Verbally induced placebo effects on heat pain tolerance in preschool-aged children

Unlike in adults and older children, placebo hypoalgesia has not been experimentally studied in preschool-aged children. Because of their cognitive developmental stage and sensitivity to adult-provided cues, this age group may be particularly susceptible to pain modulation through verbal suggestions. Similar to a typical clinical context, we examined verbally induced placebo effects in 117 children aged 3 to 6 years using a developmentally adapted heat pain tolerance task. A placebo condition ("magical" analgesic cream) was compared with either a control cream or a natural history condition. Behavioral (heat pain tolerance [HPTol]) and self-reported pain outcomes were assessed. Child and parental characteristics were evaluated as potential predictors of the placebo effect. Significant placebo effects on HPTol were observed compared with both control conditions, with larger effects in the placebo vs control cream comparison. No placebo effect was found for self-reported pain. Analyses of potential predictors indicated stronger placebo effects in younger children, in those with higher inhibitory control, and in children of mothers with greater optimism. No other child or parental characteristic significantly predicted the placebo effect. This is the first report that verbal suggestions can elicit robust behavioral placebo effects on HPTol in preschool-aged children, suggesting that expectation-based interventions may be harnessed even at this early developmental stage. The larger placebo effect observed when compared with a control cream than with a natural history condition suggests that treatment contrasts may modulate placebo responding in young children. The dissociation between behavioral and self-reported measures highlights the need for multimethod pain assessment in early childhood.