Growing evidence supports the positive impact of music on child health
Venue: Acta paediatrica

The study by Uggla et al. (1) in this issue of Acta Paediatrica adds valuable knowledge to the growing literature on the use of music in clinical child care. The authors performed a randomised control trial (RCT) on the effects that specifically designed music therapy had on the heart rates of children, from two to 16 years of age, receiving haematopoietic stem cell transplants. As with all good initial studies, this research has prompted a number of questions for future research. The authors argue that the kind of music therapy they introduced may have prevented the development of posttraumatic stress disorder (PTSD) after stem cell transplantation, which is itself a traumatic experience. On the basis of previous studies, they stated that the high heart rates observed during such surgery were an indicator of an increased risk of future PTSD after the operation. The results of their study provided the first confirmation of their hypothesis that individualised and interactive music therapy would lower the heart rate in these children and possibly also lower the risk of subsequent PTSD. However, the latter hypothesis was not tested in this study as there was no follow up. First of all, there are a couple of technical notes that need to be highlighted. The sample sizes were small, with 12 in the music group and nine in the control group. In a straight forward randomisation process with such small numbers, researchers run the risk that, from some points of view, the groups may not be comparable from the start. One way of avoiding this would have been to match subjects in pairs with regard to the most important variables, which in this case were clinical condition, age and heart rate. The randomisation would then have taken place within each matched pair. In this way, important baseline group differences could have been avoided. The results would have been easier to interpret had the groups had equal heart rates at baseline. But having said that, I do accept their conclusion that the music therapy was successful in lowering heart rates in the music therapy group. A puzzling aspect of this study is that such a large group of subjects and parents 16 of 40 families initially refused to participate, and a smaller problem was that one patient in the music group and two children in the control group were lost during the intervention and follow up periods. It would be interesting to know more details about why so many children and, or, parents did not want to participate in the music therapy. How was this raised with them? Did the staff display a negative attitude? Were the parents afraid that the music therapy would distract the staff0s attention from the medical treatment? Many questions remain. It is obvious that if the staff had displayed a detached or critical attitude about the study it may have dramatically reduced the participation rate. There is a growing body of literature on how heart rate variability provides a very sensitive indicator of autonomic balance and imbalance. In the Uggla et al. study, the authors, quite sensibly, used heart rate assessments that were part of the daily hospital routine. Because they were able to show significant results, despite the fact that they carried out such a simple assessment, it is likely that they would have been able to show more diverse and clearer effects if they had analysed heart rate variability by carrying out more extensive continuous recordings of the children's heart rates. Numerous RCTs have shown that listening to partly self selected music has stimulated parasympathetic activity and reduced sympathetic activity in adult patients facing stressful situations, such as before or waking up from surgery (2) having a caesarian section (3) and undergoing heart examinations such as myocardial scintigraphy (4) Listening to music could also affect endocrine function as well as heart rates in relation to medical interventions. A well known example is the RCT by Nilsson (5) which showed that subjects waking up from heart surgery displayed rising plasma oxytocin levels if they were allowed to listen to individually preselected music, whereas the opposite trend was observed in the comparison group, who woke up in silence. This is of particular importance because oxytocin relieves pain and anxiety. It is also relevant to this study, as oxytocin seems to play an important role in establishing social relationships. It has been shown that oxytocin receptor polymorphism, together with childhood social experiences, may contribute to the shaping of an adult's personality and brain structure and the neural correlates of mentalisation (6) This may serve as a further illustration of the potential importance of beneficial music experiences in helping to prevent PTSD after child trauma. It has been known for some time that slow rhythmic cues activated by eye movement desensitisation and