8 For example, one study showed a clear relationship between impact torture and disorder (16), whilst another series of studies demonstrated that psychic truama alone produced disorder (31-32). This conflict is somewhat modified by a recent empirical study, which demonstrated that, although PTSD was a probable result of physical injury, it was more a consequence of the perception of injury than the actual severity of the injury itself (33). Thus, there remains a controversy over the dose-response theory, and the findings that attitudinal variables, or the subjective perception of trauma, seem to have a determining effect on the acquisition of post traumatic disorders requires further work. The study of the natural history of post traumatic disorders has also been subject to conflicting findings. Although there is little doubt that PTSD usually follows trauma, there has been some debate about the course of post traumatic disorders, especially over the notion that there is a delayed subtype. This argument has been partially resolved by a recent study from Israel, examining veterans who sought psychiatric help between 6 months and 5 years after the 1982 Lebanon War (34). This study suggested that 40% of cases represented delayed help-seeking, 33% was exacerbation of subclinical PTSD, 13% was reactivation of old PTSD, and 10% was delayed onset PTSD. The study of the long-term course of post traumatic disorders has been best documented in studies of Holocaust survivors, some of which demonstrate clinical disturbance in second and third-generation survivors (35). However, it is not clear that the disturbance measured in the grandchildren of concentration camp victims can be described as PTSD, and there is debate as to whether studies have unequivocally demonstrated inter-generational effects of post traumatic disorders (36). An additional complication lies in recent work indicating vicarious traumatisation in people who work with victims of trauma (37-38). Vicarious traumatisation lends at least theoretical support to the argument for intergenerational effects, but the concept of vicarious trauma still requires good empirical validation.