Physical inflammation is the body’s natural and protective response to injury, such as a sore throat or a knot on the head when a child takes a fall.
However, there is growing evidence that a similar process happens when a person experiences psychological trauma, and this type of inflammation can lead to mental and emotional problems. Earlier studies have linked depression and inflammation, especially in those who have experienced early childhood suffering, but overall, findings have been inconsistent.
In an effort to sort out these discrepancies, researchers Drs. Gregory Miller and Steve Cole conducted a longitudinal study in which they recruited a large group of female adolescents who were healthy, but at high risk for developing depression.
The researchers followed the participants for 2 ½ years, giving interviews and taking blood samples to measure their levels of C-reactive protein and interleukin-6, two types of inflammatory markers. The subjects’ exposure to childhood adversity was also evaluated.
The findings reveal that when an individual who suffered from early childhood adversity became depressed, the depression was accompanied by an inflammatory response. Furthermore, among subjects with earlier suffering, high levels of interleukin-6 forecast the risk of depression six months later.
In subjects who had no childhood adversity, there was no tie between depression and inflammation.
“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,” said Miller.
Another vital aspect in their research is that the inflammatory reaction among the high-adversity individuals was still detectable six months later, even if their depression had lessened, meaning that the inflammation is chronic.
“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,” added Miller.
Further research is needed to expand the findings beyond young females and particularly in people with more severe, long-term depression. This type of research may eventually help doctors and clinicians better manage depression for especially vulnerable patients.
“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,” said Dr. John Krystal, editor of Biological Psychiatry, where the study was published.
Source: Biological Psychiatry