WHAT IS PAIN?
Pain seems to have an obvious function. Pain provides constant feedback about the body enabling us to make adjustments to how we sit or sleep. Pain is often a warning sign that something is wrong and results in protective behavior such as avoiding moving in a particular way or lifting heavy objects. Pain also triggers help-seeking behavior and is a common reason for patients visiting their doctor. Pain also has psychological consequences
and can generate fear and anxiety. From an evolutionary perspective, therefore, pain is a sign that action is needed. It functions to generate change either in the form of seeking help or avoiding activity. However, pain is not that simple. Some pain seems to have no underlying cause and functions to hinder rather than to help a person carry on with their lives. Such pain has a strong psychological component. Researchers differentiate between acute pain and chronic pain. Acute pain is defined as pain which lasts for six months or less. It usually has a definable cause and is mostly treated with pain killers. A broken leg or a surgical wound is an example of acute pain. In contrast, chronic
pain lasts for longer than six months and can be either benign in that it varies in severity or progressive in that it gets gradually worse. Chronic low back pain is often described as chronic benign pain whereas illnesses such as rheumatoid arthritis result in chronic progressive pain. Most of the research described in this post is concerned with chronic pain which shows an important role for psychological factors. (PAIN THEORIES)
EARLY PAIN THEORIES – PAIN AS A SENSATION
Early models of pain described pain within a biomedical framework as an automatic response to an external factor. Descartes, perhaps the earliest writer on pain, regarded pain as a response to a painful stimulus. He described a direct pathway from the source of pain (e.g. a burnt finger) to an area of the brain which detected the painful sensation. Von Frey (1895) developed the specificity theory of pain, which again reflected this very simple stimulus-response model. He suggested that there were specific sensory receptors that transmit touch, warmth, and pain and that each receptor was sensitive to specific stimulation. This model was similar to that described by Descartes in that the link between the cause of pain and the brain was seen as direct and automatic. In a similar vein, Goldschneider (1920) developed a further model of pain called the pattern theory. He suggested that nerve impulse patterns determined the degree of pain and that messages from the damaged area were sent directly to the brain via these nerve impulses. Therefore these three models of pain describe pain in the following ways:
- Tissue damage causes the sensation of pain.
- Psychology is involved in these models of pain only as a consequence of pain (e.g. anxiety, fear, depression)
- Psychology has no causal influence.
- Pain is an automatic response to external stimuli. There is no place for interpretation or moderation. The pain sensation has a single cause.
- The pain was categorized into being either psychogenic pain or organic pain. Psychogenic pain was considered to be ‘all in the patient’s mind’ and was a label given to pain when no organic basis could be found. Organic pain was regarded as being ‘real pain’ and was the label given to pain when some clear injury could be seen.
INCLUDING PSYCHOLOGY IN THEORIES OF PAIN
The early simple models of pain had no role in psychology. However, psychology came to play an important part in understanding pain throughout the twentieth century. This was based on several observations:
First, it was observed that medical treatments for pain (e.g. drugs, surgery) were, in the main, only useful for treating acute pain (i.e. pain with a short duration). Such treatments were fairly ineffective for treating chronic pain (i.e. pain which lasts for a long time). This suggested that there must be something else involved in the pain sensation which was not included in the simple stimulus-response models.
It was also observed that individuals with the same degree of tissue damage differed in their reports of the painful sensation and/or painful responses. Beecher (1956) observed soldiers’ and civilians’ requests for pain relief in a hospital during the Second World War. He reported that although soldiers and civilians often showed the same degree of injury, 80 percent of the civilians requested medication, whereas only 25 percent of the soldiers did. He suggested that this reflected a role for the meaning of the injury in the experience of pain; for the soldiers, the injury had a positive meaning as it indicated that their war was over. This meaning mediated pain experience.
The third observation was phantom limb pain. The majority of amputees tend to feel pain in an absent limb. This pain can actually get worse after the amputation and continues even after complete healing. Sometimes the pain can feel as if it is spreading and is often described as a hand being clenched with the nails digging into the palm
(when the hand is missing) or the bottom of the foot being forced into the ankle (when the foot is missing). Phantom limb pain has no peripheral physical basis because the limb is obviously missing. In addition, not everybody feels phantom limb pain and those who do, do not experience it to the same extent. Further, even individuals who are born with missing limbs sometimes report phantom limb pain. (PAIN THEORIES)
These observations, therefore, suggest variation between individuals. Perhaps this variation indicates a role for psychology.