A new study is adding to the growing body of evidence that smoking raises the risk of developing chronic pain.
In a study published online in the journal Human Brain Mapping, researchers at Northwestern University’s Feinberg School of Medicine found that smokers were three times more likely than nonsmokers to develop chronic back pain. The study also provided the first evidence that links chronic pain and smoking with a part of the brain associated with addiction and reward.
“Smoking affects the brain,” said Bogdan Petre, lead author of the study and a technical scientist at the Feinberg School of Medicine. “We found that it affects the way the brain responds to back pain and seems to make individuals less resilient to an episode of pain.”
The findings come from a yearlong study of 160 adults with new cases of back pain. At five different times during the course of the year, patients were given MRI brain scans and a questionnaire asking about the intensity of their back pain, smoking status and other health issues.
Researchers analyzed MRI activity between two parts of the brain (nucleus accumbens and medial prefrontal cortex), which are known to be involved in addictive behavior and motivated learning. The two brain regions “talk” to one another — and scientists discovered that the strength of that connection helps determine who will become a chronic pain patient.
“That circuit was very strong and active in the brains of smokers,” Petre said. “But we saw a dramatic drop in this circuit’s activity in smokers who — of their own will — quit smoking during the study, so when they stopped smoking, their vulnerably to chronic pain also decreased.”
Another significant finding is that pain medication and anti-inflammatory drugs did help patients manage their pain, but they didn’t change the activity of their brain circuitry. Patients who quit smoking did appear to reduce their chance of developing chronic back pain.
“This is the first evidence explicitly linking smoking, pain chronification, and brain addiction/motivation circuitry,” wrote Petre. “The results suggest that smoking cessation may be a viable option to diminish propensity to transition to chronic pain.”
Many other studies have also linked smoking with chronic pain.
In a 2012 study of more than 5,300 patients with spinal disorders and back pain, researchers at the University of Rochester found that patients who quit smoking or never smoked had less pain than those who continued to smoke.
Another study of over 10,000 people in Norway found that smokers and former smokers were more sensitive to pain than non-smokers. Smokers had the lowest tolerance to pain induced by cold water, while men and women who had never smoked had the highest pain tolerance.