Chronic Stress and Chronic Pain: Disability After Trauma and Global Trends

Introduction

The concept of pain has remained a topic of long debate since its emergence in ancient times. It is considered that the initial ideas about pain as a new entity were defined before 1800. Since then, different theories of pain have emerged and become central topics of debate. The existing theories of pain may be appropriate for the interpretation of some aspects of pain, but the history of pain problems is as long as that of human beings and the understanding of pain mechanisms is still far from very well defined and requires extensive research.

Modern theories sought a consensus definition for pain, and in 1975, the International Association for the Study of Pain defined the pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage”.(IASP,2011)

As a physical phenomenon, the emotional state of a person, as well as the context or situation associated with the pain also impacts the perception of the nociceptive or noxious event. For example, if a human experiences a painful event associated with any form of trauma a reoccurrence of similar physical pain will not only inflict physical trauma but also the emotional and mental trauma first associated with the painful event. That was a basic hypothesis primarily for defining the concept of posttraumatic stress disorder (PTSD). Research has shown that should a similar injury occur to two people, one person who associates large emotional consequence to the pain and the other person who does not, the person who associates a large consequence on the pain event will feel a more intense physical pain that the person who does not associate a large emotional consequence with the pain.

Acute pain with its unpleasant features plays an important role in protecting the body from potential injury and represents the characteristic evolutionarily created with the aim of survival. Painful sensation promotes a change in actions and behavior which could stop any further injury. On the other hand, chronic pain represents a pathologic condition which neither serves the defense of the organism nor is it harmless. By the International Association for the Study of Pain (IASP), the pain is considered to be chronic when it lasts or recurs for more than 3 to 6 months(Chadi,2017)

It is estimated that chronic pain affects about 20% of people worldwide3-6 and its treatment is considered to be a significant unmet therapeutic need.

The link between stress and chronic pain is a well known but this interaction still demands further investigation. It is possible that there are common central mechanisms that facilitate both stress and nociception. Investigation of this relationship that exist between stress and nociception could possibly lead us to the atypical approach in pain treatment (Ponsford,2008).

In this text the author aimed to give the overview of pain pathways and pain matrix, discuss the potential mechanisms that underlies transformation of pain from acute to chronic form and to point out the key site of action of the currently available medications. Special attention will be devoted to the reports of so far conducted investigations supporting and explaining potential synergistic mechanisms of stress and chronic pain, pointing out the direction for further investigations in search of more effective drugs or treatments for chronic pain.

Pain is a multidimensional sensation comprising sensory information, affective processing and a cognitive-evaluative component. Furthermore, pain leads to changes in autonomic body functions such as blood pressure, heart frequency. Pain perception can be substantially altered in different psychiatric disorders.