Infant distress could lead to long-term pain

Local study asserts premature babies are more prone to depression, sensitivity

On the heels of a debunked myth that preemies aren’t developed enough to feel pain, local scientists are now studying the long-term impact of infant distress and how it may be linked to pain problems and mental health issues later in life.

As recently as the mid-1980s, the medical community believed preemies, and even some newborns, could not feel pain because their nervous systems weren’t yet completely developed. As a result, medical procedures, including major surgeries, were routinely performed on days-old babies without anesthesia.

And while it is now understood that babies can in fact feel pain, evidence is mounting that infection, trauma or stress experienced early in life can result in “molecular memory,” and lead to a variety of pain problems, from increased sensitivity to pain, lower pain thresholds, chronic pain, inflammatory diseases and depression.

Researcher Tuan Trang, assistant professor with the Faculty of Medicine at U of C, says infants “do experience pain and some procedures likely have profound impacts later on in life.”

Trang’s partner, Nikita Burke, PhD with the Faculty of Veterinary Medicine and the Hotchkiss Brain Institute, said much of the evidence that debunked the myth came from parents noticing that children who were premature had more issues around pain than their siblings.

“There is a critical window very early in life where pain appears to have long-lasting impact,” Burke says. “The vast changes going on at that time in the developing spinal cord and brain could explain why a noxious event then can have longterm effects.”

Scientists have been able to identify the immune cells, or “microglia,” that are instrumental in the development, repair and protection of the central nervous system.

But what is not yet known is how microglia react and respond to certain types of pain, an important part of the study in that communication between the immune and nervous systems is key in the development of chronic pain.

Researchers are isolating the microglia of animal models, examining the microglia memory or footprint at the molecular level.

“We look at altered structure and function, and whether certain genes are turned on or off in response to early life injury.”

The U of C research is particularly important in a world where 15 million babies are born prematurely each year, many who may need up to 10 painful procedures in their earliest days.

“With more and more babies exposed to pain early in life, the consequences can be quite profound,” Burke said.

According to the Canadian Premature Babies Foundation, one in every 12 babies born in Canada are premature, or one in every 10 worldwide.

As well, Alberta has the highest pre-term birth rate in all of Canada, with about 4,700 babies born prematurely in Alberta every year.

Burke added that as women in developed countries like the U.S. and Canada continue to put off having children to their later years, their risk of premature births will continue to increase.

Burke and Trang’s research is supported by the Alberta Innovates Postdoctoral Scholarship. Alberta Innovates is a provincial government-funded research group supporting work in health, energy, the environment and emerging technology sectors.

There is a critical window early in life where pain appears to have a long-lasting impact.