Why Some People Don’t Feel Pain ? Pain helps us navigate the world. Pain tells us when something is hot so we don’t burn ourselves. Pain tells us when we’re hurt so we don’t damage our bodies further. As annoying and uncomfortable as it is, it actually saves us. Pain protects us from harm. But not everyone is so…lucky. Some people are born with a genetic mutation that leaves them unable to feel pain. There’s actually a few mutations that lead to the condition called congenital insensitivity to pain. One mutation occurs in the PRDM12 gene. According to a study published in the journal Nature Genetics, this mutation leads to a malformation of nerve cells or neurons. Without functioning nerves, there’s nothing to detect a painful experience.
Another mutation that causes people to not feel pain occurs in the SCN9A gene. It causes disruptions not in the nerves, but in the way nerves talk to each other. Nerve cells communicate by sodium ions, as these ions get passed through channels from one nerve cell to the next, the pain signal travels from the injury site where it’s felt, up the spinal cord and into the brain. But a mutation in the SCN9A gene stops these channels, called Nav1.7 channels, from forming. Without these channels, pain messages can’t be sent.
So scientists being scientists, made mice with this mutation in a study published in the journal Nature Communications! And not surprisingly, the mice couldn’t feel pain. When their tails were exposed to extreme heat or cold, they showed no response. But surprisingly, even though they felt no pain, their body tried to soothe it. The mutated mice showed high levels of enkephalins, a type of opioid, the brain’s natural painkiller at the site of injury. So even though these mice couldn’t feel pain, their bodies recognized that pain and tried to make the mice feel better. So the researchers thought, hey, people who have less opioids in them tend to feel more pain, I wonder what would happen if people who don’t feel pain had less of these soothing opioids. So they gave a woman who cannot feel pain naloxone, a medication typically used to treat opioid drug overdose, and shot her with a heated laser.
The drug stopped her opioid production. And voila! She felt pain! Scientists said that the woman “quite enjoyed” the sensation. But uh, what good is it making people feel pain? Whether we like it or not, pain evolved to save us. Just take a look at our nerves that transmit pain. Nociceptors sensory receptors are nerves whose only job is to transmit pain from the point of injury to the brain. And they are fast, like pain can make it’s way through these cells in 5–30 milliseconds or about about one meter per second. It’s so quick and uncomfortable, because it gets you away from whatever is causing the pain super fast.
Some evolutionary biologists think that a lesser warning, more of a “red flag” wouldn’t be enough for us to react so suddenly and strongly against a potential danger. And we do know what happens when we don’t have these kind of alarm bells in our body. According to a study published in the Journal of Clinical Investigation, those who are born without the ability to feel pain often suffer from infections they don’t realize they have, self injury, and they have shorter lives! So the next time you stub your toe, don’t yell out an expletive, yell out “thank you!” it’s saving your life.