Epidemiologic studies have linked exposure to severe environmental stress, such as natural disasters and combat operations, to the onset of specific psychiatric disorders. Some research also suggests that these exposures may be associated with the onset of chronic diseases as well. However, these chronic disease outcome studies often have been obscured by bias and confounding.
The medical histories of 1399 male Vietnam veterans approximately 20 years after combat exposure (mean years = 17) were analyzed by lifetime posttraumatic stress disorder (PTSD) status (lifetime PTSD = 332 cases). These men were included in a national, random in-person study of United States Army veterans of the Vietnam War (study completion rate = 65%).
After controlling for preservice, in-service, and postservice factors (including intelligence, race, region of birth, enlistment status, volunteer status, Army marital status, Army medical profile, hypochondriasis, age, smoking history, substance abuse, education, and income), associations were found for reported circulatory [odds ratio (OR) = 1.62, p = .007], digestive (OR = 1.47, p = .036), musculoskeletal (OR = 1.78, p = .008), endocrine-nutritional-metabolic (OR = 1.58, p = .10), nervous system (OR = 2.47, p < .001), respiratory (OR = 1.54, p = .042), and nonsexually transmitted infectious diseases (OR = 2.14, p < .004) after military service.
Although this study has some limitations, it suggests that there is a direct link between severe stress exposures and a broad spectrum of human diseases. In the future, medical researchers and clinicians should focus more on the medical consequences of exposure to severe environmental stress and seek to better integrate psychobiologic models of disease pathogenesis.