Interestingly, there is growing evidence that a similar process happens when a person experiences psychological trauma. Unfortunately, this type of inflammation can be destructive.
Previous studies have linked depression and inflammation, particularly in individuals who have experienced early childhood adversity, but overall, findings have been inconsistent. Researchers Gregory Miller and Steve Cole designed a longitudinal study in an effort to resolve these discrepancies, and their findings are now published in a study in Biological Psychiatry.
They recruited a large group of female adolescents who were healthy, but at high risk for experiencing depression. The volunteers were then followed for 2 ½ years, undergoing interviews and giving blood samples to measure their levels of C-reactive protein and interleukin-6, two types of inflammatory markers. Their exposure to childhood adversity was also assessed.
The researchers found that when individuals who suffered from early childhood adversity became depressed, their depression was accompanied by an inflammatory response. In addition, among subjects with previous adversity, high levels of interleukin-6 forecasted risk of depression six months later. In subjects without childhood adversity, there was no such coupling of depression and inflammation.
Dr. Miller commented on their findings: "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 important aspect to their findings is that the inflammatory response among the high-adversity individuals was still detectable six months later, even if their depression had abated, meaning that the inflammation is chronic rather than acute. "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 Dr. Miller.
"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.
Further research is necessary, to extend the findings beyond female adolescents and particularly in individuals with more severe, long-term depression. However, findings such as these may eventually help doctors and clinicians better manage depression and medical illness for particularly vulnerable patients.
###
The article is "Clustering of Depression and Inflammation in Adolescents Previously Exposed to Childhood Adversity" by Gregory E. Miller and Steve W. Cole (doi: 10.1016/j.biopsych.2012.02.034). The article appears in Biological Psychiatry, Volume 72, Issue 1 (July 1, 2012), published by Elsevier.
Notes for editors
Full text of the article is available to credentialed journalists upon request; contact Rhiannon Bugno at +1 214 648 0880 or Biol.Psych@utsouthwestern.edu. Journalists wishing to interview the authors may contact Dr. Gregory Miller at + 604 822 3269 or gemiller@psych.ubc.ca.
The authors' affiliations, and disclosures of financial and conflicts of interests are available in the article.
John H. Krystal, M.D., is Chairman of the Department of Psychiatry at the Yale University School of Medicine and a research psychiatrist at the VA Connecticut Healthcare System. His disclosures of financial and conflicts of interests are available here.
About Biological Psychiatry
Biological Psychiatry is the official journal of the Society of Biological Psychiatry, whose purpose is to promote excellence in scientific research and education in fields that investigate the nature, causes, mechanisms and treatments of disorders of thought, emotion, or behavior. In accord with this mission, this peer-reviewed, rapid-publication, international journal publishes both basic and clinical contributions from all disciplines and research areas relevant to the pathophysiology and treatment of major psychiatric disorders.
The journal publishes novel results of original research which represent an important new lead or significant impact on the field, particularly those addressing genetic and environmental risk factors, neural circuitry and neurochemistry, and important new therapeutic approaches. Reviews and commentaries that focus on topics of current research and interest are also encouraged.
Biological Psychiatry is one of the most selective and highly cited journals in the field of psychiatric neuroscience. It is ranked 4th out of 126 Psychiatry titles and 15th out of 237 Neurosciences titles in the Journal Citations Reports® published by Thomson Reuters. The 2010 Impact Factor score for Biological Psychiatry is 8.674.
About Elsevier
Elsevier is a world-leading provider of scientific, technical and medical information products and services. The company works in partnership with the global science and health communities to publish more than 2,000 journals, including The Lancet and Cell, and close to 20,000 book titles, including major reference works from Mosby and Saunders. Elsevier's online solutions include ScienceDirect, Scopus, Reaxys, MD Consult and Nursing Consult, which enhance the productivity of science and health professionals, and the SciVal suite and MEDai's Pinpoint Review, which help research and health care institutions deliver better outcomes more cost-effectively.
A global business headquartered in Amsterdam, Elsevier employs 7,000 people worldwide. The company is part of Reed Elsevier Group PLC, a world-leading publisher and information provider, which is jointly owned by Reed Elsevier PLC and Reed Elsevier NV. The ticker symbols are REN (Euronext Amsterdam), REL (London Stock Exchange), RUK and ENL (New York Stock Exchange).
Media contact
Rhiannon Bugno
Editorial Office, Biological Psychiatry
+1 214 648 0880
biol.psych@utsouthwestern.edu
END