War is a known risk factor 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., 2005a,b) and provides baseline data with which to compare data from specific inquiries. Thus, after the Persian Gulf War, many methodological and scientific details were in place to support an assessment of the psychological 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 3, 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). Psychiatric disorders in the general population are not uncommon, and are often disabling and chronic (Kessler et al., 2005a,b). Diagnosable psychiatric disorders are found in about one-third of the US adult population at any given time, but their prevalence in military populations is lower, which may be largely as a result of the healthy-warrior effect. Psychiatric disorders can be grouped into several classes, such as mood disorders (that is, depression and bipolar disorder); anxiety disorders (that is, generalized anxiety disorder, obsessive-compulsive disorder, panic disorder, PTSD, and social phobia); disorders involving perceptions of physical symptoms and health, which are called somatoform disorders (for example, hypochondriasis and somatization disorder); and substance use disorders (for example, abuse of and dependence on drugs and alcohol). Specific criteria for diagnosing those mental health disorders are given in the Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) (American Psychiatric Association, 2000) or the ICD-10 Classification of Mental and Behavioural Disorders: Diagnostic Criteria for Research.
The specification of characteristics of mental diagnoses has made research on their incidence and prevalence possible, so that there are guidelines differentiating them from transient experiences of distress or sadness that do not signify the presence of mental disease. Major 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 accompanied by other symptoms such as 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. A major depressive episode is categorized as major depressive disorder (MDD) or, when it accompanies mania, as bipolar disorder. PTSD is a subtype of anxiety disorder.
PTSD is diagnosed on the basis of exposure to a traumatic event. After this exposure, the person experiences a specific constellation of symptoms such as severe distress on recollection of the event, avoidance of reminders of the situation, numbing of general responsiveness, and such signs of hyperarousal as irritability, sleep disturbance, or exaggerated startle reflexes. The