Pain sensitivity

Pain sensitivityGenetic testing and pain sensitivity

According to the definition by the International Association for the Study of Pain, pain is an unpleasant sensory and emotional experience, associated with actual or potential tissue damage. On the other hand, it is not necessary that tissue damage is primary the cause of pain, and that pain always accompanies a certain damage in the tissue.

Perception of pain is the result of agitation of peripheral or visceral nociceptors. These are special pain-nerve endings that can trigger an action potential according to a sufficient stimulus (mechanical or thermal). The impulse is carried through nerves into the central nerve system. Pain differs depending on the stimulated fibres (thinner or thicker) and it can be sharp or blunt. Sharp pain differs from the blunt pain. A sharp pain happens when a person clearly knows where it hurts, while with the blunt pain it is harder to determine the area of the pain.

The exact mechanisms of pain perception are not well understood. However it is known that mutations in some genes can affect the intensity of pain. Scientists discovered great difference in pain perception between some individuals. Additional test showed the difference is due to specific mutation in SCN9A gene. SCN9A gene is important for the formation of sodium channels, which are important factors of nociception (nervous signalling as response to different potential harmful environment factors). Therefore, through the transport of sodium, SCN9A gene should regulate pain perception.

One well known fact is that women are more pain sensitive that men. That was proven through special brain imaging. Studies show that differences are due to sex hormones. For example, trials showed that pain perception changes during phases of menstrual cycle.