Why Are Some People More Sensitive To Pain Than Others?

The existence of people more sensitive to pain than others is well known. We all experience this difference firsthand. Among different individuals, even of the same age or family, pain sensitivity can be highly variable. Likewise, the response of each body to analgesics for pain management is highly variable.

But what exactly is pain? This is not easy to define. In the scientific community, there is a consensus in describing that the pain is an unpleasant experience associated with actual or potential harm.

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

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

The pain threshold is the minimum amount of stimulus that can be supported until we feel the sensation we identify as painful. This limit is specific to each individual and is modified by some other factors besides genetics.

Pain Sensitivity Factors

As we anticipated,  some people are more sensitive to pain than others for genetic reasons. However, these genetics are affected continuously and over time. The factors that affect them are:

• Epigenetics:  Some scientific studies have looked at pain sensitivity of identical twins to discover genetic variability. Twins have the same DNA but don’t react the same way 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’s desensitization.
• Attention: it is also known that the attention given to pain can increase or decrease it. In exercises where the patient with pain must pay attention to other things, the pain tends to be perceived as milder.
• Sleep: Some people are more sensitive to pain than others due to sleep deprivation. Scientific studies have also investigated this variable and found results that indicate that poor quality sleep increases brain activity in areas that interpret pain. The worse the rest, the lower the pain threshold.

The least sensitive to pain

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

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

While it may seem like an advantage over people who are more sensitive to pain, in reality it isn’t. The absence of pain is a danger to the life of those who have this characteristic.

By not realizing the pain, the body loses the opportunity to respond to potential or real dangers. Let’s imagine that driving a nail into the foot did not trigger a defense response and the nail caused an infection. Likewise, if pain in an internal organ fails to give the corresponding warning, the disease can progress to death.

People more sensitive to pain

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

In addition to the genetic component, some people are more sensitive to pain than others because of morphines and addictions. 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 often associated with another state known as allodynia. Allodynia is pain caused by situations that shouldn’t be painful, such as rubbing clothes, for example. Those who are more sensitive to pain often experience pain due to mild stimulation.