Abstract:  It has been repeatedly documented that posttraumatic stress disorder (PTSD) is a common negative outcome in trauma-related research. Nevertheless, traumatized individuals also reported positive psychological changes in various aspects of life such as personal strength, relationship, and appreciation of life, that were collectively defined as posttraumatic growth (PTG). PTG has been described in many studies as evident in survivor reports following a wide range of traumatic events. Importantly, PTSD and PTG may co-exist in trauma survivors, leading to a heated discussion on the relation between PTSD and PTG. Nevertheless, the relation between PTSD and PTG still remains mixed. For example, some studies found a positive relation between them, indicating that individuals who had high PTSD reported increased PTG. In contrary, some found a negative relation, suggesting that PTG and PTSD could be conceptualized as the two ends of the same continuum. Some even failed to find a significant relation between them, arguing that PTSD and PTG were two independent constructs. The inconsistent findings inhibited our understanding in the relation between the two constructs, thus it is necessary to examine simultaneously the predictive factors of PTSD and PTG to elucidate their relation. Wherein, social support is considered as one of the most important predictors of posttraumatic reactions. Several theories were proposed to explain the role of social support in posttraumatic outcomes, and studies indicated that social support was a protector for PTSD while a facilitator for PTG. Nevertheless, few research has examined the linkages between social support, PTSD, and PTG from a longitudinal perspective. In order to advance the gaps and to assess the longitudinal relation between social support, PTSD, and PTG, we selected 303 children to fill out a social support questionnaire, a children posttraumatic stress scale, and a posttraumatic growth inventory at 6 months (T1), 12 months (T2), and 18 months (T3) after the Ya’an earthquake, respectively. Firstly, a cross-lagged model between PTSD and PTG was built, and the results indicated that PTG had no significant effect on PTSD from T1 to T3, but PTSD at T1 had a significant positive effect on PTG at T2. However, the effect of PTSD at T2 on PTG at T3 was non-significant. Then, we inserted social support into the above cross-lagged model, and found no change in the relation between PTSD and PTG. Additionally, social support at T1 had a direct and negative effect on PTSD at T2 but not vice-versa, and there were not any significant mutual effects between social support and PTG from T1 to T2. Moreover, PTSD at T2 had a significant negative effect on social support at T3 but not vice-versa, and there were significant positive and mutual effects between social support and PTG from T2 to T3.

Key words:  social support, PTSD, PTG, longitudinal study