Pain may be relative, but could pain tolerance or the perception of pain be directly related to genes? A recent study has found that 4 specific genes may be good predictors of how different people sense pain.
The genes in the study conducted by the American Academy of Neurology (AAN) were COMT, DRD2, DRD1, and OPRK1. Researchers looked for these 4 gene variants in 2,721 people diagnosed with chronic pain. Variants of genes are also called alleles, and these alleles determine everything from eye color to whether or not you can curl your tongue. The presence or absence of certain alleles like those above can indicate a lower tolerance for pain.
The study participants were taking opioid medications. Participants rated their pain levels on a scale from 0 to 10, with 10 being the highest level of pain. The percentage of levels broke down as follows:
- 9%: Low pain levels with a score of 1-3
- 46%: Moderate pain levels with a score of 4-6
- 45%: High pain levels with a score of 7-10
The findings were remarkable:
- In the low pain group, the DRD1 gene variant was more prevalent than the high pain group by 33%
- The COMT and OPRK variants were found in the high pain group 25% and 19% more often
- The DRD2 variant was 25% more common in the high pain perception groups when compared to the moderate pain perception
Sometimes physicians, friends, and family members quickly dismiss pain as being all in a patient’s head, but this research shows that pain tolerance is controlled to some extent by genes. Study author Tobore Onojjighofia, MD, MPH, with Proove Biosciences and a member of the American Academy of Neurology points out that:
“Chronic pain can affect every other part of life. Finding genes that may play a role in pain perception could provide a target for developing new therapies and help physicians better understand their patients’ perceptions of pain.”
Previous studies have been conducted on the allele COMT. Participants with 2 copies of the “val” form of this gene have higher pain tolerance, while those with 2 copies of the “met” form are more likely to have a lower pain tolerance. The theory is that the “val” copies helped participants break down dopamine and cope better with pain, increasing tolerance. The “met” copies weaken the body’s pain tolerance.
Dr. Jon-Kar Zubieta from the University of Michigan in Ann Arbor was the lead author in the study and had this to say of the findings:
“Participants who had two copies of the val form withstood quite a bit more pain than others in the study, while at the same time reporting that they felt less pain and fewer pain-related negative emotions. Our findings and those of other groups underlie the need to think about pain as the result of complex interfaces between injury and our own capacity to regulate its severity and significance.”
This knowledge may increase capacity for pain tolerance in patients with chronic pain, but what else helps determine pain tolerance?
Psychological tendencies may determine levels of pain tolerance. According to the American Pain Foundation, more than 76 million people report feeling pain that lasts longer than 24 hours. This can be acute pain, the most common being musculoskeletal pain from sports injuries, or chronic pain, most often somewhere in the back.
25% of adults from 20 to 44, 30% of adults from 45 to 64, and 21% of adults 65 and older report pain lasting longer than 24 hours. More women than men report pain, but it is not clear if women have a higher or lower pain tolerance.
Some surprising factors that can influence pain tolerance include:
- Hair color: Redheads have a gene variant (MC1R) that not only indicates hair color but also sensitivity to pain
- Handedness: A 2009 study published in Neuroscience Letters found that dominant hands have higher pain tolerance than non-dominant hands
- Psychology: The ability to get better at handling pain through meditation, biofeedback, and other alternative techniques may help increase pain tolerance
In addition to genetic and psychological influences on pain tolerance, there is a cultural element to pain tolerance.
A review of literature on cross-cultural pain tolerance found that although there were few differences in pain tolerance among Caucasian, African-American, Asian, and Hispanic groups, the expression of pain differed among Eastern and Western cultures. Eastern cultures were more likely to turn inward and not express pain verbally or demonstratively, while Western cultures were highly verbal and interested in eliminating pain as quickly as possible.
There were also differences in levels of diagnoses of chronic pain conditions such as fibromyalgia, with Caucasian groups being diagnosed at much higher rates than their African-American and Hispanic counterparts. These results indicate that as more research is done on pain tolerance, a certain level of cultural sensitivity may be necessary in order to obtain accurate results.
Pain tolerance is highly complex and involves the interplay of genetics, psychology, and cultural factors.
Continued study of all of these elements can help doctors better understand ways to help treat patients with chronic pain. Knowing that certain genes are in control may be reassuring to patients who have felt in the past that maybe they were imagining or exaggerating their pain.
How would you rate your own level of pain tolerance?
Image by Nigel Brown via Flickr