The famous saying, “what doesn’t kill you makes you stronger,” is so universally accepted that it is used in everyday conversations and popular songs.

But a new study finds the truism is actually false. According to researchers, past stressful experiences do not create resilience to future trauma.

In fact, the research suggests the opposite is true: Past stressors sensitize people to future traumas, increasing their chances of developing a mental health disorder.

“We hope that this research will spur interest in the face of the increasing number of natural disasters per year — a major consequence of climate change — such as the devastating earthquake that affected Chile and neighboring countries,” said Cristina Fernandez, a psychiatric epidemiologist at Brown University in Rhode Island and the study’s lead author. “The immediate global impacts of these catastrophic events on disease, death, and the economy are largely well recognized. Unfortunately, despite a high disease burden, mental illness has thus far not achieved commensurate visibility, policy attention, or funding.”

The study was a collaborative effort led by scientists at Brown University and the University of Concepción in central Chile.

The team examined 1,160 Chileans in 2003 and 2011 — before and after the sixth most powerful earthquake on record and subsequent tsunami struck their country in 2010.

When the study began in 2003, none of the participants had a history of post-traumatic stress disorder (PTSD) or major depressive disorder (MDD), according to the researchers. After the 2010 earthquake, 9.1% of the survivors were diagnosed with PTSD and 14.4% with MDD­.

The risk of developing these disorders was particularly high among individuals who experienced multiple pre-disaster stressors, such as a serious illness or injury, death of a loved one, divorce, unemployment or financial struggles, legal troubles, or loss of a valuable possession.

To be at increased risk for post-disaster PTSD, individuals had to have crossed a “severity threshold” of four or more pre-disaster stressors, the researchers explained.

MDD displayed a slightly different pattern: Every pre-disaster stressor, even a single stressor increased a person’s risk of developing post-disaster MDD, and each additional stressor further increased the risk, according to the study’s findings.

The researchers say that, overall, both findings suggest that the Chilean disaster survivors who had experienced multiple stressors and traumas were at a greater risk of developing a post-disaster mental health disorder compared to those who had experienced few or no prior stressors.

“Unfortunately, the same may well hold true with COVID-19,” said Stephen Buka, a professor of epidemiology at Brown’s School of Public Health and senior author of the paper. “We’re already witnessing how black and Latino Americans are experiencing higher rates of COVID-19 infections and fatalities. All evidence suggests that disadvantaged groups, who frequently have higher levels of prior life stresses, such as limited finances and job instability, will be most likely to suffer the most from serious mental health conditions following the pandemic.”

The team hopes its research will help other countries understand the importance of accessible mental health care.

“Personal and national mental health preparedness kits, such as the ones utilized in Chile, help mitigate the negative effects of disasters and can serve as a model for other countries,” said Benjamin Vicente, a principal investigator of the study from the University of Concepción. “Along with strict building codes, Chile has a national health care service, which includes integrated primary and mental health care centers, most of which have trained personnel to provide disaster coping strategies when needed.

The study was published in the British Journal of Psychiatry.

Source: Brown University