War is a known health risk for psychiatric conditions (Pizarro et al. 2006; Wessely 2005). The description of the extent and type of psychiatric affliction and its course has depended on the development of modern psychiatric diagnostic systems and epidemiologic methods. The development of a structured diagnostic system and diagnostic instruments has facilitated the diagnosis of behavioral disorders. Moreover, the prevalence of psychiatric disorders in epidemiologic samples drawn from the general population has become available (Kessler et al. 2005) and provides baseline data with which to compare data from specific inquiries. Thus, after the Persian Gulf War, many methodologic and scientific details were in place to support a sound assessment of the psychologic consequences of war. The Persian Gulf War was highly unusual in that the air war lasted 40 days and the ground war concluded in 5 days, so there was a limited theater and set of conditions amenable in many respects to scientific study. In fact, each of the large cohort studies of Gulf War veterans, described in Chapter 4, included items pertaining to mental health. Nested within them was analysis of mental health characteristics based on direct interview techniques or validated symptom scales.
Types of psychiatric ill health that could be associated with the Gulf War, particularly posttraumatic stress disorder (PTSD), were predicted on the basis of their descriptions from previous wars (O'Toole et al. 1996; Roy-Byrne et al. 2004). As background, psychiatric disorders in the general population are common, as well as disabling and chronic (Department of Health and Human Services 1999). Diagnosable psychiatric disorders are found in about 20% of the US population, but their prevalence in military populations is lower, largely as a result of the healthy-warrior effect. Psychiatric disorders can be grouped into several large classes, for example, mood disorders (that is, depression and bipolar disorder); anxiety disorders (that is, generalized anxiety disorder, obsessive-compulsive disorder, panic disorder, post-traumatic stress disorder, and social phobia); and substance use disorders (for example, abuse of drugs and/or alcohol).
The specification of characteristics of mental diagnoses has made research on their incidence and prevalence possible (Tasman et al. 2003). Depression, a type of mood disorder, is characterized by lifelong vulnerability to episodes of depressed mood and loss of interest and pleasure in daily activities. Some symptoms of clinical depression include sleeping too little or too much, reduced appetite and weight loss or increased appetite and weight gain, restlessness, irritability, difficulty concentrating, feeling guilty, hopeless or worthless, and thoughts of suicide or death. Depression is categorized as major depressive disorder (MDD) or, when it accompanies mania, as bipolar disorder. PTSD is a subtype of anxiety disorder; it occurs after exposure to a traumatic event and is diagnosed when a person manifests severe distress on recollection of the event, avoids the situation, and suffers symptoms of anxiety in daily life. Substance abuse is defined as a maladaptive pattern of substance use (there are many types of abused substances) that results in a failure to fulfill major social roles (such as work or family-care performance), that involves use of the substance despite physical hazards and in association with legal consequences, and that involves use despite deleterious social and interpersonal consequences.
The prevalence of those disorders in the general population is addressed in the US National Comorbidity Survey Replication, a nationally representative face-to-face household