**1.1 Depression and other anxiety disorders after motor vehicle accidents**

Major depression is also highly prevalent in individuals injured in a motor vehicle accident. The prevalence of major depression as determined by structured clinical interviews ranges from 10–19% at 0–3 months after the accident (O'Donnell et al., 2004; Matsuoka et al., 2008; Shalev et al., 1998) to 10–14% at 4–12 months after it (O'Donnell et al., 2004; Shalev et al., 1998). Although many symptoms overlap between posttraumatic stress disorder and major depression, the high comorbidity cannot be explained solely by this (Franklin & Zimmerman, 2001). Exposure to traumatic events has been shown to be linked not only to posttraumatic stress disorder, but also to depression (Duncan et al., 1996; Kilpatrick et al., 1987), and a recent study suggested that traumatic experiences during young adulthood and middle age are strong predictors of anxiety and depression among older adults (Dulin & Passmore, 2010). The treatment of psychiatric morbidity after injury is thus a matter of some urgency, especially for high-risk individuals. However, as it is difficult for emergency department staff to screen patients early after the event using a conventional questionnairebased tool, given the large number of motor vehicle accident survivors they handle (Nishi et al., 2006), it is desirable to find indicators for posttraumatic stress disorder which can be easily assessed in order to provide preventive strategies as early as possible.
