Human Studies

The experience of pain relief arises from physiological and psychological factors, and attributes such as the commercial features of analgesic treatments have been shown to influence placebo analgesia by affecting treatment expectations. Therefore, treatment valuation from price information should influence the placebo analgesic effect. This hypothesis was tested in a functional magnetic resonance imaging (fMRI) study in which healthy subjects were enrolled in a two-day experiment. On day 1, the participants (n=19) had treatment experiences with two different placebo creams during a conditioning session without receiving information on treatment price. On day 2, placebo analgesia was tested after providing price information (high vs. low) while fMRI was performed. The results showed that the higher-priced placebo treatment lead to enhanced pain relief. Placebo analgesia in response to the higher priced treatment was associated with activity in the ventral striatum, ventromedial prefrontal cortex and ventral tegmental area. The behavioral results indicate that the experience of pain was influenced by treatment valuation from price. Our findings reveal that the context of values in pain control is associated with activity in expectation- and reward-related circuitry. Perspective: Treatment with higher price was associated with enhanced placebo analgesia, and this effect was influenced by activities in expectation and reward processing brain areas. The context of value such as medical cost influences cognitive evaluation processes to modulate pain. Our study may help evaluate a patient's preference toward high-priced drugs.

Cognitive-behavioral therapy (CBT) is effective for pediatric chronic pain, but little is understood about which youth are most likely to benefit. The current study aimed to identify individual characteristics for which CBT yielded the greatest (and least) clinical benefit among adolescents with chronic pain participating in a multi-center randomized controlled trial (RCT) of internet-delivered CBT (WebMAP2). A total of 273 adolescents ages 11-17 with chronic pain (Mage=14.7; 75.1% female) were randomly assigned to internet-delivered CBT or internet-delivered pain education and evaluated at pre-treatment, post-treatment, and two longer-term follow-up periods (6 and 12 months). Multi-level growth models tested several adolescent- and parent-level moderators of change in pain-related disability including (1) adolescent age, sex, pain characteristics, distress, and sleep quality and (2) parent education level, distress, and protective parenting behaviors. Young adolescents (ages 11-14 vs. older adolescents ages 15-17) and those whose parents experienced lower levels (vs. higher levels) of emotional distress responded better to internet CBT treatment, showing greater improvements in disability up to 12 months post-treatment. This study expands knowledge on who benefits most from internet-delivered psychological treatment for youth with chronic pain in the context of a large multicenter RCT, suggesting several avenues for maximizing treatment efficacy and durability in this population. Perspective: This study identified adolescent- and parent-level predictors of treatment response to Internet-based CBT for pediatric chronic pain up to 12 months later. Younger adolescents and those whose parents had lower levels of distress may particularly benefit from this intervention. Older adolescents and those whose parents exhibit higher distress may require alternative treatment approaches.

Opioid-induced hyperalgesia (OIH) is a phenomenon whereby opioids increase patients' pain sensitivity, complicating their use in analgesia. We explored practitioners' attitudes towards, and knowledge concerning diagnosis, risk factors, and treatment of OIH.

Children's experience of chronic pain is influenced by the psychological and behavioural responses of their parents. However, the vast majority of research has been cross-sectional, precluding examination of how these dynamic relationships unfold over time. This study used a micro-longitudinal design to examine the daily relationships between parent mood and protective responses and child chronic pain. We also examined the moderating roles of child and parent pain catastrophizing to determine how the affective-motivational context may alter the influence of parent factors. Participants included 95 youth with idiopathic chronic pain (Mage=14.08; 71.6% female) and their parents. At baseline, parents and youth reported on their catastrophic thinking about child pain. For 7 consecutive days, parents completed daily assessments of their mood and protective responses, while youth completed assessments of their pain intensity, unpleasantness, and interference. Multi-level path analyses were conducted. At a daily level, greater parent protectiveness significantly predicted higher youth pain unpleasantness, interference, and intensity; more negative parent mood significantly predicted higher youth pain intensity and unpleasantness. Higher baseline youth pain catastrophizing predicted a stronger daily association between parent mood and youth pain unpleasantness and intensity. Higher baseline parent pain catastrophizing predicted a weaker daily association between parent protectiveness and youth pain interference. Findings suggest that parent mood and protective responses are dynamic, daily predictors of child pain. Findings also underscore the importance of addressing parents' daily mental health and protectiveness, among youth with chronic pain, and suggest different intervention targets depending on levels of child and parent catastrophizing.