How Infant Pain Changes Sensitivity In Adults

Something I think is barbaric is circumcisions being done w/o anesthetic. I have heard a recording of a baby screaming during the procedure. Anybody who thinks the babies aren't in agony is plain stupid.

http://www.sciencedaily.com/releases/2009/09/090927130048.htm

ScienceDaily (Sep. 25, 2009) — Scientists at Georgia State University have uncovered the mechanisms of how pain in infancy alters how the brain processes pain in adulthood.

Research is now indicating that infants who spent time in the neonatal intensive care unit (NICU) show altered pain sensitivity in adolescence. These results have profound implications and highlight the need for pre-emptive and post-operative pain medicine for newborn infants.

The study, published online in the journal Frontiers in Behavioral Neuroscience, sheds light on how the mechanisms of pain are altered after infant injury in a region of the brain called the periaqueductal gray, which is involved in the perception of pain.

Using Sprague-Dawley rats, Jamie LaPrairie, a graduate student in associate professor Anne Murphy's laboratory, examined why the brief experience of pain at the time of birth permanently decreased pain sensitivity in adulthood.

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While it's beneficial to decrease pain sensitivity in some cases, it's not good to be completely resilient to pain.

"Pain is a warning sign that something is wrong," Murphy explained. "For example, if your hand is in water that's too hot, pain warns you to remove it before tissue damage occurs."

[Decreased sensitivity to pain is connected to increased levels of delinquent behaviour as adults.]

Interestingly, while there is an increase in endorphin and enkephalin proteins in adults, there is also a big decrease in the availability of mu and delta opioid receptors. These receptors are necessary in order for pain medications, such as morphine, to work. This means that it takes more pain-relieving medications in order to provide relief as there are fewer available receptors in the brain. Studies in humans are reporting the same phenomenon.
The number of invasive procedures an infant experienced in the NICU is negatively correlated with how responsive the child is to morphine later in life; the more painful procedures an infant experienced, the less effective morphine is in alleviating pain.

The study by LaPrairie and Murphy has major implications for the treatment of infants in neonatal intensive care. On average, a prematurely born infant in a neonatal intensive care unit will experience 14 to 21 invasive procedures a day, including heel lance, insertion of intravenous lines, and intubation. All of these procedures are quite painful and are routinely conducted without prior analgesics or anesthetics.

"It's imperative that pain be treated," Murphy said. "We once assumed that a newborn infant is insensitive to pain, and this is clearly not the case. Even at that period of time, the central nervous system is able to respond to pain, and our studies show that the experience of pain completely changes the wiring of the brain in adulthood."