form may occur in the months following onset, most studies suggest that PTSD is more likely to manifest in the chronic form with effects that are enduring. Military-related PTSD may be more complex and more persistent than other subtypes of the disease.

PTSD can be diagnosed as early as one month after exposure to a traumatic event.2 The text revision of the fourth edition of the Diagnostic and Statistical Manual for Mental Disorders (DSM-IV-TR) specifies six criteria (Criterion A through Criterion F) that must be satisfied for a diagnosis; these are summarized in Table 3-1 (APA, 2000). PTSD is designated as either acute or chronic, depending on its duration. Acute PTSD is diagnosed between one to three months after a traumatic exposure and has symptoms that last fewer than three months. PTSD that is present beyond three months after the traumatic event is termed chronic. When PTSD does not appear until six months or more after the exposure to the traumatic event, it is termed delayed onset.

The symptoms of PTSD and the accompanying impaired function may be continuous or sporadic (Schnurr et al., 2003) and are often exacerbated by the presence of adversity or new life stressors. In a 20-year follow-up of Israeli combat casualties, among those who had PTSD one year after a combat stress reaction, 22.6 percent did not have PTSD at the end of the second year. However, among the group with PTSD at the end of the first year but not at the end of the second year, by the end of the third year 36.8 percent once again had PTSD (Solomon and Mikulinver, 2006). Stressors associated with age-related changes in familial structure as well as with job and health status can contribute to the exacerbation of symptoms and to a subsequent variation in the degree of impairment. Some data indicate that aging and its accompanying loss of cognitive executive function3 may increase the severity and frequency of PTSD symptoms in later life.

COMORBIDITY AND FUNCTIONAL IMPAIRMENT OR DISABILITY

As Posttraumatic Stress Disorder—Diagnosis and Assessment (IOM, 2006) notes, determining comorbidity is an essential component of assessing a patient with PTSD. In that report, comorbidity was defined as the presence of at least one disorder in addition to the presenting diagnosis; that is, in addition to the PTSD. The rates of comorbidity are high among

2

Acute stress disorder may be diagnosed in circumstances where “[t]he disturbance lasts for a minimum of 2 days and a maximum of 4 weeks and occurs within 4 weeks of the traumatic event” (DSM IV-TR; APA, 2000).

3

Executive function refers to processes involving the prefrontal cortex related to decision making, memory, and learning (Koso and Hansen, 2005; Shors, 2006).



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