Children do not have a greater placebo analgesia response rate than adults, but conditioning appears to play a more important role in their pain responses, according to research published in The Journal of Pain.
The findings suggest that the influence of past experiences plays a greater role in children’s perceptions of future outcomes than in adults.
Previous clinical trials have examined the placebo effect in children, but different components that may have skewed results could not have been dissociated. (For example, children’s migraines last for a shorter amount of time than adults’, and some conditions such as childhood migraine and some types of epilepsy can resolve during adolescence. These factors could have affected results in previous clinical trials.)
For this study, Nathalie Wrobel, MSc, from the Department of Neurology at the University Hospital Essen, Germany, and colleagues recruited 27 children (aged 10 to 15 years, mean = 13.5 ± .23) and 30 adults (23 to 40 years, mean 27.5 ± .61) Participants were partially deceived as to the nature of the study and were told that the study’s purpose was to examine differences in pain perception and analgesia across the life span.
Participants went through two days of experiments: the first day was conditioning, and the second was testing. They were exposed to a heat probe on their forearm to evoke pain levels of visual analog scale (VAS) 20 and 50. Cream was applied to spots on the participants’ arms from two different tubes—the researchers told participants that one of the tubes was a lidocaine-like anesthetic cream that could reduce or even completely abolish pain, and they told participants the other was a control cream. In reality, both creams were the same and did nothing to reduce pain.
On day one, after the creams were applied, they waited ten minutes for the creams to “take effect,” and then they were removed. The researchers then applied the heat sensor at higher levels on the spot where the control cream had been and at lower levels where the placebo cream had been. This was to enforce the belief that the placebo cream was really a painkiller. On the second day, the researchers applied heat to both spots at the same levels.