Genes may be important in back, neck pain

NEW YORK (Reuters Health) - A person's genetic makeup may play an important role in the odds of suffering neck or back pain, new research suggests.

In a study of more than 15,000 twins ages 20 to 71, Danish researchers found that genetic susceptibility seemed to explain a large share of the risk of suffering back and neck aches.

Chronic and recurrent pain along the spine is one of the most common health complaints among adults, yet the precise cause remains unknown in most cases. And in general, researchers know little about the mechanisms underlying these aches and pains.

The latest findings on the topic, reported in the journal Arthritis & Rheumatism, add to evidence that while there are likely many contributors to back and neck pain, genes are an important one.

Recent research, for example, has found that genetic susceptibility may be the main factor in a person's likelihood of progressive degeneration in the spinal discs, which can be a cause of chronic back and neck pain.

That is in contrast to the traditional view that spinal disc degeneration is largely the product of aging and "wear and tear."

Understanding how genes and environment interact to create health problems is a "prerequisite" for preventing them, noted Dr. Jan Hartvigsen, a professor at the University of Southern Denmark and the lead researcher on the new study.

"So far, we have not -- in spite of millions of dollars spent -- been able to effectively prevent the most common forms of back and neck pain," Hartvigsen told Reuters Health in an email. "And today there are more chronic spine-pain sufferers than ever."

For their study, Hartvigsen and colleagues analyzed information from 7,664 twin pairs involved in the Danish Twin Registry -- 56 percent of whom were fraternal twins, and 44 percent identical.

Twin studies like these allow researchers to weed out the influences of genes and environment on people's disease risks, behaviors and traits.

Identical twins share the same genetic makeup, while fraternal twins share about half of their genes, making them no more genetically similar than non-twin siblings. So if, for example, genes were more important in the risk of a health problem than environmental exposures, identical twins would be more similar in their risk than fraternal twins would be.

When Hartvigsen and his colleagues looked at the twins' reports of back and neck pain, they found that genes appeared to explain a significant portion of the risk. Genetic susceptibility accounted for about 38 percent of the variation among individuals in the risk of lower back pain.

Genes were similarly important in middle back pain and neck pain, the study found.

The specific genes involved, and the mechanisms by which they make some people more vulnerable to back and neck pain, are unknown.

A surprising finding from this study, Hartvigsen said, was that the importance of genes in different types of pain -- including chronic, long-standing pain or more intermittent, recurrent pain -- was "remarkably similar."

"This is an indication," he said, "that (the) same genes are in play regardless of where the pain is and, to some extent, regardless of the duration."

SOURCE: Arthritis & Rheumatism, October 15, 2009.