FRIDAY, Dec. 30 (HealthDay News) --Among 9/11 responders at the World Trade Center, the onset of respiratory problems and post-traumatic stress disorder (PTSD) seems to be strongly correlated, with indications that PTSD may lay the groundwork for the development of breathing issues, a new study finds.

"This study illustrates the integral relationship between mental health and physical diseases that WTC responders suffer," study co-author Dr. Benjamin Luft said in a Stony Brook University Medical Center news release.

"The analysis not only shows that relationship but also connects PTSD as a possible co-factor in responders' diseases," said Luft, medical director of Stony Brook's World Trade Center Health Program. The findings, he suggested, add ballast to the view that "the illnesses suffered by 9/11 responders are a compilation of problems that often present as an entire syndrome of diseases and conditions."

Luft and his colleagues report their findings in the current online edition of Psychological Medicine.

The researchers look at data from examinations conducted between 2002 and 2008 among more than 8,500 so-called "traditional responders" (mostly police officers) as well as more than 12,300 "nontraditional responders," such as maintenance and transportation workers.

The exams, which looked at WTC exposure, PTSD, respiratory symptoms and pulmonary function, took place at WTC Health Program Clinics that were part of a network set in place by the U.S. National Institute for Occupational Safety and Health (NIOSH).

The team found that PTSD was more common among nontraditional responders than among police (23 percent vs. about 6 percent). Respiratory illness was also somewhat more common among nontraditional responders than police (more than 28 percent versus about 23 percent). Pulmonary function, however, was comparable across groups.

In all, the researchers concluded that PTSD and respiratory difficulties were correlated, and that PTSD may have a "mediating role" in terms of respiratory risk.

"The results are indicative that PTSD appears to have a major and complex role in relation to respiratory illnesses in this patient population," study co-author Dr. Evelyn Bromet, an expert in psychiatric epidemiology and disaster research, said in the release. "Our findings mirror research results found in several veterans' populations and in patients in primary care settings around the world. Mental and physical health are integrally linked. It is not always obvious which one is the driver, but in the end, what matters is that both mental and physical health are recognized and treated with equal care and respect."

"The results are a first step in nailing down the exact relationship between PTSD and respiratory illness," Luft said. "We need to continue to study the relationship and its implications to help us to better treat responders who suffer from multiple mental and physical conditions."

More information

For more on the health impact of 9/11, visit the New York City government.