 2021). Chronic pain and disability are regarded as complex and dynamic, however, capturing this complexity in research remains challenging. Next to a substantive contribution, this study also explores new methodological avenues that could move us closer to a dynamic understanding of pain by adopting a complex systems approach and extending it into the laboratory.
References
Gatzounis, R., den Hollander, M., & Meulders, A. (2021). Optimizing long-term outcomes of exposure for chronic primary pain from the lens of learning theory. The Journal of Pain, 22(11), 1315-1327.
Hayes, A. M., & Andrews, L. A. (2020). A complex systems approach to the study of change in psychotherapy. BMC medicine, 18, 1-13.
Leeuw, M., Goossens, M. E., Linton, S. J., Crombez, G., Boersma, K., & Vlaeyen, J. W. (2007). The fear-avoidance model of musculoskeletal pain: current state of scientific evidence. Journal of behavioral medicine, 30, 77-94.
Lonsdorf, T. B., & Merz, C. J. (2017). More than just noise: Inter-individual differences in fear acquisition, extinction and return of fear in humans-Biological, experiential, temperamental factors, and methodological pitfalls. Neuroscience & Biobehavioral Reviews, 80, 703-728.
Meulders, A. (2019). From fear of movement-related pain and avoidance to chronic pain disability: a state-of-the-art review. Current Opinion in Behavioral Sciences, 26, 130-136.
Pincus, T., Smeets, R. J., Simmonds, M. J., & Sullivan, M. J. (2010). The fear avoidance model disentangled: improving the clinical utility of the fear avoidance model. The Clinical journal of pain, 26(9), 739-746.
Vlaeyen, J. W., & Linton, S. J. (2012). Fear-avoidance model of chronic musculoskeletal pain: 12 years on. Pain, 153(6), 1144-1147.
Presenting Author
Gwen van der Wijk
Poster Authors
Topics
- Mechanisms: Psychosocial and Biopsychosocial