Natural Disaster Exposure Adds Up on Mental Health Toll Over Time

Natural disasters accumulate post traumatic stress symptoms (PTSS) and functional impairment in individuals whether impacted directly, indirectly due to concern for friends or family, or even through media coverage, a survey-based analysis of two hurricanes found.

The strongest association to PTSS after Hurricane Irma in 2017 was from direct loss or injury (unstandardized b coefficient 0.35, P<0.001), Dana Rose Garfin, PhD, of the Sue & Bill Gross School of Nursing at the University of California Irvine, and her co-authors reported in JAMA Network Open.

But previous hurricane-related loss or injury, previous mental health ailments, not evacuating from an evacuation zone, and even hurricane-related media exposure were also all associated with a linear increase in PTSS after Hurricane Irma (b 0.03-0.18).

“It may seem small, but this is on average out of over 1,600 people,” Garfin noted, so some individuals had more substantial impacts.

Hurricane Irma-related PTSS was positively associated with PTSS and functional impairment after Hurricane Michael 1 year later, independent of demographics, socioeconomics, life events, physical loss owing to hurricanes, and pre-hurricane mental health.

In short, individuals who experienced repeated direct or indirect exposure to hurricanes had increased mental health symptoms, which suggested that they were more susceptible to psychological symptoms with each disaster, the group concluded.

“As we are exposed to escalating weather-related disasters — a lot of them are going to be made more severe and frequent due to climate change — we may expect a mental health crisis, because our study shows that over time, people do not habituate to the effects of these disasters. They have additive effects,” Garfin told MedPage Today. “The more people experienced these events the worse their mental health is.”

Participants in the study experienced global distress (a combination of depression, anxiety, and somatization), as well as ongoing fear and worry. Garfin noted that those symptoms increased over time and correlated with functional impairment, suggesting that those experiences affected their daily social lives.

In a commentary accompanying the paper, Masaki Nakabayashi, PhD, suggested that these findings could be broadly applied to many other kinds of disasters, such as cyclones in Southeast Asia and typhoons in East Asia, as well as global health pandemics like COVID-19. He noted that these findings could be the basis for more comprehensive analysis of the effect of these disasters on populations that, in turn, could lead to “more practical policy implications to mitigate damage.”

Nakabayashi also added that the research could inform studies into whether “the recurrent waves of COVID-19 and the increase in the number of infections may similarly be associated with adverse mental health outcomes.”

Garfin’s group surveyed 2,873 Florida residents before Hurricane Irma made landfall in South Florida between Sept. 8-11, 2017. They received 1,637 responses (57.0%) from that first wave of surveys. They sent follow-up surveys to those respondents a month later and had 90% retention from wave 1. Another follow-up survey was sent between Oct. 22-Nov. 6, 2018, in the aftermath of Hurricane Michael, which struck the Florida Panhandle. They received 1,113 responses to that survey (75.3% retention from wave 2; 66.7% retention from wave 1).

The surveys took 15 to 20 minutes to complete with answers on a 5-point scale, depending on the targeted information.

Among the initial 1,637 respondents in wave 1, mean age was 51 years, and 55% were women. In total, 83.6% of participants reported no prior mental health diagnoses, 11.4% reported having a depression or anxiety diagnosis, and 5% reported both diagnoses.

Respondents reported exposure to Hurricane Irma-related media for an average of 7.9 hours, including 3.8 hours of television, radio, and print news; 2.2 hours of online news; and 1.9 hours of social media.

The survey was one Garfin and a colleague had long awaited an opportunity to administer. So when Hurricane Irma was preparing to make landfall in South Florida, they quickly secured grant funding and ethical approval in order to execute the first wave of the survey in just a few days time.

In light of the quick turnaround, Garfin said the team was surprised at the response rate from the study participants. She noted that a much lower response rate might have been expected, given the circumstances for the participants.

“I actually think it speaks to the fact that people are interested in taking surveys and responding to things that are important to them,” Garfin said. “I think that’s why we were able to retain a strong follow-up as well, because this is something that’s important to people. They wanted to share their experiences with us.”