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It’s been one of those months and one of those weeks. Busy, busy, busy, but good busy – grant success and publication success – a very rare combination for which you have to be thankful. Here’s our most recent publication, which I am very grateful to have been involved with.
Approximately 50% of people injured in motor vehicle collisions continue to report symptoms 12 months later. They demonstrate a constellation of symptoms that vary between individuals. For years, clinicians and researchers have hunted high and low for a unifying diagnosis or mechanism that might explain this persistent pain. Me, being me, couldn’t find any literature investigating the role of reward processing in those with chronic WAD. So, I went to work and collected data. And then with the help of the super impressive leader in her field, Professor Susanne Becker in Germany, we looked at associations between respondent’s responses and their physical and psychological health manifestations.
What Is Reward Processing?
In chronic pain, brain imaging studies suggest a shift from more pain centric to emotional brain networks. Changes in motivational/reward brain circuits in chronic pain have been suggested. It appears likely that motivation/reward processing is deficient and underlies persistent clinical features associated with this changed brain processing. Two motivational systems are believed to underlie behaviour: a behavioural activation system (BAS), regulating motivation to approach behaviour, and a behavioural inhibition system (BIS), regulating aversive motives and escape/avoidance. These systems are assumed to be key in pain behaviour and are hypothesized to be involved in the development of psychological symptoms, specifically pain catastrophizing and reduced quality of life. Clear as mud right! Essentially, one system helps with positive behaviour to move toward something desired and one helps with your motivation to avoid unpleasant outcomes. In theory, that’s how it should work, but in different pain conditions, this sometimes doesn’t occur, leading people to speculate that the changes in reward processing may be associated with a change in behaviours when people transition to chronic pain.
What Did We Find?
In line with current theories, we found a large proportion (30%–50%) of patients with whiplash-associated disorders (WAD) showing signs of altered function in the BIS (reduced motivation to avoid unpleasant outcomes) and BAS (reduced motivation to move towards something pleasant) suggesting altered reward processing and motivation in these patients. These changes were associated with increased pain interference, disability and all mental health measures, but not pain. Interestingly, with some fancy stats, we showed that the changes in reward processing were not associated with different psychological manifestations to worsen symptoms. That is, pain was associated with worse disability, but pain did not influence BIS or BAS to change this association.
What Might This Mean?
Although associations between worse health outcomes and motivation were demonstrated, it does not appear as though motivation (as a trait) alters the health outcomes of people with chronic WAD moreso than pain itself. On the contrary side of these findings, altered BIS/BAS did not influence the effect of psychological manifestations on pain or disability. Thus, although interesting, the BIS/BAS measure in of itself is not going to alter our current understanding of chronic pain in those with whiplash…the journey continues!!!
Reference:
Smith, A. & Becker, S. Increased behavioural inhibition and decreased behavioural activation in whiplash-associated disorders: Associations with health outcomes. Eur J Pain. First Published: 22 September 2024. https://doi.org/10.1002/ejp.4721
