Your lifestyle or environment could change how your body reacts to pain, according to new research from King’s College London. The new findings suggest that a person can activate or silence the genes that regulate pain sensitivity by altering factors in their environment — a discovery that changes previous notions that pain sensitivity is inflexible. The findings could lead to future treatments for controlling pain sensitivity at the level of our genes.

“The main implications to the general public are that pain sensitivity thresholds are potentially reversible, because the molecular mechanisms involved in pain sensitivity can change in response to external stimuli,” the study’s lead author, Dr. Jordana Bell, told Medical Daily. “Therefore, there is the potential to epigenetically regulate the genes that contribute to pain sensitivity, and to help develop effective pain relief treatment for patients suffering with chronic pain.”

The King’s College researchers tested and compared the DNA of 25 pairs of identical twins. Twin studies are useful for comparing how gene expression changes throughout a person’s lifetime because identical twins have identical genes at birth. Any changes in one twin’s DNA after birth would be a result of their individual experiences, whether that means a different environment or different lifestyle choices.

The researchers measured the twin’s sensitivity to pain by using a heat probe on their arm. When the heat became too painful, the participant would press a button. This gave the researchers an indication of each individual’s pain threshold. They then used DNA sequencing to examine the participant’s genes closer.

They found that some twins had huge variations in pain sensitivity — while one twin could tolerate intense pain, her sister could tolerate only a slight amount of pain. These variations seemed to correspond with chemical changes to the genes involved with pain sensitivity. For example, researchers found chemical tags on the gene TRPA1, which is being used in the development of painkillers.

These chemical tags, which researchers believe accumulate or dissolve on our DNA according to our external experiences, can "silence" or "activate" genes. Thus, if a gene involved with pain sensitivity is switched on or switched off, it affects how our body reacts to pain. Scientists call this an "epigenetic" change.

"Epigenetic switching is like a dimmer switch for gene expression," Tim Spector, a genetic epidemiology professor at King’s College said in a news release. “This landmark study shows how identical twins, when combined with the latest technology to look at millions of epigenetic signals, can be used to find the small chemical switches in our genes that make us all unique — and in this case respond to pain differently.”

The impact of different environments on gene expression is a relatively new field. Research in rats have shown that experiences like bullying or an unstimulating environment can leave epigenetic marks on rodent pups, which in turn affect that pup’s ability to handle stress.

Source: Bell J, Loomis A, Butcher L, et al. Differential methylation of the TRPA1 promoter in pain sensitivity. Nature Communciations. 2014.