Although Berkley is still working against the tide, her collaborative findings are beginning to influence clinical practice.

Karen Berkley

MacKenzie Professor, Program In Neuroscience

For more than 35 years Karen Berkley, a MacKenzie Professor in the Neuroscience Program, has been researching what the National Institutes of Health estimates is the costliest health problem in America—chronic pain.

Pain hurts, but chronic pain can kill.

"There are all kinds of data showing that unrelenting and unalleviated pain can be lethal," Berkley explains. "It can shorten life and clearly reduces the quality of life."

Although the experience of pain gets our prompt attention, we haven't approached cures with the same enthusiasm we show for many other conditions and diseases.

"Because it's not immediately fatal, like a heart attack, or as easy to track and measure, like cancer or coronary disease," Berkley says, "we're not likely to view chronic pain as an urgent medical problem."

And there's that thorny problem in treating chronic pain—we may not always be able to trace its cause.

Thus the diagnosis, "It's all in your head."

Which is exactly where pain is created, according to Berkley and her co-researchers in Japan, Italy, Sweden, Canada, Britain, and other universities and clinics in the U.S. Their work is bringing hope to hundreds of millions of people who suffer from chronic pain, but first they must alter current thinking.

Most researchers and clinicians have used the traditional "spinal cord gate theory" to explain the "Ouch!" response to pain and how we identify its location.

According to the theory, painful sensations, or signals, are delivered via nerve fibers to a quadrant in the spinal cord, which then—acting as a "gate"—opens and passes them on to the brain. The "pain message" conveys a specific site and duration to the brain.

What Berkley and fellow researchers believe, however, is that this explanation does not sufficiently take into account the complexity of the pain process.

"The beauty of the central nervous system," Berkley says, "is that it has this dynamic ability to make decisions about how and whether you experience pain based on who you are and where you are and what your past history is. Once you realize how many pieces of information are considered in the process, it changes how you study pain and how you treat it."

Usually our central nervous system creates experiences of pain as a way to promote our survival—the pain directs our attention to physical injuries or pathologies. But in some instances our central nervous system fools us and may decide to create unnecessary pain.

With so many different pieces of information entering the pain equation, the causes of a specific patient's chronic pain are likely to be unique, and frequently difficult to determine.

But because most pain research has focused on a specific body organ, such as the heart or colon, and healthcare specialists focus on a discrete system, such as the gastrointestinal or reproductive, we are not likely to consider the range of physiological and psychosocial interactions that create chronic pain.

"Our culture is used to associating pain with a specific site," Berkley says. "You claim your thumb hurts, so we check your thumb. If nothing evident is wrong, we say, 'You're crazy!' But you're not. With some chronic pain conditions, the central nervous system is just fooling us. So we need a more accurate, and dynamic, model to guide us."

Although Berkley is still working against the tide, her collaborative findings are beginning to influence clinical practice. Her work has been published in all major journals in the field. Because she is recognized as the expert on pain and gender differences, she is regularly invited to present at conferences and to serve on national and international committees.

But because of clinicians' lack of knowledge about chronic pain and beliefs that curing pain is not as important as curing high profile conditions and diseases, many patients don't receive available treatments and needlessly continue to live diminished lives.

Berkley's lifelong interest in the causes and cures of pain began with her interest in helping women who suffer from pelvic pain and menstrual cramps.

Many women in their reproductive years experience menstrual cramps, which, if severe, are sometimes associated with endometriosis. Diagnosed in 10-15% of women, endometriosis occurs when cells from the lining of the uterus escape and attach themselves to the outside of reproductive or other organs in the abdomen.

The condition can cause chronic pain or sub-fertility, or both.

Berkley's collaborative research, initially done on rats and then replicated on human tissue, has already identified an important component of the pathology.

She and her colleagues discovered that nerves develop in some of these abnormal growths and communicate directly with the brain.

One result?

"Women with endometriosis can experience other conditions that cause chronic pain, such as irritable bowel syndrome and migraine headaches."

Berkley's investigations of endometriosis and chronic pain dovetail perfectly.

"Endometriosis can serve as a prototype for studying and developing treatments for other kinds of pain, in men as well as women," Berkley says.

"And studying endometriosis allows me to follow all of the things that are meaningful and important in reaching my goal—reducing the amount of pain experienced in the world."