Why Are Some People More Sensitive To Pain Than Others?

The existence of people more sensitive to pain than others is common knowledge. We have all experienced that difference firsthand. Between different individuals, even of the same age or the same family, pain sensitivity can be highly variable. In the same way, the response of each organism to analgesics to treat pain is highly variable.

But what is pain? It is not totally easy to define. In the scientific community there is consensus in describing that pain is an unpleasant experience associated with real or potential harm.

As it is difficult to define, it is also difficult to treat and interpret it. For general practitioners, dealing with a pain situation is a difficult task. If we add to this the fact that some people are more sensitive to pain than others, then finding the right pain approach for each person becomes a thorny path.

It is estimated that more than half of the changes in pain sensitivity among humans can be attributed to genetic causes. Basically, it’s like saying that  the pain threshold we endure is in our DNA.

The pain threshold is the minimum amount of stimulus that can be endured until we feel the sensation that we identify as painful. That threshold is specific to each individual and is modified by some other factors, other than genetics, which we are now going to tell you about.

Pain sensitivity factors

As we anticipated, there are people more sensitive to pain than others for genetic reasons. But that genetics is affected continuously and with the passage of time. The factors that affect it are:

• Epigenetics: Some scientific studies have analyzed the pain sensitivity of identical twins in order to discover variability about genetics. Twins have the same DNA content, but they do not react the same to pain. Studies conclude that the social context and lifestyle modify the pain threshold.
• Desensitization: pain is a sensation perceived by receptors in the body called nociceptors. When the pain stimulus is chronic and prolonged over time, the nociceptors turn off. That is desensitization.

• Attention: It is also known that the attention given to pain can increase or decrease it. In exercises where the patient with pain is proposed to pay attention to other things, the pain tends to be perceived as milder.
• Sleep: there are people more sensitive to pain than others due to a bad rest. Scientific studies have also investigated this variable and found results that indicate that a bad sleep increases the activity of the brain in the areas that interpret pain. The worse the rest, the lower the pain threshold.

The least sensitive to pain

There are unusual genetic alterations where the result is insensitivity to pain. At the beginning of its discovery, this condition was called pure analgesia. With time and a greater understanding of genetics the diagnosis became more accurate. Today we have identity for alterations, such as pain insensitivity channelopathy or the mutation of the SCN11A gene.

Genetic mutations that alter pain sensitivity leading to analgesia usually consist of changes in nociceptors. Some other mutations affect the nerves that carry pain information to the brain.

Although it seems an advantage over people more sensitive to pain, in reality it is not. The absence of pain is a danger to the life of those who have this characteristic.

By not perceiving pain, the body loses the opportunity to respond to potential or actual dangers. Let’s imagine that driving a nail into the foot did not elicit a defense response and the nail produced an infection. In the same way, if a pain in an internal organ does not give the corresponding warning, the disease can progress to death, even.

People most sensitive to pain

At the other extreme, opposite to those insensitive to pain, we have people who are more sensitive to pain. They are the ones who interpret pain signals in an exaggerated way, making even the least bit unbearable. Also in this disorder there are genetic alterations with first and last names, such as primary erythemalgia. The affected gene is SCN9A, which will increase the nerve transmission of pain.

Anyway, beyond the genetic, there are people more sensitive to pain than others because of morphines and addictions. Those individuals who chronically use morphine derivatives as pain relievers, or who are addicted to heroin, may become more sensitive to pain over time.

This state of hyperalgesia is usually associated with another known as allodynia. Allodynia is the pain that is generated by situations that should not be painful, such as rubbing clothing, for example. Those who are more sensitive to pain usually feel pain from low stimuli.