Katja Weimer
Postdoctoral Researcher, Department of Psychosomatic Medicine and Psychotherapy, Medical University Hospital Tübingen

Social mediators and moderators of placebo effects in children and twins

Recent research has shown that placebo effects could be elicited through social observational learning in adults, and social mediators and moderators were repeatedly discussed to have an impact on placebo effects in children. Social observational learning as well as expectations of parents could be important in children as they have fewer own experiences in medical settings, but only few studies investigated such factors. Furthermore, studies with mono- and dizygotic twins could give further insights into effects of shared and individual learning experiences as well as into the impact of genetics on placebo effects.
In a series of studies, effects of social mediators and moderators on placebo effects in children, adolescents, and adult twins were investigated: 1) An experimental study tested the relationship between placebo effects on cognitive performance and expectations in children and their parents; 2) Impact of parents’ expectations, mood, and traits on children’s pain experience was investigated in a questionnaire-based study in the context of dental treatments; 3) In a 2×2 study design, children observed an effective intervention to reduce heat pain in their mother or an unfamiliar woman (a trained model), either live or in a video; 4) In the control group of the later study, placebo effects by verbal suggestions only were tested in children and their mothers; 5) Placebo analgesia was induced through conditioning in mono- and dizygotic adult twins to analyze effects of an individual learning experience, a shared environment, and genetics.
In summary, placebo effects could be induced through direct observation of an effective treatment and verbal suggestions in children (except on cognitive performance), and trough conditioning in twins. However, there were no relationships in placebo analgesia between family members, neither between children and parents nor between twins. Placebo effects seem to be mainly affected by individual learning experiences.


Katja Weimer is a postdoctoral researcher at the Department of Psychosomatic Medicine and Psychotherapy, Medical University Hospital Tübingen. She studied psychology at the University of Koblenz-Landau, and completed her PhD about placebo effects on motion sickness and gender differences under supervision of Prof. Paul Enck in Tübingen in 2012. Since then, she investigated mechanisms and aspects of placebo effects on cognitive performance and pain in adults and children. Her current work focuses on placebo effects in children, and social learning of placebo effects in children and adults which is funded by an own grant of the German Research Foundation. Currently, Paul Enck and Katja Weimer are establishing a German twin registry, “TwinHealth”, at the University Hospital Tübingen. Furthermore, she is interested in the impact of study designs on placebo effects, and is engaged in psychophysiological research in children with functional bowel disorders and obesity, and in adults with somatic symptom disorders.