In the short term, pain keeps you alive. It's an essential warning signal, a command that is impossible to ignore. When you yank your finger off a hot stove—or sit down to get the pebble out of a shoe—pain is doing its job.
When the alert system goes awry, chronic pain may set in. It can arise mysteriously, persist for a long time and be very difficult to treat. Sometimes the cause is obvious. But pain's origin may be elusive—an inexplicable headache or a bad back that won't stop hurting. Finding surefire treatments has been difficult because the phenomenon is so complicated. Emotions, memory and expectations all influence chronic pain, and in turn are influenced by it.
Because persistent pain is so complex, a cure for it is not yet on the horizon. But while we wait, a new understanding of why we hurt offers opportunities to use our minds to soften the sting.
Heartburn and Heartbreak: It's All Connected
When you are in agony, the last thing you want to be told is that it's all in your head. But in truth, pain does come from your head, in a group of interconnected brain regions known as the pain matrix. Some regions are involved in delivering descriptive information about the feeling—where it is, how intense it is, whether it's a dull soreness or a sharp prick. Another part, the anterior cingulate cortex, registers the unpleasant "hurt" of pain. It connects the physical sensation of pain to feelings of distress.
Interestingly, the anterior cingulate cortex doesn't distinguish between psychic and bodily injury—it lights up whether you've been hit in the stomach or hit by rejection—and is sensitive to your state of mind. "It is particularly dampened by good mood and enhanced by a bad mood," says M. Catherine Bushnell, director of the McGill University Centre for Research on Pain. "Change the mood, and it changes the pain." One of Bushnell's patients had brain damage that destroyed sensory regions but left his cingulate intact. When he was pinched and prodded with his eyes closed, he didn't know if it was his left arm or toe that hurt, says Bushnell. "All he knew was that he didn't like it."
The same area apparently influences empathy as well. Researchers in England studied happy couples' responses to each other's twinges. When one partner watched the other endure pain, his or her cingulate responded. The higher the person scored on a test of empathy, the stronger the response. In addition, the more empathetic you are, the more vividly you anticipate your own pain: In a sense, you're empathizing with your future self.
Though people with chronic pain are often presumed to be neurotic, the idea of a "pain-prone personality" is not well supported by research. "The evidence is quite mixed," says Frank Keefe of Duke University Medical Center's Pain Prevention and Treatment Research program. "If you treat the pain, some of the personality factors that supposedly caused it actually improve." In other words, pain might make you grumpy or high strung, rather than grumpiness predisposing you to pain.
On the other hand, "catastrophizing"—focusing on the worst possible scenario—amplifies the hurt. People who catastrophize believe that the ache is unbearable, and that they are beyond help. It's not just anxiety: Thinking this way can actually increase painful sensations. Brain scans show that catastrophizers have heightened activity throughout the pain matrix. While personality traits—or experiences like trauma—can predispose people to catastrophize, it is a habit of mind rather than an ingrained characteristic. As a result, it can be changed through behavioral techniques that demonstrate to sufferers that they have some control over their discomfort. Says Keefe, "If you drive down catastrophizing, it's like giving a drug—you can actually see a change in the pain."
The Bad News: You Learn to Suffer
Just like muscles, brain circuits grow stronger when you use them—great when you're learning to play the piano, but terrible in the case of a constantly aching joint. "Pain pathways are like a trail in the forest," says Gavril Pasternak, director of molecular neuropharmacology at Memorial Sloan-Kettering Cancer Center in New York City, "If you have a path that is already worn, it is easier to follow and it becomes strengthened."
Through the same neurological process that makes you gradually get better at hitting a racquetball or driving a stick shift, your brain "gets better" at perceiving the pain—you become more sensitive and more likely to register a poke or a twinge as painful. Eventually, people with chronic pain disorders such as fibromyalgia (which affects joints and soft tissues) can find even mild sensations agonizing. Imaging studies reveal what's going on: A gentle touch causes brain areas that process pain to react. Similar findings have been reported in people with unexplained chronic lower back pain. It's not a conscious process—it's one way the brain naturally responds to repeated stimulation.
Many people who have lost a limb cope with a similar problem. They feel as though their missing body part still hurts. That phantom limb pain often echoes the injury that led to the amputation. Similarly, torture survivors may feel a persistent ache in the regions of the body that were abused. The pain has been seared into the brain circuitry, even though the injury has long since healed.
The Good News: You Can Learn Not to Feel the Burn
Thankfully, like other things you've learned, you can sometimes "forget" chronic pain. Pathological forms of learning, also involved in problems like addictions, seem to be especially hard to undo, but there's some evidence they can be halted or even reversed.
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