rate. In two other studies of terrorist attacks (Curran et al., 1990; Weisaeth, 1989) PTSD rates higher than 40 percent are reported.
In addition to PTSD, many of the victims of a terrorist attack may suffer the death of family members, close friends, or work colleagues, which can lead to a complicated bereavement with its own elevated risk for depression, self medication, and substance abuse. Many studies indicate that depression is a common co-morbid condition with PTSD. Somatic sequelae to anxiety-related reactions have been reported in most studies of PTSD as well as following the Persian Gulf war. Carmeli, Liberman, and Mevorach (1994) reported that American veterans had a 38 percent prevalence rate of somatic symptoms, and Deahl et al. (1994) report a 50 percent prevalence of some ''psychological disturbance suggestive of PTSD" in British soldiers who handled and identified dead bodies of allied and enemy soldiers during the recent Gulf War. These reports suggest that chemical and biological terrorist attacks might cause high rates of PTSD and risks for physical illnesses and suicide, not only among rescue workers but especially among unprepared witnesses to grotesque sights and untrained "good samaritans" voluntarily joining rescue and first aid efforts.
The early identification of persons at risk for long-term psychological effects is complicated by the fact that PTSD symptoms within a few days of a traumatic event have been shown to have low predictive validity by themselves for later psychiatric outcome (Shalev, 1992). Recording of signs and symptoms in the immediate aftermath of the traumatic event should certainly be supplemented by systematic recording of objective and subjective features of the terrorist attack and its aftermath by all who were at the scene. The latter sort of information has often been critical to post hoc "prediction" of long-term dysfunction. PTSD is difficult to treat, and even when treated shortly after onset, as was the case with the Japanese sarin victims, 30 percent of the patients required ongoing therapeutic treatment (Nakano, 1995). In addition to the need for rapid identification of those who may require immediate or long-term psychiatric treatment, neuropsychological testing is important to evaluating effects on cognition, memory, and personality as well as any possible organic sequelae from the chemical agents used in terrorist attack.
At the acute stage of the aftermath of a biological or chemical terrorist attack, acute autonomic arousal and panic may result in both the victims and the emergency responders (Hazmat teams, police, fire, medical) incapacitating the assistance infrastructure. The severity of these anticipated