Variability, Pain Genes and the Pain Practitioner

Abstract

Most practitioners are aware that there is considerable variability in the pain experience reported by different people. Variability is a key characteristic of acute pain in response to noxious stimuli; we each have our own ‘pain threshold’. It is also characteristic of chronic pain associated with injury or disease, even when the underlying tissue disorder is essentially identical. A notable example is phantom limb pain in amputees. Some amputees report essentially no phantom limb pain at all, while in others, severe disabling pain lasts a lifetime. Reamputation usually fails to relieve phantom limb pain, suggesting that factors associated with the patient are the underlying cause, not details of the surgery [1]. Individual differences in pain response are traditionally attributed to psychosocial and cultural factors, personality, personal inclination and upbringing (i.e., environmental factors). New evidence, however, indicates that genetic factors contribute as much to individual pain response as environment and upbringing [2]. Why should a pain professional be interested to know that pain experience is affected by genes? There are basically four reasons. Stigma First, people who report having severe pain in the absence of easily observed signs of injury or disease are often stigmatized as weak in character, or malingerers. They may even be suspected of trying to cheat ‘the system’; of exaggerating their complaints to garner sympathy from family and friends, and undeserved benefits from employers, insurance companies and the government. Such stigmatization is usually unfair, it undermines self image and is likely to add considerably to the patient’s distress and suffering (and to that of his/her loved ones). For the pain professional, stigma is almost always harmful to efforts at reducing pain. Knowledge, of the therapist and the patient, that one person may have much more pain than another, not because of a character flaw, but for genetic reasons, is sure to provide comfort. If it’s the luck of the genetic draw, it’s not your fault! It should be noted that this benefit does not require actual knowledge of the pain genes involved or even knowledge that, in the specific patient at hand, excessive pain is indeed due to bad luck in the genetic draw. The simple knowledge that science has shown that genes count can reassure your patient. It can also