**7. Hypothesis for PTSD**

Hobfoll's conservation of resources (COR) model has been well supported by previous studies on natural disasters (Sumer, Karanci, Berument, & Gunes, 2005). According to

Risk Factors and Hypothesis for Posttraumatic

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Hobfoll's conservation of resources stress theory (Hobfoll, 1989; Chou et al., 2007), resource loss is an important determinant of individual stress and physical and mental health, including PTSD. Brewin et al. (2000) also found that the effect sizes of all risk factors were modest. Factors operating during or after the trauma (e.g., trauma severity, lack of social support, and additional life stress), however, had somewhat stronger effects than did pretrauma factors.

Consequently, multiple risk factors constitute a network that results in psychiatric illness. According to Hobfoll's conservation of resources theory, resource loss is an important determinant of individual stress and physical and mental health, including PTSD. Our hypothesis states that an individual reaches a sub-threshold of psychiatric illness and then develops the illness due to a decreasing availability of resources, an accumulation of risk factors, and/or a major stressful event. Furthermore, unresolved, sub-clinical psychiatric symptoms caused by a disaster or major life event may increase a survivor's sensitivity to future stresses. When faced with stress, frustration (e.g., life events), or traumatic events (e.g., brain damage or deprivation of internal or external resources) individuals, either suddenly or gradually, become more vulnerable to psychiatric impairment and diseases such as PTSD. An individual might reach a sub-threshold of PTSD and then develop the illness due to a decreased availability of resources, an accumulation of risk factors (personality traits, poor social interactions, etc.) or a major stressful event. Furthermore, unresolved, subclinical psychiatric symptoms caused by a disaster may increase a survivor's sensitivity to future stresses. Other factors that tend to increase an individual's vulnerability to psychiatric problems include brain damage, heredity, personality traits, life events, and social interactions.
