A new study shows that 41 percent of World Trade Center responders have GERD, twice that of the general population. GERD is a condition in which the lower esophageal sphincter doesn't function properly, allowing the stomach's contents to rise up into the esophagus, causing a burning sensation in the chest or throat.

The likelihood of having GERD was linked to mental health disorders, including post-traumatic stress disorder and depression. The more extensive the mental health issues, the more likely patients were to have GERD.

About 47 percent of those diagnosed with one mental health disorder also had GERD. About 64 percent of those who had two mental health disorders had GERD, while the rates of GERD rose to 70 percent and 72 percent for those who had three or four mental health disorders, respectively.

"These patients were exposed to a very complex trauma -- both psychological and physical," explained senior study author Dr. Benjamin Luft, a professor of medicine at State University of New York at Stony Brook and director of the Long Island World Trade Center Medical Monitoring and Treatment Program. "Unless you treat both of these things at the same time, they tend to exacerbate one another. It's the close interaction between mind and the body. The physical may impact you psychologically, and the psychological may impact you physically."

The study was scheduled to be presented Monday at the American College of Gastroenterology's annual meeting in San Diego.

Previous research has found that people with mental health issues tend to have more reflux disease or other gastrointestinal disturbances, said Dr. David A. Johnson, past president of the American College of Gastroenterology.

Research has shown that people who are stressed are more sensitive to discomfort of gastric acid in the esophagus. Studies in animals have shown that over time, stress can weaken the ability of the esophagus to withstand acid reflux. Other research has shown that people who don't sleep well are more bothered by acid reflux. The lack of sleep lowers the "sensory threshold" for pain.

"The study offers a very interesting and potentially very meaningful observation," Johnson said. "We do know that stress does have a relationship to GERD."

Researchers looked at records of 697 World Trade Center rescue, recovery and clean-up workers who were examined in 2005 and 2007 as part of the World Trade Center Medical Monitoring and Treatment program, which follows and treats several thousand Ground Zero workers, many of whom have suffered persistent mental health and respiratory ailments.

"It's not as readily apparent as to why they would have a gastrointestinal problem," Luft said. "Though as a result of being there, when you are exposed to a tremendous amount of dust, a lot of what goes into your mouth, nose and lungs is also swallowed and can enter the gastrointestinal tract as well."

One explanation for some of the respiratory ailments is that the dust at Ground Zero was extremely alkaline, or acidic, and may have damaged the lining of the mucosal membranes. Something similar could have happened to the membranes of the gastrointestinal tract, Luft said.

The study also found that smoking and obesity, known risk factors for GERD, did not increase the risk of GERD, while spending a lot of time at Ground Zero did.

In a second study to be presented at the meeting, researchers found that active-duty military who were exposed to infectious gastroenteritis were more likely to have "functional gastrointestinal disorders," including diarrhea, irritable bowel syndrome, functional constipation and dyspepsia (indigestion).

Infectious gastroenteritis is caused by viruses, bacteria or parasites.

Researchers used electronic medical records from the Defense Medical Surveillance System to identify 31,866 cases of gastrointestinal disease among active-duty personnel between 1999 and 2007. For some, the gastrointestinal disturbances were long-lasting. About 29 percent of active duty personnel were still being treated for gastrointestinal disorders two years after diagnosis.

More information

The National Digestive Diseases Information Clearinghouse has more on GERD.