Delayed post-traumatic stress and memory inflation of life-threatening events following a natural disaster: prospective study

Association between housing damage, present bias and delayed-onset post-traumatic stress symptoms among older adults 9 years after a natural disaster

BACKGROUND

Previous studies suggest that experience of natural disasters may heighten present bias. Research also suggests that impaired self-control (in particular, heightened present bias) could be linked to delayed-onset post-traumatic stress symptoms (PTSS) among survivors of natural disasters. We examined a hypothesis that the association between disaster experiences and delayed-onset PTSS is mediated through present bias among older survivors of the 2011 Japan earthquake and tsunami.

METHODS

The baseline survey was conducted for older adults who lived in a city located 80 km west of the epicentre 7 months before the disaster. Approximately 2.5 and 8.5 years after the disaster, we surveyed older survivors to assess the trajectory of PTSS (2230 participants). We implemented analyses by three analytical groups: (1) resilient versus delayed-onset, (2) resilient versus improved and (3) resilient versus persistent.

RESULTS

Logistic regression models showed that major housing damage was linked to raised present bias in all analytical groups (OR 2.47, 95% CI 1.04 to 5.87; OR 2.75, 95% CI 1.20 to 6.29; OR 2.65, 95% CI 1.15 to 6.10, respectively). The present bias, however, was significantly associated with only delayed-onset PTSS (OR 2.05, 95% CI 1.14 to 3.69). In the group of resilient versus delayed onset, housing destruction was also associated with delayed-onset PTSS (OR 2.44, 95% CI 1.11 to 5.37), and the association was attenuated by present bias (OR 2.36, 95% CI 1.07 to 5.18).

CONCLUSIONS

Present bias could mediate the association between housing damage and delayed-onset PTSS among older survivors of a natural disaster.

Natural disasters and mental health

Natural disasters are large-scale adverse events resulting from natural processes of the earth, often associated with death, trauma, and destruction of property. They threaten harm or death to a large group of people; cause disruption of services and social networks and a communal loss of resources; and involve identifiable mental and physical health outcomes, among those affected. While majority of individuals who experience a traumatic event due to natural disasters do not develop psychopathology, natural disasters can threaten our psychological well-being in many ways and they can result in both short and long-term psychological distress and thus create a significant burden of mental health conditions on individuals and the community affected by them. In this paper we provide a narrative review that focuses on the mental health effects of natural disasters. We discuss effective, evidence-based interventions that can help enhance the sense of safety, hope, and optimism, as well as serve to promote social connectedness for those who are impacted. We describe how these interventions, developed by keeping in mind the cultural context and the needs of the community, can be provided pre, peri and post-disaster period to improve the adverse mental health effects of the disaster.