Given the great burden on psychological health of a physically debilitating disease, it is intuitive to believe that depression may be caused by the onset of physical illness. Or that individuals suffering from depression may be more likely to make lifestyle choices contributing to poorer health. However, a rapidly growing body of research is now suggesting that the bi-directional relationship between depression and illness may be much more complex. In fact, there is increasing evidence to suggest that specific immune responses, namely those involved in inflammation, may be both indicative of, and a risk factor for, depression.
A new perspective article published in Biology of Mood & Anxiety Disorders this week highlights the important link between depression and inflammation. Marsland et al. discuss recent literature on the topic, and present a detailed overview of the emerging field studying innate immune activation and mood disorders. The authors state that converging evidence supports reciprocal pathways linking inflammation and the disruption of mood, and that the relationship between the two is complex and may involve several physiological systems and processes.
This article has highlighted a dramatic need for further research in this field in order to better establish this complex relationship. The understanding of this biological mechanism may have several important clinical implications, not only to the treatment of mood disorders, but also in the administration of pro-inflammatory treatments and the effects of these drugs on phsychological well-being of patients.