Placebo Analgesia Response No Higher in Children than In Adults

The placebo effect was defined as the difference in perceived pain intensity on the placebo-treated site compared with the control site during the test phase on day 2. As expected, pain ratings on the placebo site were significantly lower than on the control site (main effect of condition: F(1,45) = 19.3, P < .001)  indicating significant analgesic placebo effect in both children and adults.

However, the researchers observed no significant difference in the perceptions of pain in adults vs children (no significant group by condition interaction: F(1,45) = .02, NS), indicating that the placebo analgesic response in children is not greater than in adults (Cohen α: children = .64, adults = .64).

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The researchers then examined how the conditioning phase affected the placebo analgesic effect during the test phase. They found that the placebo effect in children was significantly predicted by the conditioning phase (b = .67, β = .53, t₍₂₂₎ = 2.8, P < .01) but not in adults (b = −.4, β = −.03, t₍₂₁₎ = −.32, NS). The conditioning effect explained 27.8% of the variance in the placebo effect in the group of children (R² = .28, F(1,23) = 8.5, P < .01).

“Our experimental study points toward an increased relevance of learning processes for treatment outcomes in children,” the researchers wrote. “Given that the foundation for one’s treatment experiences is laid during childhood and may influence an individual’s treatment experiences and attitude for life, future studies should explore the role of placebo responses and particularly the role of associative learning processes in children and adolescents in more detail.”

Reference

1. Wrobel N, Fadai T, Sprenger C, Hebebrand J et al. Are Children the Better Placebo Analgesia Responders? An Experimental Approach. The Journal of Pain. 2015; doi:10.1016/j.jpain.2015.06.01.