Inflammation is the body’s natural response to injury caused by invading pathogens, whether this be a sore throat due to bacteria from a cold, a wound that has become infected, or any other foreign pathogen that the body has to fight in order to get rid of it. Evidence is now growing that psychological traumas cause a similar response, although this type of inflammation can be destructive.

In a study published in Biological Psychiatry, researchers have examined the discrepancies of earlier research findings; inconsistent results in studies that showed an association between depression and inflammation, especially in those with early childhood adversity.

Drs. Gregory Miller and Steve Cole selected a large group of female teenagers for their longitudinal study who were healthy but had a high risk for developing depression. Miller and Cole assessed whether any participants were exposed to childhood adversity and followed them for 2 ½ years. During the follow-up, the team interviewed the participants and took blood samples to measure their C-reactive protein and interleukin-6 levels, which are two inflammatory markers.

The team discovered that depression in those who experienced early childhood adversity was accompanied by an inflammatory response and that they had high levels of interleukin-6 forecasted risk of depression six months later. They did not observe a link between depression and inflammation in participants who experienced no childhood adversity.

Dr. Miller explained:

“What’s important about this study is that it identifies a group of people who are prone to have depression and inflammation at the same time. That group of people experienced major stress in childhood, often related to poverty, having a parent with a severe illness, or lasting separation from family. As a result, these individuals may experience depressions that are especially difficult to treat.”

Another significant finding was that the inflammatory response in those who experienced childhood adversity was still evident after six months, even if their depression had abated, as it shows that the inflammation is chronic rather than acute.

Dr. Miller continued: “Because chronic inflammation is involved in other health problems, like diabetes and heart disease, it also means they have greater-than-average risk for these problems. They, along with their doctors, should keep an eye out for those problems.”

Dr. John Krystal, Editor of Biological Psychiatry commented:

“This study provides important additional support for the notion that inflammation is an important and often under-appreciated factor that compromises resilience after major life stresses. It provides evidence that these inflammatory states persist for long periods of time and have important functional correlates.”

The researchers suggest conducting additional studies, which include a broader spectrum of participants, in particular individuals with more severe and long-term depression. They conclude saying that findings like their study outcome may help doctors and clinicians in the future to better manage depression and medical illness, particularly in vulnerable patients.

Written by Petra Rattue