For many years, it was widely and controversially believed that babies don’t really “feel” pain because their central nervous systems are perhaps not developed enough to be able to process and respond to painful things. But a new study contests this idea and finally offers some much needed insight into the nature of the pain experience in infants.
According to the results, infant brain activity triggered by pain closely resembles what we see in adults, suggesting that our experiences of pain are similar. These findings have important implications for pain management strategies in this population and call for a re-evaluation of current guidelines on how to alleviate pain in infants. The study has been published in eLife.
While it’s easy to tell when an adult is in pain (the “ouch!” usually gives it away), studying pain in infants isn’t quite so easy. Obviously, babies can’t tell you that something hurts, and it’s also difficult to discern between pain responses and reflex reactions. Furthermore, in order to study brain activity using techniques like magnetic resonance imaging (MRI), the participants need to lie extremely still, and babies have a habit of wriggling around a lot.
Consequently, our understanding of pain in infants has been lacking, and for many years it was assumed that they could not experience the unpleasant components of pain. Pain management strategies were therefore very different for adults and infants, and some guidelines still recommend that certain procedures, even some minor surgeries, be performed without painkillers.
But that could be about to change, thanks to a detailed new study that set out to compare brain activity in response to pain in babies and adults. For the investigation, scientists from Oxford University enrolled 10 healthy infants aged between one and six days old and 10 healthy adults between the ages of 23 and 36. Participants were then placed inside an MRI scanner and the babies were encouraged to sleep by their parents so that they remained still.
Both the adults and the infants were then exposed to a painful stimulus by means of a poke to the foot, which apparently feels like a pinprick. The greatest force applied to the infants was four times smaller than the highest used in adults to reduce the risk of tissue damage. Brain activity in response to the stimuli was then measured in both groups, but adults were also asked to verbally report their pain.
Of the 20 regions found to be active during pain in the adult participants, 18 also displayed activity in the infants. Furthermore, activity in response to the greatest applied force in the infants, which corresponded to a weak poke, mirrored the activity observed in adults when a force four times as great was used. Together, these findings not only indicate that infants and adults feel pain in similar ways, but also that infants have a significantly lower pain threshold.
“Thousands of babies across the UK undergo painful procedures every day but there are often no local pain management guidelines to help clinicians,” says lead researcher Rebeccah Slater. “We have to think that if we would provide pain relief for an older child undergoing a procedure then we should look at giving pain relief to an infant undergoing a similar procedure.”