Distinctiveness of prolonged grief disorder symptoms among survivors of the Great East Japan Earthquake and Tsunami.

Prolonged Grief Disorder (PGD) has been proposed for diagnostic classification as an independent psychiatric disorder. Previous research has investigated it in relation to other axis I disorders in order to determine whether it could be considered an independent nosological entity. The distinctiveness of this condition was apparent in cases of ordinary bereavement and in those following human-made disasters. However, this disorder may be expanded to include bereavement resulting from natural disasters. The present study aims to explore the differences between this disorder and posttraumatic stress disorder or major depressive disorder as experienced after the Great East Japan Earthquake and Tsunami. The subjects were 82 hospital workers. Each type of disorder was assessed by means of the Inventory of Complicated Grief, the Impact of Event Scale-Revised, and the Center for Epidemiological Studies Depression Scale. Exploratory factor analysis showed 3 dimensions, with PGD items independently clustering in the same dimension. Our findings support the uniqueness of PGD even in a post-natural disaster situation in a non-Western culture and warrant grief intervention for high-risk bereaved survivors.